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14,800 | Heart failure, atrial fibrillation and neuromuscular disorders influence mortality in left ventricular hypertrabeculation/noncompaction. | The prognosis of patients with left ventricular hypertrabeculation/noncompaction (LVHT) is controversial. The aim of the study was to assess parameters influencing mortality and to compare the mortality of LVHT patients with that of the general population of Austria.</AbstractText>Included were patients with LVHT diagnosed echocardiographically between June 1995 and February 2011. They underwent a baseline cardiologic examination and were invited for neurological investigation. Between January and February 2011, their survival status was assessed. LVHT was diagnosed in 162 patients (46 females, aged 53 ± 16 years) with a prevalence of 0.31%/year. One hundred and sixteen patients (72%) underwent a neurological investigation which revealed specific neuromuscular disorders (NMD) in 25 and NMD of unknown etiology in 74 patients, and 17 subjects were assessed as normal. During the follow-up of 67 months, mortality was 4.8%/year and the standardized mortality ratio was 6.27, compared with the Austrian population. By multivariate analysis, predictors of mortality were heart failure (hazard ratio 3.91, 4.48 and 5.37 for the New York Heart Association class II, III and IV, respectively), atrial fibrillation (hazard ratio 3.26) and NMD (hazard ratio 1.86).</AbstractText>Prognostic predictors in LVHT are heart failure, atrial fibrillation and NMD. Whether optimal therapy of heart failure and atrial fibrillation will improve the prognosis of LVHT patients has to be addressed by further studies.</AbstractText>Copyright © 2011 S. Karger AG, Basel.</CopyrightInformation> |
14,801 | Prognostic factors of atrial fibrillation following elective coronary artery bypass grafting: the impact of quantified intraoperative myocardial ischemia. | Atrial fibrillation (AF) occurs in 28-33% of the patients undergoing coronary artery revascularization (CABG). This study focuses on both pre- and peri-operative factors that may affect the occurrence of AF. The aim is to identify those patients at higher risk to develop AF after CABG.</AbstractText>Two patient cohorts undergoing CABG were retrospectively studied. The first group (group A) consisted of 157 patients presenting AF after elective CABG. The second group (group B) consisted of 191 patients without AF postoperatively.</AbstractText>Preoperative factors presenting significant correlation with the incidence of post-operative AF included: 1) age > 65 years (p = 0.029), 2) history of AF (p = 0.022), 3) chronic obstructive pulmonary disease (p = 0.008), 4) left ventricular dysfunction with ejection fraction < 40% (p = 0.015) and 5) proximal lesion of the right coronary artery (p = 0.023). The intraoperative factors that appeared to have significant correlation with the occurrence of postoperative AF were: 1) CPB-time > 120 minutes (p = 0.011), 2) myocardial ischemia index < 0.27 ml.m2/Kg.min (p = 0.011), 3) total positive fluid-balance during ICU-stay (p < 0.001), 4) FiO2/PO2 > 0, 4 after extubation and during the ICU-stay (p = 0.021), 5) inotropic support with doses 15-30 μg/Kg/min (p = 0.016), 6) long ICU-stay recovery for any reason (p < 0.001) and perioperative myocardial infarction (p < 0.001).</AbstractText>Our results suggest that the incidence of post-CABG atrial fibrillation can be predicted by specific preoperative and intraoperative measures. The intraoperative myocardial ischemia can be sufficiently quantified by the myocardial ischemia index. For those patients at risk we would suggest an early postoperative precautionary anti-arrhythmic treatment.</AbstractText> |
14,802 | Fusion of imaging technologies: how, when, and for whom? | Over the past decade, electroanatomic mapping has emerged as a useful tool for complex ablation procedures. A more recent advancement is the development of image integration. Image integration refers to the process of registering a previously acquired MRI or CT scan of the heart with the mapping space during the ablation procedure. The technique of image integration is now relied on by many electrophysiology laboratories to guide complex ablation procedures, particularly atrial fibrillation ablation and ablation of patients with ventricular tachycardia in the setting of structural heart disease. An even more recent development is image fusion. This refers to taking information about the myocardial substrate, especially intramyocardial scar, and registering it with the active mapping space. This technique remains in its infancy but shows great promise in facilitating complex ablation procedures. The purpose of the article is to review the development, state of the art, and future of these image integration and fusion techniques. |
14,803 | Electrophysiologic profile of dronedarone on the ventricular level: beneficial effect on postrepolarization refractoriness in the presence of rapid phase 3 repolarization. | Dronedarone (D) is developed to maintain sinus rhythm in patients suffering from atrial fibrillation. The aim of the present study was to investigate, whether dronedarone also has an antiarrhythmic potential in the ventricle and to elucidate the mechanisms for its low proarrhythmic potential in an experimental whole heart model.</AbstractText>Thirty-five rabbits underwent chronic treatment with D (n = 15; 50 mg · kg(-1) · d(-1)) and amiodarone (A; n = 20; 50 mg · kg(-1) · d(-1)). Hearts were perfused on a Langendorff apparatus. Results were compared with hearts acutely treated with sotalol (S; 50-100 μM; n = 14). A 12-lead electrocardiogram and up to 8 ventricular epi- and endocardial monophasic action potentials showed a significant prolongation of QT interval (D: +24 milliseconds, A: +28 milliseconds, S: +35 milliseconds (50 μM), +56 milliseconds (100 μM); P < 0.02) compared with baseline. In contrast to D and A, S led to a significant increase in dispersion of repolarization and exhibited reverse use dependence. D, A, and S increased refractory period, resulting in a significant increase in postrepolarization refractoriness (effective refractory period minus action potential duration; D = +12 milliseconds; A = +14 milliseconds; S = +25 milliseconds; P < 0.05). S led to a triangular action potential configuration, whereas D and A caused a fast phase 3 prolongation. After lowering of potassium concentration, 50% of S-treated hearts showed torsade de pointes, in contrast to an absence of torsade de pointes in D and A.</AbstractText>Prolongation of myocardial repolarization and postrepolarization refractoriness by D may act antiarrhythmic. A fast phase 3 repolarization in the absence of both increased dispersion of repolarization and reverse use dependence prevents proarrhythmia.</AbstractText> |
14,804 | Quantitative waveform measures of the electrocardiogram as continuous physiologic feedback during resuscitation with cardiopulmonary bypass. | There are few if any real-time physiologic measures that currently provide feedback during resuscitation from cardiac arrest. Such measures could be used to guide therapy not simply based on process guidelines but on the physiologic response of the patient from moment to moment. To this end, we applied an existing technology - quantitative waveform measures (QWMs) of the ventricular fibrillation (VF) electrocardiogram (ECG) - as a continuous measure of myocardial response to reperfusion with cardiopulmonary bypass (CPB) after prolonged cardiac arrest.</AbstractText>Sixteen domestic, mixed-breed swine were sedated, anesthetized and paralyzed. Mechanical ventilation with room air was provided. Large diameter bypass catheters were placed in the right external jugular vein and right femoral artery for cardiopulmonary bypass (CPB). VF was induced with a 3-s 100mA transthoracic shock and left untreated for 15, 20, 25, or 30min, followed by 10min of centrifugal pump CPB (Bard CPS). Continuous Lead II ECG was recorded with an electronic data acquisition system (Power Lab, ADInstruments). Four QWMs representing 4 signal characteristics of the VF ECG were calculated in 5-s windows throughout the course of untreated VF and resuscitation with CPB.</AbstractText>Four animals were assigned to each VF duration group. QWM recovery was inversely correlated with untreated VF duration, and was drastically reduced above 20min of untreated VF. Return of spontaneous circulation (ROSC) was highly unlikely after 20min of untreated VF.</AbstractText>QWMs of the VF ECG provided a real-time metric of myocardial electrophysiologic response to reperfusion with CPB. Resuscitation from greater than 20min of untreated cardiac arrest was unlikely. QWMs may be useful for titrating CPB duration before defibrillation and assessing CPR quality independently of process guidelines.</AbstractText>Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,805 | Impact of resuscitation system errors on survival from in-hospital cardiac arrest. | An estimated 350,000-750,000 adult, in-hospital cardiac arrest (IHCA) events occur annually in the United States. The impact of resuscitation system errors on survival during IHCA resuscitation has not been evaluated. The purpose of this paper was to evaluate the impact of resuscitation system errors on survival to hospital discharge after IHCA.</AbstractText>We evaluated subjective and objective errors in 118,387 consecutive, adult, index IHCA cases entered into the Get with the Guidelines National Registry of Cardiopulmonary Resuscitation database from January 1, 2000 through August 26, 2008. Cox regression analysis was used to determine the relationship between reported resuscitation system errors and other important clinical variables and the hazard ratio for death prior to hospital discharge. Of the 108,636 patients whose initial IHCA rhythm was recorded, resuscitation system errors were committed in 9,894/24,467 (40.4%) of those with an initial rhythm of ventricular fibrillation or pulseless ventricular tachycardia (VF/pVT) and in 22,599/84,169 (26.8%) of those with non-VF/pVT. The most frequent system errors related to delay in medication administration (>5 min time from event recognition to first dose of a vasoconstrictor), defibrillation, airway management, and chest compression performance errors. The presence of documented resuscitation system errors on an IHCA event was associated with decreased rates of return of spontaneous circulation, survival to 24h, and survival to hospital discharge. The relative risk of death prior to hospital discharge based on hazard ratio analysis was 9.9% (95% CI 7.8, 12.0) more likely for patients whose initial documented rhythm was non-VF/pVT when resuscitation system errors were reported compared to when no errors were reported. It was 34.2% (95% CI 29.5, 39.1) more likely for those with VF/pVT.</AbstractText>The presence of resuscitation system errors that are evident from review of the resuscitation record is associated with decreased survival from IHCA in adults. Hospitals should target the training of first responders and code team personnel to emphasize the importance of early defibrillation, early use of vasoconstrictor medication, and compliance with ACLS protocols.</AbstractText>Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,806 | Cardiovascular protection with danshensu in spontaneously hypertensive rats. | The objective of the present study was to evaluate the cardiovascular protective effects of Danshensu, a water-soluble active component of Danshen, in spontaneously hypertensive rats (SHR). SHR (male, 9 weeks old, n=30) were divided into three groups: 1) saline control (n=10); 2) a Danshensu (10 mg/kg/d, intraperitoneally (i.p.)) treatment group (n=10); and 3) a Valsartan (10 mg/kg/d, intragastrically (i.g.)) treatment group (n=10). Age-matched Wistar-Kyoto rats (n=10) were used as normotensive controls. Saline and drug treatments were administered for 6 weeks. When the rats were 15 weeks old, their hearts were excised and arrhythmias were induced by an ex vivo ischemia/reperfusion protocol. The heart weight to body weight index was significantly increased in SHR, and this increase was attenuated with Danshensu treatment (both p<0.05). Systolic blood pressure and diastolic blood pressure were also decreased with Danshensu treatment, from 145±3 and 103±10 mmHg to 116±7 and 87±2 mmHg in SHR and Danshensu-treated groups, respectively (both p<0.05). The incidences of ventricular tachycardia and ventricular fibrillation decreased from 100 to 50% and 30% in SHR, respectively, with Danshensu treatment (both p<0.05). Serum nitric oxide content and inducible nitric oxide synthase activity were significantly increased with Danshensu (both p<0.05). In addition, Danshensu increased the K(+) current density and Ca(2+) activated K(+) channel current density of mesenteric vascular smooth muscle cells isolated from SHRs. Together, these results demonstrate that Danshensu imparts cardiovascular protection by modifying vascular responses during the progression of hypertension. |
14,807 | Pulmonary hypertension adversely affects short- and long-term survival after mitral valve operation for mitral regurgitation: implications for timing of surgery. | We investigated the impact of preoperative pulmonary hypertension (PH) on early and late outcomes after mitral valve operation for mitral regurgitation.</AbstractText>Systolic pulmonary artery pressure (sPAP) was measured before operation in 873 consecutive patients who underwent mitral valve surgery for mitral regurgitation between January 2002 and January 2010. PH was classified as none (sPAP < 40 mm Hg), mild (40 ≤ sPAP < 50 mm Hg), moderate (50 ≤ sPAP < 60 mm Hg), or severe (sPAP ≥ 60 mm Hg).</AbstractText>Increased preoperative sPAP was associated with greater left ventricular dysfunction and dilation, left atrial enlargement, more atrial fibrillation, and tricuspid regurgitation. Operative mortality was correlated with the degree of preoperative PH (2%, 3%, 8%, and 12% for none, mild, moderate, and severe PH, respectively, P < .0001). Long-term survival was related to preoperative sPAP (5-year survival: 88%, 79%, 65%, and 53% for none, mild, moderate, and severe PH, respectively; P < .0001). In multivariable analyses, sPAP was a predictor of both operative mortality (odds ratio, 1.023 per 1 mm Hg increase; 95% confidence interval, 1.003-1.044; P = .0270) and late death (hazard ratio, 1.018 per 1 mm Hg increase; 95% confidence interval, 1.007-1.028; P = .001). Among 284 patients with isolated degenerative mitral regurgitation due to leaflet prolapse, actuarial survival was 97.5%, 91.2%, and 80.5% for none, mild, and moderate to severe PH, respectively (P = .0002).</AbstractText>Preoperative sPAP is a powerful predictor of early and late survival after mitral valve operation for mitral regurgitation. Even modest increases in sPAP adversely affect outcomes. Mitral valve operation should be performed before the development of PH.</AbstractText>Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.</CopyrightInformation> |
14,808 | Improvement in the assessment of diastolic function in a clinical echocardiography laboratory following implementation of a quality improvement initiative. | The aim of this study was to demonstrate improvement in the characterization of diastolic function in the routine practice of a clinical echocardiography laboratory after the implementation of a quality improvement initiative. The echocardiographic analysis of left ventricular (LV) diastolic dysfunction is an inherently complex process involving the integration of multiple indices for accurate assessment.</AbstractText>A baseline survey of 50 randomly chosen echocardiographic studies was reviewed for the accuracy of diastolic function assessment. A four-step quality improvement protocol was then initiated: (1) sonographer and physician education; (2) the implementation of data acquisition protocol changes using LV inflow, tissue Doppler velocity of the mitral annulus in early diastole (e'), flow propagation velocity of LV inflow (Vp), and left atrial volume index (LAVI), along with the establishment of uniform criteria for diagnostic interpretation; (3) peer review of performance; and (4) focused interactive case review sessions.</AbstractText>At baseline, measurements of LV inflow were most often correct (100% accurate), while measurements of e' (82% accurate), Vp (12% accurate), and LAVI (12% accurate) and the proper classification of diastolic function (44% accurate) were significantly limited. After the quality improvement initiative, there were significant increases in the accuracy of all recorded measurements, with e' 92% accurate (a 10% improvement; P < .10), Vp 67% accurate (a 55% improvement; P < .001), LAVI 80% accurate (a 68% improvement, P < .001), and proper characterization of diastolic function 76% accurate (a 32% improvement, P < .001).</AbstractText>A multifaceted quality improvement protocol including staff education, systematic support with enhanced infrastructure, and peer review with feedback can be effective for improving the clinical performance of a nonacademic echocardiography laboratory in the characterization of diastolic function.</AbstractText>Copyright © 2011 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.</CopyrightInformation> |
14,809 | Late outcome of 132 Senning procedures after 20 years of follow-up. | Risk factors and rates of reoperation, arrhythmias, systemic right ventricular dysfunction (RVD), and late death after a Senning procedure were investigated.</AbstractText>One-hundred thirty-two patients underwent a Senning operation between 1977 and 2004 (105 simple and 27 complex transpositions of the great arteries). Mean follow-up time was 19.5 ± 6.6 years. Surviving patients were evaluated by transthoracic echocardiography and electrocardiography. Right ventricular function was assessed in 70 patients by isotopic ventriculography or magnetic resonance imaging.</AbstractText>Operative and late mortality were 5.3% (7/132) and 9.6% (12/125), respectively. Nine patients were reoperated for left ventricular outflow tract obstruction or baffle stenosis. Survival rate was 91.5%, 91%, 89%, and 88% at 1, 5, 10, and 20 years, respectively. Probability of maintaining permanent sinus rhythm was 80%, 65%, 55%, and 44%. Twelve patients required pacemaker implantation. Probability of no supraventricular tachycardia, atrial flutter/fibrillation or ventricular tachycardia was 95.5%, 91.5%, 88%, and 75%, respectively. These parameters were similar for simple and complex transposition. Probability of right ventricular ejection fraction >40% was 100% at 5 and 10 years, and 98% at 20 years for simple transposition, and 100%, 92%, and 58% for complex transposition. This difference was statistically significant. Risk factors for RVD were complex transposition (p < 0.001), body weight (p = 0.008), no cardioplegia (p < 0.001), and tricuspid valve regurgitation (p = 0.004).</AbstractText>Senning procedure results in very good long-term survival out to 20 years. Both RVD and baffle stenosis were rare, but there was a concerning incidence of arrhythmia over time suggesting careful long-term surveillance.</AbstractText>Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,810 | [Premature sudden death--consider serious familial heart rhythm disturbances]. | We describe 3 patients from a region in the centre of the Netherlands with several relatives who died prematurely from sudden cardiac arrest. These premature deaths appeared to be caused by a unique familial sudden death syndrome. These patients and their relatives did not present any distinguishable signs, symptoms or abnormalities on further examinations apart from premature cardiac arrest occurring in about 50% of the affected family members before the age of 60 years. Genetic analysis appeared to be the only means to identify family members at risk, carrying lethal changes in their DNA that presumably involve the DPP6-gene. Patients who survive a premature sudden cardiac arrest and relatives of patients who died prematurely from sudden cardiac arrest should be referred to a cardiogenetics outpatient clinic. Timely recognition of persons affected allows appropriate treatment and may implicate an implantable cardioverter defibrillator. |
14,811 | [Amiodaron: decades of administration]. | The review of long-term international clinical experience with amiodaron covers pharmacological properties of the drug, mechanisms of development of its pharmacodynamic effects basing on its action on ionic channels, receptors, impact on thyroid function. Unique pharmacokinetics of amiodaron, high antiarrhythmic efficacy of the drug in supraventricular and ventricular arrhythmia, positive experience in primary and secondary prevention of sudden death are characterized. Amiodaron is effective in patients with atrial fibrillation including those with organic heart disease and chronic cardiac failure. It is safe in relation to different cardiac side effects which are minimal but has some non-cardiac side effects which require control during long-term treatment. |
14,812 | A case of Brugada syndrome coexisting with vasospastic angina: Caution should be taken when using calcium channel blockers. | Although calcium channel blockers have been reported to aggravate Brugada-type electrocardiogram (ECG) abnormalities, there have been few reports in clinical settings. We present a case of Brugada syndrome coexisting with vasospastic angina, in whom Brugada-type ST-segment elevation was aggravated and ventricular fibrillation attacks occurred by calcium channel blocker treatment. When prescribing calcium channel blockers to patients with Brugada syndrome, it is important to pay careful attention to changes in their ECG pattern. |
14,813 | Clinical and microbiological profiles of infective endocarditis in a tertiary hospital in Aseer region, Saudi Arabia. | We aimed to evaluate demographic data, underlying cardiac abnormalities, clinical profile, microbiological features, treatments and complications of infective endocarditis (IE) in a tertiary hospital in Aseer region, Saudi Arabia.</AbstractText>A retrospective study of all cases with the diagnosis of definite endocarditis according to modified Duke Criteria admitted to ACH between May 2002 and April 2007. Data were reviewed on demographic and clinical data, underlying cardiac disease, microbiological findings, treatments and complications of IE.</AbstractText>The study included 44 patients (28 males and 16 females; mean age 31.1 ± 16 years; range 13-65 years). Infective endocarditis developed on a native valve in 31 (70.5%), a mechanical prosthetic valve in 10 (22.7%), mitral valve prolapse in 2 (4.5%) and ventricular septal defect in 1 (2.3%). Rheumatic heart disease in 31 cases (70.5%) was the most common preexisting valvular abnormality in native valve endocarditis. The mitral valve was the most commonly affected valve 28 (63.6%). Fever occurred in 40 (90.9%) of the cases. Electrocardiography was abnormal in 34 cases (77.3%). Trans-thoracic and/or trans-esophageal echocardiography showed a vegetation in 22 (50%). Staphylococci in 10 cases (22.7%) and Streptococci in 8 cases (18%) were the most common causative agents and cultures were negative in 20 cases (45.5%). Twenty-two patients (50%) underwent surgical treatment. Congestive heart failure occurred in 16 (36.4%) cases, atrial fibrillation in 6 (13.6%) cases, and cerebrovascular accidents in 4 (9%) cases.</AbstractText>Our data reflects the clinical and microbiological profiles of IE in a tertiary hospital in Aseer region, Saudi Arabia.</AbstractText> |
14,814 | Evaluation of QT and P wave dispersion and mean platelet volume among inflammatory bowel disease patients. | In inflammatory bowel disease (IBD) number of thromboembolic events are increased due to hypercoagulupathy and platelet activation. Increases in mean platelet volume (MPV) can lead to platelet activation, this leads to thromboembolic events and can cause acute coronary syndromes. In IBD patients, QT-dispersion and P-wave dispersion are predictors of ventricular arrhythmias and atrial fibrilation; MPV is accepted as a risk factor for acute coronary syndromes, we aimed at evaluating the correlations of these with the duration of disease, its localization and activity.</AbstractText>The study group consisted of 69 IBD (Ulcerative colitis n: 54, Crohn's Disease n: 15) patients and the control group included 38 healthy individuals. Disease activity was evaluated both endoscopically and clinically. Patients with existing cardiac conditions, those using QT prolonging medications and having systemic diseases, anemia and electrolyte imbalances were excluded from the study. QT-dispersion, P-wave dispersion and MPV values of both groups were compared with disease activity, its localization, duration of disease and the antibiotics used.</AbstractText>The P-wave dispersion values of the study group were significantly higher than those of the control group. Duration of the disease was not associated with QT-dispersion, and MPV levels. QT-dispersion, P-wave dispersion, MPV and platelet count levels were similar between the active and in mild ulcerative colitis patients. QT-dispersion levels were similar between IBD patients and the control group. No difference was observed between P-wave dispersion, QT-dispersion and MPV values; with regards to disease duration, disease activity, and localization in the study group (p>0.05).</AbstractText>P-wave dispersion which is accepted as a risk factor for the development of atrial fibirilation was found to be high in our IBD patients. This demonstrates us that the risk of developing atrial fibrillation may be high in patients with IBD. No significant difference was found in the QT-dispersion, and in the MPV values when compared to the control group.</AbstractText> |
14,815 | Prognostic utility of T-wave alternans in a real-world population of patients with left ventricular dysfunction: the PREVENT-SCD study. | The predictive value of T-wave alternans (TWA) for lethal ventricular tachyarrhythmia in patients with left ventricular (LV) dysfunction is controversial. Also, long-term arrhythmia risk of patients ineligible for the TWA test is unknown.</AbstractText>This was a multicenter, prospective observational study of patients with LV ejection fraction ≤40% due to ischemic or non-ischemic cardiomyopathies, designed to evaluate the prognostic value of TWA for lethal ventricular tachyarrhythmia. The primary end point was a composite of sudden cardiac death, sustained rapid ventricular tachycardia (VT) or ventricular fibrillation (VF), and appropriate defibrillator therapy for rapid VT or VF.</AbstractText>Among 453 patients enrolled in the study, 280 (62%) were eligible for the TWA test. TWA was negative in 82 patients (29%), who accounted for 18% of the total population. The median of follow-up was 36 months. The 3-year event-free rate for the primary end point was significantly higher in TWA-negative patients (97.0%) than in TWA non-negative patients (89.5%, P = 0.037) and those ineligible for the TWA test (84.4%, P = 0.003). Multivariable analysis identified both non-negative TWA [hazard ratio (HR) 4.43; 95% confidence interval (CI) 1.02-19.2; P = 0.047) and ineligibility for the TWA test (HR 6.89; 95% CI 1.59-29.9; P = 0.010) to be independent predictors of the primary end point.</AbstractText>TWA showed high negative predictive ability for lethal ventricular tachyarrhythmia in patients with LV dysfunction, although the TWA-negative patients accounted for only 18% of the entire population. Those ineligible for the TWA test had the highest risk for lethal ventricular tachyarrhythmia.</AbstractText> |
14,816 | Renal sympathetic denervation for treatment of electrical storm: first-in-man experience. | Sympathetic activity plays an important role in the pathogenesis of ventricular tachyarrhythmia. Catheter-based renal sympathetic denervation (RDN) is a novel treatment option for patients with resistant hypertension, proved to reduce local and whole-body sympathetic activity.</AbstractText>Two patients with chronic heart failure (CHF) (non-obstructive hypertrophic and dilated cardiomyopathy, NYHA III) suffering from therapy resistant electrical storm underwent therapeutic renal denervation. In both patients, RDN was conducted with agreement of the local ethics committee and after obtaining informed consent.</AbstractText>The patient with hypertrophic cardiomyopathy had recurrent monomorphic ventricular tachycardia despite extensive antiarrhythmic therapy, following repeated endocardial and epicardial electrophysiological ablation attempts to destroy an arrhythmogenic intramural focus in the left ventricle. The second patient, with dilated nonischemic cardiomyopathy, suffered from recurrent episodes of polymorphic ventricular tachycardia and ventricular fibrillation. The patient declined catheter ablation of these tachycardias. In both patients, RDN was performed without procedure-related complications. Following RDN, ventricular tachyarrhythmias were significantly reduced in both patients. Blood pressure and clinical status remained stable during the procedure and follow-up in these patients with CHF.</AbstractText>Our findings suggest that RDN is feasible even in cardiac unstable patients. Randomized controlled trials are urgently needed to study the effects of RD in patients with electrical storm and CHF.</AbstractText> |
14,817 | Incidence and outcome of out-of-hospital cardiac arrest with public-access defibrillation. A descriptive epidemiological study in a large urban community. | Detailed characteristics of those who experience an out-of-hospital cardiac arrest (OHCA) with public-access defibrillation (PAD) are unknown.</AbstractText>A prospective, population-based observational study involving consecutive OHCA patients with emergency responder resuscitation attempts was conducted from July 1, 2004 through December 31, 2008 in Osaka City. We extracted data for OHCA patients shocked by a public-access automated external defibrillator (AED) and evaluated the patients' and rescuers' characteristics. The main outcome measure was neurologically favorable 1-month survival. During the study period, 10,375 OHCA patients were registered and of 908 patients suffering ventricular fibrillation arrest, 53 (6%) received public-access AED shocks by lay-rescuers, with the proportion increasing from 0% in 2004 to 11% in 2008 (P for trend<0.001). Railway stations (34%) were the places where PAD shocks were most frequently delivered, followed by nursing homes (11%), medical facilities (9%), and fitness facilities (7%). In 57% of cases, the subject received public-access AED shocks delivered by non-medical persons, including employees of railway companies (13%), school teachers (6%), employees of fitness facilities (6%), and security guards (6%). The proportion of neurologically favorable 1-month survival tended to increase from 0% in 2005 to 58% in 2008 (P for trend=0.081).</AbstractText>Railway stations are the most common places where shocks by public-access AEDs were delivered in large urban communities of Japan, and among lay-rescuers railway station workers use AEDs more frequently.</AbstractText> |
14,818 | Isolated severe tricuspid regurgitation in a post pneumonectomy patient with chronic atrial fibrillation. | Severe primary tricuspid regurgitation is a rare entity, with most cases of tricuspid regurgitation being functional and secondary to pulmonary hypertension from left heart pathologies. We report an unusual case of a female patient with a history of left pneumonectomy and chronic atrial fibrillation many years earlier, and who subsequently developed tricuspid annular dilatation, resulting in severe isolated primary tricuspid regurgitation despite normal pulmonary artery pressures and left ventricular systolic function. She required multiple hospitalizations for right heart failure and continued to be NYHA class IV despite receiving maximal medical management. She finally underwent an isolated tricuspid valve ring annuloplasty, which gave her symptomatic relief. Postoperatively, she improved to NYHA class 1-II still with chronic atrial fibrillation and mild to moderate tricuspid regurgitation at the time of her death 9 years later from pneumonia. |
14,819 | [Arrhythmology today: risks associated with anti-arrhythmic therapy in an internal medicine outpatient clinic]. | Arhytmology that is focused on diagnostics and therapy of heart rhythm disturbances and their complications has undergone dramatic development in last 2 decades. Widespread use of catheter ablation, introduction of implantable cardioverter-defibrillators for prevention of sudden cardiac death and finally, development of cardiac resynchronization therapy have lead to decreased importance of drug treatment. Antiarhythmic drugs remain therapy of choice in management of atrial fibrillation and in some ventricular arrhythmias, especially in patients with implantable cardioverter-defibrillator backup. Therefore, this review deals predominantly with a strategy of antiarythmic therapy in atrial fibrillation and discusses possible risks. |
14,820 | Role of clonidine in perioperative acute atrial fibrillation. | We report a case of acute onset atrial fibrillation (AF) that presented for emergency surgery where rate control and sinus rhythm were successfully achieved using clonidine. Patient had acute AF with high blood pressure. Metoprolol failed to decrease the ventricular rate and blood pressure but with clonidine, we could achieve both the goals. Also, rhythm reverted to a sinus rhythm and continued to be in sinus rhythm after administering clonidine. |
14,821 | Reversible cardiac conduction block and defibrillation with high-frequency electric field. | Electrical impulse propagation is an essential function in cardiac, skeletal muscle, and nervous tissue. Abnormalities in cardiac impulse propagation underlie lethal reentrant arrhythmias, including ventricular fibrillation. Temporary propagation block throughout the ventricular myocardium could possibly terminate these arrhythmias. Electrical stimulation has been applied to nervous tissue to cause reversible conduction block, but has not been explored sufficiently in cardiac tissue. We show that reversible propagation block can be achieved in cardiac tissue by holding myocardial cells in a refractory state for a designated period of time by applying a sustained sinusoidal high-frequency alternating current (HFAC); in doing so, reentrant arrhythmias are terminated. We demonstrate proof of concept using several models, including optically mapped monolayers of neonatal rat ventricular cardiomyocytes, Langendorff-perfused guinea pig and rabbit hearts, intact anesthetized adult rabbits, and computer simulations of whole-heart impulse propagation. HFAC may be an effective and potentially safer alternative to direct current application, currently used to treat ventricular fibrillation. |
14,822 | Dofetilide reduces the frequency of ventricular arrhythmias and implantable cardioverter defibrillator therapies. | Patients with an implanted cardioverter defibrillator (ICD) and ventricular arrhythmias leading to ICD therapies have poor clinical outcomes and quality of life. Antiarrhythmic agents and catheter ablation are needed to control these arrhythmias. Dofetilide has only been approved for the treatment of atrial fibrillation. The role of dofetilide in the control of ventricular arrhythmias in patients with an ICD has not been established.</AbstractText>Evaluate the safety and efficacy of dofetilide in a consecutive group of patients with an ICD and recurrent ventricular tachycardia (VT) and/ or ventricular fibrillation (VF) after other antiarrhythmic drugs have failed to suppress these arrhythmias.</AbstractText>We studied 30 patients (age 59 ± 11; 5 women) with symptomatic VT or VF and ICDs for secondary prevention of sudden cardiac death. These patients had an average of 1.8 ± 4.5 episodes of VT/VF per month despite antiarrhymic therapy. Twenty-one patients (70%) had recurrent appropriate ICD therapies prior to initiation of dofetilide, and 9 (30%) VTs below the programmed detection rate of the ICD. Twenty-three patients (77%) had coronary artery disease. Mean ejection fraction was 30 ± 14% and 26/30 (87%) had congestive heart failure. All patients had previously failed 2 ± 1 antiarrhythmic drugs including amiodarone (n = 19) and sotalol (n = 10).</AbstractText>During the first month of treatment, 25 patients (83%) had complete suppression of VT/VF and of the 21 patients with ICD therapies 16 (76%) had no therapies during the first month of treatment. During a follow-up period of 32 ± 32 months, dofetilide reduced the monthly episodes of VT/VF from 1.8 ± 4.5 to 1.0 ± 3.5 (P = 0.006). Monthly ICD therapies decreased from 0.9 ± 1.4 to 0.4 ± 1.7 (P = 0.037). In 9 patients that presented with slow VTs under the ICD detection zone, dofetilide reduced monthly VT/VF episodes from 0.7 ± 0.6 to 0.1 ± 0.1 (P = 0.01) and 6 (67%) had no further ICD therapies. Dofetilide was discontinued in 13 patients (43%) after 24 ± 30 months due to failure to control VT/VF (n = 7), placement of a left ventricular assist device (n = 3), catheter ablation (n = 1), heart transplantation (n = 1), and left ventricular restoration surgery (n = 1). There were 7 documented deaths (2 patients died suddenly; 3 patients of progressive heart failure; and 2 of non-cardiac causes).</AbstractText>In patients with an ICD and ventricular arrhythmias, dofetilide decreases the frequency of VT/VF and ICD therapies even when other antiarrhythmic agents, including amiodarone, have previously been ineffective. Recurrences still occur in some patients requiring catheter ablation, mechanical support, or heart transplantation.</AbstractText>© 2011 Wiley Periodicals, Inc.</CopyrightInformation> |
14,823 | Atrial Coronary Arteries: Anatomy And Atrial Perfusion Territories. | Coronary anatomy has traditionally focused on ventricular circulation. This is largely due to the extent to which coronary artery disease contributes to ischemic heart disease through ventricular myocardial damage. Atrial fibrillation and other tachyarrhythmias that involve the atria, however, remain a major cause of morbidity and mortality. In order to increase mechanistic research and therapeutic interventional procedures for diseases of the atria, an optimal knowledge of atrial anatomy is necessary. While substantial clarity exists regarding the distribution of nerve terminals and the organization of muscle bundles, the anatomy of coronary atrial circulation remains understudied. Historically, the high anatomical variability of atrial coronary branches led to unstandardized nomenclature in the literature. In this review, we delineate the anatomic courses of key atrial coronary branches and their perfusion territories, clarify their nomenclature, and propose unifying anatomical concepts of atrial circulation that we believe to be critical to the success of modern electrophysiologic and surgical procedures. |
14,824 | Ascorbic acid mitigates the myocardial injury after cardiac arrest and electrical shock. | To examine the effects of ascorbic acid (AA) administrated during cardiopulmonary resuscitation (CPR) on the myocardial injury in a rat model of ventricular fibrillation (VF) and electrical shock (ES).</AbstractText>VF was induced in male Wistar rats and left untreated for 5 min, followed by 1 min of CPR, and then one ES of 5 J. At the start of CPR, animals received either intravenous administration of AA (100 mg/kg) or Tempol (30 mg/kg), two antioxidants, or 0.9% saline (VF + ES group). After ES, animals were immediately killed. Myocardial lipoxidation was determined by malondialdehyde (MDA) assay. The histology and ultrastructural changes of myocardium were also evaluated. The mitochondrial permeability transition pore (mPTP) opening was measured based on the mitochondrial swelling rate. The complex activities and respiration of mitochondria were assessed, too.</AbstractText>Increased myocardial injury and mitochondrial damage in the VF + ES group were noted. AA and Tempol alleviated such damages. Both AA and Tempol improved accelerated mitochondrial swelling; decreased complex activities and respiratory dysfunction occurred in the VF + ES group. The animals receiving AA and Tempol during CPR had better successful resuscitation rates and 72-h survival than the VF + ES group.</AbstractText>Intravenous administration of AA and Tempol at the start of CPR may reduce lipid peroxidation and myocardial necrosis, diminish mitochondrial damage, facilitate resuscitation, and improve outcomes after VF + ES.</AbstractText> |
14,825 | Living with life-saving technology - coping strategies in implantable cardioverter defibrillators recipients. | To describe coping strategies and coping effectiveness in recipients with an implantable cardioverter defibrillator and to explore factors influencing coping.</AbstractText>Implantable cardioverter defibrillators are documented as saving lives and are used to treat ventricular tachycardia and ventricular fibrillation. Despite the implantable cardioverter defibrillator not evidently interfering with everyday life, there is conflicting evidence regarding the psychosocial impact of an implantable cardioverter defibrillator implantation such as anxiety, depression, perceived control and quality of life and how these concerns may relate to coping.</AbstractText>Cross-sectional multicentre design.</AbstractText>Individuals (n = 147, mean age 63 years, 121 men) who had lived with an implantable cardioverter defibrillator between 6-24 months completed the Jalowiec Coping Scale-60, Hospital Anxiety and Depression Scale, Control Attitude Scale and Quality of Life Index-Cardiac version.</AbstractText>Implantable cardioverter defibrillators recipients seldom used coping strategies, and the coping strategies used were perceived as fairly helpful. Optimism was found to be the most frequently used (1·8 SD 0·68) and most effective (2·1 SD 0·48) coping strategy, and recipients perceived moderate control in life. Anxiety (β = 3·5, p ≤ 0·001) and gender (β = 12·3, p = 0·046) accounted for 26% of the variance in the total use of coping strategies, suggesting that the more symptoms of anxiety and being women the greater use of coping strategies.</AbstractText>Most recipients with an implantable cardioverter defibrillator did not appraise daily concerns as stressors in need of coping and seem to have made a successful transition in getting on with their lives 6-24 months after implantation. Relevance to clinical practice.  Nurses working with recipients with an implantable cardioverter defibrillator should have a supportive communication so that positive outcomes such as decreased anxiety and increased perceived control and quality of life can be obtained. Through screening for anxiety at follow-up in the outpatient clinic, these recipients perceiving mental strain in their daily life can be identified.</AbstractText>© 2011 Blackwell Publishing Ltd.</CopyrightInformation> |
14,826 | A 35-year-old pregnant woman presenting with sudden cardiac arrest secondary to peripartum cardiomyopathy. | We present a case of successful resuscitation from cardiac arrest after 25 minutes of ventricular fibrillation (VF) secondary to peripartum cardiomyopathy. This case highlights a rare disease, but also, more importantly, the successful use of the five links of survival: early access to 9-1-1, early cardiopulmonary resuscitation (CPR), early defibrillation, early advanced life support, and postresuscitative care. We also demonstrate the importance of high-quality resuscitation practices in order to achieve a successful outcome. Manual compressions can be performed at a guidelines-compliant rate. With training, users are able to achieve high compression fractions. Pre/post shock delays can be minimized to further increase compression fraction. Nationally, CPR interruptions are often long. We recommend closer attention to uninterrupted 2-minute cycles of CPR, minimizing delays in CPR through training, and a focus on a closely choreographed approach. User review of transthoracic impedance feedback data should play a vital role in a cardiac arrest quality-improvement program. |
14,827 | Long-term use and tolerability of irbesartan for control of hypertension. | In this review, we discuss the pharmacological and clinical properties of irbesartan, a noncompetitive angiotensin II receptor type 1 antagonist, successfully used for more than a decade in the treatment of essential hypertension. Irbesartan exerts its antihypertensive effect through an inhibitory effect on the pressure response to angiotensin II. Irbesartan 150-300 mg once daily confers a lasting effect over 24 hours, and its antihypertensive efficacy is further enhanced by the coadministration of hydrochlorothiazide. Additionally and partially beyond its blood pressure-lowering effect, irbesartan reduces left ventricular hypertrophy, favors right atrial remodeling in atrial fibrillation, and increases the likelihood of maintenance of sinus rhythm after cardioversion in atrial fibrillation. In addition, the renoprotective effects of irbesartan are well documented in the early and later stages of renal disease in type 2 diabetics. Furthermore, both the therapeutic effectiveness and the placebo-like side effect profile contribute to a high adherence rate to the drug. Currently, irbesartan in monotherapy or combination therapy with hydrochlorothiazide represent a rationale pharmacologic approach for arterial hypertension and early-stage and late-stage diabetic nephropathy in hypertensive type II diabetics. |
14,828 | Relationship between R-R interval variation and left ventricular function in sinus rhythm and atrial fibrillation as estimated by means of heart rate variability fraction. | Reduced heart rate variability (HRV) is associated with a poor outcome in patients with sinus rhythm (SR) or atrial fibrillation (AF). However, cut-off points for HRV measures differ between SR and AF. We hypothesized that a global index of 24-hour HRV based on evaluation of scatterplot would describe HRV irrespective of cardiac rhythm.</AbstractText>407 patients with ischemic heart disease (317 male, 90 female, mean age 57 ± 9 years) were studied. 331 patients had SR and 76 patients had AF. 24-hour ECGs were recorded, and standard HRV indices were calculated. Scatterplots was used to determine the HRV fraction (HRVF, %). HRV measures were compared in respect to left ventricular ejection fraction (LVEF £ 35% or 〉 35%).</AbstractText>Standard HRV measures were higher in AF-patients despite the mean RR interval was lower. In patients with LVEF £ 35%, standard HRV indices were lower in SR group, in AF group only SDNN and RMSSD were reduced. The HRVF was comparably reduced (SR 39.3 ± 15.3%, AF 37.3 ± 17.9%). In patients with LVEF 〉 35%, HRVF did not differ between SR (47.2 ± ± 10.5%) and AF (46.1 ± 12.1%). The HRVF correlated with SDNN and SDANN (~0.85) in SR. Correlations were weaker in AF (~0.6). Standard HRV indices and HRVF showed similar relations with LVEF, but only in AF at the same range.</AbstractText>The HRV fraction allows for HRV evaluation irrespective of cardiac rhythm. The index elicited a similar dependence of HRV on left ventricular function in SR and AF.</AbstractText> |
14,829 | Frequency, determinants and outcome of pulmonary hypertension in patients with aortic valve stenosis. | The frequency, causes and prognostic implications of pulmonary hypertension (PHT) in patients with severe aortic stenosis (AS) are not well defined. The objectives of this study were to determine the frequency of PHT [pulmonary artery systolic pressure (PASP) >50 mm Hg] in patients with severe AS, identify the factors associated with PHT and assess the relationship between PHT and clinical outcome.</AbstractText>Patients with severe AS (aortic valve area ≤1.0 cm) and an echocardiographic estimate of PASP were identified by using the institutional echocardiography laboratory database. Patients with atrial fibrillation, mitral valve stenosis or a mitral prosthesis were excluded from analysis. The associations between clinical and echocardiographic parameters and PHT and the relationship between PHT and outcome were examined.</AbstractText>During the study period, 216 patients fulfilled the inclusion criteria (age: 75 ± 11 years; 43% men), and PHT was present in 64 patients (29.6%). By multivariate analysis, reduced left ventricular (LV) systolic function (LV ejection fraction ≤45% and lower stroke volume) and impaired LV diastolic function (mitral inflow E/A ratio ≥1.5 and greater left atrium size) were independent predictors of PHT. Mortality was higher among patients with PHT managed medically (adjusted hazard ratio, 1.87; 95% confidence interval, 1.06-3.30; P = 0.011), whereas patients with PHT who underwent aortic valve replacement had an excellent outcome.</AbstractText>PHT is common in patients with AS and is related to the severity of LV systolic and diastolic dysfunction. PHT is associated with poorer outcome in medically treated patients.</AbstractText> |
14,830 | Ventricular tachycardia or ventricular fibrillation occurs less often in patients with left bundle branch block and combined resynchronization and defibrillators than in patients with narrow QRS and conventional defibrillators. | Mortality in chronic heart failure (CHF) patients with left bundle branch block (LBBB) is high. Cardiac resynchronization therapy (CRT) reduces symptoms and mortality in CHF patients with LBBB. Whether CRT promotes or prevents ventricular tachycardia (VT)/ventricular fibrillation (VF) remains controversial, however. Therefore, we aimed to analyse arrhythmia-related CRT effects and characterized the VT/VF incidence in CRT-defibrillator patients and matched controls with conventional implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden cardiac death.</AbstractText>We enrolled 134 patients [110 men, left ventricular ejection fraction (LVEF) 24 ± 8%, 71 coronary artery disease, CRT-ICD 67, conventional ICD matched controls 67, follow-up 31 ± 17 months] and monitored overall survival and the time to a first VT/VF episode. Controls did not have LBBB. They were otherwise matched for age, LVEF, and follow-up duration. Gender and underlying disease did not differ between the groups. Kaplan-Meier analysis revealed more favourable arrhythmia-free survival in CRT-ICD vs. conventional ICD patients [hazard ratio (HR) 2.26, confidence interval (CI) 1.09-4.67, log rank P = 0.023]. The difference persisted in the multivariate Cox regression analysis (HR 3.25, CI 1.18-8.93, P= 0.022). Overall survival was similar in both groups (HR 1.45, CI 0.55-3.82, P = 0.45).</AbstractText>Chronic heart failure patients with LBBB treated with CRT-ICD, experience less and delayed VT/VF episodes compared with matched controls without LBBB receiving conventional ICD. In the long-term, CRT appears to exert antiarrhythmic effects and to attenuate the particularly high arrhythmia-related risk of CHF patients with LBBB. The incremental benefit of adding the ICD option to CRT pacing in LBBB patients appears questionable.</AbstractText> |
14,831 | Coupled pacing controls rapid heart rates better than paired pacing during atrial fibrillation. | Delivery of a ventricular extrastimulus shortly after the effective refractory period (ERP) of a sensed (coupled pacing; CP) or a paced (paired pacing; PP) ventricular event can instantly decrease the mechanical pulse rate (MPR) during rapidly conducting atrial fibrillation (AF). We compared the short-term rate-controlling effects of CP and PP during AF with rapid ventricular rates.</AbstractText>Sixteen patients with ongoing, spontaneous AF were examined. Mechanical pulse rate was registered via arterial pressure tracings. During CP a coupling interval (CI) of ERP+20 ms was used to reach an optimal haemodynamic effect. Paired pacing was started at a basic cycle length (CL) of 500 ms followed by an extrastimulus with an CI of ERP+20 ms. Drive train was changed at 50 ms increments until the lowest MPR was reached. Proarrhythmic effects were characterized by the number of premature ventricular complexes (PVCs). Mechanical pulse rate significantly decreased in all patients during CP (113 ± 9 vs. 58 ± 4/min). Using CP the controlled rhythm remained irregular (CL range: 896 ± 24-1452 ± 67 ms) while no PVCs were observed. With different drive trains PP resulted in different regular MPRs (range 62 ± 6-80 ± 4/min), but the lowest MPR achieved was significantly higher in the PP group than in the CP. Paired pacing caused premature beats in nine patients (56%) resulting in loss of continuous MPR control.</AbstractText>Both CP and PP can reduce the MPR during rapidly conducting AF. Coupled pacing is more applicable, but PP has the advantage to achieve different target heart rates. Paired pacing has more proarrhythmic effects as compared with CP.</AbstractText> |
14,832 | Subarachnoid hemorrhage causing cardiopulmonary arrest: resuscitation profiles and outcomes. | Aneurysmal subarachnoid hemorrhage (SAH) is a common cause of cardiopulmonary arrest (CPA). The outcomes of SAH patients presenting with CPA are extremely poor, and long-term survivors have occasionally been reported, but the circumstances under which SAH-CPA patients achieve long-term survival are unclear. Neurosurgeons will have to determine whether a SAH-CPA patient is brain-dead or not more often after enactment of the revised Organ Transplantation Act. Prediction of survival length may be important not only to neurosurgeons, but also to the transplantation team. A retrospective study was conducted to elucidate how often brainstem function was recovered in resuscitated SAH-CPA patients and whether the recovery was associated with longer survival. Among 315 patients with non-traumatic SAH admitted to our institution during 6 years, 35 (11%) presented with CPA. Ventricular fibrillation (VF) as initial cardiac rhythm was rare, observed only in 1 patient. The survival length ranged from 1 to 15 days (mean 3.5 ± 0.7 days), and none achieved long-term survival. Return of brainstem function, represented by spontaneous respiration and/or reactive pupils, was observed in 6 patients (17%), but was only partial and transient. Cardiac arrest to return of spontaneous circulation interval tended to be shorter in patients with transient recovery of the brainstem function than in those without recovery. However, the survival length was not significantly different between the two groups. In addition to the 35 SAH-CPA patients, another 44 SAH patients lost both brainstem reflexes and spontaneous respiration within 72 hours of admission. As a result, 79 (25%) of the 315 SAH patients were considered to have sustained fatal, irreversible brain damage. Review of previous experience suggests that SAH-CPA patients may survive only if the cause of cardiac arrest is VF and not brainstem damage/respiratory arrest. Approximately one-third of resuscitated SAH-CPA patients may die within 24 hours of arrival, for whom the declaration of brain death may be difficult. |
14,833 | Paediatric arrhythmias in the emergency department. | Emergency department (ED) staff need to rapidly establish accurate diagnosis and management for children with arrhythmias. Limited data are available on the presenting features, epidemiology and management of arrhythmias encountered in the ED. The aim of this study was to characterise the incidence, presenting features, management and outcomes of arrhythmias at a large tertiary children's hospital ED.</AbstractText>Retrospective review of medical records identified via the ED electronic database using ICD-10 codes for arrhythmias including cardiac arrests over a 6-year period (2002-2008). Patients <18 years were analysed using predefined criteria.</AbstractText>There were a total of 444 non-arrest arrhythmias with an incidence of 11.5:10 000 presentations. Median age of patients at presentation was 10.4 years; 45% were male. Supraventricular arrhythmias (SVTs) represented the largest subgroup (n=250, 56%). Conduction disorders (n=18), ventricular tachycardia (n=17) and atrial flutter/fibrillation (n=7) were rare. There were 19 cardiac arrests. Fifty-seven (13%) patients had underlying congenital heart disease. For ongoing SVT (n=135), vagal manoeuvres were used in 74%, and antiarrhythmic drugs in 64%. In five patients with SVT, drugs other than adenosine were used. Defibrillators were used only on 2 occasions for arrthymias and 6 times for cardiac arrests. 18 of 19 children in cardiac arrest died.</AbstractText>In this largest paediatric series outside the intensive care and postoperative setting, arrhythmias were uncommon, defibrillator use was very rare, and observed mortality was low.</AbstractText> |
14,834 | In vivo porcine left atrial wall stress: Effect of ventricular tachypacing on spatial and temporal stress distribution. | Animal models of ventricular tachypacing (VTP) have been successfully used to reproduce the relevant features observed in patients with atrial fibrillation, such as increased atrial pressure and volume, ion-channel alterations and fibrosis. After performing VTP on a healthy Yorkshire pig, we measured an increase in volume of 60%, a two-fold rise in pressure, and a complex pattern of local mechanical, histological and biochemical changes, including a generalized stiffening of the wall. A protocol recently developed was employed to generate computational models of the porcine left atrium mechanics in healthy conditions and after VTP. Comparison of the stress distribution in the healthy vs. VTP case provided a map of how pressure overload affects and modifies left atrium mechanics. Overall, a positive increase in stress was computed after the VTP treatment. Regions of large increase in the stresses post-VTP were the appendage boundaries, the area around the lower pulmonary vein and the area in the front of the atrium towards the appendage. Due to the elevated stress, the back of the atrium mainly modified its mechanical response, while the appendage remodeled both its shape and its mechanical properties. Large changes in the shape of the mitral valve annulus could be observed as a consequence of the remodeling in the front of the atrium. The relation between local mechanical stress and remodeling that emerges from the results is in agreement with our hypothesis that the structural changes in the atrium are a consequence of a stress-mediated mechanism. |
14,835 | Strong coherence between heart rate variability and intracardiac repolarization lability during biventricular pacing is associated with reverse electrical remodeling of the native conduction and improved outcome. | Reverse electrical remodeling (RER) of the native conduction with cardiac resynchronization therapy (CRT) is associated with decreased mortality and antiarrhythmic effect of CRT. Still, mechanisms of RER are largely unknown. In this study, we explored repolarization lability during biventricular pacing.</AbstractText>The width of native QRS was measured in lead II electrocardiogram before and at least 6 months after implantation of Cardiac Resynchronization Therapy Defibrillator (CRT-D) devices (Medtronic, Inc [Minneapolis, MN, USA] and Boston Scientific Corporate [Natick, MA, USA]) in 69 patients (mean age, 66.3 ± 13.9 years; 39 men [83%]) with either bundle-branch block (44 patients [64%]) or nonspecific intraventricular conduction delay (25 patients [36%]) and New York Heart Association class III and IV heart failure. Narrowing of the native QRS duration for at least 10 milliseconds was considered a marker of RER. Beat-to-beat QT variability and coherence was measured on surface electrocardiogram and intracardiac near-field electrogram during biventricular pacing. Reverse electrical remodeling was observed in 22 patients (32%) in whom coherence between heart rate variability and intracardiac repolarization lability was stronger (0.483 ± 0.243 vs 0.237 ± 0.146, P = .018) and normalized intracardiac QT variance was smaller (0.28 ± 0.0031 vs 0.46 ± 0.0048, P = .049), as compared with that in patients without RER. During a further 24 ± 13 months of follow-up, 21 patients (33%) died or experienced sustained ventricular tachycardia (VT)/ventricular fibrillation. Low intracardiac coherence (≤0.116) was associated with increased risk of death or sustained VT/VT (hazard ratio, 4.33; 95% confidence interval, 1.51-12.40; P = .006).</AbstractText>Strong coherence between heart rate variability and intracardiac repolarization lability during biventricular pacing is associated with RER of the native conduction with CRT. Low coherence is associated with increased risk of VT/ventricular fibrillation or death.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,836 | Arrhythmic manifestations in patients with congenital left ventricular aneurysms and diverticula. | Congenital left ventricular aneurysms and diverticula (LVA/Ds) are rare cardiac malformations that can be detected using echocardiography or other imaging techniques. Some of these patients present with ventricular arrhythmias. This study investigated clinical characteristics of patients with congenital LVA/D presenting with arrhythmic manifestations. Over the previous 20 years 250 patients were diagnosed to have congenital LVA/D at our institution. Diagnosis was made using echocardiography after exclusion of coronary artery disease, local cardiac inflammatory processes, traumatic causes, or cardiomyopathies. At initial presentation 32 of the 250 patients (13%, average age 45 years, range 25 to 65, 21 men and 11 women) exhibited arrhythmias. At least 2 LVA/Ds were present in 6 of these patients. LVA/Ds were localized at the posterobasal, apical, anteroseptal, and anterolateral walls in 12, 11, 4, and 5 patients, respectively. The most common complaints at presentation were syncope or presyncope in 18 patients and palpitations in 11 patients. One patient had survived sudden cardiac death. Long-term electrocardiographic recordings showed ventricular tachycardia (VT) or ventricular fibrillation in 17 patients (53%). Twelve patients underwent electrophysiologic testing. Nine patients had inducible ventricular tachyarrhythmia, whereas induced tachycardia was similar to that during spontaneous arrhythmia in 7 patients. In conclusion, patients with congenital LVA/Ds who present with arrhythmic manifestations commonly have VT. Electrophysiologic testing can reproduce clinical VT in most of these patients. |
14,837 | Comparison of invasive and non-invasive measurements of haemodynamic parameters in patients with advanced heart failure. | Measurement of haemodynamic parameters using a Swan-Ganz catheter is of clinical importance in patients with advanced heart failure; however, its applicability is limited due to its invasiveness. The aim of the study was to estimate the concordance between invasive and non-invasive measurements of haemodynamic parameters in patients with advanced heart failure.</AbstractText>We examined 25 patients with advanced heart failure (20 men, age: 64 ± 11 years, New York Heart Association class III/IV: 88/12%, left ventricular ejection fraction: 37 ± 20%), 13 (52%) demonstrated decompensated heart failure. Resting haemodynamic parameters were measured simultaneously using two methods: an invasive Swan-Ganz catheterization and a thermodilution technique; and a non-invasive recording using a device for finger arterial pressure waveform analysis. The following parameters were analysed: stroke volume (SV, ml), cardiac output (CO, l/min) and systemic vascular resistance (SVR, dyne × s/cm⁵). The concordance between these two methods was assessed using the variability coefficient calculated according to a Bland-Altman method. Comparing the invasive and non-invasive measures, variability coefficients were: 13, 18 and 11% for SV, SVR and CO, respectively. Similar variability coefficients were obtained when invasive and non-invasive measurements were compared in prespecified subgroups of patients, distinguished based on the presence of decompensation, atrial fibrillation and values of SBP.</AbstractText>Evaluation of haemodynamic parameters using a non-invasive method based on a pressure pulse contour model reveals an adequate concordance with the measures obtained using an invasive approach. Our results suggest that a non-invasive method for haemodynamic monitoring could be applied in clinical practice in patients with advanced heart failure.</AbstractText> |
14,838 | Short-term exercise preserves myocardial glutathione and decreases arrhythmias after thiol oxidation and ischemia in isolated rat hearts. | The purpose of this study was to determine if exercise (Ex) protects hearts from arrhythmias induced by glutathione oxidation or ischemia-reperfusion (I/R). Female Sprague-Dawley rats were divided into two experimental groups: sedentary controls (Sed) or short-term Ex (10 days of treadmill running). Twenty-four hours after the last session, hearts were excised and exposed to either perfusion with the thiol oxidant diamide (200 μM) or global I/R. Ex significantly delayed the time to the onset of ventricular arrhythmia after irreversible diamide perfusion. During a shorter diamide perfusion protocol with washout, Ex significantly decreased the incidence of arrhythmia, as evidenced by a delayed time to the first observed arrhythmia, lower arrhythmia scores, and lower incidence of ventricular fibrillation. Ex hearts exposed to I/R (30-min ischemia/30-min reperfusion) also showed lower arrhythmia scores and incidence of ventricular fibrillation compared with Sed counterparts. Our finding that Ex protected intact hearts from thiol oxidation was corroborated in isolated ventricular myocytes. In myocytes from Ex animals, both the increase in H(2)O(2) fluorescence and incidence of cell death were delayed after diamide. Although there were no baseline differences in reduced-to-oxidized glutathione ratios (GSH/GSSG) between the Sed and Ex groups, GSH/GSSG was better preserved in Ex groups after diamide perfusion and I/R. Myocardial glutathione reductase activity was significantly enhanced after Ex, and this was preserved in the Ex group after diamide perfusion. Our results show that Ex protects the heart from arrhythmias after two different oxidative stressors and support the hypothesis that sustaining the GSH/GSSG pool stabilizes cardiac electrical function during conditions of oxidative stress. |
14,839 | Deterioration of mitral valve competence after the repair of atrial septal defect in adults. | Although mild mitral regurgitation (MR) associated with atrial septal defect (ASD) is believed to improve by ASD closure alone, new-onset MR or aggravation of preexisting mild MR may also develop after ASD closure. We sought to determine the preoperative risk factors for the postoperative deterioration of mitral valve competence in adults with ASD.</AbstractText>Retrospective review of 286 adults with ASD who had undergone surgical closure of ASD between January 2004 and December 2009 was performed. Patients with significant preoperative MR (≥III/IV) that necessitated mitral valve intervention were excluded. Preoperative MR grades were 0 in 204 patients, I in 67 patients, and II in 15 patients.</AbstractText>After ASD repair, MR degree did not change or improved in most of the patients (204 of 286, 71%), whereas 82 patients (82 of 286, 29%) showed aggravated or new-onset MR, including 18 patients whose MR degree increased by grade 2 or more. Univariable analysis revealed older age, preoperative atrial fibrillation, large left atrial size, large indexed ASD size, high peak tricuspid regurgitation velocity, and associated tricuspid valve surgery or Maze procedure as risk factors for new-onset or aggravated MR, but only older age (odds ratio, 1.058; 95% confidence interval, 1.025 to 1.092; p = 0.0005) and indexed ASD size (odds ratio, 1.120; 95% confidence interval, 1.042 to 1.205; p = 0.0022) remained significant on multivariable analysis. The ratio of postoperative left ventricular end-diastolic volume to preoperative left ventricular end-diastolic volume was greater in patients with new-onset or aggravated MR (p = 0.016).</AbstractText>Mitral valve competence may deteriorate after ASD closure in older patients with large ASD.</AbstractText>Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,840 | Incidence and predictors of implantable cardioverter-defibrillator therapy in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy undergoing implantable cardioverter-defibrillator implantation for primary prevention. | The purpose of this study was to define the incidence and predictors of implantable cardioverter-defibrillator (ICD) therapy in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) after placement of an ICD for primary prevention.</AbstractText>Patients with a diagnosis of ARVD/C often receive an ICD for prevention of sudden cardiac death.</AbstractText>Patients (n = 84) from the Johns Hopkins registry with definite or probable ARVD/C who underwent ICD implantation for primary prevention were studied. Detailed phenotypic, genotype, and ICD event information was obtained and appropriate ICD therapies were adjudicated based on intracardiac electrograms.</AbstractText>Over a mean follow-up of 4.7 ± 3.4 years, appropriate ICD therapy was seen in 40 patients (48%), of whom 16 (19%) received interventions for potentially fatal ventricular fibrillation/flutter episodes. Proband status (p < 0.001), inducibility at electrophysiologic study (p = 0.005), presence of nonsustained ventricular tachycardia (p < 0 .001), and Holter premature ventricular complex count >1,000/24 h (p = 0.024) were identified as significant predictors of appropriate ICD therapy. The 5-year survival free of appropriate ICD therapy for patients with 1, 2, 3, and 4 risk factors was 100%, 83%, 21%, and 15%, respectively. Inducibility at electrophysiologic study (hazard ratio: 4.5, 95% confidence interval: 1.4 to 15, p = 0.013) and nonsustained ventricular tachycardia (hazard ratio: 10.5, 95% confidence interval: 2.4 to 46.2, p = 0.002) remained as significant predictors on multivariable analysis.</AbstractText>Nearly one-half of the ARVD/C patients with primary prevention ICD implantation experience appropriate ICD interventions. Inducibility at electrophysiologic study and nonsustained ventricular tachycardia are independent strong predictors of appropriate ICD therapy. An increase in ventricular ectopy burden was associated with progressively lower event-free (appropriate ICD interventions) survival. Incremental risk of ventricular arrhythmias and ICD therapy was observed with the presence of multiple risk factors.</AbstractText>Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,841 | Evidence of atrial functional mitral regurgitation due to atrial fibrillation: reversal with arrhythmia control. | The purpose of this study was to determine whether atrial fibrillation (AF) might cause significant mitral regurgitation (MR), and to see whether this MR improves with restoration of sinus rhythm.</AbstractText>MR can be classified by leaflet pathology (organic/primary and functional/secondary) and by leaflet motion (normal, excessive, restrictive). The existence of secondary, normal leaflet motion MR remains controversial.</AbstractText>We performed a retrospective cohort study. Patients undergoing first AF ablation at our institution (n = 828) were screened. Included patients had echocardiograms at the time of ablation and at 1-year clinical follow-up. The MR cohort (n = 53) had at least moderate MR. A reference cohort (n = 53) was randomly selected from those patients (n = 660) with mild or less MR. Baseline echocardiographic and clinical characteristics were compared, and the effect of restoration of sinus rhythm was assessed by follow-up echocardiograms.</AbstractText>MR patients were older than controls and more often had persistent AF (62% vs. 23%, p < 0.0001). MR patients had larger left atria (volume index: 32 cm(3)/m(2) vs. 26 cm(3)/m(2), p = 0.008) and annular size (3.49 cm vs. 3.23 cm, p = 0.001), but similar left ventricular size and ejection fraction. Annular size, age and persistent AF were independently associated with MR. On follow-up echocardiogram, patients in continuous sinus rhythm had greater reductions in left atrial size and annular dimension, and lower rates of significant MR (24% vs. 82%, p = 0.005) compared with those in whom sinus rhythm was not restored.</AbstractText>AF can result in "atrial functional MR" that improves if sinus rhythm is restored.</AbstractText>Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,842 | Vagal activity modulates spontaneous augmentation of J-wave elevation in patients with idiopathic ventricular fibrillation. | Although J-wave elevation in the inferolateral leads could be related to idiopathic ventricular fibrillation (IVF), little is known about the pathophysiologic characteristics of J-wave elevation in patients with IVF.</AbstractText>This study aimed to determine the relationship between augmentation of J-wave elevation and changes in RR interval or autonomic nervous activities in patients with IVF.</AbstractText>Eight patients with IVF and 22 controls with J-wave elevation (≥0.1 mV) in lead V5 were studied. The J-wave amplitude was automatically measured in lead CM5 of a digital Holter electrocardiogram, and the J-RR relationship was determined. Based on the analysis of heart rate variability, the relationship between the J-wave amplitude and the natural logarithm of high-frequency (HF) components (J-ln HF relationship) or the ratio of low frequency (LF) components to HF components (J-LF/HF relationship) was also determined.</AbstractText>The J-RR slope (mm/s) was greater in patients with IVF than in controls (3.5 ± 0.7 vs 2.4 ± 0.8; P <.01), as was J-wave amplitude (mm) at an RR interval of 1.2 seconds (2.8 ± 0.9 vs 2.0 ± 0.6; P <.05). The J-wave amplitude was correlated positively with ln HF and negatively with LF/HF, and the slopes of both J-ln HF and J-LF/HF regression lines were greater in patients with IVF than in controls. During an entire 24-hour period, there was no difference between the 2 groups in either HF or LF/HF. Nine of the total 11 episodes (82%) of spontaneous ventricular fibrillation occurred between 18:00 and 6:00.</AbstractText>In patients with IVF as compared with control subjects, J-wave elevation was more strongly augmented during bradycardia and was associated with an increase in vagal activity. This could be related to the occurrence of ventricular fibrillation predominantly at night in patients with IVF.</AbstractText>Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,843 | Clinical impact of the number of extrastimuli in programmed electrical stimulation in patients with Brugada type 1 electrocardiogram. | Use of programmed electrical stimulation (PES) for risk stratification of Brugada syndrome (BrS) is controversial.</AbstractText>To elucidate the role of the number of extrastimuli during PES in patients with BrS.</AbstractText>Consecutive 108 patients with type 1 electrocardiogram (104 men, mean age 46 ± 12 years; 26 with ventricular fibrillation [VF], 40 with syncope, and 42 asymptomatic) underwent PES with a maximum of 3 extrastimuli from the right ventricular apex and the right ventricular outflow tract. Ventricular arrhythmia (VA) was defined as VF or nonsustained polymorphic ventricular tachycardia >15 beats. Patients with VA induced by a single extrastimulus or double extrastimuli were assigned to group SD (Single/Double), by triple extrastimuli to group T (Triple), and the remaining patients to group N.</AbstractText>VA was induced in 81 patients (VF in 71 and polymorphic ventricular tachycardia in 10), in 4 by a single extrastimulus, in 41 by double extrastimuli, and in 36 by triple extrastimuli. During 79 ± 48 months of follow-up, 24 patients had VF events. Although the overall inducibility of VA was not associated with an increased risk of VF (log-rank P = .78), group SD had worse prognosis than did group T (P = .004). Kaplan-Meier analysis in patients without prior VF also showed that group SD had poorer outcome than did group T and group N (P = .001). Positive and negative predictive values of VA induction with up to 2 extrastimuli were, respectively, 36% and 87%, better than those with up to 3 (23% and 81%, respectively).</AbstractText>The number of extrastimuli that induced VA served as a prognostic indicator for patients with Brugada type 1 electrocardiogram. Single extrastimulus or double extrastimuli were adequate for PES of patients with BrS.</AbstractText>Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,844 | Isolating the pulmonary veins as first-line therapy in patients with lone paroxysmal atrial fibrillation using the cryoballoon. | Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Nowadays, catheter-based ablative approaches are mainly reserved for drug-refractory patients. However, the value of an ablative therapy as a first-line alternative remains elusive. The aim of our study was to analyse the acute procedural success and clinical outcome of patients with lone paroxysmal AF undergoing cryoballoon ablation (CBA) as first-line treatment.</AbstractText>Eighteen individuals (mean age 44 ± 9 years, range 23-61 years, 15 males) with lone paroxysmal AF preferring a catheter-based treatment to drug treatment as first-line therapy were consecutively enrolled in our study. Mean left atrial size was 39 ± 4 mm and mean left ventricular ejection fraction 58 ± 3%. After a mean of 2.4 CBA (range 2-4) applications pulmonary vein (PV) isolation could be demonstrated in 70 (97%) PVs. Additional lesions with a focal ablation catheter were needed to isolate one right inferior pulmonary vein and one left superior pulmonary vein in two different patients. At the end of the procedure, all (100%) PVs were isolated. After a 2-month blanking period, 16 patients (89%) were free of symptomatic AF recurrence at a mean follow-up of 14 ± 9 months and without antiarrhythmic drugs (AADs).</AbstractText>Cryoballoon ablation in patients with lone paroxysmal AF yields a high acute efficacy rate with a great chance of being free of symptomatic AF recurrence without antiarrhythmic drugs on a mid-term follow-up period, when offered as a first-line treatment.</AbstractText> |
14,845 | Atrial function after left atrial epicardial cryoablation for atrial fibrillation in patients undergoing mitral valve surgery. | To explore the effects on atrial and ventricular function of restoring sinus rhythm (SR) after epicardial cryoablation and closure of the left atrial appendage (LAA) in patients with mitral valve disease and atrial fibrillation (AF) undergoing surgery.</AbstractText>Sixty-five patients with permanent AF were randomized to mitral valve surgery combined with left atrial epicardial cryoablation and LAA closure (ABL group, n = 30) or to mitral valve surgery alone (control group, n = 35). Two-dimensional and Doppler echocardiography were performed before and 6 months after surgery.</AbstractText>At 6 months, 73% of the patients in the ABL group and 46% of the controls were in SR. Patients in SR at 6 months had a reduction in their left ventricular diastolic diameter while the left ventricular ejection fraction was unchanged. In patients remaining in AF, the left ventricular ejection fraction was lower than at baseline. The left atrial diastolic volume was reduced after surgery, more in patients with SR than AF. In patients in SR, the peak velocity during the atrial contraction and the reservoir function were lower in the ABL group than in the control group.</AbstractText>In patients in SR, signs of atrial dysfunction were observed in the ABL but not the control group. Atrial dysfunction may have existed before surgery, but the difference between the groups implies that the cryoablation procedure and/or closure of the LAA might have contributed.</AbstractText> |
14,846 | A case of exhaustion of implantable cardioverter defibrillator therapies due to inappropriate programming. | Strategically chosen tachycardia detection and therapy options targeting non-sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) can efficiently reduce the morbidity related to implantable cardioverter defibrillator (ICD) therapy. We report a case of a 60-year-old woman with ischemic cardiomyopathy who underwent ICD implantation due to frequent episodes of non-sustained VT. In this case, the inappropriate setting for VF detection in addition to the limited flexibility in device programming for tachycardia confirmation led to the rapid exhaustion of all available shock therapies. |
14,847 | Cardioplegia and ventricular late potentials in cardiac surgical patients. | Ventricular late potentials (LP) recording with signal-averaged electrocar- diogram allow identifying patients at risk of sudden death and ventricular tachycardia. Cardiac surgery with cardiopulmonary bypass (CPB) could predispose to the development of myocardial ischemia related to imperfect cardioplegia. To the best of our knowledge, no study investigated the protection of cardioplegia and CPB regarding the occurrence of LP in patients without previous myocardial infarction and undergoing cardiac surgery.</AbstractText>In 61 elective patients scheduled for cardiac surgery involving CPB, signal-averaged electrocar- diogram was performed the day before and 24-48 h after the surgery. The electrodes were positioned according to Frank's orthogonal derivations. Twenty five patients were excluded because of poor quality signals, leaving 36 patients (age, 64 ± 14) available for the analyses. An abnormal signal-averaged electrocardiogram was considered when ≥2 of the recorded indexes were present. McNemar's tests were performed on the dichotomized values to investigate differences in pre-post scores.</AbstractText>The mean CPB duration was of 110 ± 57 min. Patients scheduled for cardiac surgery do not exhibited LP after CPB (no significant difference in pre-post CPB scores, P = NS). The probability of a patient with a negative score transitioning to a positive score was 0.23 (P = NS).</AbstractText>The present study in cardiac surgical patients suggests that cardioplegia associated to CPB has no significant impact on the occurrence of LP, irrespective of surgery performed.</AbstractText> |
14,848 | On-chip constructive cell-network study (II): on-chip quasi-in vivo cardiac toxicity assay for ventricular tachycardia/fibrillation measurement using ring-shaped closed circuit microelectrode with lined-up cardiomyocyte cell network. | Conventional in vitro approach using human ether-a-go-go related gene (hERG) assay has been considered worldwide as the first screening assay for cardiac repolarization safety. However, it does not always oredict the potential QT prolongation risk or pro-arrhythmic risk correctly. For adaptable preclinical strategiesto evaluate global cardiac safety, an on-chip quasi-in vivo cardiac toxicity assay for lethal arrhythmia (ventricular tachyarrhythmia) measurement using ring-shaped closed circuit microelectrode chip has been developed.</AbstractText>The ventricular electrocardiogram (ECG)-like field potential data, which includes both the repolarization and the conductance abnormality, was acquired from the self-convolutied extracellular field potentials (FPs) of a lined-up cardiomyocyte network on a circle-shaped microelectrode in an agarose microchamber. When Astemisol applied to the closed-loop cardiomyocyte network, self-convoluted FP profile of normal beating changed into an early afterdepolarization (EAD) like waveform, and then showed ventricular tachyarrhythmias and ventricular fibrilations (VT/Vf). QT-prolongation-like self-convoluted FP duration prolongation and its fluctuation increase was also observed according to the increase of Astemizole concentration.</AbstractText>The results indicate that the convoluted FPs of the quasi-in vivo cell network assay includes both of the repolarization data and the conductance abnormality of cardiomyocyte networks has the strong potential to prediction lethal arrhythmia.</AbstractText> |
14,849 | Impact of type 2 diabetes and the metabolic syndrome on myocardial structure and microvasculature of men with coronary artery disease. | Type 2 diabetes and the metabolic syndrome are associated with impaired diastolic function and increased heart failure risk. Animal models and autopsy studies of diabetic patients implicate myocardial fibrosis, cardiomyocyte hypertrophy, altered myocardial microvascular structure and advanced glycation end-products (AGEs) in the pathogenesis of diabetic cardiomyopathy. We investigated whether type 2 diabetes and the metabolic syndrome are associated with altered myocardial structure, microvasculature, and expression of AGEs and receptor for AGEs (RAGE) in men with coronary artery disease.</AbstractText>We performed histological analysis of left ventricular biopsies from 13 control, 10 diabetic and 23 metabolic syndrome men undergoing coronary artery bypass graft surgery who did not have heart failure or atrial fibrillation, had not received loop diuretic therapy, and did not have evidence of previous myocardial infarction.</AbstractText>All three patient groups had similar extent of coronary artery disease and clinical characteristics, apart from differences in metabolic parameters. Diabetic and metabolic syndrome patients had higher pulmonary capillary wedge pressure than controls, and diabetic patients had reduced mitral diastolic peak velocity of the septal mitral annulus (E'), consistent with impaired diastolic function. Neither diabetic nor metabolic syndrome patients had increased myocardial interstitial fibrosis (picrosirius red), or increased immunostaining for collagen I and III, the AGE Nε-(carboxymethyl)lysine, or RAGE. Cardiomyocyte width, capillary length density, diffusion radius, and arteriolar dimensions did not differ between the three patient groups, whereas diabetic and metabolic syndrome patients had reduced perivascular fibrosis.</AbstractText>Impaired diastolic function of type 2 diabetic and metabolic syndrome patients was not dependent on increased myocardial fibrosis, cardiomyocyte hypertrophy, alteration of the myocardial microvascular structure, or increased myocardial expression of Nε-(carboxymethyl)lysine or RAGE. These findings suggest that the increased myocardial fibrosis and AGE expression, cardiomyocyte hypertrophy, and altered microvasculature structure described in diabetic heart disease were a consequence, rather than an initiating cause, of cardiac dysfunction.</AbstractText> |
14,850 | Increased prevalence of cardiovascular risk factors in patients with acute coronary syndrome and indications for treatment with oral anticoagulation. | Antiplatelet drugs currently constitute the basic treatment of coronary artery disease (acute coronary syndrome [ACS], stable angina and patients treated with percutaneous coronary interventions [PCI]). The number of patients with indication for dual antiplatelet therapy with comorbidities with high thrombo-embolic risk (such as atrial fibrillation [AF], venous thrombotic disease, valvular diseases) is increasing. That is why the need for simultaneous administration of dual antiplatelet and oral anticoagulant therapy (triple therapy) has become more common recently. The AF is the most common indication for chronic anticoagulation. Because of the lack of large randomised trials regarding triple therapy, characteristics of this group has not been well established.</AbstractText>To assess the presence of cardiovascular (CV) risk factors and concomitant diseases in patients with ACS requiring triple therapy.</AbstractText>Retrospective analysis included 2279 patients diagnosed with ACS who were admitted to the Departments of Cardiology in Cracow in 2008. In this group, 365 (16%) patients had indications for chronic anticoagulation. Demographic and clinical characteristics of these patients were compared with those of patients included in other published registries.</AbstractText>Patients requiring triple therapy were aged 73.2 ± 9.5 years. Hypertension was diagnosed in 80%, hyperlipidaemia in 63%, smoking in 36%, prior myocardial infarction in 33%, prior stroke in 15%, previous treatment with PCI in 13%, coronary artery bypass grafting in 7%, diabetes in 36%, heart failure in 46%, anaemia in 33% and chronic ulcer disease or gastroesophageal reflux disease in 9%. The mean left ventricular ejection fraction was 46 ± 15%. Compared with other registries of patients without indications for triple therapy, our patients had significantly more frequently hypertension, diabetes and were older.</AbstractText>Patients after an ACS requiring triple therapy have more often a history of comorbidities and CV risk factors when compared with the group of patients with ACS without indication for triple therapy.</AbstractText> |
14,851 | Beneficial effects of terlipressin in pediatric cardiac arrest. | : Vasopressin and its analog, terlipressin (TP), are potent vasopressors that may be useful therapeutic agents in the treatment of cardiac arrest (CA), septic and catecholamine-resistant shock, and esophageal variceal hemorrhage. The American Heart Association 2000 guidelines recommend its use for adult ventricular fibrillation arrest, and the American Heart Association 2005 guidelines note that it may replace the first or second epinephrine dose. There is little reported experience with TP in cardiopulmonary resuscitation (CPR) of children. The purpose of this retrospective case series was to report successful return of spontaneous circulation after the rescue administration of vasopressin after prolonged CA and failure of conventional CPR, advanced life support, and epinephrine therapy in children.</AbstractText>: Nine pediatric patients with asystole, aged 11 months to 14 years, who experienced 12 episodes of refractory CA and did not respond to conventional therapy. Terlipressin was administered as intravenous bolus doses of 20 mcg/kg to standard cardiopulmonary resuscitation.</AbstractText>: Return of spontaneous circulation was monitored and achieved in 6 of the 12 episodes. The mean duration of CPR was 24.8 minutes in these 12 episodes of CA with TP administration, with a range of 10 to 50 minutes (median, 23 minutes). Five survivors were discharged home without sequelae and with good neurologic status (score 1 by the pediatric cerebral performance category).</AbstractText>: The combination of TP to epinephrine during CPR may have a beneficial effect in children with CA. However, the recommendations for its use in the pediatric literature are based on limited clinical data.</AbstractText> |
14,852 | Preserved heart rate variability during therapeutic hypothermia correlated to 96 hrs neurological outcomes and survival in a pig model of cardiac arrest. | Therapeutic hypothermia initiated with cardiopulmonary resuscitation improves neurologic outcomes and survival after prolonged cardiac arrest. However, the potential mechanism by which hypothermia improves neurologic outcomes remains unclear. In the current study, we investigated the effect of rapid head cooling on 96-hr neurologic outcomes and survival by heart rate variability analysis in a pig model of prolonged cardiac arrest.</AbstractText>Prospective randomized controlled animal study.</AbstractText>University-affiliated research laboratory.</AbstractText>Yorkshire-X domestic pigs (Sus scrofa).</AbstractText>A protocol of 10 mins of untreated ventricular fibrillation followed by 5 mins of cardiopulmonary resuscitation in a pig model of cardiac arrest was used in this study. Sixteen male domestic pigs weighing between 39 and 45 kg were randomized into two groups, hypothermia (n = 8) and control (n = 8). For the hypothermia group, intranasal-induced head cooling was initiated with cardiopulmonary resuscitation and persisted for 4 hrs after resuscitation. For the control group, cardiopulmonary resuscitation was started with normothermia.</AbstractText>Time and frequency domain heart rate variability was calculated in 5-min sections of electrocardiographic recordings at baseline and 4 hrs after resuscitation. Neurologic outcomes were evaluated every 24 hrs during the 96-hr postresuscitation observation period. No differences in the baseline measurement and resuscitation outcome were observed between the groups. However, the 96-hr cerebral performance categories of the hypothermic group were significantly lower than control (1.0 ± 0.0 vs. 4.0 ± 1.9, p = .003). Four hrs after resuscitation, mean RR interval, heart rate variability triangular index, and normalized very-low-frequency power were restored to baseline in the hypothermia group. Square root of the mean squared differences of successive RR intervals and SD of instantaneous RR intervals were significantly improved in the cooled animals compared with controls. A significant correlation between 4-hr heart rate variability and 96-hr cerebral performance category was observed in this study.</AbstractText>Selective head cooling maintains a certain level of autonomic nervous system function in this pig model of cardiac arrest. The preserved heart rate variability during postresuscitation hypothermia was associated with favorable 96-hr neurologic recovery and survival.</AbstractText> |
14,853 | Left atrial remodeling and response to valsartan in the prevention of recurrent atrial fibrillation: the GISSI-AF echocardiographic substudy. | Left atrial (LA) dilation precedes or appears early after the onset of atrial fibrillation (AF) and factors in perpetuating the arrhythmia. Angiotensin receptor blockers were proposed for reversing LA remodeling. We evaluated the effect of valsartan on LA remodeling in patients with a recent episode of AF and the effect of LA size on AF recurrence (AFr).</AbstractText>LA and left ventricular (LV) echocardiographic variables were measured at baseline and 6 and 12 months in 340 patients from GISSI-AF, a trial testing valsartan prevention of AFr. Reversal of remodeling was considered as a decrease in LA size over 12 months. Changes in patients with and without recurrence and the relationship to duration of AFr were analyzed. Patients were 68.4±8.8 years old, with history of hypertension (85.3%) and cardioversion in the previous 2 weeks (87.4%) or ≥2 AFr in the previous 6 months (40.4%). Baseline LA maximal volume (LAVmax) was severely increased (>40 mL/m(2)); LV dimensions and function were relatively normal. Over 12 months, 54.4% of patients had AFr. LAVmax was unchanged by rhythm, time, or randomized treatment. Higher baseline LAVmax and lower LA emptying fraction were linearly related to increasing AFr duration during follow-up.</AbstractText>GISSI-AF patients in sinus rhythm and history of AF showed severely increased LAVmax with mostly normal LV volume, mass, and systolic and diastolic function. Valsartan for 1 year did not reverse LA remodeling or prevent AFr. Half of the patients without AFr had severe LA dilation; therefore, mechanisms other than structural remodeling triggered recurrence.</AbstractText> |
14,854 | Reliability of left ventricular volumes and function measurements using three-dimensional speckle tracking echocardiography. | Although the accuracy of three-dimensional speckle tracking echocardiography (STE) to quantify left ventricular (LV) volumes and function has been demonstrated, its reliability has not been studied in great detail. The aim of the study was to determine inter-observer, intra-observer, and test-retest reliability of echocardiographic measurements of LV volumes and function using three-dimensional STE.</AbstractText>A total of 140 consecutive patients presenting for routine echocardiographic examination underwent three-dimensional STE. Twenty-three of the 140 patients (16%) were excluded from the analysis due to atrial fibrillation or insufficient image quality. In the remaining 117 patients [69 males, age 59 ± 16 years, ejection fraction (EF) 51 ± 13%], intra-observer and inter-observer reliability of LV volumes, EF, and global and segmental strain measurements was determined, whereas test-retest reliability was assessed in a subgroup of 50 patients. LV volumes and EF measurements demonstrated good reliability [intraclass correlation coefficient (ICC): 0.85-0.99; standard error of measurement (SEM): 3.1-9.2 mL and 1.7-4.0%, respectively]. Reliability of global circumferential strain measurements (ICC: 0.85-0.97; SEM: 1.4-2.6%) was superior to longitudinal (ICC: 0.66-0.92; SEM: 1.0-2.1%) and radial strain measurements (ICC: 0.52-0.88; SEM: 4.4-8.1%), with similar results found for segmental strain measurements (P < 0.001 for all). Reliability was not significantly affected by the image quality or temporal resolution of 3D data sets for any parameter.</AbstractText>Good intra-observer, inter-observer, and test-retest reliability support the use of three-dimensional STE for routine evaluation of LV volumes and EF. Global and segmental circumferential strain measurements also demonstrate high reliability, whereas analysis by a single observer is currently recommended for longitudinal and radial strain due to limited inter-observer and test-retest reliability.</AbstractText> |
14,855 | Imaging cardio-vascular anatomy and function in D-Transposition of the great arteries after mustard procedure. | We used cardiovascular magnetic resonance (CMR) to demonstrate cardio-vascular anatomy and function in a 42 year-old man with a D-Transposition of the great arteries who survived a sudden cardiac arrest. |
14,856 | Human atrial action potential and Ca2+ model: sinus rhythm and chronic atrial fibrillation. | Understanding atrial fibrillation (AF) requires integrated understanding of ionic currents and Ca2+ transport in remodeled human atrium, but appropriate models are limited.</AbstractText>To study AF, we developed a new human atrial action potential (AP) model, derived from atrial experimental results and our human ventricular myocyte model.</AbstractText>Atria versus ventricles have lower I(K1), resulting in more depolarized resting membrane potential (≈7 mV). We used higher I(to,fast) density in atrium, removed I(to,slow), and included an atrial-specific I(Kur). I(NCX) and I(NaK) densities were reduced in atrial versus ventricular myocytes according to experimental results. SERCA function was altered to reproduce human atrial myocyte Ca2+ transients. To simulate chronic AF, we reduced I(CaL), I(to), I(Kur) and SERCA, and increased I(K1),I(Ks) and I(NCX). We also investigated the link between Kv1.5 channelopathy, [Ca2+]i, and AF. The sinus rhythm model showed a typical human atrial AP morphology. Consistent with experiments, the model showed shorter APs and reduced AP duration shortening at increasing pacing frequencies in AF or when I(CaL) was partially blocked, suggesting a crucial role of Ca2+ and Na+ in this effect. This also explained blunted Ca2+ transient and rate-adaptation of [Ca2+]i and [Na+]i in chronic AF. Moreover, increasing [Na+]i and altered I(NaK) and I(NCX) causes rate-dependent atrial AP shortening. Blocking I(Kur) to mimic Kv1.5 loss-of-function increased [Ca2+]i and caused early afterdepolarizations under adrenergic stress, as observed experimentally.</AbstractText>Our study provides a novel tool and insights into ionic bases of atrioventricular AP differences, and shows how Na+ and Ca2+ homeostases critically mediate abnormal repolarization in AF.</AbstractText> |
14,857 | Prophylactic implantable cardioverter-defibrillator treatment in the elderly: therapy, adverse events, and survival gain. | In elderly patients, obscurity remains regarding the benefit of implantable cardioverter-defibrillator (ICD) treatment as primary prevention of sudden cardiac death. This study assesses implant rates, therapy, adverse events, and survival gain in the elderly primary prevention ICD patient.</AbstractText>A total of 1395 patients treated with an ICD for primary prevention of sudden cardiac death at the Leiden University Medical Center were included and allocated to three groups according to age. Endpoints consisted of appropriate shocks and survival gain, defined as the time following first appropriate ICD shock to death. Mean follow-up was 2.9 ± 2.1 years. Fifty-one per cent of the patients were <65 years, 35% were 65-74 years, and 14% were ≥75 years. Prior to the year 2000, no ICDs were implanted in patients ≥75 years; 29% of the ICDs were implanted in patients 65-74 years. After 2005, 53% of the ICD recipients were ≥65 years at the time of implant, including 16% aged ≥75 years (P = 0.03). Five-year cumulative incidence of appropriate shocks was 19% for patients <65 years, 23% for patients 65-74 years, and 13% for patients ≥75 years (P = 0.47). At 1-year following appropriate shock, cumulative incidence for death was 35% for patients ≥75 years as compared with 7% for patients <65 years (P < 0.01).</AbstractText>In routine clinical practice, the percentage of patients ≥75 years receiving an ICD for primary prevention is increasing. Despite experiencing comparable rates of appropriate ICD shocks, life prolongation by ICD is significantly less in elderly as compared to younger patients.</AbstractText> |
14,858 | Evolutionary innovations in cardiac pacing. | Cardiac pacing has played a significant role in mitigating morbidity and mortality associated with bradyarrhythmias. Throughout the years, advances made in battery reliability, lead performance, and device portability have rapidly expanded the use of cardiac pacemakers in many different disease states. Despite the benefits, there has been growing awareness of the potential deleterious effects of long-term artificial electrical stimulation including the development of ventricular dyssynchrony and atrial fibrillation. Given their association with an increased risk for heart failure and possibly death, several advances aimed at minimizing them have been made in recent years including changes in atrioventricular pacing algorithms, novel pacing mode modifications, and better identification of hemodynamically optimal pacing sites. This article reviews the advances made and the future direction of innovations in cardiac pacing. |
14,859 | Anticoagulation therapy in older adults newly diagnosed with atrial fibrillation. | Atrial fibrillation (AF) is the most common chronic arrhythmia and the most serious heart rhythm irregularity in individuals older than 70. It is usually not life threatening in and of itself, but it can lead to serious medical problems, including stroke, additional heart rhythm problems, and heart failure. Symptoms of AF vary considerably. Some patients are asymptomatic and have a self-limiting arrhythmia of short duration that converts to normal sinus without any intervention. Symptomatic patients may experience minor palpitations, severe palpitations, or even more vague symptoms such as lightheadedness, shortness of breath, or fatigue. More serious symptoms, such as syncope, new or worsening heart failure, or a cerebral vascular accident, may occur. The initial goals of treatment include controlling ventricular rate and addressing anticoagulation status. New guidelines help clinicians effectively manage anticoagulant therapy for older adults newly diagnosed with AF. |
14,860 | Life-threatening atrial tachycardia after the Senning operation in a patient with transposition of the great arteries. | Atrial tachycardia (AT) is recognized as a risk factor of sudden death (SD) in patients with transposition of the great arteries (TGA) after atrial switch operation. A 20-year-old man with TGA who had undergone a Senning operation experienced a near-miss SD event 1 day after appearance of AT. He was successfully resuscitated by electrical defibrillation for documented ventricular fibrillation. An electrophysiological study showed three types of AT, and all of them were terminated by radiofrequency catheter ablation (RFCA). We consider that symptomatic AT against cardiac medications is indicated for RFCA therapy. |
14,861 | Long-term cognitive outcomes following out-of-hospital cardiac arrest: a population-based study. | To report the neurologic outcomes in long-term survivors of out-of-hospital cardiac arrest with ventricular fibrillation as the presenting rhythm (OHCA VF) at a population level.</AbstractText>All adults who experienced OHCA VF in Olmsted County, MN, from 1990 to 2008, survived more than 6 months postarrest, and were alive at the time of study recruitment were invited to participate in structured neuropsychological testing and a neurologic examination. Cognitive test results were compared to the normal population using the Mayo's Older Adults Normative Studies. Linear regression models were fit to evaluate each neuropsychological test result in relation to call-to-shock time, sex, age at cardiac arrest, time elapsed since event, witnessed vs unwitnessed arrest, and administration of bystander cardiopulmonary resuscitation.</AbstractText>Of 332 OHCA VF arrests, 140 people (42.2%, 95% confidence interval 36.9%-47.5%) survived to discharge. No patient entered a minimally conscious or permanent vegetative state. Long-term survivors (n = 47, median survival 7.8 years postarrest) had lower scores on measures of long-term memory and learning efficiency (p = 0.001) but higher than average scores on verbal IQ (p = 0.001). Nearly all survivors were functionally independent and scored high on the Mini-Mental State Examination (MMSE) (median Barthel Index 100/100, median MMSE 29/30).</AbstractText>Long-term survivors of OHCA VF have long-term memory deficits compared to the normal population at the same age and education level. These findings provide a baseline for cognitive outcomes studies of OHCA VF as new techniques are developed to improve survival.</AbstractText> |
14,862 | Cardiac manifestations of myotonic dystrophy type 1. | To estimate the degree of cardiac involvement regarding left ventricular ejection fraction, conduction abnormalities, arrhythmia, risk of sudden cardiac death (SCD) and the associations between cardiac involvement and cytosine-thymine-guanine (CTG)-repeat, neuromuscular involvement, age and gender in patients with myotonic dystrophy type 1 (MD1).</AbstractText>A Pub-Med search for the period 1980 to 2010 was performed according to specified criteria. Cardiac parameters including left ventricular ejection fraction (LVEF), conduction abnormalities and arrhythmia were compiled and only studies without ascertainment bias were included. Eighteen studies, 1828 MD1-patients, were included. The prevalence of atrioventricular block grade 1 (AVB1) was 28.2%, QTc>440 ms 22%, QRS>120 ms 19.9%, frequent ventricular premature contractions (VPC) 14.6%, atrial fibrillation/flutter (AF/AFL) 5%, right/left bundle branch block (RBBB/LBBB) 4.4/5.7% and non-sustained ventricular tachycardia (NSVT) 4.1%. Left ventricular systolic dysfunction (LVSD) was reported in 7.2% of the patients. There was an overall positive association between CTG-repeat size and cardiac involvement and between the degree of neuromuscular and cardiac involvement. Male gender and age were positively associated with arrhythmia and conduction abnormalities. The prevalence of pacemaker- (PM) and implantable cardioverter defibrillator-(ICD) implantations were 4.1% and 1.1%, respectively. The risk of SCD in this MD1-population was 0.56% per year.</AbstractText>MD1-patients have a high level of cardiac morbidity and mortality, strongly emphasizing the need of pre-symptomatic screening for arrhythmia and heart failure, as effective and well-documented preventive means are available.</AbstractText>Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,863 | Cardiac remodeling with rhythm versus rate control strategies for atrial fibrillation in patients with heart failure: insights from the AF-CHF echocardiographic sub-study. | In patients with heart failure and atrial fibrillation, the AF-CHF (Atrial Fibrillation and Congestive Heart Failure) trial did not demonstrate the superiority of rhythm control (RhyC) over a rate control (RaC) strategy on cardiovascular mortality. Nevertheless, deleterious hemodynamic effects of atrial fibrillation can lead to further decrease in left ventricular (LV) function and progression of symptoms. This echocardiographic sub-study was designed to compare the effects of the two treatment strategies on LV ejection fraction (LVEF), chamber volumes and dimensions, valvular regurgitation and functional status.</AbstractText>A total of 59 patients (29 RhyC, 30 RaC) aged 67±8 years (14% women), enrolled in the AF-CHF trial at the Montreal Heart Institute underwent standardized echocardiograms at baseline and at 12 months. Mean LVEF at baseline was severely depressed (RhyC: 27.0±4.9% and RaC: 27.6±7.4%, p=0.73), and improved to a similar degree in both groups (RhyC: +8.0±10.4% and RaC: +4.5±10.6, both p<0.05; p=0.19 for RhyC versus RaC). Other echocardiographic parameters, such as LV end-systolic volume index and degree of mitral and tricuspid regurgitation, remained unchanged. New York Heart Association functional class and distance walked in 6 min improved significantly in both groups (RhyC: +48.9±78.7 m and RaC: +47.2±96.7 m, both p≤0.01), with no difference between RhyC and RaC strategies.</AbstractText>Improvements in LVEF and functional status are observed after 12 months in patients with heart failure and atrial fibrillation, regardless of whether rate or rhythm control strategies are used.</AbstractText>Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,864 | Suppression of ischemic and reperfusion ventricular arrhythmias by inhalational anesthetic-induced preconditioning in the rat heart. | Inhalational anesthetic-induced preconditioning (APC) has been shown to reduce infarct size and attenuate contractile dysfunction caused by myocardial ischemia. Only a few studies have reported the effects of APC on arrhythmias during myocardial ischemia-reperfusion injury, focusing exclusively on reperfusion. Accordingly, the aim of the present study was to examine the influence of APC on ventricular arrhythmias evoked by regional no-flow ischemia. APC was induced in adult male Wistar rats by 12-min exposures to two different concentrations (0.5 and 1.0 MAC) of isoflurane followed by 30-min wash-out periods. Ventricular arrhythmias were assessed in the isolated perfused hearts during a 45-min regional ischemia and a subsequent 15-min reperfusion. Myocardial infarct size was determined after an additional 45 min of reperfusion. The incidence, severity and duration of ventricular arrhythmias during ischemia were markedly reduced by APC. The higher concentration of isoflurane had a larger effect on the incidence of ventricular fibrillation than the lower concentration. The incidence of ventricular tachycardia and reversible ventricular fibrillation during reperfusion was also significantly reduced by APC; the same was true for myocardial infarct size. In conclusion, we have shown that preconditioning with isoflurane confers profound protection against myocardial ischemia- and reperfusion-induced arrhythmias and lethal myocardial injury. |
14,865 | Distinguishing "benign" from "malignant early repolarization": the value of the ST-segment morphology. | Means for distinguishing the very common "benign early repolarization" from the very rare but malignant form are needed. Recently, the presence of early repolarization with "horizontal ST segment" was found to predict arrhythmic death during long-term follow-up in a large population study. We therefore speculated that the combination of "J waves with horizontal ST segment" would correlate with a history of idiopathic ventricular fibrillation (VF) better than the mere presence of J waves.</AbstractText>To determine whether the morphology of the ST segment adds diagnostic value to the mere presence of J waves in a case-control series of idiopathic VF.</AbstractText>We reanalyzed our case-control study showing that the presence of J waves strongly correlates with a history of idiopathic VF among 45 patients with this disorder, 124 controls matched for age and gender ("matched-control" group), and 121 young athletes. This time we focused only on those patients with J waves and graded their ST-segment morphology as either "horizontal" or "ascending" according to predefined criteria.</AbstractText>The presence of J waves was associated with a history of idiopathic VF with an odds ratio of 4.0 (95% confidence intervals = 2.0-7.9), but having both J waves and horizontal ST segment yielded an odds ratio of 13.8 (95% confidence intervals = 5.1-37.2) for having idiopathic VF.</AbstractText>We report, for the first time, that the combination of J waves with horizontal/descending ST segment improved our ability to distinguish patients with idiopathic VF from controls matched by gender and age.</AbstractText>Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,866 | Inflammatory activation and carbohydrate antigen-125 levels in subjects with atrial fibrillation. | Atrial fibrillation (AF) might be associated with an inflammatory activation and reduced left ventricular (LV) function. Less is known with regard to newly introduced markers of LV dysfunction such as carbohydrate antigen-125 (CA-125) in subjects with AF. The aim of this study was therefore to assess possible associations between AF, inflammatory markers and CA-125.</AbstractText>Forty-eight consecutive patients with AF and 58 control patients in sinus rhythm were enrolled in this study. Patients with acute heart failure, chronic inflammatory or neoplastic disease were excluded from the study. Circulating levels of hs-C-reactive protein (CRP), interleukin-8 (IL-8), IL-6, soluble IL-2 receptor (sIL-2r), TNF-α and CA-125 were assessed; all patients underwent clinical examination with NYHA class assessment and echocardiography. Patients with AF were characterised by higher levels of IL-8 (180 ± 266 vs. 39 ± 43 pg/mL, P < 0·001), sIL-2r (987 ± 1045 vs. 680 ± 336 U/mL, P < 0·05) and TNF-α (26 ± 25 vs. 9 ± 4 pg/mL, P < 0·001). Patients with AF duration < 6 months had higher levels of CRP (54 ± 73 vs. 12 ± 14 mg/dL, P < 0·05) and IL-8 (251 ± 225 vs. 99 ± 123 pg/mL, P < 0·05) when compared with AF duration > 6 months. CA-125 levels were not statistically different if comparing subjects with AF with controls and AF > 6 months with AF < 6 months. Among patients with AF, CA-125 levels were significantly related to NYHA class, (r = 0·33, P < 0·05) as well as IL-6 levels (r = 0·31, P < 0·05). Results remained statistically significant even after multivariable correction for age, gender and LV ejection fraction.</AbstractText>AF is characterised by an inflammatory activation. Impaired functional class in AF subjects might be associated with increased CA-125 levels and higher inflammatory markers.</AbstractText>© 2011 The Authors. European Journal of Clinical Investigation © 2011 Stichting European Society for Clinical Investigation Journal Foundation.</CopyrightInformation> |
14,867 | [Totally subcutaneous cardioverter-defibrillator (S-ICD®) : recent experience and future perspectives]. | The implantable cardioverter defibrillator (ICD) is an established therapy for patients at risk of sudden cardiac death. Nevertheless the endocardial electrode in conventional systems plays a major role in long-term complications (difficult removal, risk of endocarditis, etc.). The totally subcutaneous ICD (S-ICD®, Cameron Health, San Clemente, CA, USA) represents a new and particularly significant development in ICD therapy which, since it requires no electrode in or on the heart, results in significantly fewer perioperative and long-term complications (e.g., thromboembolism and endocarditis risk). Although we see an indication for primary and secondary prevention, patients need to be informed about the limited data from randomized trials with the S-ICD®. As there is no permanent pacing option, patients in whom a pacemaker is indicated are not appropriate candidates for S-ICD®. In addition, patients with ventricular tachycardias that can be terminated by antitachycardic pacing are not recommended for the device. In the present article, we report our initial experience with the 18 patients implanted with the S-ICD® to date, comment on the available studies and offer a critical perspective. |
14,868 | [Treating congestive heart failure with cardiac contractility modulation (CCM) : possibilities and study overview]. | Cardiac contractility modulation (CCM) is a device therapy for patients with systolic heart failure. CCM therapy applies non-excitatory signals during the absolute refractory period of the heart cycle. It influences myocardial contractility by modulating the regulation of calcium cycling. CCM therapy has been proven to enhance peak VO(2), quality of life and exercise tolerance in patients with congestive heart failure. It can be used as an additional therapy to an implantable cardioverter defibrillator (ICD), if present. CCM therapy should be considered in symptomatic patients with congestive heart failure, a left ventricular ejection fraction ≤35% and NYHA class II-III. Atrial fibrillation, high grade arrhythmias and an AV block of more than 300 ms represent contraindications. Patients with a left bundle branch block of >120 ms should be considered for the implantation of a biventricular ICD prior to implantation of a CCM device. |
14,869 | Recurrent torsades de pointes after catheter ablation of incessant ventricular bigeminy in combination with QT prolongation. | A 45-year-old woman, who had received a single-chamber implantable cardioverter defibrillator (ICD) due to ventricular fibrillation 5 years ago, was admitted for catheter ablation of incessant right ventricular outflow tract bigeminy. After successful ablation recurrent torsades de pointes associated with a prolonged corrected QT (QTc) interval were initiated by polymorphic premature ventricular complexes. Genetic testing revealed a heterozygous missense mutation in the SCN5A-gene (p.Arg190Gln, Exon 5), consistent with long QT-syndrome 3. DDDR pacing following implantation of an atrial lead prevented further ventricular tachyarrhythmias. |
14,870 | Association of rate-controlled persistent atrial fibrillation with clinical outcome and ventricular remodelling in recipients of cardiac resynchronization therapy. | Whether patients with persistent atrial fibrillation (AF) obtain the same degree of benefit with cardiac resynchronization therapy (CRT) as those in sinus rhythm remains unclear.</AbstractText>We enrolled 93 patients undergoing CRT implantation, 20 (22%) of whom had rate-controlled persistent AF. The primary endpoint was CRT response defined as 1 class improvement in Specific Activity Scale and 15% reduction in left ventricular end-systolic volume (LVESV) during 12 months. Other endpoints included changes in 6-minute walk distance, quality of life, B-type natriuretic peptide, and survival.</AbstractText>Baseline characteristics were similar in those with and without AF. Response to CRT was observed in 42% vs 54% of those with and without AF, respectively (P=0.3). Both groups had significant improvements in 6-minute walk distance, quality of life, and LVESV, but the improvement in LVESV was smaller in those with AF (13.7%±14.9% vs 27.7%±23.7%; P=0.02). During 2.8±1.4 years of follow-up, AF was associated with a 2.2-fold increased risk of death or transplantation (95% confidence interval, 1.2-3.9; P=0.01).</AbstractText>Compared with patients without rate-controlled persistent AF, those with rate-controlled persistent AF had similar rates of clinical improvement but less left ventricular reverse remodelling in the first year after CRT. AF was associated with a markedly higher risk of death or transplantation in long-term follow-up. Given these findings, randomized studies assessing CRT efficacy in those with AF are warranted.</AbstractText>Copyright © 2011 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,871 | J-wave syndromes. from cell to bedside. | The J wave, a deflection that follows the QRS complex of the surface electrocardiogram, is usually partially buried in the R wave in humans, appearing as a J-point elevation. An early repolarization (ER) pattern characterized by J-point elevation, slurring of the terminal part of the QRS, and ST-segment elevation has long been recognized and considered to be totally benign. Recent studies have presented evidence demonstrating that an ER pattern in inferior leads or inferolateral leads is associated with increased risk for life-threatening arrhythmias, named early repolarization syndrome. Early repolarization syndrome and Brugada syndrome share similar electrocardiographic characteristics, clinical outcomes, risk factors, as well as a common arrhythmic platform related to amplification of I(to)-mediated J waves. Although Brugada syndrome and early repolarization syndrome differ with respect to the magnitude and lead location of abnormal J wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression, termed J-wave syndromes. Early repolarization syndrome has been proposed to be divided into 3 subtypes: type 1, displaying an ER pattern predominantly in the lateral precordial leads, is prevalent among healthy male athletes and rarely seen in ventricular fibrillation survivors; type 2, displaying an ER pattern predominantly in the inferior or inferolateral leads, is associated with a higher level of risk; whereas type 3, displaying an ER pattern globally in the inferior, lateral, and right precordial leads, is associated with the highest level of risk for development of malignant arrhythmias and is often associated with ventricular fibrillation storms. |
14,872 | Atrial fibrillatory rate and irregularity of ventricular response as predictors of clinical outcome in patients with atrial fibrillation. | Atrial fibrillation (AF) remains the most common arrhythmia encountered in clinical practice. Electrocardiogram (ECG)-based predictors of clinical outcome, however, have mostly been studied during sinus rhythm, whereas noninvasive risk stratification of patients with AF remains largely unexplored. Advances in ECG signal processing have led to the development of noninvasive methods of atrial fibrillatory rate (AFR) assessment using spatiotemporal QRST cancellation and time frequency analysis that demonstrated its predictive value for the outcome of pharmacologic and catheter-based interventions for AF. Recently, the prognostic value of AFR was evaluated in patients with congestive heart failure and indicated that reduced AFR may be an independent predictor of total and congestive heart failure-related mortality. A high degree of irregularity of the RR intervals during AF and its dependence on the modulation of the atrioventricular conduction rather than sinus node automaticity hampers the use of conventional heart rate variability approach in patients with AF. However, RR irregularity measures that can be applied to short-time ECG recordings appear to be promising predictors of clinical outcome. |
14,873 | Genetic suppression of atrial fibrillation using a dominant-negative ether-a-go-go-related gene mutant. | Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Gene therapy-dependent modulation of atrial electrophysiology may provide a more specific alternative to pharmacological and ablative treatment strategies.</AbstractText>We hypothesized that genetic inactivation of atrial repolarizing ether-a-go-go-related gene (ERG) K(+) currents using a dominant-negative mutant would provide rhythm control in AF.</AbstractText>Ten domestic swine underwent pacemaker implantation and were subjected to atrial burst pacing to induce persistent AF. Animals were then randomized to receive either AdCERG-G627S to suppress ERG/I(Kr) currents or green fluorescent protein (AdGFP) as control. Adenoviruses were applied using a novel hybrid technique combining atrial virus injection and epicardial electroporation to increase transgene expression.</AbstractText>In pigs treated with AdCERG-G627S, the onset of persistent AF was prevented (n = 2) or significantly delayed compared with AdGFP controls (12 ± 2.1 vs. 6.2 ± 1.3 days; P < .001) during 14-day follow-up. Effective refractory periods were prolonged in the AdCERG-G627S group compared with AdGFP animals (221.5 ± 4.7 ms vs. 197.0 ± 4.7 ms; P < .006). Impairment of left ventricular ejection fraction (LVEF) during AF was prevented by AdCERG-G627S application (LVEF(CERG-G627S) = 62.1% ± 4.0% vs. LVEF(GFP) = 30.3% ± 9.1%; P < .001).</AbstractText>Inhibition of ERG function using atrial AdCERG-G627S gene transfer suppresses or delays the onset of persistent AF by prolongation of atrial refractoriness in a porcine model. Targeted gene therapy represents an alternative to pharmacological or ablative treatment of AF.</AbstractText>Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,874 | Increased d-dimer levels predict cardiovascular mortality in patients with systolic heart failure. | D-dimer is a fibrin degradation product, and is implicated in pathologies of cardiovascular system. Thrombosis within the vascular system in relation with inflammation and stasis might be associated with poor prognosis in patients with systolic heart failure (HF). In this study we aimed to investigate for relationship between d-dimer levels and cardiovascular mortality in patients with systolic HF. A total of 174 consecutive patients with hospitalized systolic HF were evaluated. All hospitalized patients were obtained d-dimer levels within the first 24 h following admission after obtaining informed consent. Patients were followed up for cardiovascular mortality and 40 (23%) patients died. d-dimer levels were higher among those who died compared to those who survived (2727 ± 2569 (710-4438) versus. 1029 ± 1319 (303-1061) ng/ml, P < 0.001). Optimal cut-off level of d-dimer to predict cardiovascular mortality was found to be >1435 ng/ml. D-dimer levels were negatively correlated with ejection fraction, positively correlated with left atrium size and left ventricular diastolic diameter. D-dimer >1435 ng/ml, age, diabetes mellitus, presence of atrial fibrillation, and creatinine level were found to have prognostic significance in univariate analyses. In multivariate Cox proportional-hazards model, d-dimer > 1435 ng/ml (HR = 3.250, 95% CI 1.647-6.414, P = 0.001), creatinine level (HR = 1.269, 95% CI 1.008-1.599, P = 0.043), and presence of atrial fibrillation (HR = 2.159, 95% CI 1.047-4.452, P = 0.037) remained associated with an increased risk of death after adjustment for variables found to be statistically significant in univariate analysis and correlated with d-dimer level. In conclusion, d-dimer measurement could help risk stratification in patients with systolic HF. |
14,875 | Elevated γ-glutamyltransferase in implantable cardioverter defibrillator patients. | Elevated γ-glutamyltransferase (GGT) is a new risk factor for cardiovascular diseases, but its impact on ventricular tachyarrhythmia occurrence and survival in patients with an implantable cardioverter defibrillator (ICD) is unknown.</AbstractText>Considering that GGT levels are gender-dependent, female ICD recipients were excluded from our database because of the low incidence of events. In a retrospective analysis, appropriate ICD therapy (both shocks and antitachycardia pacing due to ventricular tachyarrhythmias) occurred in 31.9% of 320 male patients who had received an ICD for primary prevention (median follow-up of 2.3 years), and in 55.1% of 423 male patients who had received an ICD for secondary prevention (median follow-up of 3.9 years). Compared to normal low GGT plasma levels (below 28 U/L), total mortality but not risk for appropriate ICD therapy was elevated for higher GGT categories (p for trend = 0.004 in primary prevention and p for trend = 0.002 in secondary prevention, respectively). In Cox regression analysis, elevated GGT (>56 U/L) remained an independent predictor of death both in primary (p = 0.011) and in secondary prevention (p = 0.006). Patients with elevated GGT and renal insufficiency defined by an estimated glomerular filtration rate <60 ml/min/1.73 m(2) suffered from excess total mortality jeopardizing the benefit of ICD therapy.</AbstractText>Elevation of GGT is an important adverse prognostic parameter in ICD patients. A possible role of GGT for improved patient selection for ICD therapy deserves further investigation.</AbstractText> |
14,876 | Clinical characteristics of patients with atrial fibrillation at a tertiary care hospital in the central region of Saudi Arabia. | To report on the clinical presentation, etiology, and laboratory features of acute and chronic atrial fibrillation (AF) in a tertiary hospital in Riyadh, Saudi Arabia.</AbstractText>We retrospectively studied records of 720 patients with AF seen in outpatients and inpatients departments at King Abdulaziz Medical City, Riyadh, during the period of 1 January 2002 to 31 August 2008.</AbstractText>Documented acute and chronic AF was present in 157 (21.8%) and 563 (78.1%) patients, respectively. Palpitations, dizziness and syncope were the most frequent symptoms in acute AF, while dyspnea and palpitations were the most common symptoms in the chronic type. Acute respiratory problems and acute myocardial infarction were significantly more common in acute AF, while congestive heart failure and acute respiratory problems (chest infection, bronchial asthma, and pulmonary embolism) were significantly more common in chronic AF. The most common causes of both types of AF were diabetes mellitus (DM) in 68.8%, hypertension (HTN) in 59.3%, chronic lung diseases (bronchial asthma, chronic obstructive pulmonary disease and interstitial lung disease) in 31.8%, valvular heart disease in 23.6%, and ischemic heart disease (IHD) in 23.1%. In 9 (1.3%) patients, no cause was detected. The echocardiographic findings of left ventricular hypertrophy, valve lesions, and depressed left ventricular function were significantly more common in chronic AF (P<0.01).</AbstractText>Nowadays, DM, HTN, and IHD are becoming the most common predisposing factors for AF in the central region of Saudi Arabia and require prevention and control.</AbstractText> |
14,877 | Impairment of pulmonary function is an independent risk factor for atrial fibrillation: the Takahata study. | Chronic pulmonary disorders, such as chronic obstructive pulmonary disease (COPD) and fibrosing lung diseases, and atrial fibrillation (AF), are prevalent in elderly people. The impact of cardiac co-morbidities in the elderly, where pulmonary function is impaired, cannot be ignored as they influence mortality. The relationship between the prevalence of AF and pulmonary function is unclear. The aim of this study was to evaluate this relationship in participants in a health check.</AbstractText>Subjects aged 40 or older (n = 2,917) who participated in a community-based annual health check in Takahata, Japan, from 2004 through to 2005, were enrolled in the study. We performed blood pressure measurements, blood sampling, electrocardiograms, and spirometry on these subjects.</AbstractText>The mean FEV(1) % predicted and FVC % predicted in AF subjects was significantly lower than in non-AF subjects. The prevalence of AF was higher in those subjects with airflow limitation or lung restriction than in those without. Furthermore, AF prevalence was higher in those subjects with severe airflow obstruction (FEV(1) %predicted < 50) than in those who had mild or moderate airflow obstruction (FEV(1) %predicted ≥ 50), although there was no difference between the prevalence of AF in subjects with 70≤ FVC %predicted <80 lung restriction and those with FVC %predicted <70. Multiple logistic regression analysis revealed that FEV(1) %predicted and FVC %predicted are independent risk factors for AF (independent of age, gender, left ventricular hypertrophy, and serum levels of B-type natriuretic peptide).</AbstractText>Impaired pulmonary function is an independent risk factor for AF in the Japanese general population.</AbstractText> |
14,878 | Multiple arrhythmic syndromes in a newborn, owing to a novel mutation in SCN5A. | Mutations in the SCN5A gene have been linked to Brugada syndrome (BrS), conduction disease, Long QT syndrome (LQT3), atrial fibrillation (AF), and to pre- and neonatal ventricular arrhythmias.</AbstractText>The objective of this study is to characterize a novel mutation in Na(v)1.5 found in a newborn with fetal chaotic atrial tachycardia, post-partum intraventricular conduction delay, and QT interval prolongation.</AbstractText>Genomic DNA was isolated and all exons and intron borders of 15 ion-channel genes were sequenced, revealing a novel missense mutation (Q270K) in SCN5A. Na(v)1.5 wild type (WT) and Q270K were expressed in CHO-K1 with and without the Na(v)β1 subunit. Results. Patch-clamp analysis showed ∼40% reduction in peak sodium channel current (I(Na)) density for Q270K compared with WT. Fast and slow decay of I(Na) were significantly slower in Q270K. Steady-state activation and inactivation of Q270K channels were shifted to positive potentials, and window current was increased. The tetrodotoxin-sensitive late I(Na) was increased almost 3-fold compared with WT channels. Ranolazine reduced late I(Na) in WT and Q270K channels, while exerting minimal effects on peak I(Na).</AbstractText>The Q270K mutation in SCN5A reduces peak I(Na) while augmenting late I(Na), and may thus underlie the development of atrial tachycardia, intraventricular conduction delay, and QT interval prolongation in an infant.</AbstractText> |
14,879 | Low safety index of domperidone: mechanism for increased odds ratio for sudden cardiac death. | Domperidone is a dopamine antagonist with anti-nausea and anti-emetic activity. There have been several reports of sudden cardiac death (SCD) associated with the compound. Recently it was estimated to increase SCD nearly fourfold. I therefore tested domperidone for liability of cardiac repolarization disturbances (triangulation, reverse use dependence, instability and dispersion or TRIaD) and induction of arrhythmias.</AbstractText>In Langendorff perfused rabbit hearts, domperidone significantly prolonged the action potential duration starting at 30 nM. It induced proarrhythmic TRIaD from 100 nM on. Since therapeutic free drug concentrations extend to 19 nM, the safety ratio for domperidone equals 100/19 = 5.25, i.e., far below the minimum safety ratio of 30. Hence, widespread use of domperidone cannot be without danger; especially since it is frequently used as an over the counter medication.</AbstractText>In light of these new preclinical and of recent clinical warnings, domperidone should best be restricted to patients in whom its benefit is proven to justify the risks. Availability without prescription and advertising as an 'innocent' relief is incorrect and unsafe, and needs to be reconsidered.</AbstractText> |
14,880 | QRS duration and QTc interval are predictors of risk for ventricular arrhythmias during cardiac resynchronization therapy. | QRS duration (QRSd) and prolonged corrected QT interval (QTc) are associated with ventricular arrhythmic events. This study was designed to determine whether CRT by means of biventricular pacing alters the QTc and QRSd, and whether such changes are related to the risk of sustained ventricular tachyarrhythmias (sVTA).</AbstractText>A total of 127 patients (102 men, mean age 63.9 +/- 8.9 years) with drug-resistant heart failure and QRS duration > or = 130 ms underwent CRT/CRT-ICD. The aetiology of the heart failure was ischaemic in 41 patients (32.3%). After a median follow-up of 24 months, 42 sVTA occurred in 35 patients (27.6%). Twenty-nine patients had a single sVTA, in five patients two sVTA and in one patient three sVTA occurred. The paced QTc was longer in sVTA patients (505 +/- 55 ms) compared with no sVTA patients (486 +/- 44 ms, P < or = 0.003). Similar responses for paced QRSd were observed (182 +/- 27 ms in sVTA patients vs 167 +/- 27 ms in no-sVTA patients, P < or = 0.03). This effect was independent from intrinsic QTc and QRSd and the aetiology of the heart failure. The mortality rate was significantly higher in patients with ventricular fibrillation and fast VT (P < or = 0.004) who experienced shock therapies. However, the sVTA were not the immediate cause of death.</AbstractText>A pacing-induced increase in QTc and QRSd is related to sVTA in patients with CRT. Further studies are needed to determine whether optimization of CRT with the goal to achieve a narrow paced QRSd can reduce the occurrence of sVTA.</AbstractText> |
14,881 | Relation of milrinone after surgery for congenital heart disease to significant postoperative tachyarrhythmias. | Milrinone reduces the risk of low cardiac output syndrome for some pediatric patients after congenital heart surgery. Data from adults undergoing cardiac surgery suggest an association between milrinone and an increased risk of postoperative arrhythmias. We tested the hypothesis that milrinone is an independent risk factor for tachyarrhythmias after congenital heart surgery. Subjects undergoing congenital heart surgery at our institution were consecutively enrolled for 38 months, through September 2010. The data were prospectively collected, including a review of full-disclosure telemetry and the medical records. Within 38 months, 603 enrolled subjects underwent 724 operative procedures. The median age was 5.5 months (range 0.0 to 426), the median weight was 6.0 kg (range 0.7 to 108), and the cohort was 45% female. The overall arrhythmia incidence was 50%, most commonly monomorphic ventricular tachycardia (n = 85, 12%), junctional ectopic tachycardia (n = 69, 10%), accelerated junctional rhythm (n = 58, 8%), and atrial tachyarrhythmias (including atrial fibrillation, atrial flutter, and ectopic or chaotic atrial tachycardia, n = 58, 8%). Multivariate logistic regression analysis demonstrated that independent of age <1 month, the use of cardiopulmonary bypass, the duration of cardiopulmonary bypass, Risk Adjusted classification for Congenital Heart Surgery, version 1, score >3, and the use of epinephrine or dopamine, milrinone use on admission to the cardiac intensive care unit remained independently associated with an increase in the odds of postoperative tachyarrhythmia resulting in an intervention (odds ratio 2.8, 95% confidence interval 1.3 to 6.0, p = 0.007). In conclusion, milrinone use is an independent risk factor for clinically significant tachyarrhythmias in the early postoperative period after congenital heart surgery. |
14,882 | Clinical and echocardiographic predictors of outcomes in patients with apical hypertrophic cardiomyopathy. | Apical hypertrophic cardiomyopathy (HC) is considered to have a favorable prognosis, but recent observations have suggested less benign clinical courses. We investigated the outcomes in patients with apical HC and evaluated the predictors. All 454 patients with apical HC (316 men, age 61 ± 11 years) were recruited. Major cardiovascular events (MACE) were defined as unplanned hospitalization because of heart failure, stroke, or cardiovascular mortality. The patients were divided into 2 groups: group 1 with MACE and group 2 without MACE. During the follow-up period (43 ± 20 months), the all-cause mortality rate was 9% (39 of 454), and 110 patients (25%) had MACE. The subjects in group 1 were older and a greater proportion had diabetes, hypertension, and atrial fibrillation. On the echocardiogram, the left atrial volume index (left atrial volume index 36 ± 17 vs 31 ± 12 ml/m(2)), transmitral E velocity (65 ± 17 vs 61 ± 16 cm/s), mitral annulus Ea velocity (4.5 ± 1.4 vs 5.1 ± 1.8 cm/s), Sa velocity (5.8 ± 1.4 vs 6.6 ± 1.4 cm/s), E/Ea ratio (15 ± 5 vs 13 ± 5), and right ventricular systolic pressure (31 ± 8 vs 28 ± 7 mm Hg) were significantly different between groups 1 and 2 (p <0.05 for all). The left atrial volume index (for each 1-ml/m(2) increase, hazard ratio 1.01, 95% confidence interval 1.00 to 1.03; p = 0.047), Sa velocity (hazard ratio 0.83, 95% confidence interval 0.72 to 0.96, p = 0.014), and E/Ea ratio (hazard ratio 1.04, 95% confidence interval 1.00 to 1.09, p = 0.030) were independent predictors of a poor prognosis, along with age and the presence of diabetes or hypertension. In conclusion, the clinical outcomes of patients with apical HC were less benign in older patients and in those with hypertension or diabetes. In addition, the left atrial volume index, Sa velocity, and E/Ea ratio were predicters of a poor prognosis in patients with apical HC. |
14,883 | Rate and irregularity of electrical activation during atrial fibrillation affect myocardial NGF expression via different signalling routes. | An irregular ventricular response during atrial fibrillation (AF) has been shown to mediate an increase in sympathetic nerve activity in human subjects. The molecular mechanisms remain unclear. This study aimed to investigate the impact of rate and irregularity on nerve growth factor (NGF) expression in cardiomyocytes, since NGF is known to be the main contributor to cardiac sympathetic innervation density. Cell cultures of neonatal rat ventricular myocytes were electrically stimulated for 48 h with increasing rates (0, 5 and 50 Hz) and irregularity (standard deviation (SD)=5%, 25% and 50% of mean cycle length). Furthermore, we analyzed the calcineurin-NFAT and the endothelin-1 signalling pathways as possible contributors to NGF regulation during arrhythmic stimulation. We found that the increase of NGF expression reached its maximum at the irregularity of 25% SD by 5 Hz (NGF: 5 Hz 0% SD=1 vs. 5Hz 25% SD=1.57, P<0.05). Specific blockade of the ET-A receptor by BQ123 could abolish this NGF increase (NGF: 5 Hz 25% SD+BQ123=0.66, P<0.05). High frequency electrical field stimulation (HFES) with 50 Hz decreased the NGF expression in a significant manner (NGF: 50Hz=0.55, P<0.05). Inhibition of calcineurin-NFAT signalling with cyclosporine-A or 11R-VIVIT abolished the HFES induced NGF down-regulation (NGF: 50 Hz+CsA=1.14, P<0.05). In summary, this study reveals different signalling routes of NGF expression in cardiomyocytes exposed to increasing rates and irregularity. Whether this translates into different degrees of NGF expression and possibly neural sympathetic growth in various forms of ventricular rate control during AF remains to be elucidated in further studies. |
14,884 | 'Cooling and cathing' the post-resuscitated. | Cronier and co-workers provide additional evidence that routine use of mild therapeutic hypothermia combined with emergent coronary angiography and percutaneous intervention results in excellent survival with intact neurological function for post-resuscitation patients with ventricular fibrillation. |
14,885 | Decadal electrocardiographic changes between age 40 and 50 in military pilots. | Cardiovascular diseases can lead to sudden in-flight incapacitation and long-term disability in aircraft pilots. Electrocardiogram (ECG) has been widely used to screen for these diseases in routine aeromedical examinations. Several ECG changes such as complete left bundle-branch block (CLBBB) and left ventricular hypertrophy (LVH) have been associated with increased likelihood of underlying structural cardiac diseases in addition to the emergence of newly recognized cardiovascular diseases such as Brugada syndrome. Therefore, the purpose of this study was to analyze decadal ECG changes in aircraft pilots between 40 and 50 yr in order to make an appropriate evaluation of these ECG changes.</AbstractText>We analyzed the ECGs from the annual aeromedical examination of age 50 compared to those 40 yr of age in a total of 176 Japan Air Self-Defense Force pilots.</AbstractText>With regard to decadal changes, we detected 34 new ECG changes (1 of sinus tachycardia, 8 sinus bradycardia, 1 atrial fibrillation, 2 premature atrial contraction, 1 premature ventricular contraction, 2 left axis deviation, 6 first-degree atrioventricular block, 1 CLBBB, 3 complete right bundle-branch block, 2 incomplete right bundle-branch block, 1 right ventricular conduction delay, and 6 LVH). Although the majority of them were concluded to be normal variants, the results of echocardiography in two hypertensive pilots without good control demonstrated abnormalities: one had mild hypertrophic nonobstructive cardiomyopathy and another had heart enlargement.</AbstractText>Thus, this study recommends additional cardiovascular examinations, including echocardiography for hypertensive pilots with ECG changes.</AbstractText> |
14,886 | Comparison of ventricular tachyarrhythmia characteristics in patients with idiopathic dilated or ischemic cardiomyopathy and defibrillators implanted for primary prevention. | Implantable cardioverter-defibrillator (ICD) therapy for primary prevention is well established in ischemic cardiomyopathy (ICM). Data on the role of ICDs in patients with dilated cardiomyopathy (DCM) and no history of ventricular tachyarrhythmia (VT/VF) are more limited.</AbstractText>DCM patients with an impaired left ventricular ejection fraction (LVEF) still represent a low arrhythmic risk subgroup in clinical practice.</AbstractText>ICD stored data of DCM patients with an LVEF ≤35% was compared to data of ICM patients meeting Multicenter Automatic Defibrillator Implantation Trial (MADIT) eligibility criteria. VT/VF occurrences and electrical storm (ES) events were analyzed.</AbstractText>There were 652 patients followed for 50.9 ± 33.9 months. There were 1978 VT and 241 VF episodes analyzed in 66 out of 203 patients (32.5%) with DCM and in 118 out of 449 patients (26.3%, P = 0.209) with ICM. Freedom of appropriate ICD treatment due to VT/VF or ES events did not differ in both patient populations (log-rank, P>0.05). In patients presenting with VT/VF episodes, mean event rates were comparable in both patient populations (3.2 ± 14.1 for DCM and VT vs 3 ± 13.9 for ICM and VT [P = 0.855], 0.4 ± 1.3 for DCM and VF vs 0.4 ± 1.8 for ICM and VF [P = 0.763], and 0.2 ± 0.7 for DCM and ES vs 0.2 ± 1 for ICM and ES [P = 0.666]).</AbstractText>DCM patients with prophylactic ICDs implanted due to heart failure and patients fulfilling MADIT criteria reveal comparable patterns of VT/VF/ES events during long-term follow-up. Incidence, mean number of events, and time to first event did not differ significantly. Findings support the current guidelines for prophylactic ICD therapy in DCM patients with heart failure.</AbstractText>© 2011 Wiley Periodicals, Inc.</CopyrightInformation> |
14,887 | Severe hypothermia in a patient with spinal cord injury without radiological abnormality. | We report a case of a 64-year-old caucasian male who was transported to the emergency department (ED) after being found unconscious on the side of the road. On arrival to the ED the patient went into ventricular fibrillation and advanced cardiac life support was started at that time. Thirty minutes into the resuscitation, after multiple rounds of code drugs and defibrillation attempts, the patient was found to be severely hypothermic with a rectal temperature of 24.9°C (76.9°F). Through the use of passive and active re-warming measures the patient's temperature increased enough to allow successful cardioversion and stabilization. Within minutes of cardiac stabilization the patient regained consciousness and was able to follow commands, but was found to be paralyzed from the neck down. Subsequent CT scans revealed no acute fractures, subluxations or acute spinal cord injury. This case represents the rare finding of severe hypothermia secondary to occult spinal cord injury. Case report was taken from case at Bayfront Hospital, St. Petersburg, Florida. |
14,888 | Hypokalemic quadriparesis in Sjogren syndrome. | We report a 58-year-old woman who presented with acute quadriparesis, bulbar weakness, atrial fibrillation, ventricular ectopics, and distal renal tubular acidosis with severe hypokalemia. She recovered completely on potassium and alkali supplementation. The patient also had hypergammaglobulinemia with probable primary Sjogren syndrome. |
14,889 | Effect of hepatitis C virus infection on the left ventricular systolic and diastolic functions. | Hepatitis secondary to infection with the hepatitis C virus (HCV) is one of the most common causes of viral hepatitis worldwide. Multiple extrahepatic manifestations of HCV infection have been recognized. Dilated and hypertrophic cardiomyopathy associated with HCV infection have been recently described in the literature; however, the effect of HCV infection on the left ventricular systolic and diastolic functions is unknown. Therefore, in this study we aimed to examine left ventricular systolic and diastolic functions in HCV patients.</AbstractText>The study included 50 anti-HCV positive patients and 50 persons for control groups. We performed transthorasic echocardiography and P-wave analysis on all participants. We compared left ventricle diastolic parameters, left ventricle ejection fraction, and P-wave dispersion (Pd) between these two groups. In the group with anti-HCV positivity, the ratio of E/A was found to be lower (1.2 ± 0.7 and 1.37 ± 0.6, P = 0.003); the ratio of E/Em was found to be higher (7.6 ± 1.51 and 6.8 ± 1.72, P = 0.0001). Maximum P-wave duration (Pmax) and Pd were higher in the patient group (99.3 ± 8 and 82.4 ± 7.8, P = 0.004; 44.1 ± 0.9 and 25.3 ± 1.5, P = 0.001). No other statistically significant difference was found between the two groups with regard to the left ventricle systolic and diastolic parameters.</AbstractText>Our findings show that HCV infection may be associated with left ventricular systolic and diastolic dysfunction and cardiac arrhythmias.</AbstractText> |
14,890 | [How beta-blockers are used in Spain? Analysis of limitations in their use in internal medicine and cardiology: CARACTER-BETA study]. | Beta-blocker treatment has a class I indication, level of evidence A, in guidelines for the treatment of heart failure, ischemic heart disease, and atrial fibrillation. However, beta-blocker use continues to be less than optimal. In this study, beta blocker use in Spain is analyzed in patients with heart failure, ischemic heart disease, and atrial fibrillation.</AbstractText>Observational, epidemiologic, cross-sectional, multicenter study including 1608 patients with heart failure, ischemic heart disease, and/or atrial fibrillation, recruited in 150 healthcare centers by cardiologists and internal medicine specialists.</AbstractText>Cardiologists enrolled 78.6% patients and internal medicine specialists 21.4%; 25.8% were recruited at hospital discharge and 74.2% at outpatient centers. Men accounted for 77% of the sample, and age was 68 (12) years. Of the total, 73% had ischemic heart disease, 42% heart failure, and 36% atrial fibrillation (multiresponse variable). Beta blockers were given to 82.8% of those consulting in cardiology compared to 71.6% of those treated in internal medicine (P<.0001). By pathology, the prescription rate was 85.1% of patients with ischemic heart disease, 77.0% of those with heart failure, and 72.4% of those with atrial fibrillation. Cardiology prescribed significantly more beta blockers for ischemic heart disease and heart failure than did internal medicine. Multivariate analysis showed that beta blocker use increased when the patient had ischemic heart disease, was treated by a cardiologist, and had dyslipidemia, stroke, and/or left ventricular hypertrophy. beta blocker use decreased with age and with a history of bronchospasm, asthma, bradycardia, chronic obstructive pulmonary disease, and/or intermittent claudication.</AbstractText>There is still room for improvement in beta blocker prescription in Spain for patients with ischemic heart disease, heart failure, and/or atrial fibrillation.</AbstractText>Copyright © 2011 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.</CopyrightInformation> |
14,891 | Invasive acute hemodynamic response to guide left ventricular lead implantation predicts chronic remodeling in patients undergoing cardiac resynchronization therapy. | We evaluated the relationship between acute hemodynamic response (AHR) and reverse remodeling (RR) in cardiac resynchronization therapy (CRT).</AbstractText>CRT reduces mortality and morbidity in heart failure patients; however, up to 30% of patients do not derive symptomatic benefit. Higher proportions do not remodel. Multicenter trials have shown echocardiographic techniques are poor at improving response rates. We hypothesized the degree of AHR at implant can predict which patients remodel.</AbstractText>Thirty-three patients undergoing CRT (21 dilated and 12 ischemic cardiomyopathy) were studied. Left ventricular (LV) volumes were assessed before and after CRT. The AHR (maximum rate of left ventricular pressure [LV-dP/dt(max)]) was assessed at implant with a pressure wire in the LV cavity. Largest percentage rise in LV-dP/dt(max) from baseline (atrial antibradycardia pacing or right ventricular pacing with atrial fibrillation) to dual-chamber pacing (DDD)-LV was used to determine optimal coronary sinus LV lead position. Reverse remodeling was defined as reduction in LV end systolic volume ≥15% at 6 months.</AbstractText>The LV-dP/dt(max) increased significantly from baseline (801 ± 194 mm Hg/s to 924 ± 203 mm Hg/s, p < 0.001) with DDD-LV pacing for the optimal LV lead position. The LV end systolic volume decreased from 186 ± 68 ml to 157 ± 68 ml (p < 0.001). Eighteen (56%) patients exhibited RR. There was a significant relationship between percentage rise in LV-dP/dt(max) and RR for DDD-LV pacing (p < 0.001). A similar relationship for AHR and RR in dilated cardiomyopathy and ischemic cardiomyopathy (p = 0.01 and p = 0.006) was seen.</AbstractText>Acute hemodynamic response to LV pacing is useful for predicting which patients are likely to remodel in response to CRT both for dilated cardiomyopathy and ischemic cardiomyopathy. Using AHR has the potential to guide LV lead positioning and improve response rates.</AbstractText>Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,892 | Atrial-selective inhibition of sodium-channel current by Wenxin Keli is effective in suppressing atrial fibrillation. | Wenxin Keli is a Chinese herb extract reported to be of benefit in the treatment of cardiac arrhythmias, cardiac inflammation, and heart failure.</AbstractText>We evaluated the electrophysiologic effects of Wenxin Keli in isolated canine arterially perfused right atrial preparations with a rim of right ventricular tissue (n = 11). Transmembrane action potentials and a pseudoelectrocardiogram were simultaneously recorded. Acetylcholine (1 μM) was used to induce atrial fibrillation (AF) and to test the anti-AF potential of Wenxin Keli (5 g/L). Wenxin Keli produced preferential abbreviation of action potential duration measured at 90% repolarization (APD(90)) in atria, but caused atrial-selective prolongation of the effective refractory period, due to the development of postrepolarization refractoriness. The maximum rate of rise of the action potential upstroke was preferentially reduced in atria. The diastolic threshold of excitation increased in both atria and ventricles, but much more in atria. The duration of the "P wave" (index of atrial conduction time) was prolonged to a much greater extent than the duration of the "QRS complex" (index of ventricular conduction time). Wenxin Keli significantly reduced I(Na) and shifted steady-state inactivation to more negative potentials in HEK293 cells stably expressing SCN5A. Wenxin Keli prevented the induction of persistent AF in 100% atria (6/6) and, in another experimental series, was found to terminate persistent acetylcholine-mediated AF in 100% of atria (3/3).</AbstractText>Wenxin Keli produces atrial-selective depression of I(Na)-dependent parameters in canine isolated coronary-perfused preparations via a unique mechanism and is effective in suppressing AF and preventing its induction, with minimal effects on the ventricular electrophysiology.</AbstractText>Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,893 | Efficacy of a new accelerated streptokinase regime in acute myocardial infarction: a double blind randomized clinical trial. | Studies of thrombolysis in acute ST-elevation myocardial infarction (STEMI) have focused on differences in outcome between groups receiving various regimes. Expedited treatment may influence the efficacy of nonfibrin specific thrombolytic agents in restoring early patency of the infarct-related artery (IRA), which is a major determinant of survival after ST-elevation myocardial infarction (STEMI).</AbstractText>We performed a randomized double blind clinical trial comparing an accelerated infusion (1.5 MU/20 min; group A, n = 200) with the conventional infusion (1.5 MU/60 min; group B, n = 100) of streptokinase (SK) in 300 patients with their first episode of acute STEMI. Demographics, clinical reperfusion rates, angiographic study findings, left ventricular ejection fraction (LVEF), in-hospital morbidity and mortality and one year mortality were compared between two groups.</AbstractText>Mean age was 59 ± 12 years (79% male). There were no differences in baseline data between groups. Clinical, electrocardiographic and physiologic reperfusion indices revealed significant faster and higher reperfusion rates and better preserved LVEF at discharge in group A. Sixty-three percent of patients in either group underwent invasive coronary angiography at a mean of 5 days with comparable findings. Atrial fibrillation, malignant ventricular arrhythmias in the second day, in-hospital and late mortalities rates occurred more frequently in group B patients. In multivariate analysis, accelerated SK infusion was the only independent predictor of higher electrocardiographic reperfusion (OR = 3.2, CI: 1.93-5.3, P < 0.001).</AbstractText>The accelerated SK infusion regimen of 1.5 MU in 20 min is safe and well tolerated with significantly faster and higher clinical reperfusion rates, more preserved LV systolic function, less atrial and ventricular sustained arrhythmias, and less in-hospital and 1 year mortality rates in acute STEMI.</AbstractText>© 2011 Blackwell Publishing Ltd.</CopyrightInformation> |
14,894 | Resuscitation strategies from bupivacaine-induced cardiac arrest. | Local anesthetic (LA) intoxication with cardiovascular arrest is a potential fatal complication of regional anesthesia. Lipid resuscitation has been recommended for the treatment of LA-induced cardiac arrest. Aim of the study was to compare four different rescue regimens using epinephrine and/or lipid emulsion and vasopressin to treat cardiac arrest caused by bupivacaine intoxication.</AbstractText>Twenty-eight piglets were randomized into four groups (4 × 7), anesthetized with sevoflurane, intubated, and ventilated. Bupivacaine was infused with a syringe driver via central venous catheter at a rate of 1 mg·kg(-1)·min(-1) until circulatory arrest. Bupivacaine infusion and sevoflurane were then stopped, chest compression was started, and the pigs were ventilated with 100% oxygen. After 1 min, epinephrine 10 μg·kg(-1) (group 1), Intralipid(®) 20% 4 ml·kg(-1) (group 2), epinephrine 10 μg·kg(-1) + Intralipid(®) 4 ml·kg(-1) (group 3) or 2 IU vasopressin + Intralipid(®) 4 ml·kg(-1) (group 4) were administered. Secondary epinephrine doses were given after 5 min if required.</AbstractText>Survival was 71%, 29%, 86%, and 57% in groups 1, 2, 3, and 4. Return of spontaneous circulation was regained only by initial administration of epinephrine alone or in combination with Intralipid(®). Piglets receiving the combination therapy survived without further epinephrine support. In contrast, in groups 2 and 4, return of spontaneous circulation was only achieved after secondary epinephrine rescue.</AbstractText>In cardiac arrest caused by bupivacaine intoxication, first-line rescue with epinephrine and epinephrine + Intralipid(®) was more effective with regard to survival than Intralipid(®) alone and vasopressin + Intralipid(®) in this pig model.</AbstractText>© 2011 Blackwell Publishing Ltd.</CopyrightInformation> |
14,895 | Predictors and course of high-degree atrioventricular block after transcatheter aortic valve implantation using the CoreValve Revalving System. | Transcatheter aortic valve implantation (TAVI) is a novel treatment for high risk or inoperable patients with symptomatic severe aortic stenosis. However, significant atrioventricular (AV) conduction system abnormalities requiring permanent pacemaker (PPM) implantation might complicate this procedure. We used best subsets logistic regression analysis to identify the independent predictors for the development of high-degree AV block (HDAVB) among 70 patients who underwent TAVI at 3 referral centers in Israel from 2008 to 2010. The mean age of the study patients was 83 ± 4.6 years. Of the 70 patients, 28 (40%) developed AV conduction abnormalities requiring PPM implantation within 14 days (median 2) of the procedure. The indications for PPM implantation were HDAVB (n = 25), new-onset left bundle branch block with PR prolongation (n = 2), and slow atrial fibrillation (n = 1). Best subsets logistic regression analysis showed that, among the 15 prespecified clinical, electrocardiographic, and echocardiographic candidate risk factors, only right bundle branch block at baseline (odds ratio 43; p = 0.002) and deep valve implantation (<6 mm from the lower edge of the noncoronary cusp to the ventricular end of the prosthesis, odds ratio 22; p <0.001) were independently associated with the development of periprocedural HDAVB. At 3 months of follow-up, HDAVB was still present in 40% of the patients who received PPM implantation for this indication. In conclusion, 40% of the patients who undergo CoreValve TAVI require PPM implantation after the procedure, with most cases (36%) associated with the development of postprocedural HDAVB. Baseline conduction abnormalities (right bundle branch block) and deep valve implantation (>6 mm) independently predicted the development of HDAVB and the need for PPM implantation after CoreValve TAVI. |
14,896 | Does rheumatic valvular heart disease affect right ventricular performance? | Right ventricular (RV) function often determines clinical outcome in patients with valvular heart disease. Though difficult to assess by echocardiography, Tei index is useful in its assessment. The aims of the study were to evaluate global RV function using the Tei index in patients with rheumatic heart disease and to observe if such abnormalities in RV function were reversible post-operatively.</AbstractText>The study included patients with atrial septal defect (ASD, Group I, n = 15) and rheumatic valvular heart disease (RVHD, Group II, n = 18). Patients with atrial fibrillation were excluded from the study. Conventional 2-D echocardiography was performed preoperatively, immediate postoperative and in last follow-up.</AbstractText>ASD group had lower left LVES and LVED dimensions as compared to RHVD (p = 0.001) and better ejection fraction (EF) than RVHD group (p = 0.02). LV Tei in the ASD group was above the normal limit (> 0.5), while RV Tei was increased in the RHVD group. The median RVSP was similar in two groups (p = 0.9). The impaired LVMPI in the ASD group improved as early as 2 weeks following surgery (p = 0.09) while in patients with RHVD it deteriorated which mirrored the reduction in median LVEF (p = 0.04). Group II that had an abnormal RV Tei pre-operatively demonstrated improvement following surgery (p = 0.03).</AbstractText>RVHD is associated with impairment of RV function. Volume overload of RV in patients of ASD is associated with normal MPI. The abnormalities in RVMPI improved as early as 2 weeks after valve surgery with sustained improvement noted at follow up.</AbstractText> |
14,897 | Defibrillation. | Defibrillation may be needed in witnessed and unwitnessed cardiac arrests. Cardiopulmonary resuscitation (CPR) must be initiated and defibrillation administered without delay. Every shock cycle includes 1-2 minutes of CPR followed by rhythm analysis. The energy level for biphasic defibrillation of ventricular fibrillation is 150 J with possible step-wise escalation to 360 J. All healthcare workers need to learn and be authorised to use an automated external defibrillator (AED). In addition, all ambulances must be equipped with AEDs when transporting patients. Self-adhesive pads/paddles must be applied firmly to the skin for best effect. Monitoring electrodes and pacemaker locations should be considered during paddle/pad placement. AED skills should be imparted to a wide variety of community groups. More efforts will be made to increase the availability of AEDs in public, residential, commercial and industrial facilities. |
14,898 | When, where and how to initiate hypothermia after adult cardiac arrest. | Therapeutich hypothermia (TH) has been shown to improve neurological outcome and survival after witnessed cardiac arrest (CA) that is due to ventricular fibrillation. Although TH is widely used following witnessed CA as well as all forms of initial rhythm, the mortality rate after CA remains unacceptably high, and additional study is needed to understand when and how to implement hypothermia in the post-resuscitation phase. Experimental studies have emphasized the importance of initiating cooling soon after the return of spontaneous circulation (ROSC) or even during cardiopulmonary resuscitation (CPR). Clinical studies have shown that pre-hospital induction of hypothermia is feasible and has no major adverse events-even when used intra-arrest-and may provide some additional benefits compared to delayed in-hospital cooling. Thus, hypothermia use should not be limited to the Intensive Care Unit but can be initiated in the field/ambulance or in the Emergency Department, then continued after hospital admission- even during specific procedures such as coronary angiography-as part of the global management of CA patients. Various methods (both non-invasive and invasive) are available to achieve and maintain the target temperature; however, only some of these methods-which include cold fluids, ice packs, iced pads and helmet and trans-nasal cooling- are easily deployed in the pre-hospital setting. |
14,899 | An atrioventricular node model for analysis of the ventricular response during atrial fibrillation. | This paper introduces a model of the atrioventricular node function during atrial fibrillation (AF), and describes the related ECG-based estimation method. The proposed model is defined by parameters that characterize the arrival rate of atrial impulses, the probability of an impulse choosing either one of the two atrioventricular nodal pathways, the refractory periods of these pathways, and the prolongation of the refractory periods. These parameters are estimated from the RR intervals using maximum likelihood estimation, except for the shorter refractory period which is estimated from the RR interval Poincaré plot, and the mean arrival rate of atrial impulses by the AF frequency. Simulations indicated that 200-300 RR intervals are generally needed for the estimates to be accurate. The model was evaluated on 30-min ECG segments from 36 AF patients. The results showed that 88% of the segments can be accurately modeled when the estimated probability density function (PDF) and an empirical PDF were at least 80% in agreement. The model parameters were estimated during head-up tilt test to assess differences caused by sympathetic stimulation. Both refractory periods decreased as a result of stimulation, and the likelihood of an impulse choosing the pathway with the shorter refractory period increased. |
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