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8,300 | Is ward experience in resuscitation effort related to the prognosis of unexpected cardiac arrest? | The aim of this study was to investigate the outcome of patients of unexpected cardiac arrest initially resuscitated by first responders with dissimilar experiences under the support of cardiac arrest team (CAT).</AbstractText>All unexpected cardiac arrest patients receiving in-hospital resuscitation with the activation of CAT in a tertiary-care teaching hospital over a 12-month period were recorded according to the Utstein criteria. We prospectively recorded various factors at resuscitation and retrospectively evaluated the outcome. Outcome measures included return of spontaneous circulation (ROSC), survival longer than 24 hours, and survival to discharge.</AbstractText>Altogether, 76 emergency calls were registered, and among these, 44 calls (58%) were cardiac arrests, including 8 ventricular tachycardia/fibrillation, 15 pulseless electrical activity, and 21 asystole. The rate of ROSC was 61%, the rate of survival longer than 24 hours was 37%, and the rate of survival to discharge was 18%. The response time of our CAT was 271 seconds (4 minutes and 31 seconds) on average. The patients who collapsed in the wards experienced in resuscitation effort received higher rates of appropriate basic and advanced cardiac life support interventions before CAT arrival (79% vs. 44%; p = 0.019), had an increased chance of ROSC (75% vs. 38%; p = 0.014), survival longer than 24 hours (54% vs. 13%; p = 0.007), and survival to discharge (29% vs. 0%; p = 0.036).</AbstractText>Hospital wards with more than 5 cardiac arrests per year have a better patient survival rate than those with fewer arrests. This is despite all ward staff receiving the same level of training.</AbstractText> |
8,301 | Standard versus over-the-head cardiopulmonary resuscitation during simulated advanced life support. | Limited space can make rescuer position changes difficult during cardiopulmonary resuscitation (CPR). Over-the-head (OTH) CPR enables one rescuer to deliver chest compressions and ventilations without changing position. The aim of the present study was to evaluate quality of OTH versus standard CPR with bag-valve-mask (BVM) ventilation in a manikin model during advanced life support (ALS).</AbstractText>In a randomised double-crossover trial, eight paramedic students performed ALS using both OTH and standard CPR with BVM. Initial rhythm was asystole, converting to ventricular fibrillation after atropine, adrenaline, and CPR. Data collection was stopped after atropine and epinephrine had been given. Data are presented as means +/- SD or median with 25% and 75% percentile.</AbstractText>There were no significant differences in ventilation or compression variables or any time factors with median total hands off times of 50% versus 52% for OTH and standard CPR respectively.</AbstractText>OTH CPR is an alternative method during CPR.</AbstractText> |
8,302 | Recurrent life-threatening ventricular dysrhythmias associated with acute hydrofluoric acid ingestion: observations in one case and implications for mechanism of toxicity. | Hydrofluoric acid (HF) is a weak inorganic acid used for etching and as rust remover. Systemic toxicity is manifested as ventricular dysrhythmias. The mechanisms for these dysrhythmias are not well elucidated.</AbstractText>An 82-year-old woman ingested 8 ounces of 7% HF. Shortly after emergency department (ED) arrival, she became pulseless, developing recurrent ventricular dysrhythmias. She was defibrillated 17 times and received several doses of calcium, magnesium, and lidocaine. After three hours, she returned to sustained NSR. She was discharged home after four days.</AbstractText>The electrocardiographic findings in this patient demonstrate hypocalcemia, which has been implicated as the culprit in HF-induced arrhythmias. However, despite correction of the hypocalcemia, the ventricular arrhythmias persisted. The proposed mechanisms of systemic HF toxicity and the relevant literature are discussed.</AbstractText>Ventricular dysrhythmias due to HF toxicity seem to be independent of either hypocalcemia or hyperkalemia. Systemic toxicity after ingestions may be delayed and precipitous.</AbstractText> |
8,303 | Changes and predictive value of dispersion of repolarization parameters for appropriate therapy in patients with biventricular implantable cardioverter-defibrillators. | The impact of cardiac resynchronization therapy (CRT) on dispersion of repolarization is controversial. The benefit of CRT on sudden cardiac death has been demonstrated only after 3 years follow-up.</AbstractText>The purpose of this study was to explore the immediate effect of CRT on dispersion of repolarization and to define the value of dispersion of repolarization parameters as predictors of appropriate implantable cardioverter-defibrillator (ICD) therapy.</AbstractText>Data from 100 patients who underwent CRT-ICD placement were analyzed retrospectively. Patients had symptoms of New York Heart Association functional class III or IV heart failure, left ventricular ejection fraction < or =35%, and QRS duration >130 ms or QRS < or =130 ms with left intraventricular dyssynchrony. ECG indices of dispersion of repolarization before and immediately after CRT implantation (QT dispersion, Tpeak-Tend [Tp-e], and Tp-e dispersion) were measured.</AbstractText>In patients who were upgraded to a biventricular system, Tp-e did not increase significantly after CRT. However, Tp-e increased significantly after CRT in patients with left bundle branch block or narrow QRS at baseline. After 12-month follow-up, 22 patients had received appropriate ICD therapy. ICD therapy and no ICD therapy groups had similar baseline characteristics, such as secondary prevention and ischemic cardiomyopathy. Postimplantation Tp-e was the only independent predictor of future ICD therapy (P = .02).</AbstractText>Immediately after CRT, Tp-e did not increase in patients who received a biventricular upgrade; however, Tp-e did increase in patients with preimplantation left bundle branch block or narrow QRS. Postimplantation Tp-e was the only independent predictor of appropriate ICD therapy.</AbstractText> |
8,304 | Left ventricular dysfunction is associated with intraventricular dyssynchrony by 3-dimensional echocardiography in children. | We used 3-dimensional (3D) echocardiography to identify and quantify left ventricular (LV) dyssynchrony in children with LV dysfunction compared with control subjects.</AbstractText>The 3D echocardiography LV full volumes were acquired in 18 children, 9 with LV dysfunction and 9 control subjects. The LV was subdivided into 16 segments (apex excluded). Time from end diastole to the minimal systolic volume for each segment was expressed as a percent of the R-R interval. The SD of these times provided a 16-segment dyssynchrony index (16-SDI). The second index (12-SDI) was similarly calculated using 6 basal and 6 mid segments. The third index consisted of 6 basal segments (6-SDI).</AbstractText>The dysfunction group exhibited significantly increased 16-SDI (P = .008) and 12-SDI (P = .01). The 16-SDI was negatively correlated with 3D ejection fraction and 2-dimensional fractional shortening.</AbstractText>Children with LV dysfunction demonstrate increased intraventricular LV dyssynchrony by 3D echocardiography, in a pattern that is negatively correlated with LV systolic function.</AbstractText> |
8,305 | Safety of stress echocardiography supervised by registered nurses: results of a 2-year audit of 15,404 patients. | Stress echocardiography has traditionally been performed under the supervision of physicians. In the last decade, at some institutions, specially trained registered nurses have taken on the task of directly supervising and conducting these stress tests with appropriate physician involvement and assistance.</AbstractText>The safety of 15,404 stress echocardiograms that were performed under the direct supervision of registered nurses during a recent 2-year period was evaluated.</AbstractText>The stress modality was treadmill exercise in 8592 (56%), dobutamine in 6755 (44%), and transesophageal atrial pacing in 57 (0.04%) patients. The mean age was 65 +/- 13 years, and 54% were male. A total of 55 patients (0.36%) had complications related to stress echocardiography, including 26 patients (0.18%) who were subsequently transferred to hospital. Complications included atrial fibrillation (n = 28, 0.18%), other supraventricular tachycardias (n = 9, 0.06%), sustained ventricular tachycardia (n = 4, 0.03%), and ventricular fibrillation (n = 2, 0.01%). Eight patients (0.05%) were hospitalized for markedly positive tests or prolonged chest pain and 4 patients (0.03%) for symptomatic hypotension. No patient had cardiac rupture or died. Complications were more common with dobutamine stress echocardiography (DSE) (47/6755; 0.7%) compared with exercise echocardiography (8/8592; 0.09%) or transesophageal atrial pacing stress echocardiography (0/57) (P < .0001). Arrhythmias were more commonly associated with DSE (39/6755, 0.58%) than exercise echocardiography (4/8592, 0.05%). Potentially life-threatening ventricular arrhythmias occurred in 6 of 6755 patients who underwent DSE (0.09%) and in none of the patients who underwent exercise echocardiography. Patients who underwent DSE were, on average, older, and had more comorbidities compared with those who underwent exercise echocardiography.</AbstractText>Stress echocardiography, when supervised directly by specially trained registered nurses, can be performed safely; complications are uncommon (1/280 stress tests) and these complication rates are comparable with previously reported studies evaluating the safety of stress echocardiography supervised by physicians.</AbstractText> |
8,306 | Optimal noninvasive assessment of diastolic heart failure in patients with atrial fibrillation: comparison of tissue doppler echocardiography, left atrium size, and brain natriuretic peptide. | The aim of this study was to evaluate whether the ratio of early diastolic transmitral velocity to early diastolic mitral annular velocity (E/E') can be applied to identify diastolic heart failure (HF) noninvasively rather than using brain natriuretic peptide (BNP) or enlargement of left atrium (LA) in patients with atrial fibrillation (AF) by comparing the severity of HF symptoms. Moreover, we investigated the relationship between the changes in E/E' and the severity of HF or LA remodeling in the follow-up period.</AbstractText>We examined 73 patients with nonvalvular AF disease and preserved left ventricular ejection fraction (>50%), ie, patients with diastolic HF accompanied with New York Heart Association (NYHA) functional class I to IV (n = 32, HF group) and those without HF (n = 41, non-HF group). No patients showed dyspnea caused by anemia, renal failure, lung disease, or other disease states except HF. We evaluated E, E', and E/E' by Doppler echocardiography, and the LA area (LAA) by 2-dimensional echocardiography. BNP levels were also examined. A follow-up study was performed in 18 of the 32 patients with HF.</AbstractText>E/E', LAA, and BNP were higher in the HF group than in the non-HF group (E/E', 15 +/- 5 vs 9 +/- 2; LAA, 24 +/- 6 vs 20 +/- 6 cm(2); and BNP, 321 +/- 200 vs 140 +/- 76 pg/mL, each P < .01). Using the receiver operating characteristic curve for identification of symptomatic diastolic HF with NYHA functional class II to IV, the areas under the curves were: E/E', 0.96 (95% confidence interval 0.91-1.0); LAA, 0.77 (95% confidence interval 0.64-0.89); and BNP, 0.85 (95% confidence interval 0.75-0.95). In the HF group, 18 patients who were re-examined 17 +/- 9 weeks after were divided into two groups, depending on the improvement in NYHA functional class, ie, improved group (n = 10) and unchanged group (n = 8). In the follow-up period, E (112 +/- 20-94 +/- 21 cm/s), E/E' (17.1 +/- 5-13.1 +/- 3), and LAA (28 +/- 5-24 +/- 4) decreased in the improved group (each P < .05), but E' and BNP did not.</AbstractText>E/E' could be useful in identifying symptomatic diastolic HF and evaluating the functional state in the process of HF in patients with AF. Moreover, E/E' is able to assess the improvement of diastolic HF in AF.</AbstractText> |
8,307 | Selective cardiac plasma-membrane K(ATP) channel inhibition is defibrillatory and improves survival during acute myocardial ischemia and reperfusion. | ATP-dependent potassium channels (K(ATP)) have been implicated in cardioprotection both during myocardial ischemia and reperfusion. We compared the effect of a non-selective K(ATP) inhibitor glibenclamide, a selective mitochondrial K(ATP) inhibitor 5-hydroxy-decanoate (5-HD) and a selective sarcolemmal K(ATP) blocker HMR 1883, on survival and incidence of arrhythmias during myocardial ischemia in conscious, and during ischemia-reperfusion in pentobarbitone anesthetized rats. Glibenclamide (5 mg/kg i.p.) or HMR 1883 (3 mg/kg i.v.) reduced ischemia-induced irreversible ventricular fibrillation and improved survival during myocardial ischemia (64% and 61% vs. 23% in controls, respectively). 5-HD (5 mg/kg i.v.) did not influence survival and the incidence of ventricular arrhythmias. The incidence of reperfusion-induced arrhythmias was reduced by both glibenclamide and HMR 1883 (3 or 10 mg/kg) resulting in improved survival during reperfusion (81%, 82% and 96% vs. 24% in controls, respectively) in anesthetized rats. 5-HD did not reduce the incidence of lethal reperfusion arrhythmias. Glibenclamide and HMR 1883 prolonged (89+/-4.6 and 89+/-4.9 ms vs. 60+/-2.4 ms in controls), while 5-HD did not change the QT interval. In conclusion, inhibition of sarcolemmal K(ATP) reduces the incidence of lethal ventricular arrhythmias and improves survival both during acute myocardial ischemia and reperfusion in rats. This beneficial effect correlates with the prolongation of repolarization. Inhibition of mitochondrial K(ATP) does not improve survival or reduce the occurrence of ischemia and/or reperfusion-induced arrhythmias and does not prolong the QT interval. The present results also suggest that the antiarrhythmic effect of K(ATP) inhibitors is not influenced by pentobarbitone anesthesia. |
8,308 | A study on pathogenesis of sudden death syndrome in broiler chickens. | Sudden death syndrome (SDS) in fast growing broiler chickens has been recognized as a patho-physiological entity for four decades, but its pathogenesis still remains unknown. More recent investigations provided evidence that link SDS to cardiac arrhythmia, but the mechanism triggering arrhythmogenesis and factors responsible for fatal outcome are poorly understood. In order to understand the chain of events leading to SDS in broilers, the present study focused on putative mechanisms that trigger arrhythmia and mechanisms that predispose the myocardium to fatal arrhythmia. Susceptibility of broilers to cardiac arrhythmia under stress conditions was evaluated using a simulated stress test with epinephrine. Detailed histopathological evaluation of the broiler heart was undertaken to identify structural features that may predispose the myocardium to fatal arrhythmia. The simulated stress challenge revealed that many broilers are highly susceptible to stress induced cardiac arrhythmia. In some broilers the stress challenge induced severe ventricular arrhythmia, and the life threatening nature of this arrhythmia was evidenced by the fact that several birds showing the most severe arrhythmic responses, died suddenly within several days after the stress challenge. Examination of hearts of broilers that died of SDS revealed microscopic lesions in the cardiomyocytes, and widespread changes in the sub-endocardial and mural His-Purkinje system (HPS). Immune staining for Caspase-3 confirmed that numerous Purkinje cells in the left ventricular myocardium from broiler chickens that died of SDS were undergoing apoptosis. The observed lesions suggest that the electrical stability of the myocardium was compromised. Taken together, our findings indicate that stress is a most likely trigger of cardiac arrhythmia in broilers, whereas the pathological changes seen in the myocardium and in the HPS in fast growing broilers provide a very conducive milieu for sustained ventricular arrhythmia. In cases where the electrical stability of the myocardium is compromised, even an episodic arrhythmic event may readily degenerate to catastrophic ventricular fibrillation and sudden death. We conclude that the combination of stress and changes in the cardiomyocytes and HPS are the key requisite features in the pathogenesis of SDS. |
8,309 | Impact of beating heart left atrial ablation on left-sided heart mechanics. | The cut-and-sew Cox-Maze procedure is the gold standard for surgical treatment of atrial fibrillation, but it is associated with long-term impairment of left atrial mechanical function. We developed a bipolar, irrigated radiofrequency ablation device. We hypothesized that beating heart radiofrequency left atrial ablation would result in minimal acute changes in left atrial hemodynamics.</AbstractText>Six healthy subjects were studied. Combination pressure-conductance catheters were inserted into the left atrium and ventricle. With the use of the device, atrial ablation was performed on the beating heart without cardiopulmonary bypass, including electrical isolation of the posterior left atrium and atrial appendage myocardium. Simultaneous left-sided heart pressure-volume and intracardiac echocardiography data were acquired before ablation, after left atrial appendage ablation alone, and after all ablation (with and without appendage occlusion). The derived indices of left-sided heart mechanical function were examined.</AbstractText>Relative to baseline, no significant diminishment in pressure-volume or intracardiac echocardiography-derived indices of global left-sided heart mechanical function were observed after ablation, with or without appendage occlusion. Mitral valve morphology and function were not significantly altered. A significant diminishment of atrial appendage systolic flow was noted after appendage ablation in association with spontaneous echocardiographic contrast in this region.</AbstractText>In this model, ablation does not seem to compromise global left-sided heart mechanical function. However, these findings mask regional diminishment in atrial appendage systolic function. This observation demonstrates that electrical isolation of the appendage should be accompanied by its occlusion or excision. Appendage occlusion after ablation does not seem to compromise left-sided heart mechanical function.</AbstractText> |
8,310 | [Again new resuscitation guidelines (2006): justification, costs and potential confusion]. | The last revision of the Dutch resuscitation guidelines, a translation of the European Resuscitation Council Guidelines 2005, is based on the recommendations of the International Liaison Committee on Resuscitation (ILCOR). The previous Dutch guidelines were issued in 2002. Most changes are based on laboratory studies and retrospective analyses. The most important changes are: recognizing circulatory arrest on unresponsiveness and abnormal breathing; a new ratio of chest compressions to ventilations i.e. 30:2 instead of 15:2; and following the procedure of checking the airway (A), taking over the circulation (C) and breathing (B). Furthermore in the event of ventricular fibrillation or ventricular tachycardia with no pulsations then one defibrillator shock only is to be given; this is in contrast with the previous application of cycles of 3 shocks. The work and costs of implementation involved in the revision of resuscitation guidelines are tremendous, especially in view of the huge number of laypersons who need to be retrained. Also, frequent changes of guidelines may cause confusion and have a negative effect on the quality of resuscitation. Therefore, it is not evident that the benefits of this revision justify its costs. It would be good to prospectively evaluate the effectiveness and costs of this revision. In the future, these data might help to decide when altered international recommendations should be translated into new Dutch resuscitation guidelines. Alternative strategies should be considered, for example only changing the guidelines for advanced life support. |
8,311 | Incidence of severe ventricular arrhythmias during pulmonary artery catheterization in liver allograft recipients. | Liver allograft recipients may develop a hyperdynamic circulation and cardiac electrophysiologic abnormalities. The incidence of severe ventricular arrhythmias in liver allograft recipients during pulmonary artery (PA) catheterization was determined. One hundred five liver allograft recipients were studied prospectively; 5 of the patients with preexisting valvular heart disease, ischemic heart disease, or arrhythmias were excluded. Severe ventricular arrhythmia, defined as 3 or more consecutive ventricular premature beats occurring at a rate of >100 per minute, was observed in 37.0% of the patients during insertion of the catheter and in 25.0% of the patients during removal of the catheter. Two patients developed ventricular tachycardia, and 2 developed ventricular fibrillation; the arrhythmias in these 4 patients did not respond to appropriate pharmacological treatment but resolved promptly after removal of the PA catheter. The catheter transit time from the right ventricle to the pulmonary capillary wedge position was longer in patients with severe ventricular arrhythmia than in those without this arrhythmia (91.6+/-103.6 s versus 53.3+/-18.4 s, P<0.05). In conclusion, patients undergoing liver transplantation have a high risk of developing a ventricular arrhythmia during PA catheterization. |
8,312 | Emergency preservation and resuscitation improve survival after 15 minutes of normovolemic cardiac arrest in pigs. | Outcome after prolonged normovolemic cardiac arrest is poor, and new resuscitation strategies have to be found. We hypothesized that the induction of deep hypothermia for emergency preservation and resuscitation (EPR) during prolonged cardiac arrest, before the start of reperfusion, will mitigate the deleterious cascades leading to neuronal death and will thus improve outcome.</AbstractText>Prospective experimental study.</AbstractText>University research laboratory.</AbstractText>Thirteen pigs, Large White breed (27-37 kg).</AbstractText>After 15 mins of ventricular fibrillation, pigs were subjected to 1) EPR (n = 6), 20 mins of hypothermic stasis induced with a cold saline aortic flush; or 2) 20 mins of conventional resuscitation (n = 7). Then cardiopulmonary bypass was initiated in both groups, followed by defibrillation. Controlled ventilation and mild hypothermia were continued for 20 hrs; survival was for 9 days. For neurologic evaluation, neurologic deficit score (100% = brain dead, 0-10% = normal), overall performance category (1 = normal, 5 = dead or brain dead), and brain histologic damage score were used.</AbstractText>In the EPR group, brain temperature decreased from 38.5 degrees C +/- 0.2 degrees C to 16.7 degrees C +/- 2.5 degrees C within 235 +/- 27 secs. Five animals achieved restoration of spontaneous circulation and survived to 9 days: two pigs with overall performance category 2 and three pigs with overall performance category 3. Their neurologic deficit score was 45% (interquartile range 35, 50) and histologic damage score was 142 (interquartile range 109, 159). In the control group, four pigs achieved restoration of spontaneous circulation: one survived to 9 days with overall performance category 3, neurologic deficit score 45%, and histologic damage score 226 (restoration of spontaneous circulation, p = .6; survival, p = .03; overall performance category, p = .02).</AbstractText>EPR is feasible in an experimental pig model and improves survival after prolonged cardiac arrest in pigs. Further experimental studies are needed before this concept can be brought into clinical practice.</AbstractText> |
8,313 | Predictors of all-cause mortality for patients with chronic Chagas' heart disease receiving implantable cardioverter defibrillator therapy. | Implantable Cardioverter Defibrillators (ICD) have sporadically been used in the treatment of either Sustained Ventricular Tachycardia (VT) or Ventricular Fibrillation (VF) in Chagas' disease patients. This study aimed at determining predictors of all-cause mortality for Chagas' disease patients receiving ICD therapy.</AbstractText>Ninety consecutive patients were entered the study. Mean left ventricular ejection fraction was 47 +/- 13%. Twenty-five (28%) patients had no left ventricular systolic dysfunction. After device implantation, all patients were given amiodarone (mean daily dose = 331, 1 +/- 153,3 mg), whereas a B-Blocking agent was given to 37 (40%) out of 90 patients.</AbstractText>A total of 4,274 arrhythmias were observed on stored electrogram in 64 (71%) out of 90 patients during the study period; SVT was observed in 45 out of 64 (70%) patients, and VF in 19 (30%) out of 64 patients. Twenty-six (29%) out of 90 patients had no arrhythmia. Fifty-eight (64%) out of 90 patients received appropriate shock, whereas Antitachycardia Pacing was delivered to 58 (64%) out of 90 patients. There were 31 (34%) deaths during the study period. Five patients were lost to follow up. Sudden cardiac death affected 2 (7%) out of 26 patients, whereas pump failure death was detected in the remaining 24 (93%) patients. Number of shocks per patient per 30 days was the only independent predictor of mortality.</AbstractText>Number of shocks per patient per 30 days predicts outcome in Chagas' disease patients treated with ICD.</AbstractText> |
8,314 | Clinical characteristics and risk stratification in symptomatic and asymptomatic patients with brugada syndrome: multicenter study in Japan. | Neither the clinical characteristics nor risk stratification in Brugada syndrome have been clearly determined. We compared the clinical and ECG characteristics of symptomatic and asymptomatic patients with Brugada syndrome to identify new markers for high-risk patients.</AbstractText>A total of 188 consecutive individuals with Brugada syndrome (mean age 53 +/- 14 years, 178 males) were enrolled in the Japan Idiopathic Ventricular Fibrillation Study (J-IVFS). Clinical and ECG characteristics were evaluated in three groups of patients: Ventricular fibrillation (VF) group: patients with documented VF (N = 33); Syncope (Sy) group: patients with syncope without documented VF (N = 57); and asymptomatic (As) group: subjects without symptoms (N = 98). Their prognostic parameters were evaluated over a 3-year follow-up period.</AbstractText>(1) Clinical characteristics: incidence of past history of atrial fibrillation (AF) was significantly higher in the VF and Sy groups than in the AS group (P = 0.04). (2) On 12-lead ECG, r-J interval in lead V2 and QRS duration in lead V6 were longest in the VF group (P = 0.001, 0.002, respectively). (3) Clinical follow-up: during a mean follow-up period of 37 +/- 16 months, incidences of cardiac events (sudden death and/or VF) were higher in the symptomatic (VF/Sy) groups than in the As group (P < 0.0001). The r-J interval in lead V2 >/= 90 ms and QRS duration in lead V6 >/= 90 ms were found to be possible predictors of recurrence of cardiac events in symptomatic patients.</AbstractText>Prolonged QRS duration in precordial leads was prominent in symptomatic patients. This ECG marker may be useful for distinguishing high- from low-risk patients with Brugada syndrome.</AbstractText> |
8,315 | Influence of meals on variations of ST segment elevation in patients with Brugada syndrome. | Glucose-induced insulin secretion is one of the contributing factors to fluctuation of ST segment elevation in Brugada syndrome.</AbstractText>The purpose of this study was to explore the influence of meals on variations of ST elevation in Brugada syndrome.</AbstractText>We assessed changes of ST segment elevation in lead V1-3 on ECG before and after taking meals, at midnight, and at 3:00 a.m. in 20 patients with Brugada syndrome. Plasma glucose, insulin, and K(+) concentrations were measured. Variations of ST elevation were defined as morphological changes and/or augmentation of ST segment level by >1.0 mm.</AbstractText>Variations of ST segment morphology or elevation level after meals were observed in 15 of 20 patients (75%). ST elevation was augmented most markedly after dinner (3.3 +/- 1.7 mm) and decreased both at midnight (2.6 +/- 1.3 mm: P < 0.01 vs after dinner) and at 3:00 a.m. (2.4 +/- 1.2 mm: P < 0.01 vs after dinner). Morphologic changes and elevation levels of ST segment were associated with changes in glucose-induced insulin levels after meals, being highest after dinner (47 +/- 33 microU/mL) and decreasing significantly at midnight (7 +/- 4 microU/mL) and at 3:00 a.m. (5 +/- 2 microU/mL). There were no correlations between ST elevation and changes in serum K(+) level or heart rate.</AbstractText>The present findings suggest that variations of ST elevation are frequently associated with meals. Aggravation of ST elevation is most prominent in the evening to night after dinner rather than the period between midnight and early morning. This information may help to predict event times at high risk for life-threatening arrhythmias in Brugada syndrome.</AbstractText> |
8,316 | Exacerbation of electrical storm subsequent to implantation of a right vagal stimulator. | A patient with advanced ischemic cardiomyopathy underwent implantation of a vagal stimulator in an attempt to control recurrent drug refractory ventricular arrhythmia. Electrical storm was exacerbated after the implant and continued after neurostimulation was discontinued. The report aims to provide a cautionary note to application of vagal stimulation for control of cardiac arrhythmia. |
8,317 | Treatment of heart failure with decreased left ventricular ejection fraction. | Class I recommendations for treating patients with current or prior symptoms of heart failure with reduced left ventricular ejection fraction (LVEF) include using diuretics and salt restriction in individuals with fluid retention. Use angiotensin-converting enzyme (ACE) inhibitors, beta blockers, and angiotensin II receptor blockers if intolerant to ACE inhibitors because of cough or angioneurotic edema. Nonsteroidal anti-inflammatory drugs, most antiarrhythmic drugs, and calcium channel blockers should be avoided or withdrawn. Exercise training is recommended. Implant cardioverter-defibrillator (ICD) is recommended in individuals with a history of cardiac arrest, ventricular fibrillation, or hemodynamically unstable ventricular tachycardia. ICD is indicated in patients with ischemic heart disease for at least 40 d post-myocardial infarction or nonischemic cardiomyopathy, an LVEF of 30% or less, New York Heart Association (NYHA) class II or III symptoms on optimal medical therapy, and an expectation of survival of at least 1 yr. Cardiac resynchronization therapy should be used in individuals with an LVEF of 35% or below, NYHA class III or IV symptoms despite optimal therapy, and a QRS duration greater than 120 ms. An aldosterone antagonist can be added in selected patients with moderately severe to severe symptoms of heart failure who can be carefully monitored for renal function and potassium concentration (serum creatinine should be <or=2.5 mg/dL in men and <or=2.0 mg/dL in women; serum potassium should be <5.0 mEq/L). |
8,318 | Outcome parameters for trials in atrial fibrillation: recommendations from a consensus conference organized by the German Atrial Fibrillation Competence NETwork and the European Heart Rhythm Association. | Atrial fibrillation (AF), the most common atrial arrhythmia, has a complex aetiology and causes relevant morbidity and mortality due to different mechanisms, including but not limited to stroke, heart failure, and tachy- or bradyarrhythmia. Current therapeutic options (rate control, rhythm control, antithrombotic therapy, 'upstream therapy') only prevent a part of this burden of disease. New treatment modalities are therefore currently under evaluation in clinical trials. Given the multifold clinical consequences of AF, controlled trials in AF patients should assess the effect of therapy in each of the main outcome domains. This paper describes an expert consensus of required outcome parameters in seven relevant outcome domains, namely death, stroke, symptoms and quality of life, rhythm, left ventricular function, cost, and emerging outcome parameters. In addition to these 'requirements' for outcome assessment in AF trials, further outcome parameters are described in each outcome domain. In addition to a careful selection of a relevant primary outcome parameter, coverage of outcomes in all major domains of AF-related morbidity and mortality is desirable for any clinical trial in AF. |
8,319 | Outcome parameters for trials in atrial fibrillation: executive summary. | Atrial fibrillation (AF), the most common atrial arrhythmia, has a complex aetiology and causes relevant morbidity and mortality due to different mechanisms, including but not limited to stroke, heart failure, and tachy- or bradyarrhythmia. Current therapeutic options (rate control, rhythm control, antithrombotic therapy, 'upstream therapy') only prevent a part of this burden of disease. Several new treatment modalities are therefore under evaluation in controlled trials. Given the multifold clinical consequences of AF, trials in AF patients should assess the effect of therapy in each of the main outcome domains. This paper describes an expert consensus of required outcome parameters in seven relevant outcome domains, namely death, stroke, symptoms and quality of life, rhythm, left ventricular function, cost, and emerging outcome parameters. In addition to these 'requirements' for outcome assessment in AF trials, further, more detailed outcome parameters are described. In addition to a careful selection of a relevant primary outcome parameter, coverage of outcomes in all major domains of AF-related morbidity and mortality is desirable for any clinical trial in AF. |
8,320 | Brugada syndrome unmasked by accidental inhalation of gasoline vapors. | Loss-of-function mutations in the gene SCN5A can cause Brugada syndrome (BrS), which is an inherited form of idiopathic ventricular fibrillation. We report the case of a 46-year-old patient, with no previous medical history, who had ventricular fibrillation after accidental inhalation of gasoline vapors. His electrocardiogram (ECG) showed a typical type-1 BrS pattern that persisted after the acute event. Genetic investigations allowed the identification of a novel SCN5A mutation leading to a frame-shift and early termination of the channel protein. Biochemical and cellular electrophysiology experiments confirmed the loss-of-function of the mutant allele. The patient was implanted with a cardioverter/defibrillator. |
8,321 | Effect of nifekalant for acute conversion of atrial flutter: the possible termination mechanism of typical atrial flutter. | Nifekalant is a class III antiarrhythmic drug, which is usually used for suppression of ventricular tachycardia (VT) and fibrillation. We studied the efficacy of nifekalant for acute conversion of atrial flutter (AFL) in a prospective, open label study in the intensive care unit (ICU) of cardiovascular medicine.</AbstractText>This study consisted of 31 patients. Twenty-six patients (84%) suffered from structural heart diseases. AFL was developed in 15 patients (48%) while on antiarrhythmic therapy with class IA or IC drugs (I-AFL group) for suppressing atrial fibrillation (AF) and in the remaining patients without such drugs (S-AFL group). Patients with prolonged QT interval, hypokalemia were excluded. All patients received one dose of 0.3 mg/kg of nifekalant over 10 minutes under continuous ambulatory monitoring. Four patients with common AFL in each group received nifekalant during electrophysiologic (EP) study.</AbstractText>Nifekalant had an overall AFL conversion efficacy of 77.4% within 60 minutes. Eleven patients in S-AFL group (68.8%) and 13 patients in I-AFL group (86.7%) could be converted with mean conversion times of 10.8 +/- 6.2 and 15.0 +/- 8.0 minutes, respectively (n.s.). Conversion rate was significantly higher in patients with a short duration of arrhythmia. The two modes of AFL termination were mainly demonstrated and the preferential mode significantly differed between the two groups. One patient in each group with excessive QT prolongation (6.5%) developed torsade de pointes (TdP), requiring electrical shock in one patient (3.3%).</AbstractText>Nifekalant can be used for conversion of AFL with a potent efficacy even in patients with structural heart diseases. However, caution should be required for developing TdP.</AbstractText> |
8,322 | Hypertension and cardiac arrhythmias. | Arterial hypertension is a widespread disease and one of important yet under-recognized and under-treated causes of atrial and ventricular arrhythmias. Hypertrophy of cardiac muscle in hypertensive patients is characterized not only by increased myocardial mass, but also by proliferation of fibrous tissue and decreased intercellular coupling, that lead to inhomogeneity of electrical properties and propensity to various arrhythmias. Many trials show the importance of treating hypertension in order to restore normal myocardial function and decrease the number of premature beats, runs of ventricular tachycardia, and attacks of atrial fibrillation. To date, the most convincing data are collected regarding the importance of blockade of renin-angiotensin-aldosterone system (RAAS) in order to avoid arrhythmias in arterial hypertension. Other antihypertensive drug classes (eg beta-blockers, calcium antagonists) are also useful, and investigational compounds that aim at regression of hypertrophy are under search. Polymorphism of genes coding the function of RAAS, pathways of synthesis and degradation of proteins and other cardiac and extracardiac systems involved in regulation of blood pressure, are recognized as promising targets for research. |
8,323 | Alterations in electrophysiology and tissue structure of the left atrial posterior wall in a canine model of atrial fibrillation caused by chronic atrial dilatation. | Chronic left atrial dilatation (CDLA) is associated with an increased incidence of atrial fibrillation (AF). The electrophysiological functions of the left atrial posterior wall (LAPW) are not well understood.</AbstractText>Eight control dogs and 8 with CDLA (developed 6 months after partial mitral valve avulsion) were studied. An electrophysiological study was performed using the noncontact mapping system. The conduction velocity was significantly decreased in the LAPW in the CDLA group. During atrial extrastimulation, a sharp curvature in the activation wavefront became apparent in the LAPW of 6 CDLA dogs, with unidirectional block in 1 dog. The effective refractory periods increased homogeneously throughout the atrium in the CDLA group. AF was much more easily inducible in the CDLA dogs than in the controls. After the onset of AF, the LAPW exhibited the earliest disorganized activity as compared with other sites in the left atrial. In the CDLA dogs, the most extensive interstitial fibrosis was observed in the LAPW.</AbstractText>Alterations in the electrophysiologic properties and tissue structure of the LAPW were observed in the CDLA dogs. This study supports the idea that the LAPW may play a role in the mechanism of AF induced by CDLA.</AbstractText> |
8,324 | Association of atrial arrhythmia and sinus node dysfunction in patients with catecholaminergic polymorphic ventricular tachycardia. | This study was performed to investigate the frequency and importance of supraventricular arrhythmia and sinus node (SN) dysfunction in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT).</AbstractText>Eight patients with CPVT (mean age: 16.8+/-8.1 years) underwent an electrophysiological study. SN recovery time (1,389+/-394 ms) was slightly prolonged, and 4 of 8 patients had abnormal values. Atrial flutter (AF) was induced by low-rate atrial pacing in 2 patients and by isoproterenol infusion in 1 patient. Atrial fibrillation (Af) was induced by isoproterenol infusion in 2 patients. One patient presented with Af during the follow-up period, and 2 of 4 patients with AF/Af presented with increased SN recovery time.</AbstractText>Patients with CPVT frequently have associated with SN dysfunction, and inducible atrial tachyarrhythmias, which indicate that the pathogenesis of CPVT is limited not only to the ventricular myocardium, but also to broad regions of the heart, including the SN and atrial muscle.</AbstractText> |
8,325 | Ventricular fibrillation and defibrillation. | Cardiac arrest in children is not often due to a disturbance in rhythm that is amenable to electrical defibrillation, contrary to the situation in adults. When a shockable rhythm is present, defibrillation using an external electric shock applied at an early stage after pre-oxygenation and chest compressions is of proven efficacy. Success at conversion of ventricular fibrillation is dependent on the delay before delivering the shock and defibrillation efficiency, which is itself a function of thoracic impedance, energy dose and waveform. |
8,326 | Doppler-derived indexes and B-type natriuretic peptide in prediction of paroxysmal atrial fibrillation in essential hypertension: a prospective study. | Onset of atrial fibrillation in hypertensive patients is usually associated with a high occurrence of cardiovascular complications. Despite its leading importance as a highly prevalent and modifiable risk factor, only a few data are available regarding the predictors of paroxysmal atrial fibrillation (PAF) in hypertensive patients.</AbstractText>This study was undertaken to determine if PAF could be predicted in hypertensive patients while in sinus rhythm using Doppler-derived indexes and the plasma B-type natriuretic peptide (BNP) concentration.</AbstractText>We prospectively evaluated 165 consecutive patients with hypertension and no known history of PAF or cardiovascular events who attended the cardiology outpatient clinic. Their mean age was 62 +/- 12, 94 male, 71 female. The conventional echocardiographic parameters were measured including: left atrial (LA) volume, mitral regurgitation (MR), left ventricular (LV) function, LV mass. The ratio of transmitral peak E-wave velocity to flow propagation velocity (E/V(p)), ratio of E-wave to mitral annular early diastolic velocity (E/E(a)) obtained by Doppler tissue at the lateral and septal corners of the mitral annulus were calculated. The plasma BNP was measured at the study entry.</AbstractText>After a mean follow-up of 15 +/- 3 months, PAF (symptomatic attacks or documented on the ECG) occurred in 36 (21.8%) of 165 patients. The patients with PAF had significant higher BNP levels than those with sinus rhythm (160 +/- 109.8 vs. 87.9 +/- 57.7 pg/ml, P < 0.001) Also, E/E(a) and E/V(p) ratios were significantly higher in hypertensives with PAF (15.1 +/- 2.8 vs. 8.39 +/- 1.33, P < 0.001), and (1.65 +/- 1.29 vs. 1.19 +/- 1.06, P < 0.001) respectively. In univariate analysis, E/V(p), E/E(a), and BNP and LV hypertrophy were significant predictors of PAF. Barely E/V(p) and E/E(a) remained independently significant after adjustment of clinical and other echocardiographic variables by multivariate logistic regression analysis (odd ratio: 3.36, P < 0.001 and 4.93, P < 0.001 respectively). A cutoff value of > or =1.7 for E/V(p) predicted PAF with 91% sensitivity and 88% specificity; E/E(a) >12 has sensitivity 98%, specificity 89%, while BNP>170 pg/ml has 83% and 72% specificity, respectively, for prediction of PAF in hypertensive patients.</AbstractText>Paroxysmal atrial fibrillation could be predicted in hypertensive patients while in sinus rhythm using Doppler-derived indexes. Increased E/V(p), E/E(a) ratios and elevated BNP appear to be useful parameters to identify patients at heightened risk. They may reflect early left ventricular dysfunction and atrial hypertension in this population.</AbstractText> |
8,327 | Image integration in electroanatomic mapping. | Over the past five years, integration of the pre-procedural MR/CT images with a 3D electroanatomic mapping system has been developed to facilitate catheter ablation of clinical arrhythmias. It presents a significant advantage over the less-detailed surrogate geometry created by the 3D mapping systems. The process of image integration consists of pre-procedural imaging, image segmentation and image registration. Clinical studies have demonstrated the feasibility and accuracy of the use of image integration to guide catheter ablation of atrial fibrillation (AF). Accurate registration of the 3D left atrial MR/CT image to the real-time catheter mapping space can be technically challenging. Several important considerations should be taken into account to minimize registration error. Enhanced ability of catheter navigation with image integration may improve the efficacy and safety of anatomically based ablation strategies such as ablations of AF and nonidiopathic ventricular tachycardia. New developments in the field include integration of pathophysiologic as well as real-time anatomic information to the 3D mapping systems, and the use of new navigation system to improve registration. |
8,328 | Effect of pravastatin on sympathetic reinnervation in postinfarcted rats. | We assessed whether pravastatin attenuates cardiac sympathetic reinnervation after myocardial infarction through the activation of ATP-sensitive K(+) (K(ATP)) channels. Epidemiological studies have shown that men treated with statins appear to have a lower incidence of sudden death than men without statins. However, the specific factor for this has remained disappointingly elusive. Twenty-four hours after ligation of the anterior descending artery, male Wistar rats were randomized to groups treated with either vehicle, nicorandil (a specific mitochondrial K(ATP) channel agonist), pinacidil (a nonspecific K(ATP) channel agonist), pravastatin, glibenclamide (a K(ATP) channel blocker), or a combination of nicorandil and glibenclamide, pinacidil and glibenclamide, or pravastatin and glibenclamide for 4 wk. Myocardial norepinephrine levels revealed a significant elevation in vehicle-treated rats at the remote zone compared with sham-operated rats (2.54 +/- 0.17 vs. 1.26 +/- 0.36 mug/g protein, P < 0.0001), consistent with excessive sympathetic reinnervation after infarction. Immunohistochemical analysis for tyrosine hydroxylase, growth-associated factor 43, and neurofilament also confirmed the change of myocardial norepinephrine. This was paralleled by a significant upregulation of tyrosine hydroxylase protein expression and mRNA in vehicle-treated rats, which was reduced after the administration of either nicorandil, pinacidil, or pravastatin. Arrhythmic scores during programmed stimulation in vehicle-treated rats were significantly higher than those treated with pravastatin. In contrast, the beneficial effects of pravastatin were reversed by the addition of glibenclamide, implicating K(ATP) channels as the relevant target. The sympathetic reinnervation after infarction is modulated by the activation of K(ATP) channels. Chronic use of pravastatin after infarction, resulting in attenuated sympathetic reinnervation by the activation of K(ATP) channels, may modify the arrhythomogenic response to programmed electrical stimulation. |
8,329 | Permanent chronic atrial fibrillation: is pulmonary vein isolation alone enough? | The efficacy of mere pulmonary vein isolation epicardially for the treatment of permanent chronic atrial fibrillation, in comparison with the left atrial endocardial maze procedure was evaluated.</AbstractText>Retrospective data collection and analysis toward the outcome of 72 consecutive patients who underwent left atrial maze procedures between January 2003 and December 2005 was performed. Surgical ablation was performed concomitantly with valve and (or) coronary procedures. Group I (n = 29) received an endocardial left atrial ablation using unipolar saline irrigated radiofrequency (Medtronic Cardioblate surgical ablation pen; Medtronic Inc, Minneapolis, MN). Group II (n = 43) received epicardial isolation of the pulmonary veins using bipolar saline irrigated radiofrequency (Medtronic Cardioblate). Follow-up included 24h electrocardiogram and echocardiography 6 and 12 months postoperatively.</AbstractText>Mean follow-up was 19.5 +/- 1.0 months (17.7 +/- 19.5 months group I vs 20.6 +/- 1.1 months group II). Both groups were comparable with regard to duration of preoperative atrial fibrillation, European system for cardiac operative risk evaluation, left ventricular ejection fraction, aortic cross-clamp time, bypass time, intensive care unit and hospital stay (p > 0.05). No maze procedure-related mortality was observed. In group I, three patients required postoperative pacemaker implantation due to atrioventricular (AV) bloc, bradycardia, and sick sinus syndrome, respectively. In group II, five patients required postoperative pacemaker implantation (three AV bloc and two bradycardia). Freedom from atrial fibrillation at last follow-up was 85.7% and 58.5% in groups I and II, respectively (p = 0.016).</AbstractText>Pulmonary vein isolation alone seems to be insufficient in treating permanent chronic atrial fibrillation. In case of chronic permanent atrial fibrillation, left atrial endocardial maze, providing the connection lines to the mitral annulus and (or) between the pulmonary veins, seems to be mandatory.</AbstractText> |
8,330 | Breakdown of atheromatous plaque due to shear force from arterial perfusion cannula. | Breakdown of an atheromatous plaque in the aorta due to jet from the arterial cannula is reported. The patient underwent mitral valve replacement under ventricular fibrillation because of severe atheromatous change in the ascending aorta, transverse aortic arch, and descending aorta. A dispersive arterial perfusion cannula was inserted into the middle portion of the ascending aorta where the atheromatous change was minimal. Postoperative epiaortic ultrasonography revealed a breakdown of the atheromatous plaque in the lesser curvature. In view of this complication, further study of the effects of shear stress to the diseased aorta should be done by clinical and flow dynamics investigation. |
8,331 | The herbal drug Catuama reverts and prevents ventricular fibrillation in the isolated rabbit heart. | Catuama, an herbal drug very popular in Brazil, was tested on the reversion and prevention of ventricular fibrillation (VF) in the isolated rabbit heart.</AbstractText>Catuama (a mixture of Trichilia catigua, Paullinia cupana, Ptychopetalum olacoides, and Zinziber officinalis) was perfused in the isolated perfused rabbit heart. Its effects on intraventricular conduction, heart rate, and monophasic action potential (MAP) duration were evaluated, and sustained VF was induced. The effects on reversion and reinduction of arrhythmia were observed, and new measures were taken in the hearts that reverted.</AbstractText>Catuama and T catigua reverted VF in all hearts, prevented reinduction, and prolonged intraventricular conduction. Catuama prolonged MAP phase 2. On the other hand, P cupana reverted VF in 3 of 5 hearts, but depressed automatism, prolonged MAP phase 3, and did not prevent reinduction.</AbstractText>Catuama reverted and prevented VF in this model. T catigua extract is probably the main agent responsible for the beneficial actions observed. Further studies are now in progress to clarify these actions.</AbstractText> |
8,332 | Giant septal cavity due to coronary artery fistula and ventricular septal dissection after cardiac surgery. | Ventricular septal dissection may rarely result from infective endocarditis, myocardial infarction or sinus of Valsalva aneurysm progression. A rare case that developed in a 66-year-old female after mitral valve replacement for severe mitral regurgitation with cordal rupture is presented and discussed. It resulted from a coronary artery fistula, from a septal branch, to a 6 cm wide saccular cystic cavity within the interventricular septum, which was detected by transthoracic echocardiography some months after surgery. Coronary arteries were anatomically normal. Coronary angiography was helpful to clarify the origin of the fistula. Later on the patient developed heart failure and atrial fibrillation, but she refused any further intervention. She has been followed up for more than 7 years and is presently stable on medical therapy. A review of the peculiar aspects of the case is done and the most relevant aspects and images are presented and discussed. |
8,333 | Relation between major and minor depression and heart rate, heart-rate variability, and clinical characteristics of patients with acute coronary syndrome. | This study examined the prevalence of major and minor depression in patients with acute coronary syndrome and their relation with heart rate and heart-rate variability, and clinical characteristics. The study group included 297 patients, 200 men and 97 women, between ages of 21 and 70 years (M age = 57.5 +/- 9.6), who were admitted to a coronary care unit with acute coronary syndrome and survived to discharge from the hospital. Major and minor depression were diagnosed using DSM-IV. There were 44.1% patients with acute coronary syndrome without depression, 29.3% with minor depression, and 26.6% with major depression. The prevalence of minor and major depression was more elevated in patients with non-ST-segment elevation myocardial infarction and unstable angina than in patients with ST-segment elevation myocardial infarction. Ventricular fibrillation and atrial fibrillation were more common in patients with major and minor depression than in patients without depression. The 24-hr. duration of heart-beat intervals and heart-rate variability were significantly lower in patients with major and minor depression than in patients without depression. This study implies that clinical depression was significantly comorbid with the acute coronary syndrome and was related to hypertension, diabetes mellitus, age, sex, type of acute coronary syndrome, left ventricular failure, higher heart rate, and lower heart-rate variability. |
8,334 | Circadian, daily, and seasonal distributions of ventricular tachyarrhythmias in patients with implantable cardioverter-defibrillators. | This study investigated the circadian, daily, and seasonal distributions of ventricular arrhythmias in patients with new implantable cardioverter-defibrillator placement at Creighton University Medical Center from January 2000 to December 2004. The incidence and distribution of ventricular tachyarrhythmias as recorded by implantable cardioverter-defibrillators were analyzed with respect to season, month, day of the week, and average daily temperature. Data from 154 consecutive patients (mean age 67 +/- 14 years; 78% men, 71% with ischemic heart disease [IHD], mean left ventricular ejection fraction 34 +/- 15%) were analyzed. During a mean follow-up of 35 +/- 19 months, a total of 1,055 episodes of spontaneously terminated ventricular tachycardia (VT) and 612 episodes of VT or ventricular fibrillation with appropriate device therapy occurred. Distributions in the incidence of VT and VT or ventricular fibrillation receiving appropriate therapy were similar in patients with IHD and non-IHD. Spontaneously terminated VT and appropriately treated VT or ventricular fibrillation episodes occurred with the greatest incidence in the winter months and the lowest incidence in summer, spring, and fall. A linear regression between the number of episodes and the average daily temperature showed a greater likelihood of the 2 events occurring on cooler days, irrespective of the cause of cardiac disease. A weekly distribution was also observed, with the greatest proportion of episodes occurring on Fridays and the lowest on Saturdays and Sundays. A bimodal circadian distribution was present, with the greatest peak occurring from 8 a.m. to 1 p.m. and a smaller peak occurring from 5 p.m. to 10 p.m. In conclusion, the occurrence of ventricular tachyarrhythmias appears to follow circadian, daily, and seasonal distributions that are similar in patients with IHD and non-IHD. The incidence inversely correlates with average daily temperatures. |
8,335 | Intermittent atrial sensing in a VDD pacemaker. | This report deals with a patient with single-lead VDD pacemaker and intermittent atrial sensing failure. At first glance, the electrocardiogram suggested a VVI mechanism of pacing, being paced QRS complexes dissociated from sinus P waves: this revealed that intracardiac atrial electrograms were too small to reach the sensing threshold. At times, however, a sinus P wave triggered ventricular pacing. This only occurred when the spontaneous atrial activity fell within a critical interval ranging from 430 to 480 milliseconds from the previous paced QRS complex. Analysis of pulsed wave Doppler mitral flow recording demonstrated that atrial sensing and related ventricular pacing occurred whenever a sinus P wave coincided with the opening click of mitral valve. In this circumstance, the atrial volume decrease allowed the freely floating atrial lead to lie close to the right atrial wall, favoring sensing of a small intracardiac electrogram. |
8,336 | Cardiac transplantation in a patient with emotionally triggered implantable cardioverter defibrillator storms. | The implantable cardioverter defibrillator (ICD) may be responsible for psychological disorders especially among patients experiencing multiple shocks. An associated hyperadrenergic state (e.g., anger, anxiety) may trigger malignant ventricular arrhythmias repeatedly treated by ICD shocks, entertaining a "vicious circle" often difficult to interrupt. Despite aggressive cardiac and psychological therapeutic efforts, this condition may be refractory, finally leading to heart transplantation, as described in this case report. |
8,337 | Relation of interleukin-6 and C-reactive protein levels to sinus maintenance after pharmacological cardioversion in persistent atrial fibrillation. | The aim of this study was to investigate whether interleukin-6 (IL-6) and C-reactive protein (CRP) have significant relation to sinus maintenance after pharmacological conversion of long-lasting atrial fibrillation (AF) with respect to use of renin-angiotensin-aldosterone system (RAS) inhibitors.</AbstractText>We studied 35 consecutive patients with AF lasting > or =1 month who had successful pharmacological cardioversion with bepridil alone or in combination with aprindine. The IL-6 and CRP levels in plasma were measured after pharmacological restoration of sinus rhythm.</AbstractText>During the 1-year follow-up period, sinus rhythm was maintained in 20 patients (Group I), and the other 15 patients had recurrence of AF (Group II). Both plasma levels of IL-6 and CRP were significantly lower in Group I than in Group II (IL-6: 1.19 +/- 0.51 versus 1.84 +/- 0.66 ng/L, P < 0.005; CRP: 0.59 +/- 0.40 versus 1.24 +/- 0.79 mg/L, P < 0.005). The use of RAS inhibitors and left atrial dimension and the left ventricular ejection fraction showed no differences between the 2 groups. There was significant positive correlation between levels of IL-6 and CRP.</AbstractText>In long-lasting persistent AF, lower levels of IL-6 and CRP appear to be associated with maintenance of sinus rhythm after pharmacological cardioversion irrespective of the use of RAS inhibitors. Further studies are needed to clarify the role of RAS inhibitors.</AbstractText> |
8,338 | Prescribing amiodarone: an evidence-based review of clinical indications. | Although amiodarone is approved by the US Food and Drug Administration only for refractory ventricular arrhythmias, it is one of the most frequently prescribed antiarrhythmic medications in the United States.</AbstractText>To evaluate and synthesize evidence regarding optimal use of amiodarone for various arrhythmias.</AbstractText>Systematic search of MEDLINE to identify peer-reviewed clinical trials, randomized controlled trials, meta-analyses, and other studies with clinical pertinence. The search was limited to human-participant, English-language reports published between 1970 and 2007. Amiodarone was searched using the terms adverse effects, atrial fibrillation, atrial flutter, congestive heart failure, electrical storm, hypertrophic cardiomyopathy, implantable cardioverter-defibrillator, surgery, ventricular arrhythmia, ventricular fibrillation, and Wolff-Parkinson-White. Bibliographies of identified articles and guidelines from official societies were reviewed for additional references. Ninety-two identified studies met inclusion criteria and were included in the review.</AbstractText>Amiodarone may have clinical value in patients with left ventricular dysfunction and heart failure as first-line treatment for atrial fibrillation, though other agents are available. Amiodarone is useful in acute management of sustained ventricular tachyarrythmias, regardless of hemodynamic stability. The only role for prophylactic amiodarone is in the perioperative period of cardiac surgery. Amiodarone may be effective as an adjunct to implantable cardioverter-defibrillator therapy to reduce number of shocks. However, amiodarone has a number of serious adverse effects, including corneal microdeposits (>90%), optic neuropathy/neuritis (< or =1%-2%), blue-gray skin discoloration (4%-9%), photosensitivity (25%-75%), hypothyroidism (6%), hyperthyroidism (0.9%-2%), pulmonary toxicity (1%-17%), peripheral neuropathy (0.3% annually), and hepatotoxicity (elevated enzyme levels, 15%-30%; hepatitis and cirrhosis, <3% [0.6% annually]).</AbstractText>Amiodarone should be used with close follow-up in patients who are likely to derive the most benefit, namely those with atrial fibrillation and left ventricular dysfunction, those with acute sustained ventricular arrhythmias, those about to undergo cardiac surgery, and those with implantable cardioverter-defibrillators and symptomatic shocks.</AbstractText> |
8,339 | Adjunctive therapy for recurrent ventricular tachycardia in patients with implantable cardioverter defibrillators. | Implantable cardioverter defibrillators (ICDs) are now the mainstay of therapy in patients with sustained ventricular tachycardia (VT), ventricular fibrillation, resuscitated sudden cardiac death, or certain high-risk markers for these arrhythmic events. Although ICDs in such patients can be life-saving, they can impair quality of life when painful or frequent discharges occur or when residual VT symptoms recur prior to delivery of ICD therapies. As such, antiarrhythmic drugs often are employed in an attempt to reduce the triggering tachyarrhythmic events. Recently, studies with beta-blockers, sotalol, amiodarone, and the investigational agent azimilide have been performed to objectify the efficacy, benefits, or risks of such therapies when administered to patients with ICDs. This review describes the considerations important to the use of these therapies in ICD patients and the results and applicability of these investigative studies. |
8,340 | [Implications of gender-specific aspects in the therapy of cardiovascular diseases]. | In cardiovascular diseases e.g. heart failure and coronary artery disease gender differences are evident in etiology, pathophysiology, clinical presentation, prognosis and response to treatment. Diabetes and hypertension are the major risk factors in women. Mechanisms leading to apparent diabetes or its clinical pre-stage are different in women and men and according to this result in different therapeutic implications. Diastolic heart failure is more frequent in women and effects and side effects of important groups of active pharmaceutical substances are, at least to some extent, different. Atrial fibrillation and ventricular arrhythmia differ in frequency of occurrence; drug induced tachycardia with QT interval prolongation is particularly frequent in women. Underlying pathomechanisms responsible for gender differences in pharmacotherapy are on the one hand differences in pharmacokinetic mechanisms. Particularly drugs which are metabolised via cytochrome P 450 CYP 3A pathway show different kinetics in women and men. In addition, important differences are evident in pharmocodynamics caused by effects of sex steroid hormones or products of X-chromosomal genes. The evidence of estrogen and testosterone receptors in cardiomyocytes and the vascular system, interaction of sex steroid hormones with cellular pathways and the role of X-chromosomal genes are the focus of basic research. Interactions of sex steroid hormone receptors with other nuclear receptors e.g. PPARs ("peroxisome proliferator-activated receptors") are another important underlying mechanism. The knowledge of different pharmacokinetic mechanisms has to be taken into consideration in pharmacotherapy of cardiovascular diseases, for example by adjustment of drug dosages in women, necessary in different groups of pharmaceutical substances or in the long run, gender differences in effects and side effects of drugs. In drug development both aspects have to be considered. There is more than one good reason to intensify basic and clinical research and research on health care on gender differences in cardiovascular diseases. |
8,341 | Renal function is associated with risk of atrial fibrillation after cardiac surgery. | Atrial fibrillation (AF) frequently occurs after cardiac surgery and is responsible for increased morbidity and resource use. The aim of the present study was to evaluate the association of impaired renal function and the development of postoperative AF.</AbstractText>Patients undergoing elective cardiac surgery in the absence of significant left ventricular dysfunction (n=253; average age 65+/-11 years) were recruited to the present prospective study. Ninety-nine patients (39.1%) developed AF during the postoperative period. Creatinine clearance, estimated by the calculated glomerular filtration rate (GFR), was prospectively assessed to determine the association of baseline renal function and the development of postoperative AF. Baseline calculated GFR was assessed as a continuous and a categorical variable (normal: greater than 90 mL/min/1.73 m(2); mildly decreased: 60 mL/min/1.73 m(2) to 89 mL/min/1.73 m(2); and moderately to severely decreased: less than 60 mL/min/1.73 m(2)). Baseline creatinine clearance was 72+/-22.2 mL/min/1.73 m(2) and 78.8+/-23.5 mL/min/1.73 m(2) in patients with and without postoperative AF, respectively (P=0.02). There was an independent association between decreasing calculated GFR and the development of postoperative AF (OR for 10 mL decrease in calculated GFR: 1.21, 95% CI 1.02 to 1.39). In addition to calculated GFR, surgery for valvular heart disease (versus coronary artery bypass grafting [OR 2.23, 95% CI 1.09 to 3.14; P<0.01]), age (OR per 10-year increase in age 1.92, 1.18 to 2.59) and perioperative nonuse of beta-adrenergic blockers (OR 1.62, 95% CI 1.12 to 3.55; P<0.01) were identified as independent predictors of postoperative AF.</AbstractText>In the setting of cardiac surgery, impaired calculated GFR is associated with an increased risk for the development of postoperative AF. These data provide additional evidence supporting the association between renal dysfunction and adverse cardiovascular outcomes.</AbstractText> |
8,342 | Efficacy of magnesium sulfate for treatment of ventricular tachycardia in amitriptyline intoxication. | In our country, tricyclic antidepressants are usually present in most of the homes. Myocardial depression and ventricular arrhythmia are the severe side effects in tricyclic antidepressant overdose. A 4-year-old boy was brought to our hospital after taking 70 mg/kg of amitriptyline. On arrival, the patient was comatose (Glasgow Coma Score was 3), had a shallow breathing pattern with bradycardia (HR <30/min), and hypotension. He was intubated and resuscitated with multiple doses of adrenaline and sodium bicarbonate. He was infused with a bolus of 20 mg/kg of normal saline for hypotension. After 30 minutes, ventricular fibrillation was detected. Lidocaine and bicarbonate were not effective in converting the rhythm to normal, therefore, synchronized cardioversion was used. After cardioversion, the rhythm converted to ventricular tachycardia. Because ventricular tachycardia did not resolve, we administered a load of less than 2 g of magnesium sulfate for 30 minutes followed by a continuous infusion of 3 mg/min. After magnesium sulfate infusion, a normal cardiac rhythm was achieved. Magnesium sulfate is a very effective treatment in intractable arrhythmias caused by high-dose amitriptyline intoxication. |
8,343 | Expanding spectrum of human RYR2-related disease: new electrocardiographic, structural, and genetic features. | Catecholaminergic polymorphic ventricular tachycardia is a disease characterized by ventricular arrhythmias elicited exclusively under adrenergic stress. Additional features include baseline bradycardia and, in some patients, right ventricular fatty displacement. The clinical spectrum is expanded by the 2 families described here.</AbstractText>Sixteen members from 2 separate families have been clinically evaluated and followed over the last 15 years. In addition to exercise-related ventricular arrhythmias, they showed abnormalities in sinoatrial node function, as well as atrioventricular nodal function, atrial fibrillation, and atrial standstill. Left ventricular dysfunction and dilatation was present in several affected individuals. Linkage analysis mapped the disease phenotype to a 4-cM region on chromosome 1q42-q43. Conventional polymerase chain reaction-based screening did not reveal a mutation in either the Ryanodine receptor 2 gene (RYR2) or ACTN2, the most plausible candidate genes in the region of interest. Multiplex ligation-dependent probe amplification and long-range polymerase chain reaction identified a genomic deletion that involved RYR2 exon-3, segregated in all the affected family members (n=16) in these 2 unlinked families. Further investigation revealed that the genomic deletion occurred in both families as a result of Alu repeat-mediated polymerase slippage.</AbstractText>This is the first report on a large genomic deletion in RYR2, which leads to extended clinical phenotypes (eg, sinoatrial node and atrioventricular node dysfunction, atrial fibrillation, atrial standstill, and dilated cardiomyopathy). These features have not previously been linked to RYR2.</AbstractText> |
8,344 | Conversion of atrial fibrillation to sinus rhythm during treatment with intravenous esmolol or diltiazem: a prospective, randomized comparison. | Prior studies have suggested that intravenous diltiazem reduces the probability of spontaneous conversion of atrial fibrillation (AF) to sinus rhythm in the electrophysiology laboratory and in patients with postoperative AF. Whether diltiazem exerts the same effect in patients presenting to the emergency department (ED) with spontaneous AF is unclear. Fifty patients presenting to the ED with new-onset or paroxysmal AF and a rapid ventricular rate (>100 beats per minute) were randomly assigned to receive intravenous diltiazem or esmolol during the first 24 hours of presentation. Conversion to sinus rhythm occurred in 10 patients (42%) in the diltiazem group compared with 10 patients (39%) in the esmolol group (P = 1.0). Diltiazem does not decrease the likelihood of spontaneous conversion of AF to sinus rhythm in the ED setting. |
8,345 | Supernormal conduction in the anomalous bundles of the Wolff-Parkinson-White syndrome: an overlooked electrophysiologic property with potential clinical implications. | The anterograde refractory period (RP) of the accessory pathway (AP) is the main determinant factor of ventricular rate during atrial fibrillation in the Wolff-Parkinson-White (WPW) syndrome. We describe 3 examples of anterograde supernormal conduction (SNC) and 1 of retrograde SNC in APs. The paradoxical early recovery of propagation due to SNC, well inside a prolonged anterograde RP in the AP, may play a relevant role to determine the rate of ventricular response during atrial fibrillation, eventually leading to extremely fast ventricular rates, syncope, and even ventricular fibrillation in patients with WPW syndrome supposed a priori to be exposed to a low risk of sudden cardiac death. This may require very precise conditions, including an enhanced adrenergic influence on the heart. Retrograde SNC in APs may also participate in the mechanism of paroxysmal supraventricular tachycardias that are not easily induced by programmed cardiac stimulation. |
8,346 | Implantable cardioverter defibrillator therapy and the need for concomitant antiarrhythmic drugs. | Implantable cardioverter defibrillators (ICDs) are increasingly used for the prevention of sudden cardiac death in patients with life-threatening ventricular arrhythmias (VAs); however, there is a potential for severe and debilitating anxiety caused by symptoms associated with ICD therapy and anticipation of shocks. Anxiety is a psycho-logic stressor, including physiologic components that may lead to adrenergic excitation triggering new arrhythmias and ICD therapies. This often requires concomitant antiarrhythmic medication to reduce the frequency of shocks and symptomatic arrhythmias treated by anti-tachycardia pacing. Although published studies have documented the efficacy of currently available antiarrhythmics, they have limitations in patients with heart failure, may affect the defibrillation threshold, and/or have been associated with major side-effects. In conclusion, for the patient with an ICD experiencing symptomatic ventricular tachycardia (VTs) episodes or ICD shocks, there is a need for pharmacologic therapy to reduce the incidence of such events without affecting the performance of the ICD or causing major side-effects. |
8,347 | Do patient characteristics or factors at resuscitation influence long-term outcome in patients surviving to be discharged following in-hospital cardiac arrest? | Few studies have focused on factors influencing long-term outcome following in-hospital cardiac arrest. The present study assesses whether long-term outcome is influenced by difference in patient factors or factors at resuscitation.</AbstractText>An analysis of cardiac arrest data collected from one Swedish tertiary hospital and from five Finnish secondary hospitals supplemented with data on 1 year survival. Multiple logistic regression analysis was used to identify factors associated with survival at 12 months.</AbstractText>A total of 441 patients survived to hospital discharge following in-hospital cardiac arrest and 359 (80%) were alive at 12 months. Factors independently associated with survival [odds ratio (OR) >1 indicates increased survival and <1 decreased survival] at 12 months were; age [OR 0.95, 95% confidence interval (CI) 0.93-0.98], renal disease (OR 0.3, CI 0.1-0.9), good functional status at discharge (OR 4.9, CI 1.3-18.9), arrest occurring at (compared with arrests on general wards) emergency wards (OR 4.7, CI 1.4-15.3), cardiac care unit (OR 2.8, CI 1.2-6.4), intensive care unit (OR 2.4, CI 1.1-5.7), ward for thoracic surgery (OR 10.2, CI 2.6-40.1) and unit for interventional radiology (OR 13.3, CI 3.4-52.0). There was no difference in initial rhythm, delay to defibrillation or delay to return of spontaneous circulation between survivors and nonsurvivors.</AbstractText>Several patient factors, mainly age, functional status and co-morbid disease, influence long-term survival following cardiac arrest in hospital. The location where the arrest occurred also influences survival, but initial rhythm, delay to defibrillation and to return of spontaneous circulation do not.</AbstractText> |
8,348 | Incessant non-sustained ventricular tachycardia after stimulus of electroconvulsive therapy with atropine premedication? | Electroconvulsive therapy (ECT) is an effective and safe treatment for a variety of neuropsychiatric disorders. Premedication with atropine has been recommended in order to avoid bradycardia and transient asystole induced by ECT. In contrast, some other arrhythmias can happen such as atrial flutter and fibrillation. But ventricular tachycardia is rare. Reported herein is a case of incessant non-sustained ventricular tachycardia, possibly triggered by atropine premedication. |
8,349 | Differences in the characteristics of induced and spontaneous episodes of ventricular fibrillation. | The degree of organization of ventricular fibrillation (VF) can be examined in terms of the regularity of the electrical activity within the ventricle. Using electrograms (EGMs) stored within implanted cardioverter defibrillators (ICDs), we examined the hypothesis that the degree of organization, or regularity, was different if the VF was induced by electrical stimulation as opposed to occurring clinically due to ischemia or scar.</AbstractText>We compared the statistical characteristics of EGMs recorded by ICDs during spontaneous episodes with those induced during device testing in the laboratory in nine subjects. Regularity of the VF EGM signals was quantified using autocorrelation, Shannon entropy (derived from cycle to cycle activation complexes), and Kolmogorov entropy (derived from eight second long episodes of VF). All three measurements showed a statistically greater degree of regularity for induced VF than in spontaneous episodes.</AbstractText>Analysis of VF EGMs using these techniques is novel and robust, providing a new way for assessing electrical organization during VF. The clinical significance and utility of differences in VF waveform regularity is unclear at this stage.</AbstractText> |
8,350 | Arrhythmogenic mechanisms in a mouse model of catecholaminergic polymorphic ventricular tachycardia. | Catecholaminergic polymorphic ventricular tachycardia (VT) is a lethal familial disease characterized by bidirectional VT, polymorphic VT, and ventricular fibrillation. Catecholaminergic polymorphic VT is caused by enhanced Ca2+ release through defective ryanodine receptor (RyR2) channels. We used epicardial and endocardial optical mapping, chemical subendocardial ablation with Lugol's solution, and patch clamping in a knockin (RyR2/RyR2(R4496C)) mouse model to investigate the arrhythmogenic mechanisms in catecholaminergic polymorphic VT. In isolated hearts, spontaneous ventricular arrhythmias occurred in 54% of 13 RyR2/RyR2(R4496C) and in 9% of 11 wild-type (P=0.03) littermates perfused with Ca2+and isoproterenol; 66% of 12 RyR2/RyR2(R4496C) and 20% of 10 wild-type hearts perfused with caffeine and epinephrine showed arrhythmias (P=0.04). Epicardial mapping showed that monomorphic VT, bidirectional VT, and polymorphic VT manifested as concentric epicardial breakthrough patterns, suggesting a focal origin in the His-Purkinje networks of either or both ventricles. Monomorphic VT was clearly unifocal, whereas bidirectional VT was bifocal. Polymorphic VT was initially multifocal but eventually became reentrant and degenerated into ventricular fibrillation. Endocardial mapping confirmed the Purkinje fiber origin of the focal arrhythmias. Chemical ablation of the right ventricular endocardial cavity with Lugol's solution induced complete right bundle branch block and converted the bidirectional VT into monomorphic VT in 4 anesthetized RyR2/RyR2(R4496C) mice. Under current clamp, single Purkinje cells from RyR2/RyR2(R4496C) mouse hearts generated delayed afterdepolarization-induced triggered activity at lower frequencies and level of adrenergic stimulation than wild-type. Overall, the data demonstrate that the His-Purkinje system is an important source of focal arrhythmias in catecholaminergic polymorphic VT. |
8,351 | A new cardiopulmonary resuscitation method using only rhythmic abdominal compression: a preliminary report. | This article introduces 2 new cardiopulmonary resuscitation (CPR) concepts: (1) the use of only rhythmic abdominal compression (OAC) to produce blood flow during CPR with ventricular fibrillation and (2) a new way of describing coronary perfusion effectiveness, namely, the area between the aortic and right atrial pressure curves, summed over 1 minute, the units being millimeters of mercury per second. We call this unit the coronary perfusion index (CPI). True mean coronary perfusion pressure is CPI/60. We also relate CPI during CPR with ventricular fibrillation to the CPI for the normally beating heart in the same animal, obtained before each experiment. This 11-pig (25-35 kg) study compares the CPI for standard chest-compression CPR and that obtained with OAC-CPR. The coronary perfusion ratio for OAC-CPR compared with standard chest-compression CPR was 1.6 +/- 0.73 (P = .024). In other words, OAC-CPR produced 60% more coronary perfusion than standard chest-compression CPR, with no damage to visceral organs. |
8,352 | Future directions in degenerative mitral valve repair. | Mitral valve repair is by far the most common operation for degenerative mitral regurgitation. If the procedure is performed before left ventricular dysfunction occurs and atrial fibrillation develops, the operative risk is very low and life expectancy is super imposable to that of the sex- and age-matched population. Despite these achievements, there are areas that could still be improved. Progress in treating degenerative mitral regurgitation is expected to move along several directions. More precise diagnostic methods will be developed to reliably quantify mitral regurgitation and identify early irreversible ventricular and atrial changes. The refinement of surgical techniques and search for new, innovative solutions should never be abandoned. Finally, transcatheter correction of mitral regurgitation represents a new, emerging field of cardiovascular medicine and is expected to have a significant impact on the surgical practice in the future. |
8,353 | Principles of reconstructive surgery in degenerative mitral valve disease. | Degenerative mitral valve disease is the most common cause of mitral regurgitation (MR) in developed countries. The most common etiologies of valvular regurgitation are Barlow's disease and fibroelastic deficiency. The mechanism of MR is type II dysfunction (leaflet prolapse) due to chordae elongation or rupture in most patients. Associated annular dilation is a common lesion in almost all patients with chronic MR. By means of segmental valve analysis, isolated posterior leaflet prolapse (P2 segment) is often observed in patients with fibroelastic deficiency, whereas the prolapse of multiple segments or bileaflet prolapse is typically seen in patients with Barlow's disease. In patients with degenerative mitral valve disease and severe MR, reconstructive surgery should be performed before the occurrence of clinical symptoms, atrial fibrillation, pulmonary hypertension, and left ventricular dysfunction or enlargement. The goals of reconstructive surgery are preservation or restoration of normal leaflet motion, creation of a large surface of coaptation, and stabilization of the entire annulus with a remodeling annuloplasty. Today, reconstructive techniques are standardized, reliable, and reproducible, and therefore should be applied systematically to all patients with degenerative valvular disease. |
8,354 | Indications for surgery in degenerative mitral valve disease. | There has been great progress during the past decade in management of patients with mitral regurgitation. Doppler echocardiography allows accurate quantification of the degree of valve leakage and tracking of the effect of regurgitation on cardiac size and function. Natural history studies have clearly delineated the deleterious effects of severe, persistent mitral valve regurgitation including an increased risk of cardiac death as well as a predisposition to the development of congestive heart failure and atrial fibrillation. In virtually all of our analyses, short-term and long-term outcomes are improved in patients who have early surgical correction of severe mitral valve regurgitation. Moreover, there are clear benefits of mitral valve repair over valve replacement, including greater regression of left heart dimensions, normalization of left ventricular function, and superior long-term survival. |
8,355 | Speckle-tracking radial strain reveals left ventricular dyssynchrony in patients with permanent right ventricular pacing. | Speckle-tracking strain analysis was used to assess the effects of permanent right ventricular (RV) pacing on the heterogeneity in timing of regional wall strain and left ventricular (LV) dyssynchrony.</AbstractText>Recent studies have shown detrimental effects of RV pacing, possibly related to the induction of LV dyssynchrony.</AbstractText>Fifty-eight patients treated with His bundle ablation and pacemaker implantation were studied. To assess the effect of RV pacing on time-to-peak radial strain of different LV segments, we applied speckle-tracking analysis to standard LV short-axis images. In addition, New York Heart Association (NYHA) functional class, LV volumes, and systolic function were assessed at baseline and after long-term RV pacing.</AbstractText>At baseline, similar time-to-peak strain for the 6 segments was observed (mean 371 +/- 114 ms). In contrast, after a mean of 3.8 +/- 2.0 years of RV pacing, there was a marked heterogeneity in time-to-peak strain of the 6 segments. In 33 patients (57%), LV dyssynchrony, represented by a time difference > or =130 ms between the time-to-peak strain of the (antero)septal and the posterolateral segments, was present. In these patients, a deterioration of LV systolic function and NYHA functional class was observed. In 11 patients, an "upgrade" of the conventional pacemaker to a biventricular pacemaker resulted in partial reversal of the detrimental effects of RV pacing.</AbstractText>Speckle-tracking analysis revealed that permanent RV pacing induced heterogeneity in time-to-peak strain, resulting in LV dyssynchrony in 57% of patients, associated with deterioration of LV systolic function and NYHA functional class. Biventricular pacing may reverse these adverse effects of RV pacing.</AbstractText> |
8,356 | Limitations of ejection fraction for prediction of sudden death risk in patients with coronary artery disease: lessons from the MUSTT study. | We determined the contribution of multiple variables to predict arrhythmic death and total mortality risk in patients with coronary disease and left ventricular dysfunction. We then constructed an algorithm to predict risk of mortality and sudden death.</AbstractText>Many factors in addition to ejection fraction (EF) influence the prognosis of patients with coronary disease. However, there are few tools to use this information to guide clinical decisions.</AbstractText>We evaluated the relationship between 25 variables and total mortality and arrhythmic death in 674 patients enrolled in the MUSTT (Multicenter Unsustained Tachycardia Trial) study that did not receive antiarrhythmic therapy. We then constructed risk-stratification algorithms to weight the prognostic impact of each variable on arrhythmic death and total mortality risk.</AbstractText>The variables having the greatest prognostic impact in multivariable analysis were functional class, history of heart failure, nonsustained ventricular tachycardia not related to bypass surgery, EF, age, left ventricular conduction abnormalities, inducible sustained ventricular tachycardia, enrollment as an inpatient, and atrial fibrillation. The model demonstrates that patients whose only risk factor is EF < or =30% have a predicted 2-year arrhythmic death risk <5%.</AbstractText>Multiple variables influence arrhythmic death and total mortality risk. Patients with EF < or =30% but no other risk factor have low predicted mortality risk. Patients with EF >30% and other risk factors may have higher mortality and a higher risk of sudden death than some patients with EF < or =30%. Thus, risk of sudden death in patients with coronary disease depends on multiple variables in addition to EF.</AbstractText> |
8,357 | Effects of epinephrine and vasopressin on cerebral microcirculatory flows during and after cardiopulmonary resuscitation. | Both epinephrine and vasopressin increase aortic and carotid arterial pressure when administered during cardiopulmonary resuscitation. However, we recently demonstrated that epinephrine reduces cerebral cortical microcirculatory blood flow. Accordingly, we compared the effects of nonadrenergic vasopressin with those of epinephrine on cerebral cortical microvascular flow together with cortical tissue Po2 and Pco2 as indicators of cortical tissue ischemia.</AbstractText>Randomized, prospective animal study.</AbstractText>University-affiliated research laboratory.</AbstractText>Domestic pigs.</AbstractText>The tracheae of ten domestic male pigs, weighing 40 +/- 2 kg, were noninvasively intubated, and the animals were mechanically ventilated. A frontoparietal bilateral craniotomy was created. Microcirculatory blood flow was quantitated with orthogonal polarization spectral imaging. Blood flow velocity in pial and cortical penetrating vessels measuring <20 microm was graded from 0 (no flow) to 3 (normal). Cerebral cortical tissue carbon dioxide and oxygen tensions (Pbco2 and Pbo2) were measured concurrently using miniature optical sensors. Ventricular fibrillation, induced with an alternating current delivered to the right ventricular endocardium, was untreated for 3 mins. Animals were then randomized to receive central venous injections of equipressor doses of epinephrine (30 microg/kg) or vasopressin (0.4 units/kg) at 1 min after the start of cardiopulmonary resuscitation. After 4 mins of cardiopulmonary resuscitation, defibrillation was attempted. Spontaneous circulation was restored in each animal. However, postresuscitation microvascular flows and Pbo2 were greater and Pbco2 less after vasopressin when compared with epinephrine. We observed that a significantly greater number of cortical microvessels were perfused after vasopressin.</AbstractText>Cortical microcirculatory blood flow was markedly reduced after epinephrine, resulting in a greater severity of brain ischemia after the restoration of spontaneous circulation in contrast to the more benign effects of vasopressin.</AbstractText> |
8,358 | Management of atrial fibrillation in patients with heart failure. | Atrial fibrillation (AF) and chronic heart failure (CHF) are two major and even growing cardiovascular conditions that often coexist. However, few data are available to guide treatment of AF in patients with CHF. This review summarizes current literature concerning the following topics: (i) prognostic relevance of AF in patients with CHF, (ii) relevance and strategies of rhythm and rate control in patients with AF and CHF, and (iii) options for prevention of AF in patients with ventricular dysfunction. In conclusion, AF is associated with increased mortality in CHF patients. However, it is not clear whether there is a causal relationship. Emerging strategies to prevent the occurrence of AF are promising tools that might improve quality of life and survival in patients with CHF. |
8,359 | [Cardiac arrest with subsequent permanent anoxaemic brain damage in a patient with the Brugada syndrome]. | The paper presents a case of a 20-year-old student with a history of cardiac arrest due to ventricular fibrillation. The episode of cardiac arrest occurred when the patient did not complain of any health problems, and there was no visible structural heart disease. Consequently, permanent anoxaemic brain damage was observed. Based on ECG examination, the Brugada syndrome was diagnosed as the cause of cardiac arrest. The ajmaline challenge test was performed in the members of the patient's family. |
8,360 | Prospective study of interleukin-6 and the risk of malignant ventricular tachyarrhythmia in ICD-recipients--a pilot study. | We investigated the relationship between interleukin-6 (IL-6) and the risk of experiencing spontaneous ventricular tachyarrhythmia (VT/VF) in patients with an implantable cardioverter-defibrillator (ICD).</AbstractText>Cytokine levels predict outcome in patients with advanced heart failure and are elevated in patients with coronary artery disease (CAD). Regarding heart rhythm disturbances, proinflammatory activity could predict the occurrence of atrial fibrillation. There is no data on cytokine levels and the risk of spontaneous VT/VF.</AbstractText>IL-6 serum concentrations were determined at baseline and follow-up in 47 consecutive ICD-patients with CAD and idiopathic dilated cardiomyopathy (IDC). Data were prospectively correlated with VT/VF-incidence.</AbstractText>Thirty-six patients (76.6%) suffered from CAD and 11 (23.4%) from IDC. Mean serum concentrations of IL-6 at baseline and at 9 months follow-up were 6.12+/-4.98 and 4.63+/-6.97. 88 spontaneous VT/VF-events occurred in 13/47 patients (27.7%). Patients with VT/VF had significantly higher IL-6 levels as compared to patients without VT/VF (8.96+/-5.97 vs. 5.04+/-4.16pg/ml at baseline (p =0.03), 7.8+/-4.88 vs. 3.42+/-6.32pg/ml at follow-up (p =0.01)).</AbstractText>Elevated IL-6 serum concentrations were prospectively associated with an increased risk of spontaneous VT/VF-events in ICD-patients with CAD or IDC. These preliminary findings support a possible association of proinflammatory activity and an increased susceptibility to spontaneous VT/VF-events.</AbstractText> |
8,361 | Number needed to treat = six: therapeutic hypothermia following cardiac arrest--an effective and cheap approach to save lives. | In 2005, the European Resuscitation Council (ERC) guidelines stated: Unconscious adult patients with spontaneous circulation after out-of-hospital ventricular fibrillation cardiac arrest should be cooled to 32 to 34 degrees C for 12 to 24 hours. Patients with cardiac arrest from a non-shockable rhythm, in-hospital patients and children may also benefit from hypothermia. There is no argument to wait. We have to treat the next unconscious cardiac arrest patient with hypothermia. |
8,362 | Percutaneous mitral valvuloplasty versus surgical treatment in mitral stenosis with severe tricuspid regurgitation. | The persistence of significant tricuspid regurgitation (TR) after percutaneous mitral valvuloplasty (PMV) is known to be an independent predictor of adverse outcome in mitral stenosis (MS). However, it remains unclear whether mitral valve (MV) surgery combined with surgical correction of TR is the better treatment option than PMV in patients with severe MS and severe functional TR.</AbstractText>We included a total of 92 consecutive patients (18 men, age 49+/-13 years) with severe MS and severe functional TR, who were potential candidates for PMV from 1997 to 2005, and the exclusion criteria were defined as the presence of left atrial thrombi, mitral regurgitation > or = grade 3, echo score > 10, and left ventricular ejection fraction (EF) < 35%. PMV was performed on 48 patients (PMV group), and MV surgery combined with tricuspid valve (TV) repair was performed on 44 patients (TVP group). The clinical events were defined as death, repeat surgical or percutaneous intervention, and readmission because of heart failure. There were no significant differences between the 2 groups in terms of gender, baseline EF, and baseline severity of pulmonary hypertension, but patients in the TVP group were older and had a higher echo score and a higher incidence of atrial fibrillation than those in the PMV group. During follow-up of 57+/-35 months, 2 deaths occurred in the TVP group, and there were 2 deaths, 7 cases of heart failure requiring surgical intervention in the PMV group. The difference of event rates between the 2 groups showed borderline significance (P=0.05), but no difference in mortality was observed. The estimated actuarial 7-year event-free survival rate was 77+/-8% in the PMV group and 95+/-3% in the TVP group. Severe TR was improved to mild or absent TR in 43 (98%) patients in the TVP group, and this was significantly higher than in the PMV group (22/48, 46%; P<0.001). In the TVP group, the right ventricle (RV) size was significantly decreased in 18 (90%) patients among 20 patients with preoperative significant RV enlargement. On stepwise multivariate logistic regression analysis, TVP group and baseline sinus rhythm were independent predictors for improvement of TR (P<0.001).</AbstractText>TV repair combined with MV surgery was related to better clinical outcomes than PMV alone, and we recommend that this surgical option should be considered preferentially in severe MS with severe functional TR, especially if atrial fibrillation or enlarged RV is associated.</AbstractText> |
8,363 | Amiodarone for atrial fibrillation following cardiac surgery: development of clinical practice guidelines at a university hospital. | Atrial fibrillation (AF) usually develops within the first 72 h following cardiac surgery, and is often self-limiting. Within 48 h of acute onset of symptoms, approximately 50% of patients spontaneously convert to normal sinus rhythm. Thus, the relative risks and benefits of therapy must be carefully considered. The etiology of AF following cardiac surgery is similar to that in non-surgical patients except that pericardial inflammation and increased adrenergic tone play an increasingly important role. Further, AF after surgery may be associated with transient risk factors that resolve as the patient moves out from surgery, and the condition is less likely to recur compared to AF arising in other circumstances. Immediate heart rate control is important in preventing ischemia, tachycardia-induced cardiomyopathy, and left ventricular dilatation. At our institution, amiodarone is frequently used as a first-line drug for treating AF after cardiac surgery. Inconsistent prescribing practices, variable dosage regimens, and a lack of consensus regarding the appropriate use of amiodarone prompted the need for developing practice guidelines. Multidisciplinary collaboration between the departments of cardiac surgery, pharmacy, and anesthesiology led to the development of a protocol for postoperative AF. We review the clinical evidence from published trials and discuss our guidelines, defining amiodarone use for AF in the cardiac surgery setting. |
8,364 | Myocardial stunning following defibrillation threshold testing. | Implantable cardioverter-defibrillators (ICDs) have a proven mortality benefit in appropriately selected people. Several retrospective studies, though, have postulated that appropriate ICD therapy may lead to fatal, pulseless electrical alternans (PEA). This case report describes an episode of transient PEA from myocardial stunning and standstill following defibrillation threshold testing. The risk of post-shock myocardial stunning and standstill should be kept in mind as a potential complication of testing. With rapid recognition and prompt intervention, this complication is potentially reversible. |
8,365 | Pharmacological modulation of gap junction function with the novel compound rotigaptide: a promising new principle for prevention of arrhythmias. | Existing anti-arrhythmic therapy is hampered by lack of efficacy and unacceptable side effects. Thus, ventricular tachycardia and fibrillation remains the strongest predictor of in-hospital mortality in patients with myocardial infarction. In atrial fibrillation, rhythm control with conventional ion channel blockers provide no therapeutic benefit relative to rate control. Several lines of research indicate that impaired gap junctional cell-to-cell coupling between neighbouring cardiomyocytes is critical for the development of cardiac re-entry arrhythmias. Rotigaptide is the first drug that has been developed to prevent arrhythmias by re-establishing gap junctional intercellular communication. During conditions with acute cardiac ischaemia, rotigaptide effectively prevents induction of both ventricular and atrial tachyarrhythmia. Moreover, rotigaptide effectively prevents ischaemia reperfusion arrhythmias. At the cellular level, rotigaptide inhibits ischaemia-induced dephosphorylation of Ser297 and Ser368, which is considered important for the gating of connexin43 gap junction channels. No drug-related toxicity has been demonstrated at plasma concentrations 77,000 times above therapeutic concentrations. In rats and dogs, rotigaptide reduces infarct size following myocardial infarction. A series of phase I trials has been completed in which rotigaptide has been administered intravenously to ~200 healthy persons. No drug-related side effects have been demonstrated in healthy human beings. Clinical safety, tolerability and efficacy in patients with heart disease are being evaluated in ongoing clinical trials. Rotigaptide represents a pioneering pharmacological principle with a highly favourable preclinical and clinical safety profile, which makes this molecule a promising drug candidate for the prevention of cardiac arrhythmias. |
8,366 | Pharmacologic targets for atrial fibrillation. | Despite advances in treatment, atrial fibrillation (AF) remains the most common arrhythmia in humans. Antiarrhythmic drug therapy continues to be a cornerstone of AF treatment, even in light of emerging non-pharmacologic therapies. Conventional antiarrhythmic drugs target cardiac ion channels and are often associated with modest AF suppression and the risk of ventricular proarrhythmia. Ongoing drug development has focused on targeting atrial-specific ion channels as well as novel non-ionic targets. Targeting non-ionic mechanisms may also provide new drugs directed towards the underlying mechanisms responsible for AF and possibly greater antiarrhythmic potency. Agents that act against these new targets may offer improved safety and efficacy in AF treatment. |
8,367 | Cardioembolic stroke followed by isolated celiac artery thromboembolism. | A 78-year-old man with Parkinson's disease, paroxysmal atrial fibrillation, and congestive heart failure was admitted to our hospital due to global aphasia and right-sided hemiparesis. A cardioembolic stroke from a left ventricular thrombus was diagnosed; several days later, anticoagulants were started. On the seventh day, the patient suddenly developed severe acidosis and kidney and liver dysfunction. He died the following afternoon. Autopsy revealed an isolated celiac artery embolism from the left ventricular thrombus. This is the first reported case of isolated celiac artery embolism occurring after acute ischemic stroke. |
8,368 | Electrophysiological properties of the atrium after cardioversion of chronic atrial fibrillation: relation to the plasma brain natriuretic peptide level. | Brain natriuretic peptide (BNP) level has been shown to increase in patients with chronic atrial fibrillation (CAF) without overt heart failure (HF). Although atrial electrical remodeling associated with CAF has been described, little is known about the effects of the BNP level on the electrophysiological properties in CAF patients.</AbstractText>In 42 CAF patients without overt HF, the atrial monophasic action potential duration (MAPD) at pacing cycle lengths (CLs) of 300-800 msec and P-wave signal-averaged electrograms were recorded after cardioversion. The MAPDs for all CLs were significantly longer in patients with a BNP concentration greater than the 50th percentile (group 1, BNP = 215 +/- 118.2 pg/mL) than in patients with a concentration less than the 50th percentile (group 2, BNP = 68.3 +/- 20.9 pg/mL), resulting in a similar value in the MAPDs at CLs of 350 and 600 msec for group 1 and the control patients (n = 8). The slope value of the MAPDs between CLs of 350 and 600 msec was normal in group 1, but slightly lower in group 2 than in group 1 and control patients. The filtered P-wave duration did not differ between the two groups.</AbstractText>These electrophysiological characteristics related to the BNP level suggest that the atrial repolarization may be affected by a latent ventricular dysfunction.</AbstractText> |
8,369 | Fatal outcome from inappropriate defibrillation. | We present a 51-year-old morbidly obese man who underwent insertion of a single-chamber implantable cardioverter defibrillator for monomorphic ventricular tachycardia occurring after myocardial infarction. After a period of satisfactory device function, a sudden change in R-wave with atrial over-sensing heralded inappropriate defibrillation and induction of ventricular fibrillation, with subsequent death of the patient. |
8,370 | Surgical ablation of atrial fibrillation in patients with congestive heart failure. | Congestive heart failure (CHF) and atrial fibrillation (AF), both of which cause morbidity and mortality, are mutually promoting diseases. We aimed to evaluate surgical AF ablation in CHF.</AbstractText>Among 212 patients (age 69 +/- 8.8 years, 87% with persistent AF) undergoing concomitant left atrial (LA) ablation, 79 (37.3%) presented CHF (n = 62 with a left ventricular ejection fraction [LVEF] 0.31-0.45, n = 17 with an LVEF < or = 0.30). Patients with CHF were similar to controls regarding AF duration (61 +/- 65.1 months vs. 54 +/- 67.2 months, not significant [NS]), LA diameter (49 +/- 7.5 mm vs. 50 +/- 9.2 mm, NS), and heart rate (78 +/- 18.4 min(-1) vs. 81 +/- 21.3 min(-1), NS), but they required more circulatory support (17.7% vs. 1.5%, P < .001) and a longer intensive care unit stay (6 +/- 9.5 days vs. 4 +/- 10.5 days, P = .032). At follow-up after 13 +/- 7.3 months, 42 patients (66%) with CHF and 81 controls (74%, NS) were in sinus rhythm (SR) (55% and 64% without antiarrhythmic drugs, respectively, NS). Univariate and logistic regression analysis revealed that AF duration and LA diameter predicted rhythm outcome but not CHF. In patients with an LVEF of 0.30 or less, SR conversion significantly improved LVEF, New York Heart Association class, and Minnesota Living with Heart Failure score. Kaplan-Meier estimates suggested superior survival of patients with stable SR (100% vs. 73%, log-rank P < .05).</AbstractText>If patients presenting with CHF and AF require cardiac surgery, concomitant AF ablation should be considered, especially if left ventricular function is severely impaired.</AbstractText> |
8,371 | [Asymptomatic recurrence of atrial tachy-arrhythmia after circumferential pulmonary vein isolation in patients with atrial fibrillation]. | To investigate the incidence, type, and predictors of asymptomatic relapse of atrial tachy-arrhythmia (ATa) after circumferential pulmonary vein isolation (CPVI) in patients with atrial fibrillation (AF).</AbstractText>Forty-eight consecutive patients with AF underwent CPVI and were followed up. Forty-eight hours Holter recording was performed 1, 3, and 6 months respectively after the initial CPVI procedure. Predictors of asymptomatic ATa relapse were determined by Logistic regression analysis for eight variables as follows: age, gender, AF type, existence of organic heart disease, diameter of left atria, left ventricular ejection fraction, procedure time, and heart rate variability after the procedure.</AbstractText>Complete Holter data were acquired in 42 patients, 26 males and 16 females, aged: 58 +/- 14, including 25 patients with paroxysmal AF and 17 with non-paroxysmal AF. The standard deviations of R-R interval (SDNN) of the non-paroxysmal AF group was 92 ms +/- 19 ms, significantly longer than that of the paroxysmal AF group (78 ms +/- 15 ms, P = 0.011). The incidence of asymptomatic ATa recurrence rates 1, 3 and 6 months after CPVI were 8%, 12%, and 8% respectively in paroxysmal AF group and 23.5%, 29.4%, and 35.3% respectively in the non-paroxysmal AF group. The incidence of asymptomatic ATa recurrence 6 months after CPVI in the non-paroxysmal AF group was significant higher than that in the paroxysmal AF group (P < 0.05). AF was the dominant arrhythmia among the asymptomatic recurrence ATa, while atrial tachycardia constituted the major arrhythmia of the symptomatic recurrent ATa.</AbstractText>(1) Asymptomatic ATa relapse is common among the patients undergoing CPVI. (2) The dominant type of asymptomatic recurrent arrhythmia is AF. (3) The independent predictors for asymptomatic ATa recurrence include non-paroxysmal AF, left atrial enlargement, and increase of SDNN.</AbstractText> |
8,372 | Automated detection of ventricular fibrillation to guide cardiopulmonary resuscitation. | Sudden death due to ventricular fibrillation (VF) is a catastrophic event, especially in out-of-hospital settings. Prompt detection of VF and preparedness to intervene with cardiopulmonary resuscitation (CPR) and especially the delivery of an electrical shock is potentially lifesaving. The reliability and accuracy of automated VF detection by current versions of automated external defibrillators (AEDs) require interruption of CPR because the ECG signal, which is the source of rhythm detection, is corrupted by chest compressions. Significantly better outcomes have been reported if effective chest compression precedes electrical defibrillation and especially if interruptions are minimized. We therefore sought a method by which VF detection could proceed without interrupting chest compressions. A VF detection algorithm was therefore derived based on a method by which continuous wavelet transform is used, together with measurement of morphologic consistency. This method was intended to distinguish between disorganized and organized rhythms. The Fourier-transform-based amplitude spectrum analysis was then used to detect the likelihood that VF was the rhythm prompting the delivery of an electrical shock. The algorithm was validated on 33,095 electrocardiographic segments, including 8840 segments corrupted by compression artifacts from 232 patients after out-of-hospital cardiac arrest. Nine thousand one hundred eighty-seven of 10,042 VF segments and 20,884 of 23,053 non-VF segments were correctly classified, with a sensitivity of 91.5% and a specificity of 90.6%. Although the proposed algorithm has a lesser predictive value for VF detection than the uncorrupted ECGs in clinical settings, it has the major potential for automated rhythm identification to guide defibrillation without repetitive interruptions of CPR. |
8,373 | Minimizing ventricular pacing to reduce atrial fibrillation in sinus-node disease. | Conventional dual-chamber pacing maintains atrioventricular synchrony but results in high percentages of ventricular pacing, which causes ventricular desynchronization and has been linked to an increased risk of atrial fibrillation in patients with sinus-node disease.</AbstractText>We randomly assigned 1065 patients with sinus-node disease, intact atrioventricular conduction, and a normal QRS interval to receive conventional dual-chamber pacing (535 patients) or dual-chamber minimal ventricular pacing with the use of new pacemaker features designed to promote atrioventricular conduction, preserve ventricular conduction, and prevent ventricular desynchronization (530 patients). The primary end point was time to persistent atrial fibrillation.</AbstractText>The mean (+/-SD) follow-up period was 1.7+/-1.0 years when the trial was stopped because it had met the primary end point. The median percentage of ventricular beats that were paced was lower in dual-chamber minimal ventricular pacing than in conventional dual-chamber pacing (9.1% vs. 99.0%, P<0.001), whereas the percentage of atrial beats that were paced was similar in the two groups (71.4% vs. 70.4%, P=0.96). Persistent atrial fibrillation developed in 110 patients, 68 (12.7%) in the group assigned to conventional dual-chamber pacing and 42 (7.9%) in the group assigned to dual-chamber minimal ventricular pacing. The hazard ratio for development of persistent atrial fibrillation in patients with dual-chamber minimal ventricular pacing as compared with those with conventional dual-chamber pacing was 0.60 (95% confidence interval, 0.41 to 0.88; P=0.009), indicating a 40% reduction in relative risk. The absolute reduction in risk was 4.8%. The mortality rate was similar in the two groups (4.9% in the group receiving dual-chamber minimal ventricular pacing vs. 5.4% in the group receiving conventional dual-chamber pacing, P=0.54).</AbstractText>Dual-chamber minimal ventricular pacing, as compared with conventional dual-chamber pacing, prevents ventricular desynchronization and moderately reduces the risk of persistent atrial fibrillation in patients with sinus-node disease. (ClinicalTrials.gov number, NCT00284830 [ClinicalTrials.gov].).</AbstractText>Copyright 2007 Massachusetts Medical Society.</CopyrightInformation> |
8,374 | Dronedarone for maintenance of sinus rhythm in atrial fibrillation or flutter. | Amiodarone is effective in maintaining sinus rhythm in atrial fibrillation but is associated with potentially serious toxic effects. Dronedarone is a new antiarrhythmic agent pharmacologically related to amiodarone but developed to reduce the risk of side effects.</AbstractText>In two identical multicenter, double-blind, randomized trials, one conducted in Europe (ClinicalTrials.gov number, NCT00259428 [ClinicalTrials.gov] ) and one conducted in the United States, Canada, Australia, South Africa, and Argentina (termed the non-European trial, NCT00259376 [ClinicalTrials.gov] ), we evaluated the efficacy of dronedarone, with 828 patients receiving 400 mg of the drug twice daily and 409 patients receiving placebo. Rhythm was monitored transtelephonically on days 2, 3, and 5; at 3, 5, 7, and 10 months; during recurrence of arrhythmia; and at nine scheduled visits during a 12-month period. The primary end point was the time to the first recurrence of atrial fibrillation or flutter.</AbstractText>In the European trial, the median times to the recurrence of arrhythmia were 41 days in the placebo group and 96 days in the dronedarone group (P=0.01). The corresponding durations in the non-European trial were 59 and 158 days (P=0.002). At the recurrence of arrhythmia in the European trial, the mean (+/-SD) ventricular rate was 117.5+/-29.1 beats per minute in the placebo group and 102.3+/-24.7 beats per minute in the dronedarone group (P<0.001); the corresponding rates in the non-European trial were 116.6+/-31.9 and 104.6+/-27.1 beats per minute (P<0.001). Rates of pulmonary toxic effects and of thyroid and liver dysfunction were not significantly increased in the dronedarone group.</AbstractText>Dronedarone was significantly more effective than placebo in maintaining sinus rhythm and in reducing the ventricular rate during recurrence of arrhythmia.</AbstractText>Copyright 2007 Massachusetts Medical Society.</CopyrightInformation> |
8,375 | Effect of ranolazine, an antianginal agent with novel electrophysiological properties, on the incidence of arrhythmias in patients with non ST-segment elevation acute coronary syndrome: results from the Metabolic Efficiency With Ranolazine for Less Ischemia in Non ST-Elevation Acute Coronary Syndrome Thrombolysis in Myocardial Infarction 36 (MERLIN-TIMI 36) randomized controlled trial. | Ranolazine, a piperazine derivative, reduces ischemia via inhibition of the late phase of the inward sodium current (late I(Na)) during cardiac repolarization, with a consequent reduction in intracellular sodium and calcium overload. Increased intracellular calcium leads to both mechanical dysfunction and electric instability. Ranolazine reduces proarrhythmic substrate and triggers such as early afterdepolarization in experimental models. However, the potential antiarrhythmic actions of ranolazine have yet to be demonstrated in humans.</AbstractText>The Metabolic Efficiency With Ranolazine for Less Ischemia in Non-ST-Elevation Acute Coronary Syndrome (MERLIN)-Thrombolysis in Myocardial Infarction (TIMI) 36 (MERLIN-TIMI 36) trial randomized 6560 patients hospitalized with a non-ST-elevation acute coronary syndrome to ranolazine or placebo in addition to standard therapy. Continuous ECG (Holter) recording was performed for the first 7 days after randomization. A prespecified set of arrhythmias were evaluated by a core laboratory blinded to treatment and outcomes. Of the 6560 patients in MERLIN-TIMI 36, 6351 (97%) had continuous ECG recordings that could be evaluated for arrhythmia analysis. Treatment with ranolazine resulted in significantly lower incidences of arrhythmias. Specifically, fewer patients had an episode of ventricular tachycardia lasting > or = 8 beats (166 [5.3%] versus 265 [8.3%]; P<0.001), supraventricular tachycardia (1413 [44.7%] versus 1752 [55.0%]; P<0.001), or new-onset atrial fibrillation (55 [1.7%] versus 75 [2.4%]; P=0.08). In addition, pauses > or = 3 seconds were less frequent with ranolazine (97 [3.1%] versus 136 [4.3%]; P=0.01).</AbstractText>Ranolazine, an inhibitor of late I(Na), appears to have antiarrhythmic effects as assessed by continuous ECG monitoring of patients in the first week after admission for acute coronary syndrome. Studies specifically designed to evaluate the potential role of ranolazine as an antiarrhythmic agent are warranted.</AbstractText> |
8,376 | Transient ventricular fibrillation. A clinical case report. | Self-terminating ventricular fibrillation (VF) was recorded in a 42-year-old woman without coronary artery or structural heart disease. Reviewing the scientific literature, we found that this type of VF had appeared in vivo in some animal models but was sparsely described in clinical practice. This most unusual case shows that potentially lethal arrhythmias may be self-terminating. |
8,377 | [Extracorporeal shock wave lithotripsy (ESWL) can be done for lithiasic patients with cardiac arrhythmias with a lithotriptor without ECG triggering system--the experience of Iaşi Urological Department]. | The recommendations for spark gap lithotripters include that the shock waves must be delivered according to the ECG, avoiding the discharge during the refractory part of the heart activity. The lithotripters we have in our department does not have from the factory an ECG correlated triggering system. Observing that ESWL for patients without heart problems did not induced arrhythmias, we decide to perform this procedure under strict cardiologic supervision to the patients having arrhythmias (chronic fibrillation, chronic atrial fibrillation, supraventricular arrhythmias, supraventricular premature beats, ventricular premature beats, ventricular tachycardia). All the ESWIL sessions did not have any major incidents and all the patients return home safe, without any changes of the cardiac medication. Even we did not notice any aggravation of the cardiac arrhythmias during ESWL we consider that the careful monitoring of the patients by the cardiologist is necessary during the procedure, most of all when the spark gap lithotripter has not an ECG triggering system. |
8,378 | Atrium-selective sodium channel block as a strategy for suppression of atrial fibrillation: differences in sodium channel inactivation between atria and ventricles and the role of ranolazine. | The development of selective atrial antiarrhythmic agents is a current strategy for suppression of atrial fibrillation (AF).</AbstractText>Whole-cell patch clamp techniques were used to evaluate inactivation of peak sodium channel current (I(Na)) in myocytes isolated from canine atria and ventricles. The electrophysiological effects of therapeutic concentrations of ranolazine (1 to 10 micromol/L) and lidocaine (2.1 to 21 micromol/L) were evaluated in canine isolated coronary-perfused atrial and ventricular preparations. Half-inactivation voltage of I(Na) was approximately 15 mV more negative in atrial versus ventricular cells under control conditions; this difference increased after exposure to ranolazine. Ranolazine produced a marked use-dependent depression of sodium channel parameters, including the maximum rate of rise of the action potential upstroke, conduction velocity, and diastolic threshold of excitation, and induced postrepolarization refractoriness in atria but not in ventricles. Lidocaine also preferentially suppressed these parameters in atria versus ventricles, but to a much lesser extent than ranolazine. Ranolazine produced a prolongation of action potential duration (APD90) in atria, no effect on APD90 in ventricular myocardium, and an abbreviation of APD90 in Purkinje fibers. Lidocaine abbreviated both atrial and ventricular APD90. Ranolazine was more effective than lidocaine in terminating persistent AF and in preventing the induction of AF.</AbstractText>Our study demonstrates important differences in the inactivation characteristics of atrial versus ventricular sodium channels and a striking atrial selectivity for the action of ranolazine to produce use-dependent block of sodium channels, leading to suppression of AF. Our results point to atrium-selective sodium channel block as a novel strategy for the management of AF.</AbstractText> |
8,379 | Regression of electrocardiographic left ventricular hypertrophy is associated with less hospitalization for heart failure in hypertensive patients. | Reduction of electrocardiographic left ventricular hypertrophy (LVH) has been associated with decreased cardiovascular death, stroke, myocardial infarction, and atrial fibrillation. However, whether reduction of electrocardiographic LVH is associated with decreased heart failure is unclear.</AbstractText>To examine the relation of reduction of electrocardiographic LVH to incident heart failure.</AbstractText>Multicenter cohort study derived from a randomized, controlled trial.</AbstractText>Losartan Intervention For Endpoint reduction in hypertension study.</AbstractText>8479 hypertensive patients without history of heart failure who were randomly assigned to losartan or atenolol treatment.</AbstractText>Change in Cornell product electrocardiographic LVH between baseline and in-study electrocardiograms, examined as both a continuous variable and a dichotomous variable (above or below the median decrease of 236 mm x msec) to predict heart failure hospitalization occurring after the 6-month follow-up visit.</AbstractText>During mean follow-up of 4.7 years (SD, 1.1 years), 214 patients were hospitalized for heart failure (2.5%): 77 patients with an in-treatment decrease of 236 mm x msec or more (4.4 per 1000 patient-years) and 137 patients with a reduction less than 236 mm x msec during treatment (6.8 per 1000 patient-years). In a univariate Cox analysis in which change in Cornell product was treated as a time-varying continuous variable, decrease in Cornell product during treatment was associated with a decreased risk for new-onset heart failure, with a 24% lower risk for heart failure for every 817-mm x msec (1 SD of the mean) lower Cornell product (hazard ratio, 0.76 [95% CI, 0.72 to 0.80]). In a parallel analysis in which change in Cornell product was entered as a time-varying dichotomous variable, a greater-than-median in-treatment decrease in Cornell product (236 mm x msec) was associated with a 43% lower risk for heart failure (hazard ratio, 0.57 [CI, 0.44 to 0.76]). After adjustment for treatment, baseline risk factors for heart failure, baseline and in-treatment blood pressure, and baseline severity of electrocardiographic LVH, in-treatment decrease of Cornell product LVH in time-varying multivariate Cox models remained strongly associated with new heart failure hospitalization, with a 19% lower risk for every 817-mm . msec lower Cornell product treated as a continuous variable (hazard ratio, 0.81 [CI, 0.77 to 0.85]) or a 36% decreased rate of new heart failure in patients with an in-treatment reduction in Cornell product of 236 mm x msec or more (hazard ratio, 0.64 [CI, 0.47 to 0.89]; P < 0.001 for all comparisons).</AbstractText>Use of electrocardiographic LVH to select patients may have increased risk compared with unselected hypertensive patients, and use of hospitalization for heart failure as the end point will underestimate the incidence of new heart failure.</AbstractText>Reduction in Cornell product electrocardiographic LVH during antihypertensive therapy is associated with fewer hospitalizations for heart failure, independent of blood pressure lowering, treatment method, and other risk factors for heart failure. ClinicalTrials.gov registration number: NCT00338260.</AbstractText> |
8,380 | [Case of intractable ventricula fibrillation by a multicomponent dietary supplement containing ephedra and caffeine overdose]. | Multicomponent dietary supplement containing ephedra and caffeine (DSEC) was widely used for weight loss and energy enhancement. The Food and Drug Administration (FDA) banned the sale of DSEC in 2004 because of side effects such as cardiotoxity. We report a rare case of intractable ventricular fibrillation, requiring frequent defibrillation, by DSEC overdose. The direct cardiotoxity of ephedra, synergistic effect of caffeine and ephedra, and hypokalemia may cause refractory ventricular arrhythmia. |
8,381 | Postoperative atrial fibrillation following coronary artery bypass graft: clinical factors associated with in-hospital death. | To identify factors associated with a higher likelihood of in-hospital death in patients submitted to coronary artery bypass graft surgery (CABG) who developed atrial fibrillation (AF) postoperatively.</AbstractText>The authors analyzed data from 397 consecutive patients submitted to CABG that developed AF postoperatively between 2000 and 2003. The patients were divided into 2 groups: group 1 (G1) comprised patients who survived (n=369); and group 2 (G2) comprised patients who died during hospital stay (n=28). Statistical analysis was performed using Student's t test and chi-square test, and p values < 0.05 were considered significant.</AbstractText>A comparative analysis between G1 and G2 showed that there was no difference between the groups as regards age (67.3 +/- 8.4 versus 69.3 +/- 9.6; p = 0.4), male gender (75.9% versus 64.3%; p = 0.1), systemic arterial hypertension (75.3% versus 85.7%; p = 0.2) and congestive heart failure (17% versus 17%; p = 1). Group 2 presented higher rates for previous acute myocardial infarction (14.6% versus 28.6%; p = 0.05), left ventricular ejection fraction < 40% (12.2% versus 32.1%; p = 0.003), previous cerebrovascular accident (0.8% versus 17.9%; p = 0.03), previous percutaneous coronary intervention (19.5% versus 39.3%; p = 0.01) and previous CABG (19.3% versus 35.7%; p = 0.03).</AbstractText>Clinical history of acute myocardial infarction, CABG, percutaneous coronary intervention, cerebrovascular accident and severe ventricular dysfunction were significantly more frequent in the group that died during hospital stay, which suggests a possible association of these factors with a higher likelihood of death following CABG.</AbstractText> |
8,382 | Off-pump total myocardial revascularization in patients with left ventricular dysfunction. | To assess off-pump myocardial revascularization in patients with significant left ventricular dysfunction.</AbstractText>Four hundred and five patients with an ejection fraction less than 35% underwent myocardial revascularization without extracorporeal circulation. The procedure was performed with the aid of a suction stabilizer and the LIMA stitch. The distal anastomoses were performed first.</AbstractText>A total of 405 patients were evaluated whose mean age was 63.4 +/- 9.78 years. Two hundred and seventy-nine patients were men (68.8%). With regard to risk factors, 347 patients were hypertensive, 194 were smokers, 202 were dyslipidemic, and 134 had diabetes. Two hundred and sixty patients were classified as NYHA functional class III and IV. Twenty patients suffered from chronic renal disease and were under dialysis. Fifty-one underwent emergency surgery, and 33 had been previously operated on. The mean ejection fraction was 27.2 +/- 3.54%. The mean EuroSCORE was 8.46 +/- 4.41. The mean number of anastomoses performed was 3.03 +/- 1.54 per patient. Forty-nine patients (12%) needed an intra-aortic balloon inserted after induction of anesthesia, whereas 73 (18%) needed inotropic support during the perioperative period. As to complications, 2 patients (0.49%) had renal failure, 2 had mediastinitis (0.49%), 7 (1.7%) needed to be reoperated because of bleeding, 5 patients (1.2%) suffered acute myocardial infarction, and 70 patients (17.3%) experienced atrial fibrillation. Eighteen (4.4%) patients died.</AbstractText>Based on the data above, we concluded that myocardial revascularization without extracorporeal circulation in patients with left ventricular dysfunction is a safe and effective technique, and an alternative for high-risk patients. Results obtained were better than those predicted by EuroSCORE.</AbstractText> |
8,383 | Identifying approaches to improve the accuracy of shock outcome prediction for out-of-hospital cardiac arrest. | Analysis of the electrocardiogram (ECG) can predict if a cardiac arrest patient in ventricular fibrillation is likely to have a return of spontaneous circulation if defibrillated. The accuracy of such methods determines how useful it is clinically and for retrospective analysis.</AbstractText>We wanted to identify if there is a potential of improving prediction accuracy by adding peri-arrest factors to an ECG-based prediction system, or constructing a prediction system that adapts to each patient. Therefore, we analysed shock outcome prediction data with a mixed effects logistic regression model to identify if there are random effects (unexplained variation between patients) influencing the prediction accuracy. We also added information about the patients' age, sex and presenting rhythm, ambulance response time and presence of bystander CPR to the model to try to improve it by reducing the random effects. For all the six predictive features analysed random effects where present, with p-values below 10(-3). The random effect size was 73-189% of the feature effect size. Adding the peri-arrest factors to the best ECG-based model gave no significant improvement.</AbstractText>The presence of random effects shows that the shock outcome prediction accuracy can be improved by explaining more of the variation between patients, for example using the approaches outlined above, and that there is within-patient correlation between samples that should be accounted for when evaluating prediction accuracy. The specific peri-arrest factors tested here did not significantly improve prediction accuracy, but other factors should be explored.</AbstractText> |
8,384 | Life-saving automated external defibrillation in a teenager: a case report. | Adolescent sudden death during sport participation is commonly due to cardiac causes. Survival is more likely when an automated external defibrillator (AED) is used soon after collapse.</AbstractText>We describe a case of sudden death in a 14 year old boy with two remarkable points, successful resuscitation at school using an AED and diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC). Bystander cardiopulmonary resuscitation (CPR) was immediately started by a witness and 5 minutes after the event the child was placed on an AED monitor that determined he was in a non shockable rhythm, therefore CPR was continued. Two minutes later, the AED monitor detected a shockable rhythm and recommended a shock, which was then administered. One minute after the shock, a palpable pulse was detected and the child began to breathe by himself. Four days after cardiac arrest, the boy was conversing and self-caring. Cardiac magnetic resonance imaging was suggestive of ARVC.</AbstractText>Ventricular fibrillation secondary to ARVC may be a devastating event and places young patients and athletes at high risk of sudden death. Immediate CPR and AED have been demonstrated to be lifesaving in such events. Therefore, we suggest that schools should have teachers skilled in CPR and accessible AEDs.</AbstractText> |
8,385 | Circadian pattern of spontaneous ventricular tachyarrhythmias in patients with implantable cardioverter defibrillators. | Previous studies have reported a circadian variation of ventricular tachyarrhythmias. However, there is no detailed information of the daily distribution of ventricular tachycardia (VT) and ventricular fibrillation (VF) episodes. The purpose of this study was to evaluate the daily distribution of episodes of ventricular tachyarrhythmia in patients with implantable cardioverter defibrillators.</AbstractText><AbstractText Label="MATERIAL/METHODS" NlmCategory="METHODS">We used data stored by last-generation implantable cardioverter-defibrillators (ICD) to retrospectively evaluate the circadian distribution of VT and VF in 70 patients with ICD. The distribution of tachyarrhythmias was categorized into four time zones: zone 1 (06:00-11:59), zone 2 (12:00-17:59), zone 3 (18:00-23:59), and zone 4 (00:00-05:59).</AbstractText>During a follow-up of a mean of 3.1+/-1.3 years, a total of 791 ventricular arrhythmias were recorded from which 631 events were VT and 160 VF. A circadian variation of episodes of ventricular tachyarrhythmia was evident. The incidence of ventricular arrhythmia sharply increased in zone 1 (8.82+/-2.13, p<0.0001). Episodes of VT had peaks in zones 1 and 2 (7.44+/-2.03 and 2.70+/-0.65, p<0.001) and episodes of VF had peaks in zones 1 and 4 (1.38+/-0.39 and 1.30+/-0.51, p<0.011). No difference was observed between patients who used betablocker and those who did not.</AbstractText>Malignant ventricular tachyarrhythmias have a circadian distribution. VT peaks occur in the morning and noon hours and VF peaks occurs at the night and morning hours. Betablocker and/or amiodarone usage do not alter this distribution.</AbstractText> |
8,386 | Variability of coronary venous anatomy in patients undergoing cardiac resynchronization therapy: a high-speed rotational venography study. | Imaging the coronary venous (CV) tree to delineate the coronary sinus and its tributaries can facilitate electrophysiological procedures, such as cardiac resynchronization therapy (CRT) and catheter ablation. Venography also allows visualization of the left atrial (LA) veins, which may be a potential conduit for ablative or pacing strategies given their proximity to foci that can trigger atrial fibrillation.</AbstractText>The aim of this study was to provide a detailed description of CV anatomy using rotational venography in patients undergoing CRT.</AbstractText>Coronary sinus (CS) size and the presence, size, and angulation of its tributaries were determined from the analysis of rotational CV angiograms from 51 patients (age 68 +/- 11 years; n = 12 women) undergoing CRT.</AbstractText>The CS, posterior veins, and lateral veins were identified in 100%, 76%, and 91% of patients. Lateral veins were less prevalent in patients with a history of lateral myocardial infarction than in patients without such a history (33% vs. 96%; P = .014). The diameters of the CS and its tributaries were fairly variable (7.3-18.9 mm for CS, 1.3-10.5 mm for CS tributaries). The CS was larger in men than in women and in cases of ischemic than in cases of nonischemic cardiomyopathy (all P <.05). The vein of Marshall, the most constant LA vein, was identified in 37 patients; its diameter is 1.7 +/- 0.5 mm, and its takeoff angle is 154 degrees +/- 15 degrees , making the vein potentially accessible for cannulation.</AbstractText>Differences in CV anatomy that are related to either gender or coronary artery disease could have important practical implications during the left ventricular lead implantation. The anatomical features of the vein of Marshall make it a feasible potential conduit for epicardial LA pacing.</AbstractText> |
8,387 | Sensitivity and specificity of an automated external defibrillator algorithm designed for pediatric patients. | Electrocardiographic (ECG) rhythm analysis algorithms for cardiac rhythm analysis in automated external defibrillators (AEDs) have been tested against pediatric patient rhythms (patients < or = 8 years old) using adult ECG algorithm criteria. However these adult algorithms may fail to detect non-shockable pediatric tachycardias because they do not account for the difference in the rates of normal sinus rhythm and typical tachyarrhythmias in childhood.</AbstractText>This study was designed to define shockable and non-shockable rhythm detection criteria specific to pediatric patients to create a pediatric rhythm database of annotated rhythms, to develop a pediatric-based AED rhythm analysis algorithm, and to test the algorithm's accuracy. Pediatric rhythm detection criteria were defined for coarse ventricular fibrillation, rapid ventricular tachycardia, and non-shockable rhythms, including pediatric supraventricular tachycardia. Pediatric rhythms were collected as sustained, classifiable, rhythms > or = 9 s in length, and were annotated by pediatric electrophysiologists as clinically shockable or non-shockable based on pediatric criteria. Rhythms were placed into a pediatric rhythm database; each rhythm was converted to digitally accessible, public-domain, MIT rhythm data format. The database was used to evaluate a pediatric-based AED rhythm analysis algorithm.</AbstractText>Electrocardiographic rhythms from 198 children were recorded. There were 120 shockable rhythms from 49 patients (sensitivity; coarse ventricular fibrillation: 42 rhythms, 100%; rapid ventricular tachycardia: 78 rhythms, 94%), for combined sensitivity of 96.0% (115/120). There were 585 non-shockable rhythms from 155 patients (specificity normal sinus: 208 rhythms, 100%; asystole: 29 rhythms, 100%; supraventricular tachycardia: 161 rhythms, 99%; other arrhythmias: 187 rhythms, 100%), for combined specificity of 99.7% (583/585). Overall accuracy for shockable and non-shockable rhythms was 99.0% (702/709).</AbstractText>New pediatric rhythm detection criteria were defined and analysis based on these criteria demonstrated both high sensitivity (coarse ventricular fibrillation, rapid ventricular tachycardia) and high specificity (non-shockable rhythms, including supraventricular tachycardia). A pediatric-based AED can detect shockable rhythms correctly, making it safe and exceptionally effective for children.</AbstractText> |
8,388 | Criteria for the electrocardiographic diagnosis of atrial flutter improve diagnostic accuracy. | We previously developed and validated diagnostic criteria for the differentiation of atrial flutter from atrial fibrillation. In this study we examine if the criteria (F waves in the frontal plane and a partially or completely regular ventricular response) can improve the diagnostic accuracy of internists.</AbstractText>Two groups of 10 internists (1 group given the criteria and 1 not) read a set of electrocardiograms (ECGs) selected from the hospital database with cardiologist-confirmed diagnoses of atrial fibrillation, atrial flutter, or "atrial fibrillation-flutter" (100 each). The final diagnoses of all ECGs were provided by a consensus of electrophysiologists. The criteria also were used to establish the criteria-based diagnoses.</AbstractText>Of the 298 ECGs analyzed, the electrophysiologist diagnosis was atrial fibrillation in 71% and atrial flutter in 29%. The concordance of the internists' diagnoses with the electrophysiologist consensus diagnoses was 66+/-12% for those not given the criteria and 81+/-4% (P <.01) for those given the criteria. The concordance of the internists' diagnoses with the criteria based diagnoses was 66+/-12% for those not given the criteria and 83+/-4% (P <.01) for those given the criteria.</AbstractText>The simple criteria of F waves in the frontal plane and a partially or completely regular ventricular response can be used to improve the differentiation of atrial flutter from atrial fibrillation based on the ECG.</AbstractText> |
8,389 | beta-Blockers for the treatment of cardiac arrest from ventricular fibrillation? | More than 160,000 people suffer sudden cardiac death each year in the US. It is estimated that ventricular fibrillation (VF) is the initial rhythm in approximately 30% of these cases. Ventricular fibrillation that does not respond to the first few defibrillation attempts is associated with mortality rates of up to 97%. Currently, no pharmacological intervention has been shown to increase long-term survival in patients with shock-refractory VF. The purpose of this review article is to evaluate whether beta-blocker administration during the resuscitation of cardiac arrest from VF or pulseless ventricular tachycardia (VT) improves outcome. We searched the MEDLINE and EMBASE databases for human clinical trials, animal experimental trials, review articles, case reports and abstracts published between 1966 and September 2006. No human prospective randomized controlled trial has studied the effects of beta-blocker administration during VF directly. Prospective trials of anti-arrhythmics with beta-blocking properties have been published, as well as several case reports/case series and experimental animal studies. The evidence thus far suggests that beta-blockade during resuscitation from VF may be associated with increasing rates of resuscitation, greater post-resuscitation survival, and improved post-resuscitation myocardial function. These positive effects on outcome may be mediated by a decrease in the oxygen requirements of the fibrillating heart, thus improving the overall balance between myocardial oxygen supply and demand during resuscitation. While no significant detrimental effects directly related to low dose beta-blockade during VF have been reported in the studies reviewed, concerns relating to possible loss of myocardial contractility and hypotension remain. To this day, high quality human trials are lacking. Preliminary human studies are needed to assess the effects of beta-blockers in the treatment of cardiac arrest from ventricular fibrillation or pulseless VT further. |
8,390 | The myocardial infarct size-limiting and antiarrhythmic effects of acyl-CoA:cholesterol acyltransferase inhibitor VULM 1457 protect the hearts of diabetic-hypercholesterolaemic rats against ischaemia/reperfusion injury both in vitro and in vivo. | The study was designed to characterise the influence of a novel acyl-CoA:cholesterol acyltransferase inhibitor, VULM 1457, on the severity of myocardial ischaemia-reperfusion injury in a model of diabetes mellitus and hypercholesterolaemia induced by co-administration of streptozotocin and a high fat-cholesterol diet. We used Langendorff-perfused rat hearts to measure the size of myocardial infarction after 30 min of regional ischaemia, followed by a 2-h reperfusion period, and open-chest rats were exposed to 6 min of ischaemia and 10 min of reperfusion to analyse ventricular arrhythmias. In addition to the high fat-cholesterol diet, VULM 1457 was administered to the diabetic-hypercholesterolaemic rats for 5 days. Decreased plasma and liver cholesterol levels and a significantly reduced occurrence of ventricular fibrillation (29% vs. 100%, P<0.01), determined via the mean number and duration of episodes (0.6+/-0.4 and 2.1+/-1.4 s vs. 2.8+/-0.8 and 53.5+/-14.4 s in diabetic-hypercholesterolaemic rats, both P<0.01), were observed in these animals. Lethal ventricular fibrillation was suppressed, and arrhythmia severity was also significantly decreased in these animals as compared to the non-treated animals (2.9+/-0.6 vs. 4.9+/-0.2; P<0.05). A smaller infarct size, normalised to the size of area at risk, was observed in the treated diabetic-hypercholesterolaemic group as compared to the non-treated group (16.3+/-1.9% vs. 37.3+/-3.1%; P<0.01). Aside from remarkable hypolipidaemic activity, VULM 1457 improved the overall myocardial ischaemia-reperfusion injury outcomes in the diabetic-hypercholesterolaemic rats by suppressing arrhythmogenesis as well as by reducing myocardial necrosis. |
8,391 | Significance of appropriate defibrillator shock 3 hours and 20 minutes following implantation in a patient with hypertrophic cardiomyopathy. | Implantable defibrillators have proved effective in terminating potentially life-threatening ventricular tachyarrhythmias in hypertrophic cardiomyopathy (HCM), although the timing of appropriate shocks may be exceedingly variable.</AbstractText>We report an unusual occurrence in a 48-year-old woman with nonobstructive HCM who experienced an appropriate shock for ventricular fibrillation only 3 hours and 20 minutes after implantation. Careful review of the clinical circumstances failed to define a specific mechanism related to the implant procedure that could have triggered the potentially lethal arrhythmia.</AbstractText>Early device interventions are not uncommon in HCM, but (as in this case) appear unrelated to mechanisms other than the unpredictable and underlying arrhythmogenic substrate in this disease.</AbstractText> |
8,392 | Evaluating the effectiveness of dispatch-assisted cardiopulmonary resuscitation instructions. | To determine the frequency of agonal breathing during cardiac arrest (CA), its impact on the ability of 9-1-1 dispatchers to identify CA, and the impact of dispatch-assisted cardiopulmonary resuscitation (CPR) instructions on bystander CPR rates.</AbstractText>A before-after observational study enrolling out-of-hospital adult CA patients where resuscitation was attempted in a single city with basic life support with defibrillation/advanced life support tiered emergency medical services. Victim, caller, and system characteristics were measured during two successive nine-month periods before (control group) and after (intervention group) the introduction of dispatch-assisted CPR instructions.</AbstractText>There were 529 CAs between July 1, 2003, and December 31, 2004. Victim characteristics were similar in the control (n = 295) and intervention (n = 234) period; mean age was 68.3 years; 66.7% were male; 50.1% of CAs were witnessed; call-to-vehicle stop was 6 minutes, 37 seconds; ventricular fibrillation/ventricular tachycardia occurred in 29.9%; and the survival rate was 4.0%. Dispatchers identified 56.3% (95% confidence interval [CI] = 48.9% to 63.0%) of CA cases; agonal breathing was present in 37.0% (95% CI = 30.1% to 43.9%) of all CA cases and accounted for 50.0% (95% CI = 39.1% to 60.9%) of missed diagnoses. Callers provided ventilations in 17.2% and chest compressions in 8.3% of cases as a result of the intervention. Long time intervals were observed between call to diagnosis (2 minutes, 38 seconds) and during ventilation instructions (2 minutes, 5 seconds). Bystander CPR rates increased from 16.7% in the control phase to 26.4% in the intervention phase (absolute rate, 9.7%; 95% CI = 8.5% to 11.3%; p = 0.006).</AbstractText>This trial demonstrates an increase in bystander CPR rate after the introduction of dispatch-assisted CPR. Agonal breathing occurred frequently and had a negative impact on the recognition of CA. There were long time intervals between call initiation and diagnosis of CA and during mouth-to-mouth ventilation instructions.</AbstractText> |
8,393 | Effect of cardiac resynchronisation therapy on occurrence of ventricular arrhythmia in patients with implantable cardioverter defibrillators undergoing upgrade to cardiac resynchronisation therapy devices. | Cardiac resynchronisation therapy (CRT) improves outcomes in selected patients with heart failure and left ventricular dysfunction. One mechanism of benefit is believed to be favourable ventricular remodelling. Whether CRT also decreases the frequency of ventricular arrhythmias and risk of sudden death is unknown.</AbstractText>To determine the effect of CRT on frequency of ventricular arrhythmias and appropriate ICD therapies.</AbstractText>Retrospective cohort study.</AbstractText>Single-centre, tertiary care facility (Mayo Clinic).</AbstractText>52 patients (46 male), aged 70 (SD 10) years, who underwent upgrade from an implantable cardioverter defibrillator (ICD) to a CRT-defibrillator were included.</AbstractText>Upgrade of ICD to CRT-defibrillator.</AbstractText>Frequency of ventricular arrhythmias prior to and following upgrade to CRT device.</AbstractText>Ejection fraction increased from 22% (SD 8%) to 27% (SD 11%) following CRT. However, the frequency of non-sustained ventricular arrhythmias, sustained ventricular arrhythmias, and ventricular fibrillation was not significantly changed prior to and following CRT (2.38 (SD 9.78) vs 58.51 (SD 412.73) per patient per month, p = 0.66; 0.07 (SD 0.17) vs 0.16 (SD 0.52), p = 0.70; 0.05 (SD 0.12) vs 0.25 (SD 1.40), p = 0.12).</AbstractText>CRT is not associated with a decrease in the frequency of ventricular arrhythmia or appropriate device therapy. Thus, use of CRT alone is not beneficial in decreasing the frequency of ventricular arrhythmias or the risk of appropriate ICD therapies.</AbstractText> |
8,394 | Fibrin glue in coronary artery bypass grafting operations: casting out the Devil with Beelzebub? | Fibrin sealants are frequently used in aortocoronary bypass operations. Although they are considered to be clinically safe, we performed a retrospective analysis of our data to examine the possible side effects of Tissucol fibrin sealant, namely the acute thrombosis of grafts and native coronary arteries resulting in severe myocardial damage and patient deaths.</AbstractText>The data of 2716 patients (2001 male, 715 female) who received an aortocoronary bypass operation from November 1995 to December 1999 were studied retrospectively. Two groups (group 1: received Tissucol, group 2: no sealant used) were compared with respect to an a priori selected set of demographic and clinical variables and with respect to their effect on the outcome using bivariate tabulation. Multiple exploratory assessments of factors possibly related to fatal outcome were done by multiple logistic regression.</AbstractText>Nine hundred ninety patients (group 1) received Tissucol, 1726 patients (group 2) did not receive it. Mean patient age was 64+/-9.1 years. Group 1 had a higher risk of death (7.8% vs 2.8%, p<0.001). The peak values of creatine kinase >500 and creatine kinase-myocardial band >50 were higher in group 1 than in group 2, p<0.001. Adjusted odds ratios for the risk of fatal outcome were: 2.01 for the use of Tissucol, 2.71 for patient age >70 years, 2.02 for aortic cross clamp time >90 min, 3.95 for postoperative ventricular fibrillation, 6.35 for postoperative cardiopulmonary resuscitation, 4.55 for postoperative aortocoronary reoperation.</AbstractText>In our analysis an increased risk of myocardial injury or even death was found in coronary artery bypass grafting patients when Tissucol fibrin sealant was used intraoperatively.</AbstractText> |
8,395 | Mutation-specific effects of lidocaine in Brugada syndrome. | Brugada syndrome (BrS) is a hereditary cardiac disease characterized by right bundle-branch block, an elevation of the ST-segment in leads V1 through V3 on the electrocardiogram, and ventricular fibrillation that can lead to sudden cardiac death. Mutations in the cardiac sodium channel gene SCN5A, which encodes the alpha-subunit of the human cardiac voltage-dependent Na+ channel (Na(v)1.5), are identified in 15-30% of patients with BrS. Most SCN5A mutations lead to a 'loss-of-function' phenotype, reducing the Na+ current during the early phases of the action potential. Anti-arrhythmic drugs that affect Na+ channels typically block these Na+ channels, thereby exaggerating the ECG abnormalities and arrhythmogenicity in the BrS. However, the N406S mutation in SCN5A causes distinct gating defects and enhanced intermediate inactivation of Na+ channels, which led to unexpected pharmacological effects of lidocaine in a patient carrying this mutation. In the presence of the N406S mutation, use-dependent block by lidocaine is reduced and recovery from intermediate inactivation is hastened by lidocaine. These findings suggest that lidocaine may improve the Brugada phenotype in patients with N406S by increasing the availability of Na+ channels. |
8,396 | Heart failure and cardiac hypertrophy. | Left ventricular failure is the final common pathway for a wide spectrum of myocardial insults, including systemic hypertension and myocardial infarction. Although left ventricular hypertrophy is an adaptive response to pressure and volume overload, this process becomes maladaptive if left untreated and pathologic cardiac hypertrophy then becomes an important and independent risk factor for the development of heart failure. Despite its importance, the transition from hypertrophy to heart failure in humans is poorly understood. The focus of treatment should be prevention of heart failure and other cardiovascular events, such as stroke and atrial fibrillation. When heart failure is present, treatment with medical and device therapy is then focused on improving functional capacity, increasing survival, and preventing progression to end-stage heart failure. |
8,397 | The "incidental" episode of ventricular fibrillation: a case report. | Polymorphic ventricular tachycardia and ventricular fibrillation (VF) carry important prognostic implications, especially in the post myocardial infarction period. However, artifact on the electrocardiographic tracing can mimic VF particularly on routinely recorded rhythm strips in hospitals. Such misinterpretation can lead to expensive (and potentially risky) diagnostic and therapeutic steps. We report on such a case and highlight the need for careful inspection of the tracing. |
8,398 | Miniaturized mechanical chest compressor: a new option for cardiopulmonary resuscitation. | After cardiac arrest, uninterrupted chest compressions with restoration of myocardial blood flow facilitates restoration of spontaneous circulation. We recognized that this may best be accomplished with a mechanical device and especially so during transport. We therefore sought to develop a lightweight, portable chest compressor which may be carried on the belt or attached to the oxygen tank typically carried on the back of the first response rescuer. A miniaturized pneumatic chest compressor (MCC) weighing less than 2 kg was developed and compared with a currently marketed "Michigan Thumper", which weighed 19 kg. We hypothesized that the 2 kg, low profile, portable device will be as effective as the standard pneumatic Thumper for restoring circulation during CPR.</AbstractText>Ventricular fibrillation was electrically induced in 10 domestic male pigs weighing 39+/-2 kg, and untreated for 5 min. Animals were then randomized to receive chest compressions with either the MCC or the Thumper. After 5 min of mechanical chest compression, defibrillation was attempted with a 150 J biphasic shock. Coronary perfusion pressure (CPP) and end tidal PCO(2) (EtPCO(2)) were measured by conventional techniques together with right carotid artery blood flow (CBF).</AbstractText>Four of five animals compressed with the Thumper and each animal compressed with the MCC were successfully resuscitated. No significant differences in CPP, EtPCO(2), CBF and post-resuscitation myocardial function were observed between groups. Resuscitated animals survived for more than 72 h without neurological impairment.</AbstractText>The low profile, 2 kg miniaturized chest compressor is as effective as the conventional Thumper in an experimental model of CPR.</AbstractText> |
8,399 | Exclusion of a patient assessment interval and extension of the CPR interval both mitigate post-resuscitation myocardial dysfunction in a swine model of cardiac arrest. | Interruptions in cardiopulmonary resuscitation (CPR), particularly as guided by automated external defibrillators, have been implicated in poor survival from cardiac arrest. Interruptions of CPR may be reduced by eliminating repetition of shocks between periods of CPR, elimination of the interval for patient assessment before CPR, and extension of the periods of CPR.</AbstractText>The effects of exclusion of a 30s post-shock assessment interval prior to CPR and use of a longer interval (180s versus 90s) of CPR on resuscitation and post-resuscitation function were assessed in a factorial design using an established swine model of cardiac arrest. Repetitive shocks were excluded. Ventricular fibrillation was induced ischemically and maintained untreated for 5min.</AbstractText>All subjects were resuscitated, 95% survived 3 days, and 97% of survivors had full neurological recovery. Exclusion of the assessment interval reduced the delay to first return of spontaneous circulation by 33.1s (P=0.004) and the delay to sustained resuscitation by 99.2s (P=0.004), reduced post-resuscitation ECG ST elevation by 0.12mV (P=0.03), and alleviated transient post-resuscitation ejection fraction reduction (P<0.0001). Extension of the CPR interval reduced transient post-resuscitation fractional area change impairment (P=0.003).</AbstractText>Exclusion of an interval for assessment of airway, breathing and signs of circulation mitigates post-resuscitation dysfunction in a swine model of cardiac arrest. Extension of the period of CPR independently provides measurable, though less comprehensive, mitigation as well.</AbstractText> |
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