Unnamed: 0 int64 0 2.34M | titles stringlengths 5 21.5M | abst stringlengths 1 21.5M |
|---|---|---|
8,000 | [A case report of inoperable gastric cancer demonstrating a clinical CR after chemo-radiation therapy employing weekly DOC]. | A 76-year-old man was admitted to our hospital complaining a weight loss and dysphagia. Gastro-intestinal fiberscopy (GIF) examination showed an early gastric cancer located at cardia. Because of his severe co-morbidities, such as unruptured intracranial aneurysm and idiopathic ventricular fibrillation, he was considered to be inoperable and only followed periodically by the GIF examination every half year. After 3 years since his first examination, the gastric cancer progressed to be T2 advanced gastric cancer. Chemo-radiation therapy (CRT) was administered for consecutive 5 weeks in the following fashion: weekly docetaxel (DOC) div 20 mg/m2 x 5 weeks, and RT 1.8 Gy/day x 5 days/week x 5 weeks. Although the CRT was completed on schedule, diarrhea of grade 3, serum creatinine elevation of grade 2, and esophageal candidiasis appeared during the therapy. A month later after the completion of CRT, the tumor disappeared thoroughly, leaving the tiny redness on the mucosa of cardia. Two months later after CRT, GIF examination reconfirmed the disappearance of the tumor. The patient has shown a clinical complete response (CR), suggesting the efficacy of CRT for inoperable gastric cancer. |
8,001 | First case report in Japan of left ventricular pacing via a coronary vein in a patient with a mechanical tricuspid valve. | Transvenous endocardial pacemaker implantation is contraindicated in patients after prosthetic tricuspid valve replacement. A 65-year-old woman underwent both replacement of the mitral and tricuspid valves and pacemaker implantation with epicardial lead for bradycardia with chronic atrial fibrillation. At 2 years after this operation, the pacemaker's battery became low, and she was admitted for a battery exchange. To avoid frequent battery exchanges because of high stimulation thresholds, a left ventricular pacing lead was implanted via a coronary vein. There were no complications and the stimulation thresholds were stable. Coronary vein leads enable a minimally invasive approach, improve safety, and give effective stimulation for patients with a prosthetic tricuspid valve. This is the first case report in Japan of left ventricular pacing in such a patient. |
8,002 | Attenuation of diastolic heart failure and life-threatening ventricular tachyarrhythmia after peripheral blood stem cell transplantation combined with cardioverter-defibrillator implantation in myeloma-associated cardiac amyloidosis. | A patient had multiple myeloma and associated cardiac amyloidosis, which caused diastolic dysfunction and recurrent ventricular fibrillation. After implantation of a cardioverter-defibrillator (ICD), the patient underwent autologous peripheral blood stem cell transplantation (PBSCT). The life-threatening arrhythmias, such as ventricular fibrillation, disappeared, and diastolic dysfunction assessed by quantitative gated single photon emission computed tomography and Doppler echocardiography improved 7 months later. This may be the first report to document improvement of both a lethal rhythm disorder and diastolic dysfunction by PBSCT following ICD implantation in a case of cardiac amyloidosis associated with multiple myeloma. |
8,003 | Inhomogenic effect of bepridil on atrial electrical remodeling in a canine rapid atrial stimulation model. | The antiarrhythmic or reverse remodeling effects of bepridil, a multi-ion channel blocker, have been recently reported, but inhomogeneity of the electrical remodeling and effects of bepridil have been observed in previous reports. In this study, the effect of long-term administration of bepridil on atrial electrical remodeling was evaluated in a comparison of the right and left atrium (RA and LA) in a canine rapid atrial stimulation model.</AbstractText>In 10 beagle dogs, rapid atrial pacing (400 beats/min) was delivered for 6 weeks and the atrial effective refractory period (AERP), conduction velocity (CV) and inducibility of atrial fibrillation (AF) were evaluated every week. In 5 of the pacing dogs, bepridil (10 mg . kg(-1) . day(-1)) was administered orally, starting 2 weeks after the initiation of the rapid pacing. At the end of the protocol, the hemodynamic parameters and extent of tissue fibrosis were evaluated and the mRNA of SCN5A, Kv4.3, the L-type Ca2+ channel (LCC) and connexin (Cx) 40, 43, and 45 in both atria were examined by quantitative real-time reverse transcriptase-polymerase chain reaction. In the pacing control group, AERP shortening, decreased CV, increased AF inducibility and downregulation of the expression of SCN5A and LCC were observed. In the bepridil group, the AERP exhibited a relatively quick recovery after bepridil was started in the first week and continued to recover gradually until the end of the protocol, but that recovery was smaller in the LA than in the RA. The CV was not affected by bepridil administration. AF inducibility was well suppressed in the RA in the bepridil group, but the induction of short-duration AF could not be suppressed in the LA. The mRNA downregulation of the LCC and SCN5A was negated by bepridil administration in the RA; but not in the LA; however, the data showed similar tendencies. There were no significant differences in the hemodynamic parameters or tissue fibrosis and the mRNA expression of Kv4.3, Cx40, 43, and 45 between the pacing control and bepridil groups.</AbstractText>Bepridil exhibited an anti-electrical remodeling effect in this study as previously reported, but the effect was inhomogeneous between the RA and LA, with the LA appearing to be more resistant to the effect of bepridil.</AbstractText> |
8,004 | Association of sinus node dysfunction, atrioventricular node conduction abnormality and ventricular arrhythmia in patients with Kawasaki disease and coronary involvement. | This study was performed to investigate the incidence of arrhythmias in patients with Kawasaki disease (KD).</AbstractText>Electrophysiologic studies (EPS) were performed in 40 patients (mean age: 10.3+/-5.1 years; 30 males, 10 females) with KD who had severe to moderate coronary artery disease. Clinical arrhythmias were documented in 4 patients (premature ventricular contractions, ventricular tachycardia, atrioventricular block, and ventricular fibrillation). Dual atrioventricular nodal pathways were demonstrated in 3 patients. Nonsustained atrial fibrillation was induced in 1 patient. The AH interval was prolonged in 2 patients. The Wenckebach rate was 164+/-37 beats/min, and 4 of the patients had a decreased Wenckebach rate. The maximum and corrected sinus node recovery times were 997+/-257 ms and 281+/-130 ms, respectively, and 7 patients were thought to be abnormal. The sino-atrial conduction time was 108+/-64 ms, and 2 patients had prolonged conduction times.</AbstractText>Although there was no relationship between coronary stenosis or obstruction and the EPS parameters, the incidence of abnormal sinus node and atrioventricular node function is apparently higher in KD patients than in the normal population. These functional abnormalities may possibly be caused by myocarditis or an abnormal microcirculation in the sinus node and atrioventricular node artery. In some patients, myocardial ischemia may provoke malignant ventricular arrhythmia.</AbstractText> |
8,005 | Tunnel propagation of postshock activations as a hypothesis for fibrillation induction and isoelectric window. | Comprehensive understanding of the ventricular response to shocks is the approach most likely to succeed in reducing defibrillation threshold. We propose a new theory of shock-induced arrhythmogenesis that unifies all known aspects of the response of the heart to monophasic (MS) and biphasic (BS) shocks. The central hypothesis is that submerged "tunnel" propagation of postshock activations through shock-induced intramural excitable areas underlies fibrillation induction and the existence of isoelectric window. We conducted simulations of fibrillation induction using a realistic bidomain model of rabbit ventricles. Following pacing, MS and BS of various strengths/timings were delivered. The results demonstrated that, during the isoelectric window, an activation originated deep within the ventricular wall, arising from virtual electrodes; it then propagated fully intramurally through an excitable tunnel induced by the shock, until it emerged onto the epicardium, becoming the earliest-propagated postshock activation. Differences in shock outcomes for MS and BS were found to stem from the narrower BS intramural postshock excitable area, often resulting in conduction block, and the difference in the mechanisms of origin of the postshock activations, namely intramural virtual electrode-induced phase singularity for MS and virtual electrode-induced propagated graded response for BS. This study provides a novel analysis of the 3D mechanisms underlying the origin of postshock activations in the process of fibrillation induction by MS and BS and the existence of isoelectric window. The tunnel propagation hypothesis could open a new avenue for interventions exploration to achieve significantly lower defibrillation threshold. |
8,006 | Fatal amiodarone-induced hepatotoxicity: a case report and literature review. | To report a fatal case of amiodarone-induced acute hepatotoxicity after intravenous amiodarone administration and similar fatal cases review.</AbstractText>A 72-year-old woman with a history of hypertension, prior cardiovascular disease, atrial fibrillation and diabetes mellitus was admitted to the hospital with acute pyelonephritis and transferred to the intensive care unit due to cerebral infarction. An antidiabetic drug, a low dose of aspirin and intravenous amiodarone therapy was started. After receiving a second dose of amiodarone (1,200 mg; injection rate 1 mg/min), the woman developed ascites, jaundice, high levels of serum transaminases, decreased prothrombin time, and finally became unconscious. Immediately after treatment was discontinued, her extremely high hepatic parameters returned to normal. According to the Naranjo probability scale, this adverse reaction was highly probable.</AbstractText>The occurrence of acute liver damage after intravenous amiodarone is rare but harmful. It can be induced by polysorbate 80, a solubilizer, by immunomediated centrilobular necrosis, or by the presence of a functional PPAR-I+/- gene.</AbstractText>Amiodarone is an effective antiarrhythmic agent for preventing and treating atrial and ventricular arrhythmias. The molecular mechanism causing acute hepatic damage after amiodarone treatment is not clear. Therefore, amiodarone must be administered with care, and liver function should be monitored closely in patients treated with this drug.</AbstractText> |
8,007 | Gender differences in selection of pacemakers: a single-center study. | Previous studies have reported gender differences in pacemaker selection.</AbstractText>This study aimed to assess gender-related differences in pacemaker mode selection in patients undergoing their first implantation.</AbstractText>A retrospective analysis was undertaken from a single-center database of pacemaker implants during the years 2001 to 2003. Univariate and multivariate analyses were used to compare pacemaker mode selection adjusted for any significant difference between the sexes.</AbstractText>A total of 274 pacemakers were implanted during the study period, 259 of which formed the basis of this study. Of the patients receiving pacemakers, 132 were male and 127 were female. The majority of patients (144 [55.6%]) had sick sinus syndrome as their indication for receiving a pacemaker, followed by complete heart block (75 [29.0%]), and second-degree or high-grade atrio-ventricular block (36 [13.9%]). Four (1.5%) patients had hypersensitive carotid sinus syndrome. The mean (SD) age of patients was 61.35 (15) years. Most (155 [59.8%]) patients were younger than age 65, and the women were significantly older than the men (P = 0.004). Atrial fibrillation (AF) was present in 53 (20.5%) patients. Dual-chamber (DDD) pacemakers were implanted in 196 (75.7%) patients, and single-chamber ventricular pacemakers in 63 (24.3%) patients. Significantly more DDD pacemakers were implanted in patients aged <65 years compared with those aged > or =65 years (P < 0.01). This difference was, however, primarily due to the higher rate of AF in the older patients versus patients aged <65 years. Although the rate of DDD implantations was observed to be higher among women (101/127 [79.5%]) compared with men (95/132 [72.0%]), the rate difference was nonsignificant, even when adjusted for the significant age difference between the sexes. Furthermore, DDD selection was independent of patients' health insurance status.</AbstractText>We found no significant difference in pacemaker mode selection between male and female patients. However, we did find that patients aged <65 years were more likely to have DDD pacemakers implanted compared with older patients. This age-dependent difference was primarily due to the higher prevalence of AF in the older age group versus the younger patients. Key words: pacemaker implant gender difference gender and pacemaker selection.</AbstractText> |
8,008 | Atrial fibrillation and morbidity and mortality in a cohort of long-term hemodialysis patients. | Atrial fibrillation is associated with increased mortality and hospitalization in the general population. Data about mortality, morbidity, and hospitalization in hemodialysis patients with atrial fibrillation are limited.</AbstractText><AbstractText Label="SETTING & PARTICIPANTS" NlmCategory="METHODS">All patients (n = 476) in 5 dialysis centers in Lombardia, Italy, as of June 2003 were enrolled and followed up until June 2006 (median age, 69 years; median hemodialysis duration, 45.2 months; and median follow-up, 36 months). 127 patients had atrial fibrillation at enrollment.</AbstractText><AbstractText Label="PREDICTORS & OUTCOME" NlmCategory="METHODS">A Cox model was used to relate: (1) atrial fibrillation, age, hemodialysis therapy duration, and comorbid conditions to all-cause and cardiovascular mortality; (2) angiotensin-converting enzyme (ACE)-inhibitor treatment and comorbid conditions to new onset of atrial fibrillation; and (3) atrial fibrillation and comorbid conditions on hospitalization.</AbstractText>There were 167 deaths (39.5% from cardiovascular disease). In multivariable models, atrial fibrillation was independently associated with increased mortality (hazard ratio [HR], 1.65; 95% confidence interval [CI], 1.18 to 2.31). This was more notable for cardiovascular (HR, 2.15; 95% CI, 1.27 to 3.64) than noncardiovascular mortality (HR, 1.39; 95% CI, 0.89 to 2.15). New-onset atrial fibrillation occurred in 35 of 349 individuals (4.1 events/100 person-years); the risk of incident atrial fibrillation was lower in those using ACE-inhibitor therapy (HR, 0.29; 95% CI, 0.10 to 0.82) and higher in those with left ventricular hypertrophy (HR, 2.55; 95% CI, 1.04 to 6.26). There were 539 hospitalizations during 3 years, with 114 hospitalizations in 162 patients with atrial fibrillation and 155 hospitalizations in 314 patients without atrial fibrillation (HR, 1.54; 95% CI, 1.18 to 2.01). Rates of stroke did not significantly differ by atrial fibrillation status (P = 0.4).</AbstractText>Because of the observational nature of this study, results for treatment need confirmation in future trials.</AbstractText>Atrial fibrillation is associated with greater total and cardiovascular mortality. Patients with atrial fibrillation were hospitalized more frequently than patients without atrial fibrillation. ACE inhibitors may decrease the risk of new-onset atrial fibrillation.</AbstractText> |
8,009 | Atrial fibrillation and obesity--results of a meta-analysis. | Obesity has been shown to be associated with atrial enlargement and ventricular diastolic dysfunction, both of which are risk factors for atrial fibrillation (AF). However, the role of obesity as a risk factor for the development of AF is unknown. The study aims to evaluate the role of obesity as a risk factor for the development of AF.</AbstractText>The MEDLINE/ PUBMED and Cochrane databases were searched for studies in human subjects published in English language between 1966 and May 2007. Studies were included in our analyses if they were population-based cohort or postcardiac surgery cohort and investigated the incidence of AF in relation to the body mass index (BMI) categories.</AbstractText>Of the 468 articles identified, 16 studies that enrolled a total of 123,249 individuals met the inclusion criteria. These 16 articles included 5 population-based cohort studies that enrolled 78,602 adult individuals from the United States and 3 European countries and 11 postcardiac surgery studies that enrolled 44,647 patients. Based on the population-based cohort studies, obese individuals have an associated 49% increased risk of developing AF compared to nonobese individuals (relative risk 1.49, 95% CI 1.36-1.64). The risk of AF increased in parallel with greater BMI in this cohort. In contrast, in the postcardiac surgery studies, obese individuals do not have an associated increased risk of developing AF compared to nonobese individuals (relative risk 1.02, 95% CI 0.99-1.06).</AbstractText>Our findings demonstrate that obesity increased the risk of developing AF by 49% in the general population, and the risk escalated in parallel with increased BMI. Thus, AF evolves as yet another pathogenetic factor by which obesity may increase cardiovascular and cerebrovascular events.</AbstractText> |
8,010 | Doppler predictors of inducibility of atrial fibrillation in patients with WPW syndrome and atrioventricular re-entrant tachycardia. | Atrial fibrillation (AF) in patients with Wolff-Parkinson-White syndrome (WPW) may induce complex ventricular arrhythmias resulting in sudden cardiac death. It is essential to find an effective non-invasive diagnostic method allowing to select patients at risk of life-threatening arrhythmias. Our objective was to examine Doppler predictors of AF in patients with WPW and atrioventricular re-entrant tachycardia (AVRT).</AbstractText>65 patients with WPW and AVRT (33 men, mean age 39 +/- 11 y) were prospectively studied. In all patients TTE was performed with measurements of left ventricle (LV) diameters, volumes and parameters of systolic and diastolic function. TTE was followed by invasive electrophysiology study (EPS) and radiofrequency current ablation of accessory pathway.AF lasting at least 30 s was induced in 29 (44.6%) patients during EPS. Reduction of right upper pulmonary vein (RUPV) systolic velocity (P < 0.005) and systolic to diastolic velocity ratio (P < 0.005) and increase in atrial reversal velocity (P < 0.05) of RUPV flow and difference between duration of RUPV atrial reversal flow and A wave of mitral profile (P < 0.05) were associated with increased risk of AF in patients with WPW syndrome and AVRT. Systolic and atrial reversal velocities were identified as independent predictors of AF in those patients.</AbstractText>Systolic and atrial reversal right upper pulmonary vein flow velocities have been shown to be independent predictors of AF inducibility in patients with Wolff-Parkinson-White syndrome and atrioventricular re-entrant tachycardia.</AbstractText> |
8,011 | Propafenone-induced Brugada-like ECG changes mistaken as acute myocardial infarction. | Brugada syndrome is one of the important causes of sudden cardiac death in young adults. The condition is associated with typical ECG changes in anteroseptal leads V1 and V2 that can be unmasked by various medications, electrolyte disturbances, and even by the febrile state in susceptible individuals. The case history is reported of a patient with atrial flutter and atrial fibrillation who developed Brugada-like ECG changes when treated with propafenone. He was mistakenly diagnosed as having acute myocardial infarction when he presented to the emergency room with acute precordial chest pain. Cardiac catheterisation revealed normal coronary arteries and normal left ventricular systolic function. A review of previous ECGs showed the temporal relationship of ECG changes to initiation of propafenone a few years earlier. The ECG changes resolved with discontinuation of propafenone and re-emerged when he was rechallenged with oral propafenone. This case highlights the importance of recognising the characteristic ECG changes of Brugada syndrome and being able to differentiate them from those of acute myocardial infarction and other conditions manifesting with similar changes. |
8,012 | CT scan findings in oesophagogastric perforation after out of hospital cardiopulmonary resuscitation. | Rupture of the oesophagus or stomach at the time of cardiopulmonary resuscitation can occur with accidental oesophageal intubation. The common site of rupture is the lesser curvature of the stomach, but can also occur at the oesophagogastric junction. The patient presented with a massive pneumoperitoneum after an out of hospital ventricular fibrillation arrest. CT scanning was helpful in making the diagnosis. In out of hospital resuscitation, current JRCALC (Joint Royal Colleges Ambulance Liaison Committee) recommendations may not avoid this complication. |
8,013 | TASER X26 discharges in swine produce potentially fatal ventricular arrhythmias. | Data from the authors and others suggest that TASER X26 stun devices can acutely alter cardiac function in swine. The authors hypothesized that TASER discharges degrade cardiac performance through a mechanism not involving concurrent acidosis.</AbstractText>Using an Institutional Animal Care and Use Committee (IACUC)-approved protocol, Yorkshire pigs (25-71 kg) were anesthetized, paralyzed with succinylcholine (SCh; 2 mg/kg), and then exposed to two 40-second discharges from a TASER X26 with a transcardiac vector. Vital signs, blood chemistry, and electrolyte levels were obtained before exposure and periodically for 48 hours postdischarge. Electrocardiograms and echocardiography (echo) were performed before, during, and after the discharges. p-Values < 0.05 were considered significant.</AbstractText>Electrocardiograms were unreadable during the discharges due to electrical interference, but echo images showed unmistakably that cardiac rhythm was captured immediately at a rate of 301 +/- 18 beats/min (n = 8) in all animals tested. Capture continued for the duration of the discharge and in one animal degenerated into fatal ventricular fibrillation (VF). In the remaining animals, ventricular tachycardia (VT) occurred postdischarge for 1-17 seconds, whereupon sinus rhythm was regained spontaneously. Blood chemistry values and vital signs were minimally altered postdischarge and no significant acidosis was seen.</AbstractText>Extreme acid-base disturbances usually seen after lengthy TASER discharges were absent with SCh, but TASER X26 discharges immediately and invariably produced myocardial capture. This usually reverted spontaneously to sinus rhythm postdischarge, but fatal VF was seen in one animal. Thus, in the absence of systemic acidosis, lengthy transcardiac TASER X26 discharges (2 x 40 seconds) captured myocardial rhythm, potentially resulting in VT or VF in swine.</AbstractText> |
8,014 | [Intraoperative coronary artery spasm with cardiac arrest: cardiologic acute intervention]. | Ventricular fibrillation occurred intraoperatively during a laparoscopy-assisted resection of the rectum in a 63-year-old patient. A coronary artery spasm was identified as the cause. It was possible to rectify the coronary artery spasm and restore a stable circulatory situation with an intracoronary injection of nitroglycerine. Excellent interdisciplinary cooperation combined with favourable timing and spatial conditions, made this outcome possible for the patient without neurological deficits. In addition to presenting the actual treatment procedure, possible underlying pathogenetic mechanisms will also be presented. |
8,015 | [Reversible dilated cardiomyopathy related to hyperthyroidism]. | Heart failure is one of the most known complications of hyperthyroidism, more commonly high-output heart failure, but some patients may develop dilated cardiomyopathy with low ejection fraction. We report a 35-year-old man, with hyperthyroidism, atrial fibrillation, and severe heart failure with 43% of ejection fraction. After the definitive treatment of the hyperthyroidism with radioiodine, heart failure was reverted, with symptomatic improvement and echocardiographic normalization including a normal ejection fraction (69%). There are several cases of reversion of heart failure due to hyperthyroidism treatment, but most of them with a high-output heart failure. Mechanisms by which hyperthyroidism can lead to heart failure and its treatment are discussed. We conclude that treatment of hyperthyroidism may reverse this thyroid related heart failure, even in severe cases with systolic dysfunction. |
8,016 | Long-term effects of cardiac resynchronisation therapy in patients with atrial fibrillation. | To compare the effects of cardiac resynchronisation therapy (CRT) in patients with heart failure (HF) in either atrial fibrillation (AF) or sinus rhythm (SR).</AbstractText>Prospective observational study.</AbstractText>295 consecutive patients with HF (permanent AF in 66, paroxysmal AF in 20, SR in 209; New York Heart Association (NYHA) class III or IV; left ventricular ejection fraction (LVEF) <or=35%, QRS >or=120 ms).</AbstractText>All patients underwent CRT without atrioventricular junction ablation.</AbstractText>The primary end point was the composite of cardiovascular death or unplanned hospitalisation for major cardiovascular events. Secondary end points included the composite of cardiovascular death or hospitalisation for worsening HF. Cardiovascular mortality, total mortality and changes in NYHA class, 6-minute walking distance, quality of life (Minnesota Living with Heart Failure questionnaire) and echocardiographic variables were also considered.</AbstractText>Over a follow-up period of up to 6.8 years, no differences emerged between patients in AF or SR in any of the mortality or morbidity end points. The AF and SR groups derived similar improvements in mean NYHA class (-1.3 vs -1.2), 6-minute walking distance (92.3 vs 78.4 m) and quality of life scores (-25.2 vs -18.7) (all p<0.001). In both the AF and the SR groups, reductions were seen in left ventricular end-systolic (-25.9 vs -34.5 ml, both p<0.001) and end-diastolic (-20.2 ml, p = 0.001 vs 26.2 ml, p<0.001) volumes and improvements in LVEF (4.69% vs 7.86%, both p<0.001).</AbstractText>Cardiac resynchronisation therapy leads to similar prognostic and symptomatic benefits in patients in AF and SR, even without atrioventricular junction ablation. Echocardiographic improvements are also comparable.</AbstractText> |
8,017 | Effects of spironolactone on electrical and structural remodeling of atrium in congestive heart failure dogs. | Renin-angiotensin-aldosterone system has been demonstrated to be associated with both congestive heart failure (CHF) and atrial fibrillation (AF). This study investigated the effects of spironolactone, a kind of aldosterone antagonist, on atrial electrical remodeling and fibrosis in CHF dogs induced by chronic rapid ventricular pacing.</AbstractText>Twenty one dogs were randomly divided into sham-operated group, control group, and spironolactone group. In control group and spironolactone group, dogs were ventricular paced at 220 beats per minute for 6 weeks. Additionally, spironolactone at 15 mg x kg(-1) x d(-1) was given to dogs 1 week before rapid ventricular pacing until pacing stopped. Transthoracic and transoesophageal echocardiographic examinations were performed to detect structural and functional changes of the atrium. Swan2 Ganz floating catheters were used to measure hemadynamics variances. Atrial effective refractory period (AERP), AERP dispersion (AERPd), intra- and inter-atrium conduction time (CT) and intra-atrium conduction velocity (CV) were determined. The inducibility and duration of AF were also measured in all groups. Finally, atrial fibrosis was quantified with Masson staining.</AbstractText>AERP did not change significantly after dogs were ventricular paced for 6 weeks. However, AERPd, intra- and inter-atrium CT increased significantly, and CV decreased apparently, which was negatively correlated to the atrial fibrosis (r = -0.74, P < 0.05). Simultaneously, left atriums were enlarged and cardiac hemadynamics worsened in pacing dogs. Although spironolactone could not affect cardiac hemadynamics effectively, it can obviously improve left atrial ejection fraction (P < 0.05). Spironolactone treatment did not alter AERP duration, but this medicine dramatically decreased AERPd (P < 0.05), shortened intra- and inter-atrium conduction time (P < 0.05), and increased atrium CV. Moreover, spironolactone decreased the inducibility and duration of AF (P < 0.05), as well as atrial fibrosis (P < 0.01) induced by chronic rapid ventricular pacing.</AbstractText>Spironolactone contributes to AF prevention in congestive heart failure dogs induced by chronic rapid ventricular pacing, which is related to atrial fibrosis reduction and independent of hemadynamics.</AbstractText> |
8,018 | Predictive factors of recurrent angina after acute coronary syndrome: the global registry acute coronary events from China (Sino-GRACE). | Many patients with acute coronary syndrome (ACS) develop recurrent angina (RA) during hospitalization. The aim of this non-randomized, prospective study was to investigate the predictive factors of RA in unselected patients with ACS enrolled in the global registry acute coronary events (GRACE) during hospitalization in China.</AbstractText>Between March 2001 and October 2004, enrolled were 1433 patients with ACS, including ST segment elevation myocardial infarction (662, 46.2%), non-ST segment elevation myocardial infarction (239, 16.7%) and unstable angina (532, 37.1%). The demographic distribution, medical history and clinical data were collected to investigate the predictive factors of RA by Logistic regression.</AbstractText>During hospitalization 275 (19.2%) patients were documented with RA including unstable angina (53.2%), non-ST segment elevation myocardial infarction (27.5%), ST segment elevation myocardial infarction (19.3%). A comorbidity of dyslipidemia, prior angina, percutaneous coronary intervention (PCI) within 6 months was more common in patients with RA, P < 0.05. In the patients with RA, a significantly higher proportion of patients with acute pulmonary edema was observed, 23 (8.4%) versus 43 (3.7%), P = 0.001. Acute renal failure was present in 8 (2.9%) of patients with RA versus 19 (1.6%) of patients without RA, P = 0.165. Hemorrhagic events were present in 6 (2.2%) of patients with RA versus 8 (0.7%) of patients without RA, ventricular tachycardia/ventricular fibrillation events in 12 patients (4.3%) versus 22 patients (1.9%), congestive heart failure in 69 patients (25.0%) versus 94 patients (8.1%), myocardial re-infarction in 28 patients (10.1%) versus 15 patients (1.3%), P < 0.05, respectively. A lower proportion of patients with RA underwent in-hospital PCI, 687 (59.3%) versus 114 (41.5%), P = 0.000. A higher proportion of patients with RA received heparin, 260 (94.5%) versus 1035 (89.4%), P = 0.006; and beta-blockers 176 (64.0%) versus 864 (74.5%), P = 0.000. Multivarible regression analysis showed that RA was associated with prior angina (OR 2.086, 95% CI 1.466 - 2.967), in-hospital PCI (OR 0.579, 95% CI 0.431 - 0.778), in-hospital congestive heart failure (OR 2.410, 95% CI 1.634 - 3.555), myocardial re-infarction (OR 7.695, 95% CI 3.701 - 15.999), beta-blocker (OR 0.626, 95% CI 0.458 - 0.855), and heparin (OR 3.411, 95% CI 1.604 - 7.382).</AbstractText>In-hospital congestive heart failure, myocardial re-infarction, prior angina history and use of heparin are stronger independent predictors of RA; beta-blockers and PCI are also important predictive factors for RA.</AbstractText> |
8,019 | Rapidly induced selective cerebral hypothermia using a cold carotid arterial flush during cardiac arrest in a dog model. | The present study was undertaken to determine whether flushing the carotid artery with normal saline at 4 degrees C (hypothermic carotid arterial flush, HCAF) during cardiac arrest can achieve selective cerebral hypothermia rapidly during cardiac arrest and improve cerebral outcome.</AbstractText>Ventricular fibrillation (VF) was induced in fourteen dogs and circulatory arrest was maintained for 9 min. Dogs were then resuscitated by cardiopulmonary resuscitation. The dogs were divided into two groups; a control group (n=7), which underwent precisely the same procedure as the experimental group but not HCAF, and an experimental group (HCAF group; n=7), which received HCAF from 8 min after the onset of VF.</AbstractText>Two dogs in the control group and in the HCAF group died within 72 h after the recovery of spontaneous circulation (ROSC) due to extracerebral complications. The remaining 10 dogs survived to final evaluation at 72 h post-ROSC. In the HCAF group, tympanic temperature decreased from 37.7 degrees C (37.5-37.8) to 34 degrees C in 1 min (1-1.5) from the start of HCAF and was maintained below 34 degrees C until 6.5 min (3-12) after the start of HCAF, whereas oesophageal and rectal temperatures were maintained above 35 degrees C. Neurological deficit scores (0-100%) at 72 h post-ROSC were 42.4% (27.0-80.6) in the control group and 18.4% (14.0-36.0) in the HCAF group (p<0.05).</AbstractText>HCAF induced selective cerebral hypothermia rapidly during cardiac arrest and improved neurological deficit scores after 9 min of no blood flow in the described canine cardiac arrest model.</AbstractText> |
8,020 | Risk stratification for primary implantation of a cardioverter-defibrillator in patients with ischemic left ventricular dysfunction. | The study was designed to develop a simple risk stratification score for primary therapy with an implantable cardioverter-defibrillator (ICD).</AbstractText>Current guidelines recommend primary ICD therapy in patients with a low ejection fraction (EF). However, the benefit of the ICD in the low EF population may not be uniform.</AbstractText>Best-subset proportional-hazards regression analysis was used to develop a simple clinical risk score for the end point of all-cause mortality in patients allocated to the conventional therapy arm of MADIT (Multicenter Automatic Defibrillator Implantation Trial)-II after excluding a pre-specified subgroup of very high-risk (VHR) patients (defined by blood urea nitrogen [BUN] >or=50 mg/dl and/or serum creatinine >or=2.5 mg/dl). The benefit of the ICD was then assessed within risk score categories and separately in VHR patients.</AbstractText>The selected risk score model comprised 5 clinical factors (New York Heart Association functional class >II, age >70 years, BUN >26 mg/dl, QRS duration >0.12 s, and atrial fibrillation). Crude mortality rates in the conventional group were 8% and 28% in patients with 0 and >or=1 risk factors, respectively, and 43% in VHR patients. Defibrillator therapy was associated with a 49% reduction in the risk of death (p < 0.001) among patients with >or=1 risk factors (n = 786), whereas no ICD benefit was identified in patients with 0 risk factors (n = 345; hazard ratio 0.96; p = 0.91) and in VHR patients (n = 60; hazard ratio 1.00; p > 0.99).</AbstractText>Our data suggest a U-shaped pattern for ICD efficacy in the low-EF population, with pronounced benefit in intermediate-risk patients and attenuated efficacy in lower- and higher-risk subsets.</AbstractText> |
8,021 | The impact of carvedilol on the defibrillation threshold. | Defibrillation threshold (DFT) is the minimum energy required to successfully terminate ventricular fibrillation. Epinephrine has been shown to increase the DFT in the beta-blocker naïve, but using cardioselective beta-blockers leads to a reduction in the DFT on infusion of epinephrine and norepinephrine. We sought to determine the impact of carvedilol therapy on the DFT after infusion of epinephrine and norepinephrine.</AbstractText>DFT was determined in patients receiving carvedilol by the step-down method (baseline DFT), and then patients (n = 27, 67.3 years, 70.0% were male, average left ventricular ejection fraction = 19%) were randomized to a 7-minute infusion of norepinephrine, epinephrine, or placebo in a double-blind manner. After the study drug infusion, DFT testing was repeated (experimental DFT) and results were compared between groups.</AbstractText>No differences in intragroup DFTs were observed among carvedilol-treated patients receiving norepinephrine (9.4 +/- 4.6 J vs 11.1 +/- 7.8 J; P = .589), epinephrine (10.6 +/- 5.3 J vs 9.8 +/- 6.3 J; P = .779), or placebo (11.1 +/- 7.0 vs 8.5 +/- 4.2; P = .349).</AbstractText>Carvedilol prevents alterations in DFT produced by stress levels of catecholamines.</AbstractText> |
8,022 | Acute in vivo evaluation of an implantable continuous flow biventricular assist system. | An implantable biventricular assist device offers a considerable opportunity to save the lives of patients with combined irreversible right and left ventricular failure. The purpose of this study was to evaluate the hemodynamic and physiologic performance of the combined implantation of the CorAide left ventricular assist device (LVAD) and the DexAide right ventricular assist device (RVAD). Acute hemodynamic responses were evaluated after simulating seven different physiological conditions in two calves. Evaluation was performed by fixing the speed of one individual pump and increasing the speed of the other. Under all conditions, increased LVAD or RVAD speed resulted in increased pump flow. The predominant pathophysiologic effect of independently varying DexAide and CorAide pump speeds was that the left atrial pressure was very sensitive to increasing RVAD speed above 2,400 rpm, whereas the right atrial pressure demonstrated much less sensitivity to increasing LVAD speed. An increase in aortic pressure and RVAD flow was observed while increasing LVAD speed, especially under low contractility, ventricular fibrillation, high pulmonary artery pressure, and low circulatory blood volume conditions. In conclusion, a proper RVAD-LVAD balance should be maintained by avoiding RVAD overdrive. Additional studies will further investigate the performance of these pumps in chronic animal models. |
8,023 | Artificial muscles to restore transport function of diseased atria. | Surgical treatment of persistent atrial fibrillation often fails to restore the transport function of the atrium. This study first introduces the concept of an atrial assist device to restore the pump function of the atrium. A micro motorless pump based on artificial muscle technology, is positioned on the external surface of the atrium to compress it and restore its muscular activity. A bench model reproduces the function of fibrillating atrium to assess the circulatory support that this pump can provide. The Atripump is a dome shape silicone coated nitinol actuator mounted on a plastic ring. A pacemaker-like control unit drives the actuator, which compresses the atrium, providing the mechanical support to the blood circulation. The bench model consists of an open circuit made of latex bladder 60 mm in diameter filled with water. The Atripump is placed on the outer surface of the bladder. Pressure, volume, and temperature changes were recorded. The contraction rate was 1 Hz with power supply of 12 V, 400 mA for 200 milliseconds. Preload ranged from 15 to 21 cm H20. The pump produced a maximal work of 16 x 10(-3) J. Maximal volume pumped was 492 ml/min. This artificial muscle pump is compact, and reproduces the hemodynamic performances of normal atrium. |
8,024 | Home monitoring remote control of pacemaker and implantable cardioverter defibrillator patients in clinical practice: impact on medical management and health-care resource utilization. | To evaluate the impact of Home Monitoringtrade mark(HM) remote control on patient medical treatment and on health-care resource utilization.</AbstractText>One hundred and seventeen patients received HM pacemakers or defibrillators. A pacing expert nurse consulted daily the website and submitted critical cases to physician. During a mean follow-up of 227 +/- 128 days, 25,210 messages were received (23,545 daily messages and 1665 alert events) resulting in 90.7% of HM supervised days. Fifty-nine minutes/week for the nurse and 12 min/week for the physician were spent for HM data analysis during 267 web-connections. The mean connection time per patient was 115 +/- 60 s. The nurse submitted to the physician 133 critical cases in 56 patients. The diagnosis were atrial fibrillation (47%), ventricular tachyarrhythmias (9%), inappropriate implantable cardioverter defibrillator intervention (4%), unsustained ventricular tachycardia (7%), device suboptimal programming (23%), and impending heart failure (10%). Sixty-six unplanned follow-up in 43 patients led to drug therapy change (44%), device reprogramming (18%), diagnosis confirmation without further intervention (24%), no confirmation (6%), further diagnostic tests (9%).</AbstractText>HM technology allowed optimization of medical treatment and device programming with low consumption of health-care resource.</AbstractText> |
8,025 | Long-term reliability of AAI mode pacing in patients with sinus node dysfunction and low Wenckebach block rate. | To compare the risk of atrioventricular (AV) conduction disturbance between patients with sinus node dysfunction on AAI pacing who had a low or high Wenckebach block rate (WBR).</AbstractText>Patients with sinus node dysfunction and normal AV conduction those underwent an electrophysiological study were studied. The patients were classified into two groups: Group L was with the patients with a WBR of 100 to 129 per minute and Group H was with the patients with a WBR > or = 130 per minute. All patients followed up every 3-6 months after an AAI pacemaker implantation. A total of 102 patients, including 35 Group L and 67 Group H, were followed for 90 +/- 44 months. Six patients died from non-cardiac cause and five patients required a new atrial lead implantation due to lead failure during follow-up. Symptomatic bradycardia requiring a new ventricular lead implantation developed in four patients (annual incidence 0.5%). In Group L, two patients developed AV block (annual incidence 0.7%). In Group H, two patients developed bradycardic atrial fibrillation (annual incidence 0.4%). Kaplan-Meier analysis revealed no significant difference between the two groups (P = 0.2983).</AbstractText>These results suggest that a long-term risk of developing AV conduction disturbance is low even in patients with a WBR of 100 to 129 per minute.</AbstractText> |
8,026 | Esmolol facilitated extubation in a patient with severe systolic dysfunction following myocardial infarction. | We describe the case of a 59-year-old-man with acute myocardial infarction and severely impaired left ventricular systolic function who was intubated because of recurrent ventricular fibrillation in the setting of coronary angioplasty. Repeated ventilator weaning attempts and extubation initially failed, as severe tachycardia and hypertension occurred each time the patient began to awaken. Pre-treatment with esmolol infusion prevented the above haemodynamic changes, allowing successful extubation. Esmolol administration at ventilator weaning seems to be a safe and effective option, even in selected patients with impaired left ventricular contractility. |
8,027 | Fish-oil supplementation in patients with implantable cardioverter defibrillators: a meta-analysis. | A recent Cochrane meta-analysis did not confirm the benefits of fish and fish oil in the secondary prevention of cardiac death and myocardial infarction. We performed a meta-analysis of randomized controlled trials that examined the effect of fish-oil supplementation on ventricular fibrillation and ventricular tachycardia to determine the overall effect and to assess whether heterogeneity exists between trials.</AbstractText>We searched electronic databases (MEDLINE, EMBASE, The Cochrane Central Register of Controlled Trials, CINAHL) from inception to May 2007. We included randomized controlled trials of fish-oil supplementation on ventricular fibrillation or ventricular tachycardia in patients with implantable cardioverter defibrillators. The primary outcome was implantable cardioverter defibrillator discharge. We calculated relative risk [RR] for outcomes at 1-year follow-up for each study. We used the DerSimonian and Laird random-effects methods when there was significant heterogeneity between trials and the Mantel-Hanzel fixed-effects method when heterogeneity was negligible.</AbstractText>We identified 3 trials of 1-2 years' duration. These trials included a total of 573 patients who received fish oil and 575 patients who received a control. Meta-analysis of data collected at 1 year showed no overall effect of fish oil on the relative risk of implantable cardioverter defibrillator discharge. There was significant heterogeneity between trials. The second largest study showed a significant benefit of fish oil (relative risk [RR] 0.74, 95% confidence interval [CI] 0.56-0.98). The smallest showed an adverse tendency at 1 year (RR 1.23, 95% CI 0.92-1.65) and significantly worse outcome at 2 years among patients with ventricular tachycardia at study entry (log rank p = 0.007).</AbstractText>These data indicate that there is heterogeneity in the response of patients to fish-oil supplementation. Caution should be used when prescribing fish-oil supplementation for patients with ventricular tachycardia.</AbstractText> |
8,028 | Safety considerations in the pharmacological management of atrial fibrillation. | The pharmacological management of atrial fibrillation (AF) requires careful consideration from a safety perspective. This article focuses primarily on maintenance therapy using antiarrhythmic drugs (AADs). The foremost safety issue for AADs is the propensity of class IA and III agents to cause torsade de pointes arrhythmias. Class IA drugs, particularly quinidine, can induce torsade de pointes at low or subtherapeutic doses, but higher doses are not necessarily associated with an increased incidence. 'Pure' class III drugs such as dofetilide induce torsade de pointes in a dose-related manner, but some class III agents with more complex actions such as amiodarone have a markedly lower potential to cause this arrhythmia. The risk of torsade de pointes precludes the use of class IA and 'pure' class III agents in patients with left ventricular hypertrophy and bradycardia. Class IC agents may cause sustained monomorphic ventricular tachycardias and are generally precluded in ischaemic and structural heart disease. Advanced heart failure patients may be treated with amiodarone or dofetilide, but most other AADs are unsuitable. The most important extracardiac toxicities occurring with AADs are those of amiodarone. Drug interactions are a significant safety issue in the management of AF, including pharmacokinetic interactions in which plasma levels of the AAD are raised - increasing the risk of proarrhythmia - and concomitant use of drugs that prolong the QT interval. Notwithstanding these considerations, most patients with AF can be considered for rhythm control, provided there is adequate pre-treatment assessment and protocols for initiation, dosing and monitoring are followed with care. |
8,029 | Impact of ambulance crew configuration on simulated cardiac arrest resuscitation. | Despite the widespread use of both two paramedic and single paramedic ambulance crews, there is little evidence regarding differences between these two staffing configurations in the delivery of patient care.</AbstractText>To determine potential differences in care provided by each of these ambulance configurations in the resuscitation of a cardiac arrest victim in ventricular fibrillation.</AbstractText>Fifteen paramedic-paramedic and 15 paramedic-EMT crews were recruited to perform resuscitation on a high-fidelity human simulator (Laerdal SimMan). Errors and their nature, time to critical interventions, and compliance with continuous cardiopulmonary resuscitation (CPR) were captured by the simulator and videotape.</AbstractText>Two paramedic crews averaged 0.7 +/- 0.5 more errors of commission, 0.5 +/- 0.4 more errors of sequence, and 0.8 +/- 0.8 more total errors per resuscitation (+/- 95% CI; p = 0.008, 0.017, and 0.036, respectively). For all interventions analyzed, only time required to achieve intubation differed between the two configurations, with two paramedic crews intubating 63.9 +/- 45.8 seconds more quickly (p = 0.009). CPR compliance was highly variable, and a meaningful statistical difference could not be determined, although performance overall was poor, with both configurations averaging less than 50% compliance.</AbstractText>Two paramedic crews were more error-prone and did not perform most interventions more rapidly with the exception of intubation. These data do not support the proposition that two paramedic crews provide higher quality cardiac care than paramedic-EMT crews in a simulated ventricular fibrillation arrest.</AbstractText> |
8,030 | Effects of region of interest tracking on the diagnosis of left ventricular dyssynchrony from Doppler tissue images. | Left ventricular dyssynchrony is often diagnosed by comparing velocity curves from Doppler tissue images of two or more myocardial regions. Velocity curves are generated by placing sample volumes or regions of interest (ROIs) within the myocardium. ROIs need to be manually relocated to maintain a midmyocardial location as the heart moves, but are frequently left in a stationary position. The error caused by use of a stationary ROI may affect the diagnosis of dyssynchrony, but this has not been quantified.</AbstractText>We hypothesized that using a stationary ROI to quantify dyssynchrony from Doppler tissue images would affect the diagnosis of dyssynchrony in patients with heart failure.</AbstractText>We quantified dyssynchrony in 18 patients with heart failure using 4 published dyssynchrony parameters: septal-to-lateral delay, maximum difference in the basal 2- or 4-chamber times to peak, SD of the 12 basal and midwall times to peak, and cross-correlation delay (XCD). Each dyssynchrony parameter was measured using both tracked and stationary ROIs.</AbstractText>Use of a stationary ROI did not change the diagnosis of dyssynchrony when using XCD. However, ROI tracking changed the diagnosis of dyssynchrony in 17%, 11%, and 17% of patients when using septal-to-lateral delay, maximum difference in the basal 2- or 4-chamber times to peak, and SD of the 12 basal and midwall times to peak, respectively. XCD showed the lowest percent difference between tracked and stationary ROIs (4 +/- 9% vs 22 +/- 53%, 50 +/- 167%, and 12 +/- 30%, respectively, for septal-to-lateral delay, maximum difference in the basal 2- or 4-chamber times to peak, and SD of the 12 basal and midwall times to peak).</AbstractText>Manual ROI tracking is required when using conventional time-to-peak parameters to diagnose dyssynchrony. XCD diagnosis of dyssynchrony can be performed accurately with a stationary ROI.</AbstractText> |
8,031 | Left atrial volume is a predictor of atrial fibrillation recurrence after catheter ablation. | Recurrence of atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA) is not uncommon, and the predictors of AF recurrence are not completely understood. This study aimed to investigate the clinical and echocardiographic factors associated with AF recurrence after RFCA.</AbstractText>Sixty-eight patients with AF who had undergone RFCA were enrolled. Echocardiographic parameters, including the size of the left ventricle and both atria, left ventricular and left atrial function, and clinical parameters were assessed. Six months after RFCA, 53 (78%) of the 68 patients were free of AF and 15 patients showed AF recurrence. Patients without AF recurrence had a greater frequency of paroxysmal AF compared with patients with recurrence (P = .04). Left atrial volume (P = .00) and right atrial volume (P = .01) were associated with AF recurrence. Multivariate analysis revealed that left atrial volume was the only predictor of AF recurrence after RFCA (P = .01). Left atrial volume of 34 mL/m(2) showed a sensitivity of 70% and a specificity of 91% to predict AF recurrence.</AbstractText>Left atrial volume could be used as a predictor of AF recurrence after RFCA. Left atrial volume of 34 mL/m(2) had a sensitivity of 70% and a specificity of 91% for the prediction.</AbstractText> |
8,032 | Evaluation of the skin-to-heart distance in the standing adult by two-dimensional echocardiography. | An electromuscular incapacitating device (EMD) delivers pulses of high-voltage electricity, causing strong muscle contraction. Data from a pig model suggest that an EMD dart tip placed within 17 mm of the epicardial surface can cause ventricular fibrillation. The current study estimates minimum skin-to-heart distance in the adult, to determine whether individuals might be at risk for ventricular fibrillation from an EMD.</AbstractText>We performed 2-dimensional echocardiograms in 150 standing adults in the parasternal, apical, and subcostal views. From each view, the shortest linear skin-to-heart distance was measured.</AbstractText>Average skin-to-heart distances were: parasternal 32.1 +/- 7.9 mm; apical 31.3 +/- 11.3 mm; and subcostal 70.8 +/- 22.3 mm. There were 9 (6%) individuals with a skin-to-heart distance less than or equal to 17 mm. The skin-to-heart distance was significantly correlated with body mass index: parasternal r = 0.57, apical r = 0.55 (P < .0001).</AbstractText>An EMD dart penetrating the skin directly over the heart might put individuals at risk for ventricular fibrillation.</AbstractText> |
8,033 | Enlarged right ventricle without shock in acute pulmonary embolism: prognosis. | An unsettled issue is the use of thrombolytic agents in patients with acute pulmonary embolism (PE) who are hemodynamically stable but have right ventricular (RV) enlargement. We assessed the in-hospital mortality of hemodynamically stable patients with PE and RV enlargement.</AbstractText>Patients were enrolled in the Prospective Investigation of Pulmonary Embolism Diagnosis II. Exclusions included shock, critical illness, ventilatory support, or myocardial infarction within 1 month, and ventricular tachycardia or ventricular fibrillation within 24 hours. We evaluated the ratio of the RV minor axis to the left ventricular minor axis measured on transverse images during computed tomographic angiography.</AbstractText>Among 76 patients with RV enlargement treated with anticoagulants and/or inferior vena cava filters, in-hospital deaths from PE were 0 of 76 (0%) and all-cause mortality was 2 of 76 (2.6%). No septal motion abnormality was observed in 49 patients (64%), septal flattening was observed in 25 patients (33%), and septal deviation was observed in 2 patients (3%). No patients required ventilatory support, vasopressor therapy, rescue thrombolytic therapy, or catheter embolectomy. There were no in-hospital deaths caused by PE. There was no difference in all-cause mortality between patients with and without RV enlargement (relative risk=1.04).</AbstractText>In-hospital prognosis is good in patients with PE and RV enlargement if they are not in shock, acutely ill, or on ventilatory support, or had a recent myocardial infarction or life-threatening arrhythmia. RV enlargement alone in patients with PE, therefore, does not seem to indicate a poor prognosis or the need for thrombolytic therapy.</AbstractText> |
8,034 | The feasibility of tissue Doppler acceleration as a new predictor of thrombogenesis in the left atrial appendage associated with nonvalvular atrial fibrillation. | Tissue acceleration utilizing the tissue Doppler imaging (TDI) technique is a new marker of ventricular contraction. We evaluated whether the left atrial appendage (LAA) wall acceleration was associated with thrombosis in patients with nonvalvular atrial fibrillation (NVAF).</AbstractText>Seven NVAF patients with thromboembolism (TE), eight without TE, and eight with normal sinus rhythm (NSR) were studied using transesophageal echocardiography. TDI was used to evaluate the LAA wall acceleration.</AbstractText>There was a decrease in the peak flow velocity in the TE group compared with the other two groups. There was greater LAA expansion in NVAF with TE groups (with TE [8.9 +/- 2.1 cm(2)] compared with the group without TE [7.3 +/- 2.8 cm(2)]), but the difference was not statistically significant; the difference was statistically significant compared with the NSR group (5.3 +/- 1.2 cm(2); P = 0.0035). The average of the continuous 40-frames area where tissue Doppler acceleration (TDA) was >0.024 cm/sec(2) was significantly lower in the TE group (0.12 +/- 0.05 cm(2)) compared to the group without TE (0.33 +/- 0.17 cm(2); P = 0.0017) and NSR group (0.30 +/- 0.13 cm(2); P = 0.0042), although wall velocity was not significantly different comparing the two NVAF groups. Furthermore, peak flow velocity of LAA was well correlated with LAA wall acceleration (r = 0.864, P < 0.0001).</AbstractText>LAA wall acceleration obtained utilizing the TDI technique may be a new predictor of thrombogenesis in patients with NVAF.</AbstractText> |
8,035 | Combination therapy of renin angiotensin system inhibitors and bepridil is useful for maintaining sinus rhythm in patients with atrial fibrillation. | The present study evaluated the effect of treatment renin angiotensin system inhibitors (RAS-I) for maintaining sinus rhythm after conversion from persistent atrial fibrillation. As the efficacy of RAS-I in atrial fibrillation is unclear, our study evaluated conversion to and maintenance of sinus rhythm by combination therapy with RAS-I and bepridil in patients in atrial fibrillation.</AbstractText>Bepridil was administered to 125 consecutive patients with paroxysmal and persistent atrial fibrillations. Two groups of patients were compared: The bepridil group was treated with bepridil alone, the RAS-I group with bepridil plus angiotensin II receptor blockers or angiotensin converting enzyme inhibitors. The primary end point was length of time to first recurrence of atrial fibrillation.</AbstractText>Maintenance of sinus rhythm was achieved in 25 patients (45%) in the bepridil group and 44 patients (63%) in the RAS-I group (persistent and paroxysmal atrial fibrillations). The difference between the bepridil group and the RAS-I group was significant (p < 0.05). Maintenance of sinus rhythm was achieved in 9 of 25 patients (36%) in the bepridil group, and in 22 of 35 patients (62%) in the RAS-I group with persistent atrial fibrillation. The difference between the bepridil group and the RAS-I group was significant (p < 0.05). Bepridil plus RAS-I was particularly effective at preventing the recurrence of atrial fibrillation in patients with left ventricular dysfunction (left ventricular ejection fraction < 50%).</AbstractText>Combination therapy with RAS-I and bepridil may be useful for maintenance of sinus rhythm.</AbstractText> |
8,036 | Trends in mortality from acute myocardial infarction in the coronary care unit. | The treatment and outcome of acute myocardial infarction (AMI) has evolved greatly over the past few decades. We compared the mortality and complication rates of patients with AMI admitted to the Coronary Care Unit (CCU) in 2002 to previously reported data.</AbstractText>All data for AMI patients admitted to National Heart Centre CCU in 2002 were collected through the Singapore Cardiac Data Bank, including demographics, in hospital complications and mortality. These were compared to previous reports from the same institution in 1988, 1975 and 1967.</AbstractText>A total of 516 cases with AMI were identified. A higher proportion of patients were aged >or=70 years in 2002 (31.8%) compared to 1988 (25%), 1975 (11%) and 1967 (5.6%). Acute percutaneous transluminal coronary angioplasty (PTCA) was performed in 250 of 516 (48%) patients in 2002. The overall in-patient and age-standardised mortality was 14.7% and 10% respectively, compared to 20.6% and 17% respectively in 1988 (P = 0.06). For the 250 patients who underwent acute PTCA, overall mortality was 5.2% compared to 24% in those who did not (P <0.001). Common in-hospital complications included heart failure (38%), non-sustained ventricular tachycardia (8%), atrial fibrillation (8%) and complete heart block (6%). Age, heart failure, bundle branch block and sustained ventricular tachycardia were associated with higher mortality by univariate analysis. On multivariate analysis, older age, heart failure and the absence of percutaneous intervention were independently associated with higher mortality.</AbstractText>In-hospital mortality for AMI patients admitted to the CCU declined from 1988 to 2002 despite a higher proportion of elderly patients. The introduction of new therapies including drugs and percutaneous intervention may have contributed to this decline.</AbstractText> |
8,037 | Clinical effects of leukofiltration and surface modification on post-cardiopulmonary bypass atrial fibrillation in different risk cohorts. | A manifestation of inflammatory injury to the heart, atrial fibrillation (AF), ranks among the most frequent and potentially life-threatening post-operative complications.</AbstractText>In a prospective randomized study, 120 patients undergoing CABG were allocated into two groups (N = 60): Group 1: Polymethoxyethylacry late-coated circuits + Leukocyte filters (Terumo,USA); Group 2:</AbstractText>Uncoated circuits (Terumo,USA). Each group was further divided into three subgroups (N = 20) with respect to low (Euroscore 0-2), medium (3-5) and high (6+) risk patients.</AbstractText>Serum IL-2 levels were significantly lower in the study group at T4 and T5 (p < 0.01). C3a levels showed significant differences in the leukofiltrated group at T4 and T5 (p < 0.05). CPKMB levels demonstrated well-preserved myocardium in the leukofiltration group, post-operatively. AF incidence was 10% (2 patients) in the study and 35% (7 patients) in the control cohorts (p < 0.05). Phagocytic capacity on fibers in filtered patients was significantly lower.</AbstractText>Leukofiltration and coating significantly reduce the incidence, ventricular rate, and duration of AF after CABG via modulation of systemic inflammatory response and platelet preservation in high risk groups.</AbstractText> |
8,038 | Sudden cardiac death risk factors in patients with heart failure treated with carvedilol. | Chronic heart failure (CHF) is associated with a high risk of sudden cardiac death (SCD). Most frequently SCD occurs in patients with NYHA class II and III.</AbstractText>To evaluate the influence of prolonged carvedilol therapy on SCD risk in CHF patients.</AbstractText>The study included 86 patients (81 men and 5 women) aged 56.8+/-9.19 (35-70) years with CHF in NYHA class II and III receiving an ACE inhibitor and diuretics but not beta-blockers. At baseline and after 12 months of carvedilol therapy the following risk factors for SCD were analysed: in angiography - occluded infarct-related artery; in echocardiography - left ventricular ejection fraction (LVEF) <30%, volume of the left ventricle (LVEDV) >140 ml; in ECG at rest - sinus heart rate (HRs) >75/min, sustained atrial fibrillation, increased QTc; in 24-hour ECG recording - complex arrhythmia, blunted heart rate variability (SDNN <100 ms) and abnormal turbulence parameters (TO and TS or one of them); in signal-averaged ECG - late ventricular potentials and prolonged fQRS >114 ms. The analysis of SCD risk factors in basic examination in patients who suddenly died was also performed.</AbstractText>During one-year carvedilol therapy heart transplantation was performed in 2 patients; 5 patients died. At 12 months the following risk factors for SCD were significantly changed: HRs >75/min (50 vs. 16 patients, p=0.006), LVEF <30% (37 vs. 14 patients, p=0.01), SDNN <100 ms (19 vs. 9 patients, p=0.04). At 12 months the number of risk factors for SCD in each patient was significantly reduced (p=0.001). In patients who suddenly died we found a greater amount of SCD risk factors in basic examination (7 vs. 5) as compared to alive patients.</AbstractText>Prolonged beta-adrenergic blockade reduces risk of sudden cardiac death through significant LVEF increase, reduction of HR at rest and improvement of HRV.</AbstractText> |
8,039 | Calcium transient dynamics and the mechanisms of ventricular vulnerability to single premature electrical stimulation in Langendorff-perfused rabbit ventricles. | Single strong premature electrical stimulation (S(2)) may induce figure-eight reentry. We hypothesize that Ca current-mediated slow-response action potentials (APs) play a key role in the propagation in the central common pathway (CCP) of the reentry.</AbstractText>We simultaneously mapped optical membrane potential (V(m)) and intracellular Ca (Ca(i)) transients in isolated Langendorff-perfused rabbit ventricles. Baseline pacing (S(1)) and a cathodal S(2) (40-80 mA) were given at different epicardial sites with a coupling interval of 135 +/- 20 ms.</AbstractText>In all 6 hearts, S(2) induced graded responses around the S(2) site. These graded responses propagated locally toward the S(1) site and initiated fast APs from recovered tissues. The wavefront then circled around the refractory tissue near the site of S(2). At the side of S(2) opposite to the S(1), the graded responses prolonged AP duration while the Ca(i) continued to decline, resulting in a Ca(i) sinkhole (an area of low Ca(i)). The Ca(i) in the sinkhole then spontaneously increased, followed by a slow V(m) depolarization with a take-off potential of -40 +/- 3.9 mV, which was confirmed with microelectrode recordings in 3 hearts. These slow-response APs then propagated through CCP to complete a figure-eight reentry.</AbstractText>We conclude that a strong premature stimulus can induce a Ca(i) sinkhole at the entrance of the CCP. Spontaneous Ca(i) elevation in the Ca(i) sinkhole precedes the V(m) depolarization, leading to Ca current-mediated slow propagation in the CCP. The slow propagation allows more time for tissues at the other side of CCP to recover and be excited to complete figure-eight reentry.</AbstractText> |
8,040 | Electrocardiographic factors playing a role in ischemic ventricular fibrillation in ST elevation myocardial infarction are related to the culprit artery. | Sudden cardiac death caused by ischemic ventricular fibrillation (VF) associated with ST elevation myocardial infarction (STEMI) is one of the most frequent causes of death.</AbstractText>We hypothesized that electrocardiographic (ECG) characteristics differ between STEMI patients with and without ischemic VF.</AbstractText>Fifty-five first STEMI patients with at least one 12-lead ECG recorded before ischemic VF were compared with 110 first STEMI patients without ischemic VF. Patients with bundle branch blocks or high-degree atrioventricular blocks with escape rhythms were not included. ECG measurements were performed manually after scanning the ECG with the most prominent ST deviation into a software environment and magnifying it 4 times.</AbstractText>Mean age was 57 +/- 12 years, and 126 patients were male. No differences were present between the VF and control group regarding baseline, enzymatic, and angiographic data. In left circumflex artery and right coronary artery myocardial infarction, a longer QRS interval (109 +/- 23 ms vs. 91 +/- 16 ms, P = .02 and 107 +/- 24 ms vs. 93 +/- 19, P = .02) was present. In the latter the PR interval (211 +/- 64 ms vs. 160 +/- 36 ms, P <.001) and ST deviation score (3.6 +/- 1.0 mV vs. 1.7 +/- 1.5 mV, P <.001) were also increased. In the left anterior descending artery group no differences in conduction intervals and ST deviation score were present.</AbstractText>Longer PR and QRS intervals in right coronary artery and left circumflex artery MI fit with the perfusion and activation pattern of the atrioventricular node and the ventricular myocardium. Myocardium perfused by the left anterior descending artery is activated earliest, hiding any intraventricular conduction delay within the QRS complex. Intramural slowed conduction could be a substrate for ischemic VF.</AbstractText> |
8,041 | Clinical trials update from the American Heart Association 2007: CORONA, RethinQ, MASCOT, AF-CHF, HART, MASTER, POISE and stem cell therapy. | This article provides information and a commentary on trials relevant to the pathophysiology, prevention and treatment of heart failure, presented at the American Heart Association 2007. These should be considered as preliminary data, as analyses may change in the final publication. Rosuvastatin did not reduce mortality compared to placebo in patients with heart failure and left ventricular systolic dysfunction due to ischaemic heart disease in the CORONA study. Results of RethinQ provide equivocal evidence of benefit from CRT in patients with heart failure, echocardiographic dyssynchrony and QRS interval <130 ms. In the MASCOT study, the addition of atrial overdrive pacing did not reduce the incidence of permanent atrial fibrillation in patients receiving CRT. The AF-CHF study failed to show a benefit of rhythm control over rate control in patients with heart failure and atrial fibrillation. Self-management skills training and education had no benefit on the combined outcome of death or heart failure hospitalisation, compared with education alone in heart failure patients in the HART study. Microvolt T-wave alternans testing failed to identify patients at increased risk of life-threatening ventricular arrhythmias in the MASTER study. POISE suggests that initiating metoprolol therapy shortly prior to non-cardiac surgery increases the risk of hypotension, stroke and death, despite reducing the risk of myocardial infarction. Three trials of stem cell therapy in post-MI patients gave conflicting results. |
8,042 | Pulmonary edema after extensive radiofrequency ablation for atrial fibrillation. | More extensive ablation strategies for the treatment of atrial fibrillation (AF) have increased success rates but are associated with new and sometimes serious complications. We describe a new complication after extensive radiofrequency (RF) ablation in the left atrium (LA) for persistent AF.</AbstractText>Electroanatomic guided circumferential ablation around both ipsilateral pulmonary veins (PV) was performed with the endpoint of complete conduction block. When necessary, supplementary RF applications were added, including ablation of complex fractionated potentials and/or isolation of other thoracic veins and/or linear left atrial lesions. RF energy was delivered via an irrigated tip catheter with a maximum power of 30-35 W. Four out of 120 patients undergoing extensive RF ablation for persistent AF (including two patients with additional LA substrate modification) developed dyspnea, bilateral pulmonary edema, and signs of a systemic inflammatory response syndrome (SIRS) (rise in body temperature, leukocyte count, and C-reactive protein (CRP levels) 18-48 hours after the procedure. There were no signs of PV stenosis, focal lung injury, left ventricular dysfunction, circulatory failure, or infection. All patients had complete recovery with supportive therapy within 3-4 days after the onset of symptoms.</AbstractText>Extensive LA radiofrequency ablation bears the risk of a severe pulmonary edema. Although the precise mechanism is elusive, clinical features point toward a systemic inflammatory response.</AbstractText> |
8,043 | Experimental studies of atrial fibrillation: a comparison of two pacing models. | Rapid ventricular pacing (RVP) is a well-established animal model of atrial fibrillation (AF). However, this model is limited by a high mortality rate and severe heart failure. The purpose of our study was to assess a new canine model of inducible AF. We performed acute, short-term, simultaneous atrioventricular pacing (SAVP) and RVP (in random order) in 14 dogs for 30 s. SAVP produced more echocardiographic pulmonary venous flow reversal, a greater increase in mean pulmonary capillary wedge pressure, and a significantly greater decrease in left atrial emptying function (-84.4 +/- 38.6% vs. -23.7 +/- 27.1%, P < 0.05) than RVP. Thirty dogs were randomized to three, longer-term, study groups: eight dogs in the control group (no pacing), eight dogs in the RVP group (2 wk at 240 beats/min followed by 3 wk at 220 beats/min), and fourteen dogs in the SAVP group (2 wk at 220 beats/min). SAVP induced less left ventricular dysfunction but more left atrial dysfunction than RVP. SAVP dogs had similar atrial effective refractory periods as RVP dogs but more heterogeneity in conduction and more AF inducibility (83% vs. 40%, P < 0.05) and maintenance (median 1,660 vs. 710 s, P < 0.05) than RVP dogs. SAVP induced more collagen turnover and was associated with a significantly greater increase in type III collagen in the atria compared with RVP dogs (6.9 +/- 1.5 vs. 4.8 +/- 1.6, respectively, P < 0.05 vs. 1.1 +/- 0.7 in unpaced control dogs). In conclusion, the SAVP model induced profound mechanical and substrate atrial remodeling and reproducible sustained AF. This new model is clinically relevant and may be useful for testing AF interventions. |
8,044 | P wave detector with PP rhythm tracking: evaluation in different arrhythmia contexts. | Automatic detection of atrial activity (P waves) in an electrocardiogram (ECG) is a crucial task to diagnose the presence of arrhythmias. The P wave is difficult to detect and most of the approaches in the literature have been evaluated on normal sinus rhythms and rarely considered arrhythmia contexts other than atrial flutter and fibrillation. A novel knowledge-based P wave detector algorithm is presented. It is self-adaptive to the patient and able to deal with certain arrhythmias by tracking the PP rhythm. The detector has been tested on 12 records of the MIT-BIH arrhythmia database containing several ventricular and supra-ventricular arrhythmias. On the overall records, the detector demonstrates Se = 96.60% and Pr = 95.46%; for the normal sinus rhythm, it reaches Se = 97.76% and Pr = 96.80% and, in the case of Mobitz type II, it demonstrates Se = 72.79% and Pr = 99.51%. It also shows good performance for trigeminy and bigeminy, and outperforms some more sophisticated techniques. Although the results emphasize the difficulty of P wave detection in difficult arrhythmias (supra and ventricular tachycardias), it shows that domain knowledge can efficiently support signal processing techniques. |
8,045 | [Sudden cardiac death--an assessment of pre-hospital proceedings]. | Sudden cardiac death (SCD) constitutes 13-18.5% of all natural deaths. This problem is socially and economically important because it affects often young people who are still professionally active. Many factors connected with the survival of the patients are beyond the emergency services' scope of operation. Patients do not often take seriously symptoms which occur before SCD. It has been estimated that about 40% of SCD took place without any witnesses. The witnesses, if present, cannot identify SCD and they do not supply any resuscitation. Additionally, ventricular fibrillation is getting the rare cause of cardiac arrest. The aforesaid situations, at the very beginning are responsible for the ineffectiveness of the resuscitation supplied by the emergency services. |
8,046 | Lethal presentations of coronary artery spasm after an event-free period of six years following initial diagnosis. | Isolated coronary artery spasm without atherosclerotic obstruction is an unusual cause of myocardial infarction (MI). A middle-aged woman presented to our institution in 2001 with acute inferior MI due to coronary artery spasm at the mid segment of the dominant left circumflex coronary artery. After being well for 6 years, she was readmitted again in 2007 with the same type of severe retrosternal chest pain. Electrocardiography (ECG) showed ST-segment elevation over the inferior leads. The chest pain resolved with sublingual nitroglycerin and emergency diagnostic coronary angiography showed normal coronary arteries. Two months later, the patient developed another episode of severe retrosternal chest pain at home, followed by cardiac arrest. An onsite ECG showed ventricular fibrillation and immediate defibrillation was carried out. She was readmitted to the hospital and recovered over the next few days. In view of the recurrent coronary artery spasm causing myocardial infarction and ventricular fibrillation, an implantable cardioverter defibrillator was implanted. The patient was well at 2-month follow up. |
8,047 | Mid-ventricular hypertrophic obstructive cardiomyopathy presenting with acute myocardial infarction. | Mid-ventricular hypertrophic obstructive cardiomyopathy is a rare type of cardiomyopathy that can be accompanied by apical aneurysm. We report the case of a patient who presented with ventricular fibrillation, ST-segment elevation on electrocardiography, and cardiac-enzyme elevation, in the presence of normal coronary arteries. Echocardiography and magnetic resonance imaging showed an hourglass appearance of the left ventricle with an aneurysm in the apex. Left-heart catheterization and continuous-wave Doppler echocardiography revealed a pressure gradient between the apical and basal chambers of the left ventricle. Impaired coronary artery circulation might play a role in the development of mid-ventricular obstruction in patients with mid-ventricular hypertrophic obstructive cardiomyopathy. |
8,048 | Outcome of cardiac arrests attended by emergency medical services staff at community outpatient dialysis centers. | Cardiac arrest is the leading cause of death among dialysis patients in the United States. We measured the outcome of cardiac arrests attended by Emergency Medical Services (EMS) staff at hemodialysis facilities in a 14-year population-based retrospective study to identify cardiac arrest cases at a dialysis unit. Associated factors were determined using unconditional logistic regression. Of the 102 cardiac arrests identified around the time of dialysis, 10 occurred before, 72 during, and 20 after hemodialysis. The initial measured abnormality was ventricular fibrillation or tachycardia in 72 cases. Of those who survived transportation to a hospital, survival to discharge was 24 with 15% survival at 1 year. Compared to arrests that occurred prior to dialysis, the odds of ventricular fibrillation were 5-fold greater in patients on dialysis but 14-fold greater in those arresting after dialysis. One-third of cases occurred after the introduction of automated external defibrillators, and in half of the cases these devices were attached prior to EMS arrival. Once these devices were attached, most were used for defibrillation. We conclude that ventricular arrhythmias are the predominant features among arrested in-center dialysis patients with most occurrences during dialysis. The role of these devices in dialysis units will need a larger study to evaluate their efficacy. |
8,049 | Delayed time to defibrillation after in-hospital cardiac arrest. | Expert guidelines advocate defibrillation within 2 minutes after an in-hospital cardiac arrest caused by ventricular arrhythmia. However, empirical data on the prevalence of delayed defibrillation in the United States and its effect on survival are limited.</AbstractText>We identified 6789 patients who had cardiac arrest due to ventricular fibrillation or pulseless ventricular tachycardia at 369 hospitals participating in the National Registry of Cardiopulmonary Resuscitation. Using multivariable logistic regression, we identified characteristics associated with delayed defibrillation. We then examined the association between delayed defibrillation (more than 2 minutes) and survival to discharge after adjusting for differences in patient and hospital characteristics.</AbstractText>The overall median time to defibrillation was 1 minute (interquartile range, <1 to 3 minutes); delayed defibrillation occurred in 2045 patients (30.1%). Characteristics associated with delayed defibrillation included black race, noncardiac admitting diagnosis, and occurrence of cardiac arrest at a hospital with fewer than 250 beds, in an unmonitored hospital unit, and during after-hours periods (5 p.m. to 8 a.m. or weekends). Delayed defibrillation was associated with a significantly lower probability of surviving to hospital discharge (22.2%, vs. 39.3% when defibrillation was not delayed; adjusted odds ratio, 0.48; 95% confidence interval, 0.42 to 0.54; P<0.001). In addition, a graded association was seen between increasing time to defibrillation and lower rates of survival to hospital discharge for each minute of delay (P for trend <0.001).</AbstractText>Delayed defibrillation is common and is associated with lower rates of survival after in-hospital cardiac arrest.</AbstractText>Copyright 2008 Massachusetts Medical Society.</CopyrightInformation> |
8,050 | Angiotensin II activates signal transducer and activators of transcription 3 via Rac1 in atrial myocytes and fibroblasts: implication for the therapeutic effect of statin in atrial structural remodeling. | Recently, activation of the local renin-angiotensin system and mitogen-activated protein kinase pathways in atrial myocardium has been found to play an important role in atrial structural remodeling related to atrial fibrillation. Another important mediator of the angiotensin II (Ang II) effect is the Janus kinase/signal transducers and activators of transcription (STAT) pathway, which has never been characterized in the atrium.</AbstractText>In cultured atrial myocytes and fibroblasts, Ang II induced tyrosine phosphorylation of STAT3 through a Rac1-dependent mechanism, which was inhibited by dominant-negative Rac1, losartan, and simvastatin. In atrial myocytes, activation of STAT3 by Rac1 was mediated by direct association of Rac1 with STAT3; however, in atrial fibroblasts, it was mediated by an indirect paracrine effect. Constitutively active STAT3 increased protein synthesis, and dominant-negative STAT3 abrogated Ang II-induced protein synthesis in atrial myocytes and fibroblasts. Rats infused long term with Ang II exhibited higher levels of activated Rac1, phospho-STAT3, collagen synthesis, and atrial fibrosis in the atria, all of which were attenuated by oral losartan and simvastatin. In human atrial tissues from patients with atrial fibrillation, Ang II and phospho-STAT3 levels were also elevated.</AbstractText>The Ang II/Rac1/STAT3 pathway is an important signaling pathway in the atrial myocardium to mediate atrial structural remodeling, and losartan and statin may be able to reverse Ang II-induced atrial structural remodeling in atrial fibrillation.</AbstractText> |
8,051 | How Do Atrial-Selective Drugs Differ From Antiarrhythmic Drugs Currently Used in the Treatment of Atrial Fibrillation? | Current pharmacologic strategies for the management of Atrial fibrillation (AF) include use of 1) sodium channel blockers, which are contraindicated in patients with coronary artery or structural heart disease because of their potent effect to slow conduction in the ventricles, 2) potassium channel blockers, which predispose to acquired long QT and Torsade de Pointes arrhythmias because of their potent effect to prolong ventricular repolarization, and 3) mixed ion channel blockers such as amiodarone, which are associated with multi-organ toxicity. Accordingly, recent studies have focused on agents that selectively affect the atria but not the ventricles. Several Atrial-selective approaches have been proposed for the management of AF, including inhibition of the Atrial-specific ultra rapid delayed rectified potassium current (IKur), acetylcholine-regulated inward rectifying potassium current (IK-ACh), or connexin-40 (Cx40). All three are largely exclusive to atria. Recent studies have proposed that an Atrial-selective depression of sodium channel-dependent parameters with agents such as ranolazine may be an alternative approach capable of effectively suppressing AF without increasing susceptibility to ventricular arrhythmias. Clinical evidence for Cx40 modulation or IK-ACh inhibition are lacking at this time. The available data suggest that Atrial-selective approaches involving a combination of INa, IKur, IKr, and, perhaps, Ito block may be more effective in the management of AF than pure IKur or INa block. The anti-AF efficacy of the Atrial-selective/predominant agents appears to be similar to that of conventionally used anti-AF agents, with the major apparent difference being that the latter are associated with ventricular arrhythmogenesis and extra cardiac toxicity. |
8,052 | Prediction of early mortality in primary intracerebral hemorrhage in an Asian population. | Primary intracerebral hemorrhage accounts for the relative minority of all strokes and yet is more fatal and disabling. Various prognostic models for mortality and functional outcome following primary intracerebral hemorrhage have been proposed, however there is little data which focuses on a multi-racial population profile characteristic of communities in South-East Asia. A reliable grading scale for this condition will allow for accurate risk stratification, treatment selection, resource allocation and possibly also aid in the definition of common enrollment criteria for clinical trials.</AbstractText>This study investigates an Asian population of primary intracerebral hemorrhage patients and defines using a variety of data mining techniques the clinical variables that significantly impact on early mortality. The models produced are then compared to ascertain which one optimally predicts this outcome.</AbstractText>Past history of stroke, known atrial fibrillation, use of warfarin, glucose level, presenting Glasgow Coma Scale (GCS) and pupil abnormality, post-resuscitation GCS and pupil abnormality, initial international normalized ratio (INR) and prothrombin time (PT) results, vomiting, seizure, total volume of clot, ventricular extension and hydrocephalus were significantly associated with early mortality. Logit with backward elimination showed that only age, presenting GCS, 1st INR result and total volume of clot were significantly associated with mortality in the final multivariate model. The use of the other data mining techniques yielded comparable results.</AbstractText>The predictors for early mortality and poor outcome in primary intracerebral hemorrhage are similar in Asian and Western populations.</AbstractText> |
8,053 | Characteristic of the prevalence of J wave in apparently healthy Chinese adults. | The J wave has been seen in idiopathic ventricular fibrillation, Brugada syndrome, and early repolarization syndrome. Although these conditions share some ECG features, the clinical consequences are markedly different. J wave presentation in healthy subjects is not a rare phenomenon, although its characteristics are poorly understood. The aim of this study was to investigate the prevalence and the characteristics of the J wave in apparently healthy Chinese adults.</AbstractText>The study was comprised of 1817 consecutive healthy Chinese subjects undergoing annual routine medical examination from April 2006 to July 2006, including 1131 men and 686 women. Routine medical examination including ECG was performed. J wave was defined as a wave on the ECG that followed the QRS complex with amplitude of at least 0.05 mV for 0.03 sec.</AbstractText>The prevalence of the J wave in all subjects was 7.26%. The prevalence of the J wave in males was significantly higher than in females (10.52 vs. 1.89%, p<0.01). The incidence of the J wave in the inferior leads (II, III, avF), right precordial leads (V1-V3), and left precordial leads (V4-V6) was 4.57, 0.50, and 2.20%, respectively. The J wave prevalence in the inferior leads was significantly higher than in the left and right precordial leads (both p<0.05). Moreover, the prevalence of the J wave had a positive correlation with age in all subjects (r=0.78, p<0.01).</AbstractText>J wave presentation on the ECG of apparently healthy people is not a rare phenomenon and is more likely to be found in the elderly, in males, and more frequently occurs in the inferior leads than in left and right precordial leads.</AbstractText> |
8,054 | Periodic acceleration (pGz) CPR in a swine model of asphyxia induced cardiac arrest. Short-term hemodynamic comparisons. | Asphyxia is one of the most common causes of pediatric cardiac arrest, and becoming a more frequently recognized cause in adults. Periodic acceleration (pGz) is a novel method of cardiopulmonary resuscitation (CPR). pGz is achieved by rapid motion of the supine body headward-footward that generates adequate perfusion and ventilation during cardiac arrest. In a swine ventricular fibrillation cardiac arrest model, pGz produced a higher return of spontaneous circulation (ROSC), superior neurological outcome, less echocardiography evidence of post resuscitation myocardial stunning, and decreased indices of tissue injury. In contrast to standard chest compression CPR, pGz does not produce rib fractures. We investigated the feasibility of pGz in severe asphyxia cardiac arrest and assessed whether beneficial effects seen in the VF model of cardiac arrest could be realized.</AbstractText>Sixteen swine weight 4+/-1 kg were anesthetized, tracheally intubated, and instrumented to measure, hemodynamics and echocardiography. Asphyxia was induced by occlusion of the tracheal tube. After loss of aortic pulsations (median time 10 min) animals were observed for three additional minutes following which all were in cardiac arrest. The animals were then randomized to receive 10 min of pGz or standard chest compression ventilation performed with a commercial device (Thumper). A single dose of epinephrine (adrenaline) and sodium bicarbonate were given and defibrillation attempted if appropriate for a maximum of 10 min. Both groups received fractional inspired O2 concentration of 100% during CPR and after resuscitation. Four animals in each group (50%) had an initial ROSC, however only two of the four initial survivors remained alive 3h after ROSC. There were no significant differences in blood pressure, coronary perfusion pressure during CPR and after early ROSC between groups. pGz treated animals had significantly lower pulmonary artery pressure; 20+/-4 mmHg compared to Thumper 46+/-5 mmHg, 30 min after ROSC (p<0.01). Surviving animals in both groups had severe myocardial dysfunction at 30 min after ROSC. At necropsy, 25% of the Thumper treated animals had rib fractures, while none occurred in the pGz group.</AbstractText>In a lethal model of asphyxia cardiac arrest, pGz is equivalent to standard CPR, with respect to acute outcomes and resuscitation survival rates but is associated with significantly lower pulmonary artery pressures and does not produce traumatic rib fractures.</AbstractText> |
8,055 | A case of Commotio cordis in a young child caused by a fall. | Commotio cordis or ventricular fibrillation caused by a blow to the chest is a rare cause of cardiac arrest in a well child. We report a case of a young child falling from a low height landing chest first with rapid onset of unconsciousness, apnoea and cyanosis. Cardiopulmonary resuscitation was given by parents under telephone instruction from an ambulance dispatch centre. On arrival of officers, 7 min after the fall, ventricular fibrillation was present but responded to defibrillation (biphasic 3 J/kg). No clinical or CT evidence of chest or brain trauma was present and investigations (ECGs, cardiac MRI, echocardiography, viral tests, metabolic tests, drug tests, serum electrolytes) did not reveal any cardiac illness or abnormal cardiac anatomy. Specifically, a long QT was absent and a Flecainide challenge for Brugada syndrome was negative. There was no family history of sudden death. No further dysrrhythmia occurred and the child recovered neurologically well after 3 days of therapeutic hypothermia (for cerebral ischaemia) and 7 days of mechanical ventilation. |
8,056 | Light chain deposition disease presenting as paroxysmal atrial fibrillation: a case report. | Light chain deposition disease (LCDD) can involve the heart and cause severe heart failure. Cardiac involvement is usually described in the advanced stages of the disease. We report the case of a woman in whom restrictive cardiomyopathy due to LCDD presented with paroxysmal atrial fibrillation.</AbstractText>A 55-year-old woman was admitted to our emergency department because of palpitations. In a recent blood test, serum creatinine was 1.4 mg/dl. She was found to have high blood pressure, left ventricular hypertrophy and paroxysmal atrial fibrillation. An ACE-inhibitor was prescribed but her renal function rapidly worsened and she was admitted to our nephrology unit. On admission serum creatinine was 9.4 mg/dl, potassium 6.8 mmol/l, haemoglobin 7.7 g/dl, N-terminal pro-brain natriuretic peptide 29894 pg/ml. A central venous catheter was inserted and haemodialysis was started. She underwent a renal biopsy which showed kappa LCDD. Bone marrow aspiration and bone biopsy demonstrated kappa light chain multiple myeloma. Echocardiographic findings were consistent with restrictive cardiomyopathy. Thalidomide and dexamethasone were prescribed, and a peritoneal catheter was inserted. Peritoneal dialysis has now been performed for 15 months without complications.</AbstractText>Despite the predominant tubular deposition of kappa light chain, in our patient the first clinical manifestation of LCDD was cardiac disease manifesting as atrial fibrillation and the correct diagnosis was delayed. The clinical management initially addressed the cardiovascular symptoms without paying sufficient attention to the pre-existing slight increase in our patient's serum creatinine. However cardiac involvement is a quite uncommon presentation of LCDD, and this unusual case suggests that the onset of acute arrhythmias associated with restrictive cardiomyopathy and impaired renal function might be related to LCDD.</AbstractText> |
8,057 | Vulnerability to re-entry in simulated two-dimensional cardiac tissue: effects of electrical restitution and stimulation sequence. | Ventricular fibrillation is a lethal arrhythmia characterized by multiple wavelets usually starting from a single or figure-of-eight re-entrant circuit. Understanding the factors regulating vulnerability to the re-entry is essential for developing effective therapeutic strategies to prevent ventricular fibrillation. In this study, we investigated how pre-existing tissue heterogeneities and electrical restitution properties affect the initiation of re-entry by premature extrastimuli in two-dimensional cardiac tissue models. We studied two pacing protocols for inducing re-entry following the "sinus" rhythm (S1) beat: (1) a single premature (S2) extrastimulus in heterogeneous tissue; (2) two premature extrastimuli (S2 and S3) in homogeneous tissue. In the first case, the vulnerable window of re-entry is determined by the spatial dimension and extent of the heterogeneity, and is also affected by electrical restitution properties and the location of the premature stimulus. The vulnerable window first increases as the action potential duration (APD) difference between the inside and outside of the heterogeneous region increases, but then decreases as this difference increases further. Steeper APD restitution reduces the vulnerable window of re-entry. In the second case, electrical restitution plays an essential role. When APD restitution is flat, no re-entry can be induced. When APD restitution is steep, re-entry can be induced by an S3 over a range of S1S2 intervals, which is also affected by conduction velocity restitution. When APD restitution is even steeper, the vulnerable window is reduced due to collision of the spiral tips. |
8,058 | Coronary artery spasm as a cause of ST elevation and inappropriate implantable cardioverter defibrillator intervention. | Coronary artery spasm can cause both brady- and tachyarrhythmia, through induction of AV block (usually linked to coronary spasm of the right coronary artery) or ventricular tachycardia/fibrillation linked to extensive myocardial ischemia. The electrocardiographic aspect of coronary artery spasm is an ST segment elevation. We describe the case of patient implanted with an implantable cardioverter defibrillator (ICD) for unexplained syncope which, during coronary artery spasm, received an inappropriate device firing due to ST segment elevation, leading to a double count of the QRS by the ICD. |
8,059 | Prophylactic catheter ablation for the prevention of defibrillator therapy. | For patients who have a ventricular tachyarrhythmic event, implantable cardioverter-defibrillators (ICDs) are a mainstay of therapy to prevent sudden death. However, ICD shocks are painful, can result in clinical depression, and do not offer complete protection against death from arrhythmia. We designed this randomized trial to examine whether prophylactic radiofrequency catheter ablation of arrhythmogenic ventricular tissue would reduce the incidence of ICD therapy.</AbstractText>Eligible patients with a history of a myocardial infarction underwent defibrillator implantation for spontaneous ventricular tachycardia or fibrillation. The patients did not receive antiarrhythmic drugs. Patients were randomly assigned to defibrillator implantation alone or defibrillator implantation with adjunctive catheter ablation (64 patients in each group). Ablation was performed with the use of a substrate-based approach in which the myocardial scar is mapped and ablated while the heart remains predominantly in sinus rhythm. The primary end point was survival free from any appropriate ICD therapy.</AbstractText>The mortality rate 30 days after ablation was zero, and there were no significant changes in ventricular function or functional class during the mean (+/-SD) follow-up period of 22.5+/-5.5 months. Twenty-one patients assigned to defibrillator implantation alone (33%) and eight patients assigned to defibrillator implantation plus ablation (12%) received appropriate ICD therapy (antitachycardia pacing or shocks) (hazard ratio in the ablation group, 0.35; 95% confidence interval, 0.15 to 0.78, P=0.007). Among these patients, 20 in the control group (31%) and 6 in the ablation group (9%) received shocks (P=0.003). Mortality was not increased in the group assigned to ablation as compared with the control group (9% vs. 17%, P=0.29).</AbstractText>In this randomized trial, prophylactic substrate-based catheter ablation reduced the incidence of ICD therapy in patients with a history of myocardial infarction who received ICDs for the secondary prevention of sudden death. (Current Controlled Trials number, ISRCTN62488166 [controlled-trials.com].).</AbstractText>Copyright 2007 Massachusetts Medical Society.</CopyrightInformation> |
8,060 | Modifying L-type calcium current kinetics: consequences for cardiac excitation and arrhythmia dynamics. | The L-type Ca current (I(Ca,L)), essential for normal cardiac function, also regulates dynamic action potential (AP) properties that promote ventricular fibrillation. Blocking I(Ca,L) can prevent ventricular fibrillation, but only at levels suppressing contractility. We speculated that, instead of blocking I(Ca,L), modifying its shape by altering kinetic features could produce equivalent anti-fibrillatory effects without depressing contractility. To test this concept experimentally, we overexpressed a mutant Ca-insensitive calmodulin (CaM(1234)) in rabbit ventricular myocytes to inhibit Ca-dependent I(Ca,L) inactivation, combined with the ATP-sensitive K current agonist pinacidil or I(Ca,L) blocker verapamil to maintain AP duration (APD) near control levels. Cell shortening was enhanced in pinacidil-treated myocytes, but depressed in verapamil-treated myocytes. Both combinations flattened APD restitution slope and prevented APD alternans, similar to I(Ca,L) blockade. To predict the arrhythmogenic consequences, we simulated the cellular effects using a new AP model, which reproduced flattening of APD restitution slope and prevention of APD/Ca(i) transient alternans but maintained a normal Ca(i) transient. In simulated two-dimensional cardiac tissue, these changes prevented the arrhythmogenic spatially discordant APD/Ca(i) transient alternans and spiral wave breakup. These findings provide a proof-of-concept test that I(Ca,L) can be targeted to increase dynamic wave stability without depressing contractility, which may have promise as an antifibrillatory strategy. |
8,061 | A rabbit ventricular action potential model replicating cardiac dynamics at rapid heart rates. | Mathematical modeling of the cardiac action potential has proven to be a powerful tool for illuminating various aspects of cardiac function, including cardiac arrhythmias. However, no currently available detailed action potential model accurately reproduces the dynamics of the cardiac action potential and intracellular calcium (Ca(i)) cycling at rapid heart rates relevant to ventricular tachycardia and fibrillation. The aim of this study was to develop such a model. Using an existing rabbit ventricular action potential model, we modified the L-type calcium (Ca) current (I(Ca,L)) and Ca(i) cycling formulations based on new experimental patch-clamp data obtained in isolated rabbit ventricular myocytes, using the perforated patch configuration at 35-37 degrees C. Incorporating a minimal seven-state Markovian model of I(Ca,L) that reproduced Ca- and voltage-dependent kinetics in combination with our previously published dynamic Ca(i) cycling model, the new model replicates experimentally observed action potential duration and Ca(i) transient alternans at rapid heart rates, and accurately reproduces experimental action potential duration restitution curves obtained by either dynamic or S1S2 pacing. |
8,062 | Electrophysiologic study-guided amiodarone for sustained ventricular tachyarrhythmias associated with structural heart diseases. | Although an electrophysiologic study (EPS) and Holter-monitoring are often helpful in evaluating the efficacy of antiarrhythmic drugs in patients with ventricular tachyarrhythmias (ventricular tachycardia/fibrillation (VT/VF)), the efficacy of EPS- or Holter-guided oral amiodarone therapy in Japanese patients is still unclear.</AbstractText>EPS was performed 1 month after starting amiodarone, and Holter-monitoring was recorded before and 1 month after amiodarone in 188 patients with sustained VT/VF because of structural heart diseases. In spite of the judgment of EPS (n=89) or Holter (n=75), all patients continued amiodarone. Patients were followed up to 3 years and the primary endpoint was VT/VF recurrence and secondary endpoint was death by all cause. Kaplan-Meier estimated the risk of VT/VF recurrence was significantly smaller with EPS-guided amiodarone (p<0.01) but not with Holter-guided amiodarone. Multivariate Cox hazard analysis revealed that EPS-guided amiodarone was an independent factor suppressing the recurrence of VT/VF (p<0.05, 95% confidence interval =0.15 to 0.96). In the subgroup analysis, EPS-guided amiodarone was effective in patients with relatively well-preserved left ventricular ejection fraction (LVEF > or =0.30) but not in patients with lower LVEF (LVEF <0.30).</AbstractText>EPS-guided amiodarone was useful for preventing recurrence of VT/VF in patients with a relatively well-preserved LVEF, but not always beneficial in patients with a lower LVEF.</AbstractText> |
8,063 | Influence of valvular insufficiency and recurrent airway obstruction on haemodynamics and therapy in warmblood horses with atrial fibrillation. | The aim of this study was to investigate the potential haemodynamic effects of valvular insufficiency and recurrent airway obstruction (RAO) in horses with atrial fibrillation (AF). Therefore in ten healthy horses (group 1) and 40 horses with AF a clinical examination, a lung examination, echocardiography and right heart catheterization for measurement of intracardic and pulmonary pressures were performed. According to the clinical findings the horses with AF were subdivided into 4 groups (group 2: AF; group 3: AF/valvular insufficiency; group 4: AF/RAO; group 5: AF/valvular insufficiency/RAO). Most of the horses of group 3 and 5 suffered from two valvular insufficiencies (mitral and tricuspid valve insufficiency: n=11, mitral and aortic valve insufficiency: n=2). The remaining horses showed a single mitral (n=6), tricuspid (n=2) or aortic valve insufficiency (n=1) or more than two valvular insufficiencies (n=4). In group 2 right ventricular mean pressure (RVPm) was higher than in group 1 and 4 (P<0.025); diastolic right ventricular pressure was higher than in group 1; PWP was higher than in group 1 and group 4; PDP was lower compared to group1. Compared to group1 in group 3 left atrial diameter (LA) was greater; the PAPs was higher and the PDP lower (P<0.05). In group 4 RVPm and PWP was lower compared to group 2. In group 5 LA, fractional shortening and diastolic left ventricular diameter were greater, PWP and PAPs were higher and PDP lower compared to group1. Twenty six of the 40 horses with AF (65%) were treated. Successful cardioversion to sinus rhythm occurred in 15 horses (58%). Therapy was successful in 50% of the treated horses of group 2 and 3, in 67% of the treated horses of group 4 and in 63% of the treated horses in group 5. In conclusion the presence of valvular insufficiency or RAO influences the haemodynamics of horses with AF. |
8,064 | Relation of recurrence of atrial fibrillation after non-ST-elevation acute myocardial infarction to left atrial abnormality. | Atrial fibrillation (AF) is common during the course of acute myocardial infarction and is associated with left atrial (LA) dilatation. However, the role of LA depolarization abnormality on the electrocardiogram (ECG) in the setting of LA dilatation was not studied in this context. Patients admitted with non-ST-segment elevation myocardial infarction (NSTEMI) who developed new-onset AF (International Classification of Diseases, Ninth Revision code 427.31) were prospectively identified. Baseline ECGs and echocardiograms before the admission event were reviewed. Follow-up was directed toward pertinent cardiovascular events, atrial tachyarrhythmias, and death as end points. Of 101 patients with NSTEMI who had new-onset AF, 88 had current echocardiograms and 69 had LA dilatation (78%). Total follow-up was 24 months (mean 21.4). Prolonged P-wave duration (> or =110 ms) and decreased left ventricular fractional shortening were most significant in those with LA dilatation and were independently associated with AF. In those with LA dilatation, the prevalence of such abnormal atrial depolarization on ECGs was 56%. AF (43% vs 15%; p = 0.03) and heart failure (63% vs 35%; p = 0.03) occurred more often in this subset, but there was no difference in mortality. However, the overall prevalence of late cardiovascular complications in this subset was higher (71% vs 45%; p = 0.02) compared with that of immediate complications (20% vs 26%; p = 0.60). In conclusion, there is higher recurrence of AF in patients with NSTEMI who have a combination of electrocardiographic and echocardiographic LA abnormalities compared with those without. |
8,065 | Trimetazidine protective effect against ischemia-induced susceptibility to ventricular fibrillation in pigs. | Ventricular fibrillation (VF) is a possible consequence of brief myocardial ischemia. Such a short ischemia does not provoke cell damage, but induces changes in intracellular cardiac metabolism due to diminished oxygen supply to the heart. Trimetazidine (TMZ) is a drug able to restore the metabolic balance between fatty acid and glucose oxidation in ischemic myocardial cells. The aim of this double-blind study was to investigate TMZ effect on VF in pigs during short-term ischemia.</AbstractText>Ischemia was induced after thoracotomy by complete, but brief (1 min) occlusion of the left anterior descending coronary artery under electrical stimulation. The ventricular fibrillation threshold (VFT), heart rate (HR), various hemodynamic parameters and malondialdehyde (MDA) blood levels were measured before and during ischemia in two groups of eight anesthetized pigs. The mass of ischemic myocardial tissue was also evaluated.</AbstractText>No effects on either the HR or the hemodynamic parameters were observed during myocardial ischemia, whereas TMZ increased the VFT and decreased both MDA blood levels (an index of lipid peroxidation) and the ischemic area.</AbstractText>TMZ limited ischemia-induced electrical dysfunction leading to cardiac susceptibility to VF by decreasing lipid peroxidation and maintaining ionic homeostasis. TMZ could therefore provide protection against ischemia-induced VF.</AbstractText> |
8,066 | Pre-excited atrial fibrillation triggered by intravenous adenosine: a commonly used drug with potentially life-threatening adverse effects. | Although serious adverse events following adenosine administration are rare, it should only be administered in an environment where continuous ECG monitoring and emergency resuscitation equipment are available. The case report describes the development of pre-excited atrial fibrillation in a 31-year-old woman with Wolff-Parkinson-White syndrome following the administration of adenosine. She had previously been fit and well and was admitted to the coronary care unit with a 2 h history of regular palpitations. A 12-lead ECG showed a narrow QRS complex tachycardia. Carotid sinus massage was unsuccessful in terminating the tachycardia and the patient subsequently received rapid boluses of intravenous adenosine. The cardiac rhythm degenerated into atrial fibrillation with ventricular pre-excitation following 12 mg adenosine. |
8,067 | Erythropoietin pretreatment protects against acute chemotherapy toxicity in isolated rat hearts. | The use of chemotherapeutic agents, such as anthracycline or trastuzumab, in oncology is limited by their cardiac toxicity. Recent experimental studies suggest that recombinant human erythropoietin (rhEPO) can be considered as a protective agent because its administration protects against cardiac ischemic injury, improving functional recovery, and reducing cell death. The aim of this study was to investigate whether pretreatment by rhEPO protects against acute cardiotoxicity induced by doxorubicin and trastuzumab, using the isolated rat heart model. Rats were treated with rhEPO (5000 IU/kg, intraperitoneally [i.p.]) or vehicle. One hour later, hearts were isolated and retrogradely perfused at constant flow. Following 20 mins of stabilization, hearts were perfused for 60 mins with modified-Krebs solution containing 6 mg/l doxorubicin or 10 mg/l trastuzumab. Hearts receiving doxorubicin were paced; those receiving trastuzumab were unpaced. Control hearts were perfused with modified-Krebs solution only. Doxorubicin exposure decreased left ventricular developed pressure (LVDP; approximately -40% of baseline) and increased end diastolic pressure (EDP; approximately +390% of baseline) and coronary perfusion pressure (CPP; approximately +70% of baseline). Incidence of ventricular tachycardia or fibrillation (VT/VF) was also significantly enhanced (86% vs. 0% in control group). Trastuzumab exposure increased CPP and EDP (approximately +70% of baseline for the both) without affecting LVDP. Prior rhEPO treatment significantly prevented doxorubicin-induced deleterious effects on LVDP, EDP, and VT/VF incidence. rhEPO administration also prevented trastuzumab-induced deleterious effects on CPP and EDP. This study shows that pretreatment by rhEPO protects myocardium against functional damage and electrophysiologic injury induced by acute doxorubicin or trastuzumab exposure. Further investigations are required to elucidate the precise mechanisms involved. |
8,068 | Arrhythmogenic right ventricular cardiomyopathy/dysplasia: risk stratification and therapy. | Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited heart muscle disease that occurs primarily in young and middle-age individuals. It is characterized by ventricular arrhythmias (VA), sudden death, and by heart failure occurring later in life (–5). Ventricular electrical instability may occur at any time during the disease depending upon possible different pathophysiologic mechanisms including: a) Inflammation and apoptosis leading to ventricular fibrillation; or b) Fibro-fatty tissue repair leading to scar-related ventricular tachycardia (VT). Heart failure may occur later in life secondary to slow, progressive loss of right and left ventricular myocardium (–8). The role of pharmacological therapy in controlling VA and preventing sudden death has been evaluated in single-center studies (9), and the results of catheter ablation have been described in small series of patients (–15). The efficacy and safety of implantable cardioverter/defibrillator (ICD) have also been reported in small, single-center studies (–19) and recently in larger single and multicenter studies (–27). The main questions regarding the risk stratification and the therapeutic strategy in ARVC/D are: 1) differential diagnosis with idiopathic VT (right ventricular outflow tract VT) in an apparently normal heart. The prognosis of this latter condition is usually excellent with rare cases of sudden cardiac death; 2) prognostic and therapeutic significance of noninvasive and invasive investigations including electrophysiologic study (EPS); 3) efficacy of antiarrhythmic drugs (AAD) to prevent VT and sudden cardiac death and the adverse effects of these drugs in this population; 4) indications and results of catheter ablation; 5) identification of patients at high risk of sudden cardiac death who need ICD implantation as well as the complications of ICD in a diseased right ventricular myocardium. It is important to recognize that ARVC/D is a progressive disease and risk factors may change during follow-up requiring periodic revaluation of risk as well as of therapy. With the identification of family members who carry a disease causing gene, the therapeutic dilemma has broadened to include risk stratification in genotype positive family members who may have occasional ventricular ectopy or have no clinical evidence of the disease. |
8,069 | [Ventricular fibrillation following deodorant spray inhalation]. | We report one case of out-of-hospital cardiac arrest with ventricular fibrillation following butane poisoning after inhalation of antiperspiration aerosol. An early management using semi-automatic defibrillator explained the success of the resuscitation. The mechanism of butane toxicity could be an increased sensitivity of cardiac receptors to circulating catecholamines, responsible for cardiac arrest during exercise and for resuscitation difficulties. The indication of epinephrine is discussed. |
8,070 | T-wave alternans, restitution of human action potential duration, and outcome. | Our aim was to study the relationship between T-wave alternans (TWA) and rate-response (restitution) of repolarization in subjects with and without ventricular systolic dysfunction.</AbstractText>T-wave alternans is a promising predictor of sudden death, yet the mechanisms linking it with human ventricular arrhythmias are unclear. From theoretic considerations, we hypothesized that abnormal TWA is linked with steep restitution of action potential duration (APD) and that both predict arrhythmic outcome.</AbstractText>We studied 53 subjects with left ventricular ejection fraction (LVEF) < or =40% and 18 control subjects. At electrophysiologic study, we recorded APD at 90% repolarization (APD(90)) in the right (n = 62) or left (n = 9) ventricle during pacing while measuring TWA from the body surface.</AbstractText>As expected, TWA (at <109 beats/min) was more likely to be abnormal in study than in control subjects (p < 0.01). However, study (LVEF 28 +/- 8%) and control (LVEF 58 +/- 12%) subjects did not differ in APD(90) restitution slope maxima (1.2 +/- 0.6 vs. 1.3 +/- 0.6, respectively; p = 0.82) or numbers with steep slope (>1; 58% vs. 67%). T-wave alternans and simultaneous APD alternans always occurred at diastolic intervals where APD restitution was not steep (p < 0.001), and there was no relationship between maximum restitution slope and TWA magnitude. Over 829 +/- 473 days, TWA (p = 0.02), but not restitution slope >1, predicted ventricular arrhythmias in subjects with LVEF < or =40%.</AbstractText>The mechanism by which TWA predicts arrhythmic mortality does not reflect the maximum slope of ventricular APD restitution. Better understanding of the mechanisms underlying TWA may enable improved prediction and prevention of ventricular arrhythmias.</AbstractText> |
8,071 | Right isthmus ablation reduces supraventricular arrhythmias after surgery for chronic atrial fibrillation. | Clinical, electrocardiographic, and echocardiographic results of atrial fibrillation (AF) ablation by left mini-Maze, with or without concomitant cavotricuspid isthmus ablation, during cardiac surgery were analyzed.</AbstractText>Eighty-seven patients undergoing radiofrequency left mini-Maze without (group A) or with (group B) concomitant cavotricuspid isthmus ablation underwent serial electrocardiography and echocardiography to assess sinus rhythm recovery and atrioventricular remodelling. Recurrence of AF, incidence of atrial flutter, hospital readmission, and episodes of congestive heart failure were recorded. Predictors of AF recurrence were evaluated.</AbstractText>Follow-up of 33.4 +/- 11.2 months demonstrated 88.5% had sinus rhythm recovery, with normalized E/A velocity in 90.9%. Freedom from AF recurrence, congestive heart failure, and hospital readmission was 72.6% +/- 7.8%, 93.3% +/- 5.5%, and 79.9% +/- 8.2%, respectively, without differences between the two groups. Atrial flutter developed in group A more frequently during hospitalization (19.5% versus 2.2%; p = 0.009) and follow-up (12.2% versus 0%; p = 0.02); freedom from atrial flutter was thus lower (79.6% +/- 7.8% versus 100%; p = 0.024). Although no differences were recorded in postoperative and follow-up New York Heart Association (NYHA) functional class or in postoperative or follow-up echocardiographic indicators between the two groups, AF patients displayed a worse NYHA than did sinus rhythm patients (discharge p = 0.009; follow-up p = 0.0002). Accordingly, only sinus rhythm patients showed reverse remodelling of longitudinal (discharge p = 0.002; follow-up p = 0.0001) and transverse diameter (discharge p = 0.0001; follow-up p = 0.001), and of follow-up left ventricular diastolic diameter (p = 0.0001). Mitral valve disease and high postoperative and follow-up echocardiographic pulmonary pressures were independent predictors of AF recurrence. Left + right ablation was the only protective factor against AF recurrence.</AbstractText>Concomitant cavotricuspid isthmus ablation should be routinely considered in AF surgery, given the shorter hospitalization, low incidence of atrial flutter onset, and beneficial effect on AF recurrences.</AbstractText> |
8,072 | Cardiac side effects of psychiatric drugs. | This review describes the common effects of psychotropic drugs on the cardiovascular system and offers guidance for practical management. Selected reports from the literature describing common side effects associated with psychotropic drugs are reviewed, and suggestions for further reading are given throughout the text. Orthostatic hypotension is the most common adverse autonomic side effect of antipsychotic drugs. Among the atypical antipsychotics the risk of orthostatic hypotension is highest with clozapine and among the conventional drugs the risk is highest with low potency agents. Rarely, orthostatic hypotension may result in neurocardiogenic syncope. QTc prolongation can occur with all antipsychotics but an increased risk is seen with pimozide, thioridazine, sertindole and zotepine. QTc prolongation is a marker of arrhythmic risk. Torsade de pointe, a specific arrhythmia, may lead to syncope, dizziness or ventricular fibrillation and sudden death. Heart muscle disease presents most commonly in the elderly as chronic heart failure, but myocarditis and cardiomyopathy, although relatively rare, are devastating, but potentially reversible complications of psychotropic drug therapy have been particularly linked to clozapine treatment. Patients with severe mental illness (SMI) are a 'high risk' population with regard to cardiovascular morbidity and mortality. It is probable that many patients accumulate an excess of 'traditional' risk factors for the development of cardiovascular disease, but other mechanisms including psychotropic drugs may also be influential in increasing risk in this vulnerable group. These risks need to be seen in the context of the undoubted therapeutic efficacy of the psychotropic armamentarium and the relief that these drugs bring to those suffering from mental disorder. |
8,073 | Electrocardiographic evidence of ventricular repolarization remodelling during atrial fibrillation. | Some atrial fibrillation (AF) patients develop excessive QTc prolongation and torsade de pointes when they take QTc-prolonging antiarrhythmic drugs (class IA/III) immediately after termination of AF. We hypothesized that this is caused by changes in ventricular repolarization during AF. We aimed to establish whether such 'ventricular repolarization remodelling' occurs.</AbstractText>We studied all patients who visited our cardiac emergency room with AF and converted to sinus rhythm (SR) in a 30 months' period. We defined four groups: (i) no antiarrhythmic drugs, electrical cardioversion (n = 30), (ii) no antiarrhythmic drugs, spontaneous AF termination (n = 19), (iii) antiarrhythmic drugs, electrical cardioversion (n = 29), and (iv) antiarrhythmic drugs, spontaneous AF termination (n = 9). We studied QTc duration at SR before AF (SR(baseline)), immediately after termination of AF (SR(postAF)), and at follow-up (SR(followup): > or =7 days after SR(postAF)). Moreover, we studied determinants of QTc prolongation at SR(postAF). We found that, in all groups, QTc at SR(postAF) was significantly and transiently prolonged compared with SR(baseline). Although of limited magnitude on average (approximately 5%), the increase was substantial (approximately 15%) in some individuals. The only independent predictor of the magnitude of QTc prolongation was QTc duration at SR(baseline); this relation had a negative correlation.</AbstractText>AF causes ventricular repolarization remodelling, resulting in QTc prolongation. QTc prolongation is substantial in some patients and may render these patients vulnerable to pro-arrhythmia from class IA/III antiarrhythmic drugs immediately after termination of AF.</AbstractText> |
8,074 | Universal scaling law of electrical turbulence in the mammalian heart. | Many biological processes, such as metabolic rate and life span, scale with body mass (BM) according to the universal law of allometric scaling: Y = aBM(b) (Y, biological process; b, scaling exponent). We investigated whether the temporal properties of ventricular fibrillation (VF), the major cause of sudden and unexpected cardiac death, scale with BM. By using high-resolution optical mapping, numerical simulations and metaanalysis of VF data in 11 mammalian species, we demonstrate that the interbeat interval of VF scales as VF(cycle) (length) = 53 x BM(1/4), spanning more than four orders of magnitude in BM from mouse to horse. |
8,075 | ST segment elevation on electrocardiogram: the electrocardiographic pattern of Brugada syndrome. | A 77-year-old white diabetic woman was brought to our emergency department (ED) after becoming lightheaded and hypotensive at home. Her routine tests including a chest radiograph were normal. Her electrocardiogram (ECG) showed significant ST segment elevation in leads V1 to V4. Serial cardiac enzymes and troponin were within normal limits. Her ECG met the criteria for type 1 Brugada syndrome. Brugada syndrome, which is more common in young Asian males, is an arrhythmogenic disease caused in part by mutations in the cardiac sodium channel gene SCN5A. To diagnose the Brugada syndrome, 1 ECG criterion and 1 clinical criterion should exist. Brugada syndrome can be associated with ventricular tachycardia or fibrillation; the only treatment proven to prevent sudden death is placement of an implantable cardioverter defibrillator, which is recommended in symptomatic patients or in those with ventricular tachycardia induced during electrophysiologic studies and a type 1 ECG pattern of Brugada syndrome. It is important to recognize the Brugada ECG pattern and to differentiate it from other etiologies of ST segment elevation on ECG. |
8,076 | The role of intracardiac echocardiography in interventional electrophysiology. | Visualization of the cardiac anatomy becomes more and more important as the complexity of interventions increases. Intracardiac echocardiography (ICE) provides good depiction of cardiac soft tissue structures and has become an important tool in today's cardiology. It has been shown to be valuable during many ablation procedures for supraventricular and ventricular arrhythmias. ICE has been used for monitoring catheter placement, observing catheter-tissue contact and lesion formation as well as titrating ablation energy. The rate of complications could be reduced, outcome of procedures improved and radiation exposure decreased. Even more, new therapy strategies have been evaluated based on ICE and it has also been used in the setting of three- dimensional imaging and image integration. |
8,077 | S1P1-selective agonist SEW2871 exacerbates reperfusion arrhythmias. | Sphingosine-1-phosphate (S1P) has been considered to play an important role in ischemia/reperfusion (I/R) injury. We used SEW2871 (SEW), a novel receptor-selective agonist for S1P1, to elucidate the role of S1P1 in myocardial I/R. Isolated perfused rat hearts exposed to S1P (1 and 10 mM) or SEW (1 and 0.1 mM) were subjected to 30 minutes of global no-flow ischemia and 2 hours of reperfusion. S1P at 1 and 10 mM significantly reduced infarct size and CK release compared with vehicle-control. The effect of 0.1 microM SEW on infarct size was modest. After I/R, S1P at both doses and SEW at 0.1 microM improved developed pressure (LVDP). SEW at 1 mM significantly prolonged the duration of ventricular tachycardia and ventricular fibrillation, leading to irreversible reperfusion tachyarrhythmias in 60% of the hearts. This is the first demonstration of the critical role of the S1P1 receptor in I/R injury. |
8,078 | The impact of acute myocardial ischemia on the ventricular defibrillation threshold during chronic oral azimilide therapy. | The effects of chronic oral azimilide therapy on the ventricular defibrillation threshold (DFT) during ischemia are unknown. The effects of azimilide on defibrillation efficacy under ischemic condition were investigated in a closed-chest animal model. Azimilide (20 mg/kg/d) was administered orally for 7 days to 10 pigs (20 to 25 kg). The control group (no treatment) comprised 15 pigs. A 2-lead defibrillation system was used. Each shock was delivered after 8 seconds of ventricular fibrillation. A step-up and step-down protocol was used to calculate mean DFT before and 10 minutes after coronary artery occlusion using an angioplasty balloon in the left descending artery. The basal DFT of the azimilide group did not differ from controls (20.8 +/- 4.8 versus 18.8 +/- 2.8; P = 0.33). After ischemia, the mean DFT of the azimilide-treated animals was similar to controls (21.8 +/- 5.2 versus 23.2 +/- 3.8 J; P = 0.54), despite significant lengthening of ventricular repolarisation (428.2 +/- 51.8 versus 494.1 +/- 46.6 msec; P = 0.005) and significant prolongation of the ventricular fibrillation cycle length (85.1 +/- 13 versus 104.7 +/- 24 msec; P < 0.04). Chronic oral azimilide treatment does not affect the DFT at baseline or during acute myocardial ischemia. |
8,079 | Postresuscitation myocardial diastolic dysfunction following prolonged ventricular fibrillation and cardiopulmonary resuscitation. | Postresuscitation myocardial dysfunction is one of the leading causes of early death after successful resuscitation from sudden death. However, the diastolic characteristics of postresuscitation myocardial dysfunction are not well defined. We therefore investigated the postresuscitation left ventricular diastolic function following prolonged cardiac arrest and subsequent cardiopulmonary resuscitation.</AbstractText>Prospective, observational animal study.</AbstractText>Medical research laboratory in a university-affiliated research and educational institute.</AbstractText>Domestic pigs.</AbstractText>Seven anesthetized pigs (40 +/- 4 kg) were studied before and after 7 mins of untreated occlusive ventricular fibrillation induced cardiac arrest. Ejection fraction, early and atrial peak transmitral flow velocities, deceleration time of early transmitral flow velocity, myocardial performance index, peak Emax and Amax mitral annulus velocities by Doppler tissue imaging, and early diastolic left ventricular flow propagation velocity were measured at baseline; 60, 120, 180, and 240 mins; and 72 hrs after resuscitation.</AbstractText>Five animals were successfully resuscitated. Left ventricular ejection fraction, E(m)/A(m) ratio, and propagation velocity were significantly decreased, and myocardial performance index was significantly increased compared with baseline measurements. Left ventricular diastolic and systolic function returned to baseline level at 72 hrs postresuscitation.</AbstractText>Left ventricular systolic dysfunction was significantly impaired after cardiac arrest and cardiopulmonary resuscitation, as previously demonstrated. This was associated with a profound left ventricular diastolic dysfunction. However, this postresuscitation left ventricular systolic and diastolic myocardial dysfunction was reversible after 72 hrs in this experimental model of ventricular fibrillation cardiac arrest.</AbstractText> |
8,080 | Identifying potentially shockable rhythms without interrupting cardiopulmonary resuscitation. | Current versions of automated external defibrillators (AEDs) mandate interruptions of chest compression for rhythm analyses because of artifacts produced by chest compressions. Interruption of chest compressions reduces likelihood of successful resuscitation by as much as 50%. We sought a method to identify a shockable rhythm without interrupting chest compressions during cardiopulmonary resuscitation (CPR).</AbstractText>Experimental study.</AbstractText>Weil Institute of Critical Care Medicine, Rancho Mirage, CA.</AbstractText>None.</AbstractText>Electrocardiographs (ECGs) were recorded in conjunction with AEDs during CPR in human victims. A shockable rhythm was defined as disorganized rhythm with an amplitude > 0.1 mV or, if organized, at a rate of > or = 180 beats/min. Wavelet-based transformation and shape-based morphology detection were used for rhythm classification. Morphologic consistencies of waveform representing QRS components were analyzed to differentiate between disorganized and organized rhythms. For disorganized rhythms, the amplitude spectrum area was computed in the frequency domain to distinguish between shockable ventricular fibrillation and nonshockable asystole. For organized rhythms, in victims in whom the absence of a heartbeat was independently confirmed, the heart rate was estimated for further classification.</AbstractText>To derive the algorithm, we used 29 recordings on 29 patients from the Creighton University ventricular tachyarrhythmia database. For validation, the algorithm was tested on an independent population of 229 victims, including recordings of both ECG and depth of chest compressions obtained during suspected out-of-hospital sudden death. The recordings included 111 instances in which the ECG was corrupted during chest compressions. A shockable rhythm was identified with a sensitivity of 93% and a specificity of 89%, yielding a positive predictive value of 91%. A nonshockable rhythm was identified with a sensitivity of 89%, a specificity of 93%, and a positive predictive value of 91% during uninterrupted chest compression.</AbstractText>The algorithm fulfilled the potential lifesaving advantages of allowing for uninterrupted chest compression, avoiding pauses for automated rhythm analyses before prompting delivery of an electrical shock.</AbstractText> |
8,081 | Electrocardiogram waveforms for monitoring effectiveness of chest compression during cardiopulmonary resuscitation. | Newer guidelines address the importance of effective chest compressions, citing evidence that this primary intervention is usually suboptimally performed during cardiopulmonary resuscitation. We therefore sought a readily available option for monitoring the effectiveness of chest compressions, specifically using the electrocardiogram.</AbstractText>Ventricular fibrillation was induced by coronary artery occlusion and untreated for 5 mins. Male domestic pigs weighing 40 +/- 2 kg were randomized to optimal or suboptimal chest compressions after onset of ventricular fibrillation. Optimal depth of mechanical compression in six animals was defined as a decrease of 25% in anterior posterior diameter of the chest during compression. Suboptimal compression, also in six animals, was defined as a decrease of 17.5% in anterior posterior diameter. For each group, the chest compressions were maintained at a rate of 100 per min. After 3 mins of chest compression, defibrillation was attempted with a 150-J biphasic shock. All animals had return of spontaneous circulation after optimal compressions. This contrasted with suboptimal compressions, after which none of the animals had return of spontaneous circulation. Amplitude spectrum area values, representing the electrocardiographic amplitude frequency spectral area computed from conventional precordial leads, like coronary perfusion pressure and end tidal PCO2, were predictive of outcomes.</AbstractText>The effectiveness of chest compressions was reflected in the amplitude spectrum area values. Accordingly, the amplitude spectrum area predictor may be incorporated in current automated external defibrillators to monitor and prompt the effectiveness of chest compression during cardiopulmonary resuscitation.</AbstractText> |
8,082 | Increasing amiodarone use in cardiopulmonary resuscitation: an analysis of the National Registry of Cardiopulmonary Resuscitation. | To examine practice patterns of amiodarone use during in-hospital cardiac arrest. This study addresses the changing pattern of amiodarone use over time, following the publication of landmark studies and the inclusion of amiodarone in the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Furthermore, this study examines the impact of hospital and patient specific factors on the use of amiodarone.</AbstractText>Retrospective cohort study, using the National Registry for Cardiopulmonary Resuscitation, an international registry of in-hospital resuscitation events.</AbstractText>All patients with an in-hospital ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) event reported to the national registry from January 1, 2000, to July 31, 2005.</AbstractText>During the study period, 14,854 of 29,552 (50%) adults (> 18 yrs old) with VF/pVT received an antiarrhythmic drug; 8,883 (60%) of these patients received amiodarone. In adults, amiodarone use for VF/pVT increased from 25% in 2000 to 72% in 2005 (p < .0001). Among children, 270 of 553 (49%) VF/pVT episodes were treated with an antiarrhythmic drug; 108 (40%) of these patients received amiodarone. Adults in institutions with larger intensive care units (> 50 beds) were more likely than those in institutions with smaller intensive care units (< or = 50 beds) to receive amiodarone; the association persisted in multivariable analysis (odds ratio [OR] = 1.825; 95% confidence interval [CI], 1.694-1.966). Thirty five percent of adults with VF/pVT who received amiodarone also received lidocaine, while 67% of children who received amiodarone also received lidocaine (p < .001). It is not possible to determine from the database the order in which medications were administered.</AbstractText>There has been a significant increase in amiodarone use for VF/pVT events over the past 5 yrs. The frequency of amiodarone use in adults correlated positively with the number of intensive care beds. These results suggest that emerging data and national guidelines affect resuscitation practice patterns.</AbstractText> |
8,083 | Cardiac resynchronization therapy in patients with chronic atrial fibrillation. | Heart failure (HF) and atrial fibrillation (AF), 2 of the most common cardiovascular disorders, often coexist in the same patient, as 1 condition can lead to the other. The best approach to AF management in patients with HF is currently under investigation, but there seems to be an abundance of evidence in support of cardiac resynchronization therapy (CRT) in this group of patients. In addition, CRT is emerging as a superior option to stand-alone right ventricular pacing in patients with structural heart disease. However, in patients with AF, an adequate rate control is critical for this therapy to be highly effective. As control of the ventricular response can be difficult to achieve in many of those patients, often a nonpharmacologic intervention is required, such as ablation of the atrioventricular node to create heart block. The definitive role for CRT with or without atrioventricular nodal ablation in patients with AF and HF is yet to be studied in large, well-designed, randomized, controlled clinical trials. |
8,084 | Mechanical properties of chest protectors and the likelihood of ventricular fibrillation due to commotio cordis. | Sudden death resulting from ventricular fibrillation (VF) caused by a nonpenetrating chest wall impact, known as commotio cordis (CC), is the second leading cause of death among young athletes. To date, seven young athletes wearing chest protectors have died from CC. The purpose of this study was to determine whether a relationship exists between mechanical properties of chest protectors and occurrence of VF, previously determined by Weinstock et al., using an established swine model. A servo-hydraulic material tester was used to determine properties of the chest protectors, including displacement, permanent deformation, stiffness, and area of pressure distribution. These properties were then compared with the occurrence of VF. We found that a decreased proportion of hits resulting in VF was significantly associated (R2 = 0.59, p = 0.001) with an increase in the area of pressure distribution. These findings are a limited, but crucial, first step in understanding the prevention of this complex and perplexing phenomenon. |
8,085 | Possible role of hydrogen sulfide on the preservation of donor rat hearts. | The aim of this study was to observe the preservative effect of hydrogen sulfide (H2S) on donor rat hearts.</AbstractText>The hearts of 24 Sprague-Dawley rats were perfused on a Langendorff perfusion column for 30 minutes. We calculated and recorded the left ventricular-developed pressure (LVDP), and positive and negative derivatives of left ventricular systolic pressure (LVSP; +dP/dt and -dP/dt). Hearts were then arrested and stored for 6 hours at 4 degrees C: group 1, Krebs-Henseleit (KH) solution; group 2, KH solution with 1 micromol/L NaHS; group 3, KH solution with 1 micromol/L NaHS and 10 micromol/L glibenclamide; group 4, St. Thomas II solution. Hearts were transferred back to the Langendorff column. After stabilizing for 30 minutes, LV performance was assessed as before. The donor hearts were kept for pathological study including myocardial water ratio, ATP content, and myocyte apoptosis index.</AbstractText>The recovery rates of +dp/dtmax, -dp/dtmax, and LVDP of groups 2 and 4 were much better than those of groups 1 and 3. The hearts contracted immediately after reperfusion in group 4. Ventricular fibrillation was seen before contraction in the other 3 groups, with the longest duration in group. No significant difference in myocardial water ratio was found. The ATP content was the highest in group 2. Apoptosis was observed in the 4 groups with the lowest apoptosis index in group 2.</AbstractText>H2S has a protective effect on rat donor hearts at the concentration of 1 micromol/L. The protective effect is better than that of St. Thomas II solution. The protective effect of H2S can be blocked by glibenclamide.</AbstractText> |
8,086 | Therapeutic hypothermia in comatose patients after out-of-hospital cardiac arrest. | Our intensive care unit has been treating comatose patients, following an out-of-hospital cardiac arrest, with therapeutic hypothermia since 2002. In all, 139 out-of-hospital cardiac arrest patients were admitted in the 4-year period 2002-5. Of these, 27% had a favourable outcome (discharged home or to rehabilitation). Forty-one per cent of patients presenting with ventricular fibrillation (VF) and 7% of non-VF patients had a favourable outcome. No patient with an estimated time from collapse to first attempt at cardiopulmonary resuscitation over 12 min survived to hospital discharge. Twenty-two per cent of patients over 70 years were discharged home, suggesting age was not a barrier to surviving out-of-hospital cardiac arrest. The introduction of a therapeutic hypothermia clinical pathway, at the end of 2003 improved the efficiency of cooling. The percentage of patients cooled to below 34 degrees C within 4 h increased from 15 to 51% and those cooled for more than 12 h increased from 30 to 83%. |
8,087 | [Invasive electrophysiology: complications, nightmares and their management]. | Most minor side effects of ablation in the right atrium and right ventricle relate to femoral venous catheterization but there is a small risk of severe complications including atrioventricular (AV) block, damage of surrounding structures and thromboembolic events. Impairment of AV conduction can occur during ablation of atrioventricular re-entrant tachycardia, ablation of anteroseptal, mid-septal and parahisian accessory pathways, ablation of ectopic atrial tachycardia originating from the vicinity of the atrioventricular node and when ablating the septal isthmus for typical atrial flutter. Damage of the right coronary artery is a very rare complication after inferior isthmus ablation with high energy. The thromboembolic risk during and after cardioversion and ablation of atrial flutter is higher than previously recognized and anticoagulation therapy decreases this risk. The risk of perforation and tamponade during ablation in the right atrium and right ventricle is very low but particular caution is necessary in thin-walled structures such as the coronary sinus and the upper right ventricular outflow tract. Phrenic nerve injury can be avoided by pacing from the mapping electrode before application of radiofrequency energy at the right atrial free wall. Limitation of power output depending on the site of ablation and titration of energy application with continuous control of temperature and impedance should be considered to minimize the risk of complications. |
8,088 | Increased prevalence of sustained return of spontaneous circulation following transition to biphasic waveform defibrillation. | We sought to assess the prevalence of shock-induced sustained return of spontaneous circulation (ROSC) and neurologically intact discharge survival before (1990-1997) and after (1998-2006) transition to biphasic waveform defibrillation in our population-controlled EMS setting.</AbstractText>All victims of out-of-hospital cardiac arrest with ventricular fibrillation as the initial rhythm from November 1990 to December 2006 were included for analysis. Data were acquired prospectively and analyzed retrospectively during two periods: before (period 1) and after (period 2) transition from monophasic damped sine to biphasic truncated exponential and rectilinear biphasic waveform defibrillation. We compared the prevalence of sustained ROSC and survival in the two periods.</AbstractText>Very high survival was observed during both periods. During period 1, sustained ROSC with shocks only was obtained in 37 (27.6%) patients; in period 2, sustained ROSC was obtained in 39 (40.2%) (p=0.04). Fifty-three (39.6%) survived to neurologically intact discharge in period 1, and 45 (46.4%) in period 2 (p=0.29). For bystander-witnessed arrests, ROSC was obtained in 34 (31.5%) in period 1 and 34 (45.3%) in period 2 (p=0.06). Forty-eight (44.4%) survived in period 1 and 39 (52.0%) in period 2 (p=0.31). We observed no other significant differences in patient or EMS-performance characteristics in the two time periods.</AbstractText>Return of sustained pulses with shocks alone increased after transition to biphasic waveform defibrillation, with no other differences to explain the increase. High survival was noted in both periods, with a trend toward higher survival in the second period.</AbstractText> |
8,089 | The effects of prostaglandin inhibition on whole-body ischemia-reperfusion in swine. | Prostaglandins (PGs), particularly PGE2 and PGI2, have a salutary effect on myocardial ischemia-reperfusion-induced myocardial damage.</AbstractText>We investigated acute PG synthesis inhibition on outcomes from whole-body ischemia-reperfusion injury using a well-characterized model of ventricular fibrillation (VF)-induced cardiac arrest in pigs. In addition, we assessed early postresuscitation myocardial function in survivors using echocardiography as well as a biochemical measure of myocardial tissue damage.</AbstractText>Twenty-six animals (weight range, 25-35 kg) received indomethacin (INDO; 2 mg/kg, nonselective cyclooxygenase (COX) 1 and 2 inhibitor), celecoxib (2 mg/kg; selective COX-2 inhibitor [COX-2-I]), or saline placebo 30 minutes before induction of VF. After 3 minutes of VF with no intervention, the animals received standard chest compression using an automated chest compression device (Thumper; Michigan Instruments, Grand Rapids, Mich) for 15 minutes. After 18 minutes of VF, a single dose of vasopressin and bicarbonate were administered and defibrillation attempted. Hemodynamics, regional blood flow, echocardiography, and serum troponin I measurements were performed before and after drug infusion or placebo, during cardiopulmonary resuscitation (CPR), and after return of spontaneous circulation (ROSC).</AbstractText>Return of spontaneous circulation to 180 minutes occurred in 9 of 10 animals receiving placebo, 7 of 8 animals given COX-2-I, and 3 of 8 animals given INDO (P = .01, placebo or COX-2-I vs INDO). Hemodynamics did not differ among groups over time. Indomethacin and COX-2-I attenuated the increase in regional blood flow in the heart and brain, observed in the placebo group, 30 minutes after ROSC. All 3 study groups had significant decrease in percentage of ejection fraction and fractional shortening after ROSC and significant increase in wall motion score index after ROSC. In the COX-2-I group, troponin I increased 9-fold compared with placebo, 180 minutes after ROSC. Whole-body ischemia-reperfusion and CPR significantly increased PGE2 and PGI2 levels. The latter were blunted by pretreatment with COX inhibition.</AbstractText>These findings suggest that PGs have a critical role in myocardial function and viability during low-blood-flow states produced by CPR and possibly other low-blood-flow clinical conditions.</AbstractText> |
8,090 | Right atrial pacing and the risk of postimplant atrial fibrillation in cardiac resynchronization therapy recipients. | In patients with cardiac resynchronization therapy (CRT) devices, right atrial (RA) pacing introduces a significant prolongation in interatrial conduction time, delaying left atrial mechanical systole and curtailing left ventricular filling. The resultant increase in left-sided filling pressures may facilitate atrial fibrillation (AF). We sought to determine whether the extent of RA pacing influences the incidence of AF after CRT.</AbstractText>Consecutive CRT patients (n = 309) followed at our institution were retrospectively studied for percentage of RA pacing and incidence of high atrial rates, as determined by regular device interrogations. Additional clinical data were collected from the medical record.</AbstractText>The mean follow-up was 18.1 +/- 13.3 months, during which 209 (67.6%) patients had at least 1 detected high atrial rate episode consistent with AF. Higher percentages of RA pacing were associated with a greater risk of postimplant AF, with its incidence increasing incrementally with quartiles of RA pacing: 44.6%, 64.3%, 79.7%, and 81.6%, respectively (P < .001). After controlling for all factors predictive of postimplant AF on univariate analysis (right atrial pacing quartile, follow-up duration, mitral regurgitation severity, and prior AF history), RA pacing quartile remained a significant predictor of post-CRT AF (hazard ratio 1.92, 95% CI 1.40-2.62, P < .001) upon multivariate analysis. In addition to predicting AF incidence, higher RA pacing quartiles were also associated with significantly greater AF burden.</AbstractText>Compared to atrial sensing, atrial pacing is associated with a 2-fold increased risk of post-CRT AF. Prospective comparison of DDD and VDD pacing modes in CRT is warranted.</AbstractText> |
8,091 | An unusual precipitant of tako-tsubo cardiomyopathy. | A 76-year-old woman presents with acute pulmonary oedema and cardiogenic shock 10h after elective electrical cardioversion for atrial fibrillation. Her echocardiogram shows new wall motion abnormalities with akinesis of the apical and mid segments of the left ventricle and her resting ECG contains deep T wave inversion and QTc prolongation. Angiography reveals non-occlusive coronary artery disease. The echocardiogram on day 6 shows resolution of left ventricular wall motion abnormalities and a return to normal systolic function. The diagnosis of tako-tsubo cardiomyopathy was made. This is the first report of this condition precipitated by electrical cardioversion. |
8,092 | Brugada syndrome in pure black Africans. | Although all races are concerned with the Brugada syndrome, no case has ever been reported among black Africans. We describe five different cases in this specific group of populations.</AbstractText>In all patients, Brugada syndrome was identified after detailed noninvasive and invasive evaluations. Sex ratio was four males for one female. Convulsive syncope was noticed in 1 patient with a family history of sudden death. Diagnostic coved-type pattern was observed spontaneously in the normal position of right precordial leads in 3 patients and in a higher position of leads in 3 patients. Sixty percent had first-degree atrioventricular block. An ajmaline test was performed in 4 patients and was positive either in normal position of leads or in superior position in all of them. Sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) was inducible during programmed ventricular stimulation in 3 patients. Right ventricular cineangiography found localized apical hypokinesia with preserved systolic function in 1 patient. Automatic cardioverter defibrillator was implanted in 2 patients. SCN5A was not found in any of the patients.</AbstractText>These observations demonstrate that Brugada syndrome is also present in black African populations, and increasingly reported cases of apparent sudden death in the sub-Saharan part of the world need to rule out cardiac electrical disturbance such as Brugada syndrome.</AbstractText> |
8,093 | [Direct referral of patients with ST-elevation acute myocardial infarction to primary percutaneous coronary intervention. Pre-hospital use of telemedicine and risk stratification]. | Primary percutaneous coronary intervention (PCI) is recommended for revascularisation of patients with ST-elevation acute myocardial infarction (STEMI) with a duration of symptoms less than 12 hours. Primary PCI is recommended even if the patient is to be transported from a non-invasive hospital to an invasive centre. Normally this transport requires an attending physician. This transport strategy is associated with an increased treatment delay. The aim of this study was to assess pre-hospital tele-transmitted electrocardiogram (tele-ECG) and risk stratification by using a questionnaire in order to assess if selected patients with STEMI can be transported safely to primary PCI without an attending physician.</AbstractText>Since January 2005 Fyn Svendborg Hospital has received pre-hospital tele-ECG recorded in patients with suspected acute coronary syndrome (ACS) with simultaneous risk stratification by using a questionnaire. Transportable STEMI patients were referred directly to an invasive centre without an attending physician.</AbstractText>During a period of 17 months tele-ECGs were recorded from 1,148 patients. 82 patients had STEMI and 71 patients were transported to an invasive centre without an attending physician. In this group, 1 case of resuscitated ventricular fibrillation was reported. 11 patients were transported to the nearest hospital: 2 to invasive centres, 7 patients were inter-hospital transported with a physician, and transport was not relevant/possible for 2 patients.</AbstractText>Pre-hospital tele-ECG and risk stratification can select patients with STEMI and transport them safely to an invasive PCI centre without an attending physician.</AbstractText> |
8,094 | A multiple ion channel blocker, NIP-142, for the treatment of atrial fibrillation. | Atrial fibrillation (AF) is one of the most frequent cardiac arrhythmia and is associated with increased cardiovascular morbidity and mortality, and the risk of stroke. Although currently available antiarrhythmic drugs are moderately effective in restoring normal sinus rhythm in patients with AF, excessive delay of ventricular repolarization by these agents may be associated with increased risk of proarrhythmia. Therefore, selective blockers of cardiac ion channel(s) that are exclusively present in the atria are highly desirable. NIP-142 is a novel benzopyrane derivative, which blocks potassium, calcium, and sodium channels and shows atrial specific action potential duration prolongation. NIP-142 preferentially blocks the ultrarapid delayed rectifier potassium current (I Kur) and the acetylcholine-activated potassium current (I KACh). Since I Kur and I KACh have been shown to be expressed more abundantly in the atrial than in the ventricular myocardium, the atrial-specific repolarization prolonging effect of NIP-142 is considered to be due to the blockade of these potassium currents. In canine models, NIP-142 was shown to terminate the microreentry type AF induced by vagal nerve stimulation and the macroreentry type atrial flutter induced by an intercaval crush. These effects of NIP-142 have been attributed to the prolongation of atrial effective refractory period (ERP), because this compound prolonged atrial ERP without affecting intraatrial and interatrial conduction times in these models. The ERP prolongation by NIP-142 was greater in the atrium than in the ventricle. NIP-142 also terminated the focal activity type AF induced by aconitine. In addition, NIP-142 reversed the atrial ERP shortening and the loss of rate adaptation induced by short-term rapid atrial pacing in anesthetized dogs. Thus, although clinical trials are required to provide evidence for its efficacy and safety, the novel multiple ion channel blocker, NIP-142, appears to be a useful agent for the treatment of several types of AF with a low risk of proarrhythmic activity. |
8,095 | [Preoperative evaluation and anesthetic management of a patient with Brugada syndrome-like ECG]. | Brugada syndrome has been known as one of the causes of sudden death due to ventricular fibrillation. We experienced anesthetic management of seven patients with ECG showing Brugada syndrome before surgery, even though they had no symptoms nor family history. All of them showed no problems through-out the operation. Such patients are often untreated, but they have the risks of cardiac accidents such as ventricular fibrillation or sudden death. For preoperative evaluation of patients with Brugada syndrome-like ECG, it is important to ask them their experience of syncope and family history. Ultrasonic cardiography and Holter ECG recording should be done. External defibrillator should be prepared and parasympathetic dominant condition must be avoided during the anesthetic management. |
8,096 | [Therapeutic effect of p-tyrosol on myocardial electric instability induced by coronary occlusion]. | In experiments on rats with left coronary artery occlusion, p-tyrosol (20 mg/kg, intravenously) showed the ability to decrease myocardial electric instability in phase 1b of ventricular arrhythmias: a fraction of rats without arrhythmia was increased by 36%, and the mean value of ventricular arrhythmia index exhibited a 3-fold decrease. |
8,097 | Acute effects of TASER X26 discharges in a swine model. | Very little objective laboratory data are available describing the physiologic effects of stun guns or electromuscular incapacitation devices (EIDs). Unfortunately, there have been several hundred in-custody deaths, which have been temporally associated with the deployment of these devices. Most of the deaths have been attributed to specific cardiac and metabolic effects. We hypothesized that prolonged EID exposure in a model animal system would induce clinically significant metabolic acidosis and cardiovascular disturbances.</AbstractText>Using an Institutional Animal Care and Use Committee-approved protocol, 11 standard pigs (6 experimentals and 5 sham controls) were anesthetized with ketamine and xylazine. The experimentals were exposed to two 40-second discharges from an EID (TASER X26, TASER Intl., Scottsdale, AZ) across the torso. Electrocardiograms, blood pressure, troponin I, blood gases, and electrolyte levels were obtained pre-exposure and at 5, 15, 30, and 60 minutes and 24, 48, and 72 hours postdischarge. p values <0.05 were considered significant.</AbstractText>Two deaths were observed immediately after TASER exposure from acute onset ventricular fibrillation (VF). In surviving animals, heart rate was significantly increased and significant hypotension was noted. Acid-base status was dramatically affected by the TASER discharge at the 5-minute time point and throughout the 60-minute monitoring period. Five minutes postdischarge, central venous blood pH (6.86 +/- 0.07) decreased from baseline (7.45 +/- 0.02; p = 0.0004). Pco2 (94.5 mm Hg +/- 14.8 mm Hg) was significantly increased from baseline (45.3 mm Hg +/- 2.6 mm Hg) and bicarbonate levels significantly decreased (15.7 mmol/L +/- 1.04 mmol/L) from baseline (30.4 mmol/L +/- 0.7 mmol/L). A large, significant increase in lactate occurred postdischarge (22.1 mmol/L +/- 1.5 mmol/L) from baseline (1.5 mmol/L +/- 0.3 mmol/L). All values returned to normal by 24 hours postdischarge in surviving animals. A minor, nonsignificant increase in troponin I was seen at 24 hours postdischarge (0.052 ng/mL +/- 0.030 ng/mL, mean +/- SEM).</AbstractText>Immediately after the discharge, two deaths occurred because of ventricular fibrillation. In this model of prolonged EID exposure, clinically significant acid-base and cardiovascular disturbances were clearly seen. The severe metabolic and respiratory acidosis seen here suggests the involvement of a primary cardiovascular mechanism.</AbstractText> |
8,098 | Progressive mitral valve thickening and progressive muscle cramps as manifestations of glycogenosis VII (Tarui's Disease). | Progressive heart valve thickening and shrinkage, and progressive muscle cramps have not been reported as manifestations of glycogenosis type VII (Tarui's disease). In a 72-year-old female, Tarui's disease was diagnosed in 1997, initially manifesting as simple partial seizures since 1977, anginal chest pain since 1982 and muscle cramps since 1983. During the following years, low voltage ECG, ectopic supraventricular tachycardia, thickening of the mitral valve, mitral valve insufficiency, enlarged left atrium, left ventricular hypertrophy and diastolic dysfunction also developed. Neurological manifestations progressed to complex partial seizures, double vision, reduced tendon reflexes, central facial palsy, bradydiadochokinesia, distal weakness of the upper extremities and worsening muscle cramps. Thickening and shrinkage of the heart valves had further increased at 72 years of age. Progression of Tarui's disease may manifest as progressive thickening of the heart valves due to glycogen storage. Valve thickening may consecutively lead to valve insufficiency, enlargement of the atrium and atrial fibrillation. Progression of neurological manifestations may manifest as worsening muscle cramps. |
8,099 | Acute clenbuterol overdose resulting in supraventricular tachycardia and atrial fibrillation. | We are presenting a case illustrating the complex metabolic and rhythm disturbances associated with acute clenbuterol intoxication.</AbstractText>Clenbuterol is a long-acting beta2-adrenergic agonist primarily used in veterinary medicine in the United States. It has become a common drug of abuse by body builders because of its reported anabolic and lipolytic properties. In this case report, a body builder using veterinary clenbuterol developed significant electrolyte and cardiac manifestations.</AbstractText>A 31-year-old man presented to the emergency department approximately 30 minutes after ingesting 1.5 ml (a tenfold dosing error) of Ventipulmin syrup (72.5 mcg/ml clenbuterol HCl). The product was brought to the emergency department (ED) by the patient. He reported no current use of anabolic steroids. He presented in an anxious state with complaints of palpitations and shortness of breath. Vital signs upon examination were as follows: BP, 122/77 mmHg (16.3/10.3 kPa); HR 254 bpm; RR, 22 bpm; Temperature, 97.1 degrees F (36 degrees C); and oxygen saturation, 100% on ambient air. His electrocardiogram (ECG) demonstrated supraventricular tachycardia with a ventricular rate of 254 bpm. Esmolol was recommended for rate control after the unsuccessful use of adenosine and diltiazem. Laboratory studies showed potassium, 2.1 mmol/L; magnesium, 1.3 mg/dL (0.54 mmol/L); phosphorus, 1.0 mg/dL (0.32 mmol/L); serum glucose, 209 mg/dL (11.6 mmol/L); creatinine, 0.8 mg/dL (70.7 micromol/L); AST, 20 U/L; ALT, 55 U/L; hemoglobin, 12.6 g/dL (126 g/L); CPK total, 87 U/L; and troponin I, 0.23 mug/L. The patient's urine was negative for any drugs of abuse. Clenbuterol levels were not obtained. A second ECG, 16 hours post ingestion, reflected atrial fibrillation with a ventricular rate of 125 to 147 bpm. On hospital day 3, he was electively cardioverted to sinus rhythm; heart rate and rhythm returned to normal, and he was discharged with oral metoprolol.</AbstractText>Clenbuterol is approved for use in countries outside the U.S. as a bronchodilator for the treatment of acute asthma exacerbations in humans. Although clenbuterol is not a steroid hormone, it possesses anabolic properties that increase muscle mass. Its longer duration of action compared to other beta2-agonists (such as albuterol) make it a desired agent for body-building because of its high and prolonged serum level. The mechanism for the short and long-term cardiovascular complications of clenbuterol is complex. The anabolic effects of clenbuterol are associated with its beta2-adrenoreceptor agonist activity on striated skeletal muscles. In addition, clenbuterol promotes lipolysis through adipocyte beta3-adrenoreceptors.</AbstractText>Considering the significant number of body-building enthusiasts, physicians will continue to encounter clenbuterol abuse in their clinical practices.</AbstractText> |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.