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8,800 | Aggressive management of acute myocardial infarction: successful outcome in an older patient with cardiogenic shock. | A 71-year-old man was referred to our emergency department presenting with acute inferior and right ventricular myocardial infarction with cardiogenic shock. He developed ventricular fibrillation 80 minutes after arrival. Immediate defibrillation, mechanical ventilatory support with oxygenation, and inotropic agents were instituted. Despite restoration of sinus rhythm, his hypotension persisted. He promptly received intra-aortic balloon pump (IABP) counterpulsation and cardiac catheterisation. Coronary angiography revealed a subtotal occlusion of the left anterior descending coronary artery and complete occlusion of the right coronary artery. Since the right coronary artery was considered to be the infarct-related coronary artery, percutaneous coronary intervention (PCI) was carried out to the right coronary artery only. The patient was extubated and IABP was removed on the second and third admission day, respectively. He was discharged from the hospital eight days later. A second PCI to the left anterior descending coronary artery was performed successfully three weeks later. This case illustrates that in patients with acute myocardial infarction and cardiogenic shock, prompt application of IABP and PCI of the infarct-related coronary artery may be beneficial in reducing the catastrophic morbidity and mortality, especially in older patients. |
8,801 | A community based epidemiological and clinical study of hospitalization of patients with congestive heart failure in Northern Iwate, Japan. | Community based studies of congestive heart failure (HF) are lacking in the Japanese population.</AbstractText>To delineate the epidemiological and clinical features of advanced HF in the general Japanese population, hospitalized adult cases of HF in all hospitals within the Ninohe district were registered for 3 years. During the survey period, 190 new onset cases (males n=93; females n=97) and a total of 391 hospitalizations (including repeat admissions) were registered. The prevalence of atrial fibrillation in new HF cases was 56% in males and 45% in females. On the basis of the population of the district, the incidence of hospitalized HF was 96 in males and 92 in females per 100,000 person-years. The percentage of HF patients who were > or =65 years of age was 82% in males and 94% in females. In cases undergoing echocardiography, preserved left ventricular systolic function (left ventricular ejection fraction > or =50%) was observed in 29% of males and 41% of females. There was a significant seasonal variation in HF admissions (Spring 32%; Summer 20%; Autumn 20%; Winter 28%; p<0.01).</AbstractText>In comparison with published results of USA and European community based studies of HF, the present HF cohort showed that: (1) mean age, prevalence of preserved ejection fraction, and trends in seasonal variation were comparable; however (2) the incidence of HF was obviously lower. These epidemiological and clinical characteristics should be taken into consideration when establishing a therapeutic and preventive approach for HF.</AbstractText> |
8,802 | Porcine defibrillation thresholds with chopped biphasic truncated exponential waveforms. | Conventional biphasic truncated exponential (BTE) waveforms have been studied extensively but less is known about "chopping modulated" BTE shocks. Previous studies comparing chopped and unchopped waveforms have found conflicting results. This study compared the defibrillation thresholds (DFTs) of a variety of chopped and unchopped BTE waveforms.</AbstractText>Six anesthetized pigs were defibrillated after 15s of electrically induced ventricular fibrillation (VF). Three waveform types were studied: unchopped BTE, "short" duration chopped, and "long" duration chopped waveforms. Each type included waveforms generated with 50, 100, and 200 microF capacitances, giving 9 total waveforms. Shocks were delivered in a standard up-down protocol and the order of the waveforms was randomized. Defibrillation thresholds were calculated using a Bayesian logistic regression model.</AbstractText>DFTs of the 50, 100, and 200 microF unchopped waveforms were 122+/-22, 124+/-22, and 126+/-22 J. Short chopped DFTs were at least 75+/-23 J higher than unchopped DFTs. Long chopped DFTs averaged 66+/-20 J more than short chopped DFTs. There is a 99.5% probability that the best of the chopped waveforms has a higher DFT than the worst of the unchopped waveforms, and a 95% probability that the difference is at least 37 J. DFT differences between capacitor values were less than 7 J for all waveform types.</AbstractText>When treating swine with short-duration VF, chopped waveforms require more energy to defibrillate than unchopped waveforms. More study is required to assess the performance of chopped waveforms when treating cardiac arrest patients.</AbstractText> |
8,803 | Do statins have an antiarrhythmic activity? | Sudden cardiac death, which is mainly associated with the presence of life-threatening ventricular arrhythmias, is a common 'killer' among patients with coronary artery disease. Moreover, atrial fibrillation is the most common arrhythmia encountered in the clinical practice. The beneficial effect of statins on cardiovascular morbidity and mortality is well-established, while the exact role of this class of drugs against arrhythmias remains unclear. This review discusses the effect of statin treatment on arrhythmias that are commonly seen in the clinical setting. The underlying pathophysiological mechanisms are also overviewed. Compelling evidence from the majority of the studies reviewed shows that statins exhibit a protective effect against the occurrence of ventricular arrhythmias and atrial fibrillation. |
8,804 | Mitral regurgitation complicates postoperative outcome of noncardiac surgery. | Whether and how mitral regurgitation impacts perioperative outcome of noncardiac surgery remains unclear.</AbstractText>From November 1999 to August 2004, all patients undergoing noncardiac operations and ever examined by echocardiography within prior 12 months were screened. Those with moderate-severe or severe mitral regurgitation were enrolled provided they were not already trachea-intubated and the surgery was not performed under local anesthesia. The perioperative outcomes of these patients were analyzed, and related prognostic predictors were investigated by multivariate logistic regression analysis.</AbstractText>A total of 84 patients (43 men, mean age of 66 years, low surgical risk in 28 and intermediate in 56) complying with the inclusion criteria were included. Their surgery was complicated by frequent (31%) yet minor intraoperative adverse events of controllable hypotension and bradycardia. In contrast, the postoperative outcomes were seriously complicated with high morbidity (27.4%, mostly pulmonary edema and prolonged tracheal intubation) and mortality (11.9%). Atrial fibrillation was identified by multivariate logistic regression analysis as the predictor of inhospital death (OD 11.579, P = .003), whereas surgical risk level (OD 5.118, P = .021), left ventricular ejection fraction (OD 0.958, P = .026), and atrial fibrillation (OD 3.058, P = .045), as independent predictors of postoperative morbidity.</AbstractText>Under current anesthetic management, patients with advanced mitral regurgitation could go through fairly safe intraoperative course of noncardiac surgery despite minor complications. Their postoperative outcome was, however, complicated by extraordinarily high morbidity and mortality, especially in those with preexisting atrial fibrillation, higher surgical risk level, and lower left ventricular ejection fraction.</AbstractText> |
8,805 | Exercise capacity in atrial fibrillation: a substudy of the Sotalol-Amiodarone Atrial Fibrillation Efficacy Trial (SAFE-T). | Therapy for chronic atrial fibrillation (AF) focuses on rate versus rhythm control, but little is known about the effects of common therapeutic interventions on exercise tolerance in AF.</AbstractText>Six hundred fifty-five patients with chronic AF underwent maximal exercise testing at baseline and 8 weeks, 6 months, and 1 year after randomization to sotalol, amiodarone, or placebo therapy and attempted direct current cardioversion. Analyses of baseline determinants of exercise capacity, predictors of change in exercise capacity at 6 months and 1 year, and the short- and long-term effects of cardioversion on exercise capacity were made.</AbstractText>Age, obesity, and presence of symptoms accompanying AF were inversely associated with baseline exercise capacity, but these factors accounted for only 10% of the variance in exercise capacity. Patients most likely to benefit from cardioversion were those most limited initially, younger, not obese or hypertensive, and with an uncontrolled ventricular rate at baseline. Conversion to sinus rhythm (SR) resulted in significant reductions in resting (approximately 25 beat/min) and peak exercise (approximately 40 beat/min) heart rates at 6 months and 1 year (P < .001). Successful cardioversion improved exercise capacity by 15% at 8 weeks, and these improvements were maintained throughout the year. This improvement was observed both among those who maintained SR and those with intermittent AF.</AbstractText>Cardioversion resulted in a sustained improvement in exercise capacity over the course of 1 year, and this improvement was similar between those in SR and those with SR and recurrent AF. Patients most likely to improve with treatment tended to be younger and nonobese and have the greatest limitations initially.</AbstractText> |
8,806 | Comparative study between DD-HMM and RBF in ventricular tachycardia and ventricular fibrillation recognition. | This paper deals with automatic recognition of cardiac arrhythmias that require immediate electrical defibrillation therapy (ventricular fibrillation and ventricular tachycardia), through ECG (electrocardiogram) samples. The DD-HMM (discrete density hidden Markov model) and RBF (radial basis function) neural network algorithms were compared in the following aspects: precision, defined as correct recognition percentage and process time, defined as the delay since the ECG input until the result, indicating shock or non-shock events. The results show that RBF is more precise than DD-HMM but not so fast to evaluate. PhysioNet database files were used to train and to validate the algorithms. |
8,807 | Primary percutaneous coronary intervention and mild induced hypothermia in comatose survivors of ventricular fibrillation with ST-elevation acute myocardial infarction. | Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy for ST-elevation acute myocardial infarction (STEMI). In comatose survivors of cardiac arrest, mild induced hypothermia (MIH) improves neurological recovery. In the present study, we investigated feasibility and safety of combining primary PCI and MIH in comatose survivors of ventricular fibrillation with signs of STEMI after reestablishment of spontaneous circulation. Forty consecutive patients undergoing primary PCI and MIH from November 1, 2003 to December 31, 2005 were compared to 32 consecutive patients who underwent primary PCI but no MIH between January 1, 2000 and November 1, 2003. There were no significant differences between the MIH and no MIH groups in general characteristics, cardiac arrest circumstances and angiographic features. Except for decreases in heart rate during hypothermia interval, there was no difference between the MIH and no MIH groups in arterial pressure, peak arterial lactate (5.1 mmol/l versus 5.7 mmol/l; p = .56), need for vasopressors (65% versus 53%; p = .44), inotropes (48% versus 59%; p = .44), aortic balloon counterpulsation (20% versus 22%; p = .92), repeat cardioversion/defibrillation (30% versus 34%; p=.89) and use of antiarrhythmics (33% versus 53%; p = .13). There was also no difference in inspired oxygen requirements during mechanical ventilation and in renal function. Hospital survival with cerebral performance category 1 and 2 was significantly better in MIH group (55% versus 16%; p=.001). Our preliminary experience indicates that primary PCI and MIH are feasible and may be combined safely in comatose survivors of ventricular fibrillation with signs of STEMI. Such a strategy may improve survival with good neurological recovery. |
8,808 | Effects of the application of erythropoietin on cerebral recovery after cardiac arrest in rats. | After transient global cerebral ischaemia, selectively vulnerable areas of the brain show delayed neuronal degeneration. Recent data have demonstrated potent neuroprotective effects of the application of growth hormones like erythropoietin (EPO) after focal cerebral ischaemia. In order to assess possible effects of the application of EPO on cerebral recovery after cardiac arrest in rats, the vulnerable hippocampal CA-1 sector was investigated.</AbstractText>Thirty male Wistar rats were randomised into two groups (EPO versus placebo; n=15 per group). Cardiac arrest was induced by ventricular fibrillation during general anaesthesia. After 6 min of global cerebral ischaemia, animals were resuscitated by external chest compressions combined with defibrillation. Investigator blinded bolus application of EPO (5000 IE/kg bodyweight) and placebo was performed at three different time points, respectively: 5 min before cardiac arrest (i.v.; intravenously), 24h (i.p.; intraperitoneally) and 72 h (i.p.) after ischaemia. At 24h, 72 h and 7 days, animals were tested according to a neurological deficit score. After of reperfusion, coronal brain sections were analysed by TUNEL- and Nissl-staining. A caspase activity assay was done to determine antiapoptotic properties of EPO. Statistical analyses were done using ANOVA.</AbstractText>Neurological deficit scoring did not show differences between the groups. However, in all groups typical delayed neuronal degeneration could be found in the CA-1 sector. There was no difference in neuronal survival between the groups (viable neurons EPO (median [interquartile range]): 15.5 [10.1-21.3]; placebo: 16.8 [7.7-26.3]). Results from TUNEL-staining revealed no differences in the amount of apoptotic cell death between the groups (EPO: 71.2 [58.1-81.8]; placebo: 73.4 [67.8-78.2]). Caspase activity assays demonstrated a strong expression of general caspase activity as well as caspase-3 activity in the CA-1 sector and the nucleus reticularis thalami, without any differences between both groups.</AbstractText>Despite the well known neuroprotective properties of EPO in ischaemia induced neuronal degeneration, this study could not reveal any beneficial effects of EPO after global cerebral ischaemia due to cardiac arrest in rats.</AbstractText> |
8,809 | Pulmonary venous flow assessed by Doppler echocardiography in the management of atrial fibrillation. | Pulmonary venous blood flow (PVF) visualized by Doppler echocardiography exhibits a pulsatile behavior, which is related to left atrial pressure and function, mitral valve function, and left ventricular compliance. In atrial fibrillation (AF), the disappearance of atrial reverse flow, a decrease in systolic flow with a greater diastolic than systolic flow, a prolonged onset of systolic flow and the appearance of an early systolic reverse flow are characteristic findings. A reduction in systolic PVF expressed by reduced peak velocity, reduced velocity-time integral of systolic flow, and reduced systolic fraction of PVF has been found to be associated with reduced left atrial appendage flow, left atrial spontaneous echo contrast formation, frequency of AF paroxysms and propensity for AF recurrence following restoration of sinus rhythm. Ablation techniques targeting pulmonary vein ostia and adjacent left atrium are promising treatment options to cure AF. Monitoring the PVF response to and adjusting of ablation procedures has been suggested to optimize outcome and prevent complications such as pulmonary vein stenosis. In conclusion, assessment of PVF variables and patterns by Doppler echocardiography seems useful in the management of AF patients. Especially the reduction in systolic PVF may be used as marker for left atrial dysfunction which favors thrombus formation and AF reinitiation. Finally, PVF monitoring has the potential to an increasing role in AF ablation procedures. |
8,810 | Usefulness of the brain natriuretic peptide to atrial natriuretic peptide ratio in determining the severity of mitral regurgitation. | Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels were characterized in subjects with mitral regurgitation (MR).</AbstractText>Sixty-two cases of moderate or severe chronic MR were studied. The blood levels of neurohormonal factors were stratified by the known MR prognostic factors of New York Heart Association (NYHA) functional class, left ventricular end-diastolic diameters, left ventricular end-systolic diameter (LVDs), ejection fraction (EF), left atrial diameter and presence of atrial fibrillation (AF).</AbstractText>ANP levels were higher in NYHA class II and lower in classes I and III/IV (P=0.0206). BNP levels were higher in NYHA class II than class I (P=0.0355). The BNP/ANP ratio was significantly higher in NYHA classes II and III/IV than in class I (P=0.0007). To differentiate between NYHA classes I/II and III/IV, a cut-off BNP/ANP ratio of 2.97 produced a sensitivity of 78% and specificity of 87%. Compared with subjects in sinus rhythm, patients with AF had an enlarged left atrium and lower ANP levels. The BNP/ANP ratio correlated significantly with left atrial diameter, LVDs and EF (r=0.429, P=0.0017; r=0.351, P=0.0117; and r=-0.349, P=0.0122; respectively), and was significantly higher among all the known operative indications for MR tested (LVDs 45 mm or more, EF 60% or less, NYHA class II or greater and AF; P=0.0073, P=0.003, P=0.0102 and P=0.0149, respectively).</AbstractText>In chronic MR, levels of ANP and BNP, and the BNP/ANP ratio are potential indicators of disease severity.</AbstractText> |
8,811 | Continuous passive oxygen insufflation results in a similar outcome to positive pressure ventilation in a swine model of out-of-hospital ventricular fibrillation. | The deleterious effects of positive pressure ventilation may be prevented by substituting passive oxygen insufflation during advanced cardiac life support (ACLS) cardiopulmonary resuscitation (CPR).</AbstractText>We compared 24-h neurologically normal survival among three different ventilation scenarios for ACLS in a realistic swine model of out-of-hospital prolonged ventricular fibrillation (VF) cardiac arrest. No bystander CPR was provided during the first 8 min of untreated VF before the simulated arrival of an emergency medical system (EMS). Thirty-six swine were randomly assigned to one of three experimental groups. Group I (standard ventilation) was mechanically ventilated at 10 respirations per minute (RPM) at a tidal volume (TV) of 10 ml/kg with 100% oxygen. Group II (hyperventilation) was ventilated at 35 RPM at a TV of 20 ml/kg with 100% oxygen. In Group III (insufflation) animals, a nasal cannula was placed in the oropharynx to administer oxygen continuously at 10 l/min.</AbstractText>There was no significant difference in the 24h neurologically normal survival among groups (standard: 2/12, hyperventilation: 2/12, insufflation: 4/12; p=.53).</AbstractText>Passive insufflation may be an acceptable alternative to the currently recommended positive pressure ventilation during resuscitation efforts for out-of-hospital VF cardiac arrest. Potential advantages of this technique include: (1) easier to teach, (2) easier to administer, (3) prevention of the adverse effects of positive pressure ventilation and (4) allows EMS personnel to concentrate upon other critically important duties.</AbstractText> |
8,812 | Effects of a self-care program on the health-related quality of life of pacemaker patients: a nursing intervention study. | An experimental, multi-centre, randomized study with a nurse-led intervention was conducted with the aim of evaluating the effects on HRQoL of a 10-month self-care program for pacemaker patients. In the present study, there were no significant differences in HRQoL when comparisons were made between the experimental group and the control group. Results show two main findings for patients in the self-care program (n = 97; mean age 71 years): a significantly better HRQoL in terms of experiencing the symptoms that were the reason for pacemaker implantation, as having decreased or disappeared, and a higher level of perceived exertion in a 1 1/2-minute stair test compared with patients who had standard checkups (n = 115; mean age 73 years). It is important to actively include pacemaker patients in a self-care program while still in the acute phase in the hospital. Health care professionals should support the patient in a kind and professional manner by providing clear, relevant information, and planning a self-care program based on the nurse's assessment of the patient's needs. To enable patients to manage their life situations, training and continued education for health care professionals is necessary so that their efforts are based on a holistic approach to nursing care and recognition of the patient perspective, with emphasis on developing education and counselling for women, patients with atrial fibrillation/sick sinus disease, and patients whose pacemakers have ventricular pacing. |
8,813 | Cardiologic and neuromuscular co-morbidity influences mortality of patients with left ventricular hypertrabeculation/noncompaction: comparison with the Austrian general population. | Left ventricular hypertrabeculation/noncompaction (LVHT) is characterized by prominent trabeculations and intertrabecular recesses. LVHT patients suffer from heart failure, arrhythmias, chest pain and neuromuscular disorders (NMD). Data about long-term prognosis of LVHT are controversial. The aim of the study was to compare the mortality of LVHT patients with that of the Austrian general population and to assess which clinical and echocardiographic parameters influence mortality, and if mortality differs between patients with and without NMD.</AbstractText>In 86 patients LVHT was diagnosed echocardiographically between June 1995 and December 2004 (21 women, mean age 52 +/- 14, range 14 - 94 years). A specific NMD was diagnosed in 21, a NMD of unknown aetiology in 33, the neurologic investigation was normal in 13 and 19 patients refused examination. During a mean follow-up of 51 months (range 3 - 106 months) the mortality rate was 5.3%/year. Compared with the lifetable from the Austrian general population and considering the sex, the standardized mortality ratio (SMR) of LVHT patients was 5.584 (95% CI 3.562-8.754, p = 0.000). The SMR was high in LVHT patients with NMD of unknown aetiology, who refused the neurologic investigation, with heart failure, diabetes mellitus, syncope, ventricular ectopic beats, pathologic Q waves, left anterior hemiblock, atrial fibrillation and low-voltage ECG. Patients with more extensive LVHT had a high SMR.</AbstractText>Mortality in LVHT patients is higher than in the general population and cardiac and neurologic morbidity is the presumed cause for the increased mortality.</AbstractText> |
8,814 | Alimentary lipemia enhances procoagulatory effects of inflammation in patients with a history of acute myocardial infarction complicated by ventricular fibrillation. | Acute myocardial infarction, often occurring postprandially, can be complicated by ventricular fibrillation. The role of acute alimentary lipemia and inflammation in the occurrence of ventricular arrhythmias in acute myocardial infarction has not been described yet.</AbstractText>Before and 2 h after consumption of a defined fatty meal, blood samples of 27 patients with a history of acute myocardial infarction (AMI) were incubated with lipopolysaccharide (LPS). In 10 patients, AMI was complicated by ventricular fibrillation (VF), in 17 patients, AMI occurred without VF. CD40-ligand and CD62P expression on platelets, tissue-factor binding on monocytes and platelet-monocyte aggregates were measured with flow cytometry. Soluble CD40-ligand plasma levels were measured with an ELISA. With the meal, serum triglyceride levels increased from 211.85+/-94.60 mg/dl to 273.59+/-122.52 mg/dl (p=0.0002). LPS stimulation before the meal showed a non-significant tendency to increase platelet-monocyte aggregates and tissue factor on monocytes in both patient groups. LPS stimulation in acute alimentary lipemia significantly increased tissue-factor expression on monocytes in both patient groups and platelet-monocyte aggregates in patients with VF. Baseline plasma levels of soluble CD40L did not differ significantly between both groups. Acute alimentary lipemia significantly decreased total plasma levels of sCD40L, leading to a significantly lower level of sCD40L in patients with a history of VF.</AbstractText>Alimentary lipemia enhances procoagulatory effects of inflammatory stimulation in patients with a history of AMI complicated by ventricular fibrillation. These observations might reveal a mechanism for an increased risk of VF in acute coronary syndromes in a postprandial state.</AbstractText> |
8,815 | Incidence of early adverse events surrounding direct current cardioversion of persistent atrial fibrillation. A cohort study of practices. | To establish the incidence of early adverse events surrounding direct current (DC) cardioversion of persistent atrial fibrillation in an unselected patient cohort and to describe and analyse these complications.</AbstractText>Prospective study over a three-month period (February, March and April 2000). Outcome measures included all serious adverse events during the hospitalisation for DC cardioversion. Six hundred and eighty-four DC cardioversion were performed on 659 patients.</AbstractText>The rate of adverse events was 4.4% including 1.3% bradycardia, 0.3% ventricular arrhythmia, 0.3% QT increase, 1% serious haemorrhages, 0.4% death and 1.2% miscellaneous adverse events.</AbstractText>The perceived tolerance to DC cardioversion in atrial fibrillation should be amended with the 4.4% serious early adverse events.</AbstractText> |
8,816 | Brain natriuretic peptide detects cardiac abnormalities in mass screening. | Plasma brain natriuretic peptide (BNP) is elevated in asymptomatic patients with various cardiac abnormalities. We tested the hypothesis that measuring BNP is useful for detecting asymptomatic patients with cardiac abnormalities who are not identified by conventional health check-up programmes.</AbstractText>From 2001 to 2002, 6189 subjects (women 34.0%; mean age 56.6 years) underwent multiphasic health check-ups in our hospital, of which 4818 without cardiac abnormalities as revealed by the health check-up were enrolled in the present study. Their plasma concentrations of BNP were measured.</AbstractText>Plasma concentrations of BNP were higher than the normal reference upper limit of our hospital (21.3 pg mL(-1)) in 925 of the 4818 subjects. Echocardiography was performed in 471 subjects who were randomly selected from the 925 subjects with elevated BNP. Abnormal findings were detected in 174 subjects, comprising valvular heart disease in 83, systolic dysfunction in 10, diastolic dysfunction in 54, left ventricular hypertrophy in 41, left ventricular enlargement in 11, left atrial enlargement in 13 and paroxysmal atrial fibrillation in 3.</AbstractText>Since BNP measurement identifies additional subjects with cardiac abnormalities, it is useful for detecting asymptomatic cardiac abnormalities among apparently healthy subjects, and is suitable for use in high-quality mass screening.</AbstractText> |
8,817 | The worldwide social burden of atrial fibrillation: what should be done and where do we go? | Atrial fibrillation represents the most common arrhythmia in clinical practice and is associated with poor clinical outcome. Due to the aging of the population, the number of patients with atrial fibrillation will increase approximately 2.5-fold by the year 2050. Comparison studies between rhythm control and rate control strategies in management of atrial fibrillation have been biased by the limited efficacy of antiarrhythmic drugs in keeping an actual rhythm control, while their adverse effects may offset their antiarrhythmic benefits. In patients who are candidates for anti-bradycardia pacing atrial and dual chamber pacing have been demonstrated to be superior to single chamber ventricular pacing in reducing atrial fibrillation recurrences and in preventing progression to permanent atrial fibrillation. Algorithms aimed either to prevent atrial fibrillation relapsing or to interrupt new onset tachycardias early have been demonstrated to be safe and effective, but clinical studies which investigated their impact on clinical end points showed inconsistent results. Multifunction devices capable of delivering atrial shock have been demonstrated useful in patients who were candidates for ICD implantation because of life-threatening ventricular arrhythemias. Preliminary studies suggested a potential role of these devices in selected patients with brady-tachy syndrome without prior ventricular arrhythmias. Radiofrequency catheter ablation techniques of atrial fibrillation have been increasingly used in the last years. Both pulmonary vein ablation and left atrial circumferential ablation showed encouraging clinical results with 70-80% of patients free from atrial fibrillation with or without prior ineffective antiarrhythmic drugs. In the future, strategies to deal with the huge worldwide burden of atrial fibrillation will include a wider application of non pharmacological therapies as well as a big investment in basic and clinical research. New and more effective antiarrhythmic drugs are needed. Genetic studies will deeply change understanding and therapy of atrial fibrillation. |
8,818 | Comparison of ventricular arrhythmia burden, therapeutic interventions, and survival, in patients < 75 and patients >or= 75 years of age treated with implantable cardioverter defibrillators. | Implantable cardioverter defibrillators (ICD) reduce arrhythmic mortality in a wide range of patients with poor left ventricular (LV) function. However, whether ICD therapy is equally effective in younger and older patients remains uncertain. To address this question, we compared ICD-documented ventricular tachyarrhythmia burden in patients < 75 years of age (Group 1) and >or= 75 years of age (Group 2).</AbstractText>Data were obtained from 208 consecutive ICD-treated patients: 159 Group 1 (mean age 59 +/- 12), and 49 Group 2 (mean age 79 +/- 3). Demographic and clinical features including presenting arrhythmias, LV ejection fraction, and nature of heart disease were similar. Medications were comparable except that amiodarone use was more frequent in Group 2.</AbstractText>The numbers of combined ventricular tachycardia (VT) and ventricular fibrillation (VF) episodes per month were 0.4 +/- 2 and 0.3 +/- 2 for groups 1 and 2, respectively (P = 0.7). Individually, VT episodes per month were 0.4 +/- 2 and 0.3 +/- 2 (P = 0.7) and VF episodes per month were 0.003 +/- 0.01 and 0.03 +/- 0.2 (P = 0.2) for the two groups, respectively. The mean duration and average cycle length of arrhythmias were 3.1 +/- 20.4 s and 275 +/- 119 ms in Group 1, and 6 +/- 45 s and 285 +/- 114 ms in Group 2 (P values, 0.6 and 0.8). The mean time between the ICD implantation and the first episode of a device-treated arrhythmia was comparable in the two groups. Thirty-six patients died during follow-up; 22 (14%) Group 1 and 14 (29%) Group 2 (P = 0.02), almost exclusively on a non-sudden cardiac basis. Thus, despite higher ultimate mortality in older patients, both the nature and characteristics of spontaneous arrhythmia recurrence, and the time to first apparently beneficial therapy, were similar during follow-up in the two groups.</AbstractText>In terms of reversing potentially life-threatening arrhythmias, the rationale for ICD therapy is comparable in older and younger individuals.</AbstractText> |
8,819 | Antihypoxic, cardioprotective, and antifibrillation effects of a combined adaptogenic plant preparation. | The course of treatment with combined adaptogenic plant preparation Tonizid improved mouse survival under conditions of hypobaric hypoxia and reduced the necrotic zone/risk zone ratio during ischemia and reperfusion in rats under conditions of artificial ventilation. The test preparation decreased the size of the necrotic zone, but had no effect on the size of the risk zone. Tonizid prevented ventricular fibrillation during coronary occlusion and exhibited antihypoxic, cardioprotective, and antifibrillation properties. |
8,820 | Abolition of reperfusion-induced arrhythmias in hearts from thiamine-deficient rats. | Extensive work has been done regarding the impact of thiamine deprivation on the nervous system. In cardiac tissue, chronic thiamine deficiency is described to cause changes in the myocardium that can be associated with arrhythmias. However, compared with the brain, very little is known about the effects of thiamine deficiency on the heart. Thus this study was undertaken to explore whether thiamine deprivation has a role in cardiac arrhythmogenesis. We examined hearts isolated from thiamine-deprived and control rats. We measured heart rate, diastolic and systolic tension, and contraction and relaxation rates. Whole cell voltage clamp was performed in rat isolated cardiac myocytes to measure L-type Ca(2+) current. In addition, we investigated the global intracellular calcium transients by using confocal microscopy in the line-scan mode. The hearts from thiamine-deficient rats did not degenerate into ventricular fibrillation during 30 min of reperfusion after 15 min of coronary occlusion. The antiarrhythmogenic effects were characterized by the arrhythmia severity index. Our results suggest that hearts from thiamine-deficient rats did not experience irreversible arrhythmias. There was no change in L-type Ca(2+) current density. Inactivation kinetics of this current in Ca(2+)-buffered cells was retarded in thiamine-deficient cardiac myocytes. The global Ca(2+) release was significantly reduced in thiamine-deficient cardiac myocytes. The amplitude of caffeine-releasable Ca(2+) was lower in thiamine-deficient myocytes. In summary, we have found that thiamine deprivation attenuates the incidence and severity of postischemic arrhythmias, possibly through a mechanism involving a decrease in global Ca(2+) release. |
8,821 | Cardiac sympathetic nerve activity and ventricular fibrillation during acute myocardial infarction in a conscious sheep model. | The association between cardiac sympathetic nerve activity (CSNA) and ventricular fibrillation (VF) during acute myocardial infarction (MI) has not been assessed in conscious animal models. During the first 60 min post-MI, mean blood pressure (MBP), heart rate (HR), and CSNA were recorded continuously in 20 conscious sheep. Resistant sheep (group A, n = 10) were compared with susceptible sheep (group B, n = 10) who developed fatal VF (n = 7) or sustained ventricular tachycardia (VT, n = 3). The mean time to VF/VT was 28.1 +/- 3.3 min. In group B, MBP, HR, and CSNA were averaged at each consecutive minute from baseline at 14 min before the onset of VF/VT and compared with time-matched values in group A. When compared with those of group A, indexes of CSNA burst size increased before the onset of VF/VT: burst area/minute (F(13,208) = 2.17, P = 0.01) and burst area/100 beats (F(13,208) = 1.86, P = 0.04). By contrast, burst frequency indexes were not significantly different: burst frequency (F(13,208) = 1.6, P = 0.09) and burst incidence (F(13,208) = 1.48, P = 0.13). In group A, CSNA burst area/min and burst area/100 beats did not change across this time period (F(13,117) = 0.97, P = 0.5, F(13,117) = 0.96, P = 0.7) but increased with time in group B (F(13,91) = 2.3, P = 0.01; and F(13,91) = 2.25, P = 0.01). Between-group comparisons demonstrated no differences in time of onset of ventricular ectopic beats: 18.5 (range 12-24) in group A versus 15.0 min (range 7-22) in group B (Mann-Whitney U-test, P = 0.09). Pre-MI baroreflex slopes were similar: R-R slopes were 11.8 +/- 2 and 15.6 +/- 1.1 ms/mmHg (t(18) = -1.6, P = 0.14). CSNA slopes were -1.8 +/- 0.3 and -2.3 +/- 0.2%/mmHg (t(18) = -1.4, P = 0.2). An early increase in CSNA burst size indexes (before 60 min post-MI), mediated by an excitatory sympathetic reflex, is important in the genesis of VF/VT. |
8,822 | Optical mapping of Langendorff-perfused human hearts: establishing a model for the study of ventricular fibrillation in humans. | Our objective was to establish a novel model for the study of ventricular fibrillation (VF) in humans. We adopted the established techniques of optical mapping to human ventricles for the first time to determine whether human VF is the result of wave breaks and singularity point formation and is maintained by high-frequency rotors and fibrillatory conduction. We describe the technique of acquiring optical signals in human hearts during VF, their characteristics, and the feasibility of possible analyses that could be performed to elucidate mechanisms of human VF. We used explanted hearts from five cardiomyopathic patients who underwent transplantation. The hearts were Langendorff perfused with Tyrode solution (95% O(2)-5% CO(2)), and the potentiometric dye di-4-ANEPPS was injected as a bolus into the coronary circulation. Fluorescence was excited at 531 +/- 20 nm with a 150-W halogen light source; the emission signal was long-pass filtered at 610 nm and recorded with a mapping camera. Fractional change of fluorescence varied between 2% and 12%. Average signal-to-noise ratio was 40 dB. The mean velocity of VF wave fronts was 0.25 +/- 0.04 m/s. Submillimetric spatial resolution (0.65-0.85 mm), activation mapping, and transformation of the data to phase-based analysis revealed reentrant, colliding, and fractionating wave fronts in human VF. On many occasions the VF wave fronts were as large as the entire vertical length (8 cm) of the mapping field, suggesting that there are a limited number of wave fronts on the human heart during VF. Phase transformation of the optical signals allowed the first demonstration ever of phase singularity point, wave breaks, and rotor formation in human VF. This method provides opportunities for potential analyses toward elucidation of the mechanisms of VF and defibrillation in humans. |
8,823 | Estimation of the duration of ventricular fibrillation using ECG single feature analysis. | The duration of untreated ventricular fibrillation (VF) is of paramount importance for CPR success. Moreover, therapeutic interventions taking into account the interval between cardiac arrest onset and initiation of CPR improve outcome. This study was performed to investigate whether VF feature analysis could be used to estimate the duration of VF in patients with out-of-hospital cardiac arrest. Demographic data recorded according to the Utstein guidelines and ECG recordings of 376 cardiac arrest patients from three European areas were analysed. Ten features in the time and frequency domain derived from different sub-bands of the initial VF ECG (n=127) were evaluated. The correlation between VF ECG features and cardiac arrest times was investigated using Pearson's correlation coefficient in a subset of 40 patients with reliably estimated downtimes and artefact-free initial VF tracings. No significant correlation (p<.05) between any of the VF ECG features and downtime could be found. The duration of cardiac arrest could not be estimated reliably from human VF ECG single feature analysis. |
8,824 | Transient ventricular fibrillation and myosin heavy chain isoform profile. | The present paper deals with spontaneous ventricular defibrillation in mammals and the possibility to facilitate its occurrence. Clinical and experimental evidence suggest that in the majority of cases, ventricular fibrillation (VF) is permanent, requiring defibrillation by electric shock. However, a growing number of reports show that VF can terminate spontaneously in various mammals, including human beings. The mechanisms involved in spontaneous ventricular defibrillation are controversial. Available reports imply that intracellular Ca2+ overload is the key event triggering VF and preventing its reversal. Since the sarcoplasmatic reticulum is the main intracellular Ca2+ regulating organelle and the activity of the cardiac SR Ca2+ ATPase (SERCA 2a) is its prime element of Ca2+ sequestration, spontaneous ventricular defibrillation likely requires high level of SERCA 2a activity. We suggest that mammalian hearts with high SERCA 2a activity defibrillate spontaneously and those with low activity only after its enhancement. Since high SERCA 2a activity is co-expressed with the myosin heavy chain (MHC) isoform V1, we assumed that those hearts preferentially expressing V1 MHC are able to defibrillate spontaneously. Hearts with small amounts of V1 MHC and correspondingly lower level of SERCA 2a activity can only defibrillate following administration of compounds that augment SERCA 2a activity and prevent intracellular Ca2+ overload. |
8,825 | Aborted sudden cardiac death revealing isolated noncompaction of the left ventricle in a patient with wolff-Parkinson-white syndrome. | Isolated noncompaction of the left ventricle (INLV) is a rare congenital disorder associated with multiple cardiac arrhythmias. We report a case of INLV revealed by ventricular fibrillation in a patient with Wolff-Parkinson-White syndrome. Because of the persistence of inducible ventricular arrhythmias after ablation of the accessory pathway, implantation of an ICD was decided. |
8,826 | Mapping and ablation of trigger premature ventricular contractions in a case of electrical storm associated with ischemic cardiomyopathy. | We report a case of polymorphic ventricular tachycardia and ventricular fibrillation (PVT/VF) storm associated with ischemic cardiomyopathy (ICM). The electrocardiogram (ECG) monitor revealed frequent premature ventricular contractions (PVCs) initiated PVT/VF. Electroanatomic mapping revealed the plausible origins of PVCs were located in the scar border zone at the posterior septum of the left ventricle. Purkinje-like potentials (PLPs) always preceded PVCs and a decremental property for the PLPs and infarcted myocardium junction was observed. Ablation at these sites eliminated both PVCs and PVT/VF. |
8,827 | Selective myocardial isolation and ventricular fibrillation. | Few experimental studies have analyzed the effects of selective radiofrequency (RF) lesions upon ventricular fibrillation (VF). The RF-induced isolation of selected zones would make it possible to determine whether these zones are essential for existence of the arrhythmia.</AbstractText>In 31 Langendorff-perfused rabbit hearts, the characteristics and inducibility of VF were analyzed before and after the induction of RF lesions comprising: (1) the posterior zone of the septum and of the walls of both ventricles (n = 10); (2) the anterior zone of the septum and of the walls of both ventricles (n = 11); and (3) the midseptal zone (n = 10).</AbstractText>Complete isolation of the zone encompassed by the lesions was obtained in 5, 6, and 5 experiments of series 1, 2, and 3, respectively. In these experiments, the arrhythmia was only induced from within the zone encompassed by the lesions in one experiment belonging to series 2 (P < 0.05 with respect to baseline). In contrast, in all but one of the cases in series 2, VF could be induced from outside the isolated zone (ns vs baseline). Partial isolation was obtained in five experiments of each series. In these experiments, on pacing from within the partially isolated zone, sustained VF was not induced in any experiment (P < 0.05 with respect to baseline), while in all cases VF could be induced on pacing from the external zone (ns vs baseline).</AbstractText>In the experimental model used, the three zones studied were not essential for maintaining VF. In most cases, their partial or total isolation avoided inducibility of the arrhythmia in those zones, though not in the remaining myocardium.</AbstractText> |
8,828 | [Clinical application of brain hypothermia therapy for acute brain insults]. | Brain hypothermia therapy has been expected to lead to good neurological outcome in acute brain insults. There are a few positive results which have been proven by multicenter randomized clinical trials (RCT) in the cardiopulmonary arrest (CPA) in patients with ventricular fibrillation. Among these clinical trials, early application of hypothermia, maintenance of cerebral blood flow during hypothermia therapy and prevention of quick rewarming are pointed out to result in good outcome from clinical experiences. For brain hypothermia therapy to become an effective method for acute brain insults, indications, brain oriented intensive cares and biomarkers for the therapy must be established. RCT in acute brain insults beside CPA victims are needed in the near future. |
8,829 | ALCAPA, a possible reason for mitral insufficiency and heart failure in young patients. | ALCAPA, anomalous origin of the left coronary artery from the pulmonary artery is a rare congenital disease. We have from 1990 to 2003 operated on seven patients in our clinic. The objective of this study was to describe our experience of treating the condition and to remind other doctors of it as a possible diagnosis.</AbstractText>The patients were identified by a retrospective review of our clinical records.</AbstractText>Symptoms and signs varied from discomfort and pathologic heart murmur to ventricular fibrillation. All patients were operated on by use of cardiopulmonal bypass. Two died postoperatively within one week, two were reoperated later on because of pulmonary artery stenosis.</AbstractText>ALCAPA should be suspected if a young patient with no previous history of heart failure presents with dyspnoe, chest pain or dysrhythmia. ALCAPA must be excluded by coronary angiography in younger patients with mitral insufficiency and no other morphological findings. Patients diagnosed early and operated on have a good prognosis.</AbstractText> |
8,830 | Effects of the association of dual-site dynamic atrial overdrive and atenolol in preventing recurrent atrial fibrillation. | Evaluate the effects of optimized atrial stimulation--OAS (dual-site atrial pacing, heart rate above the intrinsic rate, and specific functional algorithm), and the use of atenolol in preventing recurrent atrial fibrillation (AF). Primary endpoint: to quantify the rate of AF episodes. Secondary endpoints: assessment of quality of life, specific cardiovascular symptoms, rate of hospital admissions, rate of electrical and pharmacological cardioversions, and adverse cardiac events.</AbstractText>Twenty-five patients with recurrent episodes of paroxysmal AF and sinus node disease had dual-site atrial and ventricular pacemakers implanted, and were started on atenolol, 100 mg/day. Next, they were randomized to two groups: GROUP I: first three months with OAS and the specific pacing algorithm (DAO) turned on, and three more months with the algorithm off. GROUP II: the inverse sequence to GROUP I. The pacing mode chosen was DDDR, and after three months patients underwent clinical and electronic evaluations of the stimulation system by: automatic mode switch (AMS), 24-hour Holter monitoring, Doppler echocardiogram, and SF-36 questionnaire. Following, a crossover comparison took place, and a new assessment was performed six months later.</AbstractText>When compared to the group with the algorithm turned off, OAS patients had lower rates of: AF/week (p < 0.001); AMS activations (p < 0.01); hospitalizations (p < 0.001); cardioversions (p < 0.001), and higher scores on the physical and mental components of quality of life.</AbstractText>The hybrid therapy adopted, OAS associated with the use of atenolol, reduced the rate of recurrent AF and improved the clinical-functional status of patients with symptomatic bradyarrhythmias.</AbstractText> |
8,831 | Unusual etiology of acute lung injury in a patient with acute myocardial infarction. | The known etiology of acute lung injury (ALI) is immensely varied and includes severe burns and trauma. Electrical and multiple defibrillation shocks can cause cutaneous burns and blunt chest trauma. The literature contains no reference to the association between ALI and cutaneous burns or blunt chest trauma secondary to defibrillation.</AbstractText>To report a patient with Acute Myocardial Infarction (AMI) who developed ALI possibly due to multiple defibrillation shocks.</AbstractText>A 51 year-old man with AMI presenting with multiple episodes of ventricular fibrillation (VF) treated with defibrillation and subsequently cutaneous burns. He developed soon afterward respiratory failure due to ALI. Cardiac failure or any known etiology of ALI was ruled out. Medical treatment included oxygen therapy, cardiac frequency control with betablockers, in addition to antiplatelet therapy. Clinical and oxymetric evolution was favourable, with resolution of the radiological infiltrates. The patient was discharged alive and in good condition at the 19th day after admission. The authors discuss possible mechanisms of ALI development by multiple defibrillation shocks.</AbstractText>In the absence of any other known etiology, multiple defibrillation shocks may have played a role in the genesis of ALI in our patient, but this remains speculative.</AbstractText> |
8,832 | Gap junctional uncoupling plays a trigger role in the antiarrhythmic effect of ischaemic preconditioning. | The aim of this study was to determine whether uncoupling of gap junctions (GJ) prior to ischaemia would modify the antiarrhythmic effect of ischaemic preconditioning (PC) in a canine model of ischaemia/reperfusion.</AbstractText>Twenty control dogs, anaesthetised with chloralose and urethane, were thoracotomised and subjected either to a 25 or a 60 min occlusion of the left anterior descending (LAD) coronary artery. This prolonged ischaemia was preceded 20 min earlier by a single 5 min LAD occlusion in preconditioned dogs (PC group; n=14) or by a 20 min intracoronary infusion of 50 microM carbenoxolone (CBX group; n=15), a relatively selective uncoupler of gap junctions. CBX was also infused in PC dogs (CBX+PC group; n=11). The severity of ischaemia (epicardial ST-segment changes, inhomogeneity of electrical activation) and of ventricular arrhythmias, such as ventricular premature beats (VPBs), ventricular tachycardiac (VT) episodes and ventricular fibrillation (VF), as well as changes in electrical impedance was assessed throughout the experiments. Connexin 43 (Cx43) phosphorylation and GJ permeability were determined at the end of the occlusion periods.</AbstractText>Compared to the controls PC and, interestingly, CBX markedly reduced, e.g. the total number of VPBs (440+/-104 vs 47+/-11 and 60+/-15; P<0.05) during the prolonged occlusion. This protection was, however, attenuated when CBX was infused in PC dogs (VPBs: 203+/-32). Changes in electrical impedance, GJ permeability and Cx43 dephosphorylation were significantly less in the PC and CBX groups than in the controls but these were again increased in the CBX+PC group.</AbstractText>Uncoupling of GJs prior to ischaemia either by PC or CBX preserves the electrical coupling of cells and results in an antiarrhythmic effect during a subsequent ischaemic insult, indicating that a partial closure of gap junctions may play a trigger role in the protection. In contrast, when CBX is administered in PC dogs the protection both against GJ uncoupling and arrhythmias is markedly attenuated, suggesting that the antiarrhythmic protection, at least in part, is mediated through GJs.</AbstractText> |
8,833 | Prevalence of markers of heart failure in patients with atrial fibrillation and the effects of ximelagatran compared to warfarin on the incidence of morbid and fatal events: a report from the SPORTIF III and V trials. | Patients with atrial fibrillation (AF) who also have heart failure have a worse outcome but the diagnosis of heart failure is often missed.</AbstractText>To compare the effects of warfarin and ximelagatran on morbidity and mortality in patients with AF with and without markers of heart failure.</AbstractText>Data for 7329 patients from two randomised controlled trials were merged. Treatment with loop diuretics or the presence of left ventricular dysfunction, were used as markers of possible heart failure. The 3555 (49%) patients with markers of heart failure had higher composite event rates on warfarin (10.81% per year [py] [95% CI 9.59 to 12.13]) compared to the 3774 (51%) patients without markers of heart failure (4.18% py [95% CI 3.44 to 5.01]). The composite event rate was lower on ximelagatran overall (6.18% py [95% CI 5.51 to 6.89] versus 7.34% py [95% CI 6.63 to 8.10] on warfarin; P=0.0219 for the difference) with similar effects in each trial and in patients with and without markers of heart failure, mainly due to fewer heart-failure events (hazard ratio 0.69 [95% CI 0.54 to 0.87]; P<0.001).</AbstractText>Patients with markers of heart failure, even if the diagnosis is not well established, are at increased risk of thromboembolic events and might be targeted for more effective antithrombotic therapy. This might include patients in sinus rhythm as well as AF.</AbstractText> |
8,834 | Retrograde flush following topical cooling is superior to preserve the non-heart-beating donor lung. | The use of non-heart-beating donors (NHBD) has been propagated as an alternative to overcome the scarcity of pulmonary grafts. Formation of microthrombi after circulatory arrest, however, is a major concern for the development of reperfusion injury. We looked at the effect and the best route of pulmonary flush following topical cooling in NHBD.</AbstractText>Non-heparinized pigs were sacrificed by ventricular fibrillation and divided into three groups (n=6 per group). After 1h of in situ warm ischaemia and 2.5h of topical cooling, lungs in group I were retrieved unflushed (NF). In group II, lungs were explanted following an anterograde flush (AF) through the pulmonary artery with 50 ml/kg Perfadex (6 degrees C). Finally, in group III, lungs were retrieved after an identical but retrograde flush (RF) via the left atrium. Flush effluent was sampled at intervals to measure haemoglobin concentration. Performance of the left lung was assessed during 60 min in our ex vivo reperfusion model. Wet-to-dry weight ratio (W/D) of both lungs was calculated as an index of pulmonary oedema. IL-1beta and TNF-alpha protein levels in bronchial lavage fluid from both lungs were compared between groups.</AbstractText>Haemoglobin concentration (g/dl) was higher in the first effluent in RF versus AF (3.4+/-1.1 vs 0.6+/-0.1; p<0.05). Pulmonary vascular resistance (dynes x s x cm(-5)) was 975+/-85 RF versus 1567+/-98 AF and 1576+/-88 NF at 60 min of reperfusion (p<0.001). Oxygenation (mmHg) and compliance (ml/cmH(2)O) were higher (491+/-44 vs 472+/-61 and 430+/-33 NS, 22+/-3 vs 19+/-3 and 14+/-1 NS, respectively) and plateau airway pressure (cmH(2)O) was lower (11+/-1 vs 13+/-1 and 13+/-1 NS) after RF versus AF and NF, respectively. No differences in cytokine levels or in W/D ratios were observed between groups after reperfusion. Histology demonstrated microthrombi more often present after AF and NF compared to RF.</AbstractText>Retrograde flush of the lung following topical cooling in the NHBD results in a better washout of residual blood and microthrombi and subsequent reduced pulmonary vascular resistance upon reperfusion.</AbstractText> |
8,835 | Drug administration in animal studies of cardiac arrest does not reflect human clinical experience. | To date, there is no evidence showing a benefit from any advanced cardiac life support (ACLS) medication in out-of-hospital cardiac arrest (OOHCA), despite animal data to the contrary. One explanation may be a difference in the time to first drug administration. Our previous work has shown the mean time to first drug administration in clinical trials is 19.4min. We hypothesized that the average time to drug administration in large animal experiments occurs earlier than in OOHCA clinical trials.</AbstractText>We conducted a literature review between 1990 and 2006 in MEDLINE using the following MeSH headings: swine, dogs, resuscitation, heart arrest, EMS, EMT, ambulance, ventricular fibrillation, drug therapy, epinephrine, vasopressin, amiodarone, lidocaine, magnesium, and sodium bicarbonate. We reviewed the abstracts of 331 studies and 197 full manuscripts. Exclusion criteria included: non-peer reviewed, all without primary animal data, and traumatic models. From these, we identified 119 papers that contained unique information on time to medication administration. The data are reported as mean, ranges, and 95% confidence intervals. Mean time to first drug administration in animal laboratory studies and clinical trials was compared with a t-test. Regression analysis was performed to determine if time to drug predicted ROSC.</AbstractText>Mean time to first drug administration in 2378 animals was 9.5min (range 3.0-28.0; 95% CI around mean 2.78, 16.22). This is less than the time reported in clinical trials (19.4min, p<0.001). Time to drug predicted ROSC (odds ratio 0.844; 95% CI 0.738, 0.966).</AbstractText>Shorter drug delivery time in animal models of cardiac arrest may be one reason for the failure of animal studies to translate successfully into the clinical arena.</AbstractText> |
8,836 | Spiral-wave dynamics depend sensitively on inhomogeneities in mathematical models of ventricular tissue. | Every sixth death in industrialized countries occurs because of cardiac arrhythmias such as ventricular tachycardia (VT) and ventricular fibrillation (VF). There is growing consensus that VT is associated with an unbroken spiral wave of electrical activation on cardiac tissue but VF with broken waves, spiral turbulence, spatiotemporal chaos and rapid, irregular activation. Thus spiral-wave activity in cardiac tissue has been studied extensively. Nevertheless, many aspects of such spiral dynamics remain elusive because of the intrinsically high-dimensional nature of the cardiac-dynamical system. In particular, the role of tissue heterogeneities in the stability of cardiac spiral waves is still being investigated. Experiments with conduction inhomogeneities in cardiac tissue yield a variety of results: some suggest that conduction inhomogeneities can eliminate VF partially or completely, leading to VT or quiescence, but others show that VF is unaffected by obstacles. We propose theoretically that this variety of results is a natural manifestation of a complex, fractal-like boundary that must separate the basins of the attractors associated, respectively, with spiral breakup and single spiral wave. We substantiate this with extensive numerical studies of Panfilov and Luo-Rudy I models, where we show that the suppression of spiral breakup depends sensitively on the position, size, and nature of the inhomogeneity. |
8,837 | Method for quantifiying conduction velocity during ventricular fibrillation. | Velocity of propagation of electrical excitation in the heart is important for the understanding of complex arrhythmias such as ventricular fibrillation (VF). In this paper, we present a method to estimate the conduction velocity of electrical activation wavefronts that are defined to be a particular isovalue of any scalar field, such as electrical activation times, electrical phase, or indeed any other quantity that can be used to determine excitation wavefronts. This general method is based on tracking trajectories of material points that are assumed to be embedded within the wavefronts, whilst the direction of propagation is assumed to be perpendicular to the wavefront. We have derived an explicit expression for the conduction velocity in terms of the spatiotemporal gradients of the scalar field used to define wavefronts. Moreover, although it is often difficult to use activation times to compute conduction velocities during complex VF, we show that other scalar fields such as detrended voltage or electrical phase, which can faithfully represent the electrical activity during fibrillatory conduction, can be used to determine conduction velocities. We demonstrate the application of our method to determine conduction velocities from contact mapping recordings over the entire epicardial surface of the fibrillating pig heart. |
8,838 | Prevalence of Brugada sign in patients presenting with palpitation in southern Iran. | Brugada syndrome is a cardiac channel abnormality that is associated with a high risk of ventricular fibrillation and sudden cardiac death and characterized by an electrocardiographic pattern of right bundle branch block and transient or persistent ST-segment elevation in leads V1-V3. No data regarding the frequency of Brugada syndrome exist in an Iranian population. The aim of this study was to determine the frequency of Brugada-type ECG pattern in southern Iran.</AbstractText>All patients presenting with palpitation were enrolled in the study. A Brugada-type ECG pattern was determined according to the criteria recommended by European Heart Association Molecular Basis of Arrhythmias Study Group. A total of 3895 patients (mean age 38.2 +/- 11.9 years, 54% women) met all study criteria. One hundred patients (2.56%) had Brugada-type ECG pattern. Of these, 21 patients (0.54%) had definite Brugada sign (Type 1 or Types 2 and 3 with conversion to Type 1 following procainamide test). Of 21 patients with definite Brugada sign, eight had Brugada syndrome, four had history of syncope, two had coved-type ECG in the family, one had polymorphic ventricular tachycardia, and one had history of sudden cardiac death in the family. Five patients underwent ICD implantation. The incidence of a Brugada-type ECG pattern was 2.43% in subjects between 17 and 30 years and 0.13% in subjects >30 years (P = 0.01).</AbstractText>Frequency of Brugada sign in an Iranian population presenting with palpitation is greater than some European countries and lower than a Japanese urban population.</AbstractText> |
8,839 | Cancellation of ventricular activity in the ECG: evaluation of novel and existing methods. | Due to the much higher amplitude of the electrical activity of the ventricles in the surface electrocardiogram (ECG), its cancellation is crucial for the analysis and characterization of atrial fibrillation. In this paper, two different methods are proposed for this cancellation. The first one is an average beat subtraction type of method. Two sets of templates are created: one set for the ventricular depolarization waves and one for the ventricular repolarization waves. Next, spatial optimization (rotation and amplitude scaling) is applied to the QRS templates. The second method is a single beat method that cancels the ventricular involvement in each cardiac cycle in an independent manner. The estimation and cancellation of the ventricular repolarization is based on the concept of dominant T and U waves. Subsequently, the atrial activities during the ventricular depolarization intervals are estimated by a weighted sum of sinusoids observed in the cleaned up segments. ECG signals generated by a biophysical model as well as clinical ECG signals are used to evaluate the performance of the proposed methods in comparison to two standard ABS-based methods. |
8,840 | Taser dart-to-heart distance that causes ventricular fibrillation in pigs. | Electromuscular incapacitating devices (EMDs), such as Tasers, deliver high current, short duration pulses that cause muscular contractions and temporarily incapacitate the human subject. Some reports suggest that EMDs can kill. To help answer the question, "Can the EMD directly cause ventricular fibrillation (VF)?", ten tests were conducted to measure the dart-to-heart distance that causes VF in anesthetized pigs [mass = 64 kg +/- 6.67 standard deviation (SD)] for the most common X26 Taser. The dart-to-heart distance that caused VF was 17 mm +/- 6.48 (SD) for the first VF event and 13.7 mm +/- 6.79 (SD) for the average of the successive VF events. The result shows that when the stimulation dart is close enough to the heart, X26 Taser current will directly trigger VF in pigs. Echocardiography of erect humans shows skin-to-heart distances from 10 to 57 mm (dart-to-heart distances of 1-48 mm). These results suggest that the probability of a dart on the body landing in 1 cm2 over the ventricle and causing VF is 0.000172. |
8,841 | BIPHASIC Trial: a randomized comparison of fixed lower versus escalating higher energy levels for defibrillation in out-of-hospital cardiac arrest. | There is little clear evidence as to the optimal energy levels for initial and subsequent shocks in biphasic waveform defibrillation. The present study compared fixed lower- and escalating higher-energy regimens for out-of-hospital cardiac arrest.</AbstractText>The Randomized Controlled Trial to Compare Fixed Versus Escalating Energy Regimens for Biphasic Waveform Defibrillation (BIPHASIC Trial) was a multicenter, randomized controlled trial of 221 out-of-hospital cardiac arrest patients who received > or = 1 shock given by biphasic automated external defibrillator devices that were randomly programmed to provide, blindly, fixed lower-energy (150-150-150 J) or escalating higher-energy (200-300-360 J) regimens. Patient mean age was 66.0 years; 79.6% were male. The cardiac arrest was witnessed in 63.8%; a bystander performed cardiopulmonary resuscitation in 23.5%; and initial rhythm was ventricular fibrillation/ventricular tachycardia in 92.3%. The fixed lower- and escalating higher-energy regimen cases were similar for the 106 multishock patients and for all 221 patients. In the primary analysis in multishock patients, conversion rates differed significantly (fixed lower, 24.7%, versus escalating higher, 36.6%; P=0.035; absolute difference, 11.9%; 95% CI, 1.2 to 24.4). Ventricular fibrillation termination rates also were significantly different between groups (71.2% versus 82.5%; P=0.027; absolute difference, 11.3%; 95% CI, 1.6 to 20.9). For the secondary analysis of first shock success, conversion rates were similar between the fixed lower and escalating higher study groups (38.4% versus 36.7%; P=0.92), as were ventricular fibrillation termination rates (86.8% versus 88.8%; P=0.81). There were no distinguishable differences between regimens for survival outcomes or adverse effects.</AbstractText>This is the first randomized trial to compare fixed lower and escalating higher biphasic energy regimens in out-of-hospital cardiac arrest, and it demonstrated higher rates of ventricular fibrillation conversion and termination with an escalating higher-energy regimen for patients requiring multiple shocks. These results suggest that patients in ventricular fibrillation benefit from higher biphasic energy levels if multiple defibrillation shocks are required.</AbstractText> |
8,842 | [Arrhythmias and cardiac electrophysiology]. | In the past few months, numerous articles have been published on arrhythmias and cardiac electrophysiology. As in previous years, a substantial proportion of researchers have concentrated on atrial fibrillation, both on catheter ablation of chronic and paroxysmal atrial fibrillation and on the development of new approaches to thromboembolism prophylaxis. The feasibility of atrial fibrillation ablation by remote control has been demonstrated and a step-wise approach to ablation has been proposed, which appears to improve outcome and reduce lesion size. In addition, multicenter randomized trials have shown that the improvements in functional class and left ventricular ejection fraction achieved by ablation in patients with chronic atrial fibrillation are greater than those resulting from pharmacological treatment. New strategies are being developed to improve the selection of patients for defibrillator implantation and to decrease the number of high-energy discharges occurring during follow-up. Controlled trials continue to demonstrate that pharmacological therapy is of little value in preventing recurrence of vasovagal syncope compared with maneuvers involving isometric muscular contraction. Finally, one of the most significant events in the last year was the publication of new clinical practice guidelines by European and American societies of cardiology. These provide important recommendations on the treatment and prevention of ventricular arrhythmias and sudden death and on the management of and thromboembolic prophylaxis in atrial fibrillation. |
8,843 | [Coronary revascularization in patients with preoperative electrical storm]. | We report 5 cases who underwent surgical coronary revascularization for subacute myocardial ischemia with preoperative electrical storm. All patients showed severe left ventricular dysfunction. Mean ejection fraction was 24.4 +/- 7.6%. Three patients had already had implantable cardioverter-defibrillator (ICD) therapy. Procedures were on-pump coronary artery bypass grafting (CABG) and mitral valvuloplasty (MVP) [case 1], on-pump CABG, MVP, left ventricular restoration (LVR) and cryoablation (case 2), and off-pump CABG (case 3-5). Case 5 necessitated conversion to on-pump for electrical storm during left circumflex artery (LCx) anastomosis. Case 3 suddenly died on the 2nd postoperative day due to electrical storm. Case 1 had recurrent attack of electrical storm postoperatively, treated by ICD, overdrive pacing, repeated intraaortic balloon pumping (IABP), deep sedation with endotracheal intubation, and finally catheter ablation. Four patients have survived 2 years (mean) postoperatively without any arrhythmia, and are all in good condition [New York Heart Association (NYHA) I] now. It was concluded that off-pump procedure was not suitable for subacute myocardial ischemia with electrical storm and that LVR with surgical cryoablation would be effective if indicated. |
8,844 | Acute pancreatitis and amiodarone: a case report. | Amiodarone, a class III antiarrhythmic drug, is one of the most effective drugs used in the treatment of ventricular and paroxysmal supraventricular tachyarrhythmia. Adverse effects of amiodarone including pulmonary toxicity, hepatotoxicity, aggravation of arrhythmia, and thyroid diseases are well understood. A 66-year old woman with acute pancreatitis was admitted to our hospital with the complaint of epigastralgia radiating to both flanks for two months. Her symptoms and elevation of pancreatic enzymes did not respond to conventional medical treatment of pancreatitis for 18 d. No known causal factors for pancreatitis such as biliary tract stone, hypertriglyceridemia and alcohol consumption could be identified. Under the suspicion of amiodarone-induced acute pancreatitis, amiodarone was substituted by propafenone. Her symptoms soon alleviated and serum lipase level declined. Three months after hospital discharge, the abdominal pain did not recur. Amiodarone was approved to treat recurrent ventricular fibrillation or sustained ventricular tachyarrhythmia that has been resistant to other medications since 1986. Pancreatitis is a very rare adverse effect associated with the use of amiodarone, and only four cases of amiodarone-induced pancreatitis have been reported in literature. We report a patient who developed acute pancreatitis during amiodarone therapy. |
8,845 | Automatic implantable cardioverter defibrillator for the treatment of ventricular fibrillation following coronary artery spasm: a case report. | Coronary artery spasm is an infrequently recognized condition that causes Prinzmetal's angina and specific electrocardiographic changes. A 50-year-old man who suffered a spontaneously aborted acute inferior myocardial infarction is presented. He underwent cardiac catheterization, which initially showed a normal coronary artery. The coronary angiogram was repeated shortly after a second presentation of acute coronary syndrome and ventricular fibrillation. Coronary spasm of very proximal right coronary artery was present, which was reversed completely with intracoronary nitroglycerin. The spasm segment was first stented. Subsequently, an automatic implantable cardioverter defibrillator was inserted because of the uncertainty of future spasm recurrence. The patient was discharged with oral isosorbide dinitrate and Amlodipine. In further follow-up, the patient had two separate shocks within 4 months of implantation. Ventricular fibrillation was the trigger for the shock therapy in both occasions. |
8,846 | Evaluation of chest barriers for protection against sudden death due to commotio cordis. | Blunt precordial blows triggering ventricular fibrillation (commotio cordis) represent a leading cause of sudden death in young athletes. Attention has focused on the primary prevention of these tragedies with chest barriers. The U.S. Commotio Cordis Registry was accessed to determine the likelihood of sudden death in athletes exposed to precordial blows while wearing chest protectors. Of 182 cases of commotio cordis, 85 (47%) occurred during practice or competition in organized sports. In 32 of these 85 competitive athletes (38%), fatal chest blows occurred despite the presence of potentially protective equipment. Athletes wore standard, commercially available chest barriers made of polymer foam covered by fabric or hard shells, generally perceived as protective from arrhythmic consequences of the blows. These events occurred in 4 sports: hockey (n = 13; 1 goalie), football (n = 10), lacrosse (n = 6; 3 goalies), and baseball (n = 3; all catchers). Scenarios included the failure of the padding to cover the precordium so that blows circumvented the protective barrier (n = 25) or projectiles that struck the chest barrier directly (n = 7). In conclusion, a significant proportion (about 40%) of sudden deaths reported in young competitive athletes due to blunt chest blows (commotio cordis) occur despite the presence of commercially available sports equipment generally perceived as protective. |
8,847 | Major adverse cardiac events during endurance sports. | Major adverse cardiac events in endurance exercise are usually due to underlying and unsuspected heart disease. The investigators present an analysis of major adverse cardiac events that occurred during 2 consecutive annual long distance races (a 36-km beach cycling race and a 21-km half marathon) over the past 5 years. All patients with events were transported to the hospital. Most of the 62,862 participants were men (77%; mean age 40 years). Of these, 4 men (3 runners, 1 cyclist; mean age 48 years) collapsed during (n = 2) or shortly after the races, rendering a prevalence of 0.006%. Two patients collapsed after developing chest pain, 1 of whom needed resuscitation at the event site, which was successful. These patients had acute myocardial infarctions and underwent primary angioplasty. The third patient was resuscitated at the site but did not have coronary disease or inducible ventricular tachycardia or ventricular fibrillation and collapsed presumably because of catecholamine-induced ventricular fibrillation. The fourth patient experienced heat stroke and had elevated creatine kinase-MB and troponins in the absence of electrocardiographic changes. In conclusion, the risk for major adverse cardiac events during endurance sports in well-trained athletes is very low. |
8,848 | Prognostic significance of exercise induced arrhythmias and echocardiographic variables in hypertrophic cardiomyopathy. | Hypertrophic cardiomyopathy (HC) often presents with exercise-induced symptoms, including arrhythmias and sudden death. The investigators prospectively studied whether exercise testing is associated with immediate complications and if stress-induced arrhythmias and echocardiographic variables are associated with long-term adverse outcomes. Exercise echocardiography with 6-channel continuous monitoring for arrhythmias was performed in consecutive patients with HC clinically referred for the test. End points included death, myocardial infarction, revascularization, stroke, atrial fibrillation, ventricular tachycardia, and myectomy. Of 86 patients with HC (mean age 56.6 +/- 16.1 years) who underwent exercise echocardiography, arrhythmias occurred in 39 (45%), including 23 (27%) with premature atrial contractions, 2 (2%) with atrial fibrillation, 28 (33%) with premature ventricular contractions (16 also had atrial arrhythmias), and 1 (1.2%) with nonsustained ventricular tachycardia (hemodynamically stable). During a follow-up of 2.6 +/- 2.8 years, major events occurred in 11 patients (3 deaths, 5 revascularizations, 3 strokes). In addition, 12 patients developed atrial fibrillation, 6 developed nonsustained ventricular tachycardia, and 13 underwent myectomies. Variables associated with major events included hypertension, male gender, and worsening wall motion score index with exercise; increased exercise duration was associated with fewer events. ST-T changes on baseline electrocardiography and premature ventricular contractions were associated with atrial fibrillation risk. In conclusion, in this cohort of patients with HC, exercise testing was safe. Test results were associated with risk for adverse events. |
8,849 | Relationship between sympathetic nerve sprouting and repolarization dispersion at peri-infarct zone after myocardial infarction. | Sympathetic nerve sprouting is thought to contribute to sudden cardiac death (SCD) in chronic myocardial infarction (MI). However, the mechanisms remain unclear. This study investigated the relationship between sympathetic nerve sprouting and repolarization dispersion at peri-infarct zones after MI. Thirty adult New Zealand White rabbits underwent coronary artery ligation (MI group: n=20) or sham operation (SO group: n=10). Eight weeks after surgery, transmural dispersion of repolarization (TDR) was examined at the peri-infarct zones in MI group and corresponding zones in the SO group at baseline and during sympathetic nerve stimulation. Sympathetic nerve sprouting was detected by immunocytochemical staining using anti-growth associated protein 43 (GAP43) and anti-tyrosine hydroxylase (TH) antibodies. The results demonstrated that TDR was significantly larger at peri-infarct zones in MI group than the corresponding zone in SO group at baseline or during sympathetic nerve stimulation. The densities of both GAP43- and TH-positive nerves were significantly higher at peri-infarct zones in infracted hearts than the corresponding zones in control hearts (both p<0.01). In the MI group, the density of GAP43- or TH-positive nerves at peri-infarct zones had a significantly positive correlation with the TDR or DeltaTDR (change in TDR) at baseline as well as with sympathetic nerve stimulation (p<0.05 for all). These results suggested that sympathetic nerve sprouting is more pronounced and heterogeneous at peri-infarct zones at 8 weeks after MI. The excessive sprouting of sympathetic nerves increases local ventricular TDR, which may be a potential mechanism for SCD in chronic MI. |
8,850 | Mitral regurgitation: determinants of referral for cardiac surgery by Canadian cardiologists. | Advances in surgery permit for earlier intervention with improved outcomes for patients with mitral regurgitation (MR). Many patients still appear to be referred to surgery late in their course. Consensus guidelines were compared with the surgical referral practices for MR among Canadian cardiologists.</AbstractText>A self-administered questionnaire was mailed to all adult cardiologists in Canada. This included seven case scenarios, as well as direct questions designed to establish the influence of factors including atrial fibrillation, pulmonary hypertension, left ventricular (LV) dilation, experience of the cardiac surgeon, symptoms and ejection fraction (EF) on referral.</AbstractText>There were 319 respondents; LVEF was rated as extremely important in 71.5% of patients and moderately important in 26% of patients. In asymptomatic patients, EF of 50% to 60% was correctly identified as a trigger for surgery by 57.2 % of cardiologists, while only 15.6% of cardiologists correctly referred New York Heart Association class II patients with normal LV function. The group complied in only 4.77 of the seven case scenarios. Compliance was inversely related to years in practice for asymptomatic patients with mild LV dysfunction, as well as in overall compliance. Referral practices were similar among clinicians, echocardiographers, interventional cardiologists and researchers, with no differences in geographic region or academic affiliation.</AbstractText>Compliance with published guidelines for patients with MR and either New York Heart Association class II or mild LV dysfunction among Canadian cardiologists was poor. Compliance was somewhat better in more recent graduates, suggesting the need to institute programs geared at enhancing knowledge of published standards and introduce practical tools to aid in their implementation.</AbstractText> |
8,851 | Effect of diltiazem and metoprolol on left atrial appendix functions in patients with nonvalvular chronic atrial fibrillation. | Thrombo-embolic events are the important cause of mortality and morbidity in patients with chronic atrial fibrillation (CAF). The origin of thromboembolism is often the left atrial appendix (LAA). Flow rate velocity (FRV) inside the LAA is the major determinant of thrombus formation. The aim of our study was to investigate the effects of diltiazem and metoprolol used for ventricular rate control on FRV of the LAA in CAF patients and thus to evaluate the positive or negative effects of these two drugs on thromboembolic events.</AbstractText>Sixty-four patients were included in the study. All patients were suffering from CAF for more than a year. The patients were allocated to two groups according with agent used for rate control- metoprolol (Group 1; n=31) and diltiazem (Group 2; n=33). Transesophageal echocardiography was applied to all patients and LAA FRV was measured by a pulse wave Doppler in the 1/3 proximal portion of the LAA. The measurements were repeated after applying 5 mg metoprolol to Group 1 and 25 mg diltiazem to Group 2 via venous cannula.</AbstractText>In Group 1 after metoprolol LAA flow velocity changed from 0.25 +/- 0.90 m/s to 0.25 +/- 0.10 m/s (p>0.05). In group 2 after diltiazem left atrial appendix FRV decreased from 0.21 +/- 0.9 m/s to 0.19 +/- 0.6 m/s (p>0.05).</AbstractText>In patients with CAF metoprolol used for ventricular rate control had no effect on LAA flow velocity and the observed decrease in LAA flow rate velocity with intravenous diltiazem was insignificant.</AbstractText> |
8,852 | Interpretation of B-type natriuretic peptide in cardiac disease and other comorbid conditions. | B-Type natriuretic peptide (BNP) is elevated in states of increased ventricular wall stress. BNP is most commonly used to rule out congestive heart failure (CHF) in dyspneic patients. BNP levels are influenced by age, gender and, to a surprisingly large extent, by body mass index (BMI). In addition, it can be elevated in a wide variety of clinical settings with or without CHF. BNP is elevated in other cardiac disease states such as the acute coronary syndromes, diastolic dysfunction, atrial fibrillation (AF), amyloidosis, restrictive cardiomyopathy (RCM), and valvular heart disease. BNP is elevated in non-cardiac diseases such as pulmonary hypertension, chronic obstructive pulmonary disease, pulmonary embolism, and renal failure. BNP is also elevated in the setting of critical illness such as in acute decompensated CHF (ADHF) and sepsis. This variation across clinical settings has significant implications given the increasing frequency with which BNP testing is being performed. It is important for clinicians to understand how to appropriately interpret BNP in light of the comorbidities of individual patients to maximize its clinical utility. We will review the molecular biology and physiology of natriuretic peptides as well as the relevant literature on the utilization of BNP in CHF as well as in other important clinical situations, conditions that are commonly associated with CHF and or dyspnea. |
8,853 | Brugada-like electrocardiographic pattern and ventricular fibrillation in a patient with primary hyperparathyroidism. | There are several causes for ST segment abnormalities in leads V1 to V3. Hypercalcaemia and Brugada syndrome are among them. Both are known to produce ventricular arrhythmia, albeit only rare cases have been reported with documented evidence of ventricular arrhythmias in association with a hypercalcaemic crisis but none when hypercalcaemic coexists with Brugada syndrome. We describe a patient with primary hyperparathyroidism who presented with ventricular fibrillation, and the ECG showed changes similar to Brugada syndrome. The provocation test with flecainide was conducted twice. This was positive, both before and after parathyroidectomy when serum calcium and parathormone levels had normalized. The patient was treated for hypercalcaemia and underwent parathyroidectomy. This is the first report of oral flecainide test unmasking the diagnostic coved Brugada ECG pattern in a patient with primary hyperparathyroidism and raising attention to hypercalcaemia as a potential trigger for life-threatening arrhythmia in Brugada syndrome. |
8,854 | [B-type natriuretic hormone--diagnostic and prognostic cardiovascular biomarker]. | Brain natriuretic hormone and N-terminal-probrain natriuretic hormone are equally important cardiovascular biomarkers. Moderately increased brain natriuretic hormone level is a reliable predictor of preclinical, asymptomatic left ventricular dysfunction. Low brain natriuretic hormone levels are extensively used to rule out acute heart failure. Increased brain natriuretic hormone is associated to age, left ventricular hypertrophy, left atrial volume, atrial fibrillation, myocardial ischemia, renal failure, pulmonary hypertension, acute pulmonary embolism and progressive aortic stenosis. In chronic heart failure only high brain natriuretic hormone values support the diagnosis. High brain natriuretic hormone level, however, is an important overall cardiovascular prognostic biomarker. In the near future brain natriuretic hormone appears to be an interesting new therapeutic modality. |
8,855 | Electrophysiologic manifestations of ventricular tachyarrhythmias provoking appropriate defibrillator interventions in high-risk patients with hypertrophic cardiomyopathy. | Our objective was to determine features of ventricular tachyarrhythmias triggering appropriate implantable cardioverter-defibrillator (ICD) interventions in hypertrophic cardiomyopathy (HCM).</AbstractText>The study cohort was 68 high-risk HCM patients who received ICDs for primary sudden cardiac death prevention from 1995 to 2003. All episodes of sustained ventricular tachyarrhythmias identified by stored intracardiac electrograms were analyzed. Nine patients had 51 episodes of sustained ventricular tachyarrhythmic events that required device therapy (mean follow-up, 3.4 +/- 2.2 years; cumulative event rate, 3.2% per year): five had 47 episodes of monomorphic ventricular tachycardia (VT); four each had one episode of ventricular fibrillation (VF). Sinus tachycardia or atrial fibrillation was the initiating rhythm in five of nine patients and in 43 of 51 episodes of events. Of the 17 episodes of monomorphic VT detected in the VT zone, 16 (94%) were terminated by antitachycardia pacing. Thirty episodes of monomorphic VT were detected in the VF zone and were terminated by defibrillation.</AbstractText>Sustained monomorphic VT is common in a high-risk cohort with HCM. Sinus tachycardia is often the initiating rhythm, suggesting that high sympathetic drive may be proarrhythmic when a susceptible substrate is present. Antitachycardia pacing is highly effective in terminating VT in this patient population.</AbstractText> |
8,856 | Detection of intramyocardial scroll waves using absorptive transillumination imaging. | Optical imaging using voltage-sensitive dyes has become an important tool for studying vortex-like electrical waves in the heart. Such waves, known as spiral or scroll waves, can spontaneously form in pathological ventricular myocardium, causing ventricular fibrillation and sudden death. Until recently, observations of scroll waves were limited to their surface manifestations, thus providing little information about the shape and location of their organizing center, the filament. We use computer modeling to assess the feasibility of visualizing filaments using dynamic transillumination imaging in conjunction with near-IR voltage-sensitive absorptive dyes (absorptive transillumination). We simulate transillumination signals produced by the intramural scroll waves in a realistic slab of ventricular tissue with trabeculated endocardial surface. The computations use a detailed ionic model of electrical excitation (LRd) coupled to a photon transport model for cardiac tissue. Our simulations show that dynamic absorptive transillumination data, with subsequent processing involving either amplitude maps, time-space plots, or power-of-the-dominant-frequency maps, can be used to reliably detect intramural scroll waves through the whole thickness (approximately 10 mm) of the ventricular wall. Neither variations in the thickness of the myocardial wall nor noise impeded the detection of intramural filaments. |
8,857 | Pravastatin inhibits arrhythmias induced by coronary artery ischemia in anesthetized rats. | We have reported that chronically administered pravastatin prevented coronary artery reperfusion-induced lethal ventricular fibrillation (VF) in anesthetized rats without lowering the serum cholesterol level. The present study was undertaken to evaluate whether pravastatin prevents ischemia-induced lethal VF, simultaneously examining myeloperoxidase (MPO) activity in ischemic myocardial tissues. Anesthetized rats were subjected to 30-min ischemia and 60-min reperfusion after chronic administration of pravastatin (0.02, 0.2, and 2 mg/kg), fluvastatin (2 and 4 mg/kg), or vehicle for 22 days, orally, once daily. ECG and blood pressure were continually recorded, and MPO was measured by a spectrophotometer. Pravastatin and fluvastatin significantly (P<0.05) decreased MPO activities, but only pravastatin decreased the incidence of ischemia-induced lethal VF. Both statins had no significant effects on body weight, blood pressure, heart rate, and QT interval as we reported earlier. Our results prove further that pravastatin has benefits to decrease cardiovascular mortality beyond its cholesterol-lowering effect. Pravastatin is more potent than fluvastatin in prevention of arrhythmias. A decrease in the neutrophil infiltration may be partly involved in the inhibitory effect of pravastatin on the ischemia-induced VF. |
8,858 | Addendum to "Personal and Public Safety Issues Related to Arrhythmias That May Affect Consciousness: Implications for Regulation and Physician Recommendations. A medical/scientific statement from the American Heart Association and the North American Society of Pacing and Electrophysiology". Public safety issues in patients with implantable defibrillators. A Scientific statement from the American Heart Association and the Heart Rhythm Society. | In 1996, the American Heart Association developed a scientific statement entitled "Personal and Public Safety Issues Related to Arrhythmias That May Affect Consciousness: Implications for Regulation and Physician Recommendations." Since then, multiple trials have established the role of implantable cardioverter-defibrillators (ICDs) for the primary prevention of sudden cardiac death in patients at risk for life-threatening ventricular arrhythmias.</AbstractText>The issue of driving for patients with ICDs implanted for primary prevention was briefly discussed in the original statement, with the recommendation that such patients not be restricted from driving beyond the initial phase of healing. This scientific statement has been developed to extend the original 1996 recommendations and to provide specific recommendations on driving for individuals with ICDs implanted for primary prevention.</AbstractText>(1) Patients receiving ICDs for primary prevention should be restricted from driving a private automobile for at least 1 week to allow for recovery from implantation of the defibrillator. Thereafter, these driving privileges should not be restricted in the absence of symptoms potentially related to an arrhythmia. (2) Patients who have received an ICD for primary prevention who subsequently receive an appropriate therapy for ventricular tachycardia or ventricular fibrillation, especially with symptoms of cerebral hypoperfusion, should then be considered to be subject to the driving guidelines previously published for patients who received an ICD for secondary prevention. (3) Patients with ICDs for primary prevention must be instructed that impairment of consciousness is a possible future event. (4) These recommendations do not apply to the licensing of commercial drivers.</AbstractText> |
8,859 | Electrophysiologic characteristics of anger-triggered arrhythmias. | Anger can precipitate ventricular arrhythmias in patients with implantable cardioverter-defibrillators (ICDs). Determining electrophysiologic characteristics of anger-triggered arrhythmias may help elucidate the mechanisms that link emotion and arrhythmia.</AbstractText>We sought to compare the morphology and initiation pattern between ventricular arrhythmias that are triggered by anger and those that are not.</AbstractText>At the time of shock, patients with ICDs recorded levels of defined mood states preceding the shock in a diary. Stored intracardiac electrograms (EGMs) were retrieved and analyzed in relation to corresponding mood states. The EGMs from 56 appropriate shocks in 24 patients (18 male, mean age 66 years, 74% with coronary artery disease) were reviewed and analyzed for morphology, mechanism of initiation (sudden onset vs. premature ventricular contraction [PVC]), pause dependence, and other characteristics.</AbstractText>Polymorphic ventricular tachycardia was more common in anger-triggered events, occurring in three (37.5%) of eight anger-triggered events compared with five (10.4%) of 48 of non-anger-triggered events (P <.05). Anger-triggered events were more likely to have PVC initiation, occurring in eight (100%) of eight, compared with 30 (68%) of 44 of non-anger-triggered events (P <.05). More anger-triggered events were pause dependent: five (62.5%) of eight versus seven (15%) of 37 non-anger-related events (P <.01). No difference in response to initial therapy was observed in anger-triggered arrhythmias.</AbstractText>Ventricular arrhythmias occurring in the setting of anger are more likely pause dependent and polymorphic. This suggests that in predisposed populations anger may create an arrhythmogenic substrate susceptible to more disorganized rhythms, a possible mechanism linking emotion and sudden death.</AbstractText> |
8,860 | Do we need pharmacological therapy for atrial fibrillation in the ablation era? | Management of atrial fibrillation (AF) remains one of the most difficult problems of modern cardiology. Pharmacological antiarrhythmic therapy is used both for termination of episodes of AF and for prevention of AF recurrences. Recently, major trials have compared the strategy of maintenance of sinus rhythm, called rhythm control, with the strategy of heart rate control during AF and found that the rhythm control strategy was not superior to rate control in terms of mortality. Although subsequent analysis identified rhythm control as a factor of improved survival, these large trials have markedly influenced the management of AF. One of the hypotheses explaining the non-superiority of the rhythm control strategy was that the benefit of sinus rhythm was offset by the side effects of antiarrhythmic agents. As a consequence, attention was directed to non-pharmacological therapies, particularly to catheter ablation of the trigger or/and the atrial substrate using radiofrequency current or cryothermia. However, despite the reported good results of various types of interventions in the hands of highly qualified teams, catheter ablation cannot be applied to all patients with AF or to all types of AF. Furthermore, catheter ablation of AF requires sophisticated electrophysiologic laboratories equipped with expensive imaging techniques and a well-trained staff that cannot be available in sufficient number to cover the growing epidemic of AF with acceptable efficacy and safety even in rich countries. Therefore, there is still a need for pharmacological therapy aimed at the prevention of AF recurrences for the majority of AF patients. So far, attempts to provide the physician with efficient antiarrhythmic agents having a good safety profile have not been successful. However, recent research resulted in promising new approaches including prevention of AF using converting enzyme inhibitors or angiotensin 2 receptor blockers, new antiarrhythmic agents with multichannel effects such as dronedarone and tedisamil and atrial specific agents that theoretically should have no ventricular proarrhythmic effect as they target specific atrial channels such as I(KAch) and I(Kur) which are absent at the ventricular level. Other possible mechanisms of AF that represent potential targets, such as modification of stretch-activated ion channels, intervention of altered connexin expression and altered gap-junctional conductance, are currently investigated. |
8,861 | Obesity as a risk factor for sustained ventricular tachyarrhythmias in MADIT II patients. | Obesity, as defined by body mass index > or =30 kg/m(2), has been shown to be a risk factor for cardiovascular disease. However, data on the relationship between body mass index (BMI) and the risk of ventricular arrhythmias and sudden cardiac death are limited. The aim of this study was to evaluate the risk of ventricular tachyarrhythmias and sudden death by BMI in patients after myocardial infarction with severe left ventricular dysfunction.</AbstractText>The risk of appropriate defibrillator therapy for ventricular tachycardia or ventricular fibrillation (VT/VF) by BMI status was analyzed in 476 nondiabetic patients with left ventricular dysfunction who received an implantable cardioverter defibrillator (ICD) in the Multicenter Automatic Defibrillator Implantation Trial-II (MADIT II).</AbstractText>Mean BMI was 27 +/- 5 kg/m(2). Obese patients comprised 25% of the study population. After 2 years of follow-up, the cumulative rates of appropriate ICD therapy for VT/VF were 39% in obese and 24% in nonobese patients, respectively (P = 0.014). In multivariate analysis, there was a significant 64% increase in the risk for appropriate ICD therapy among obese patients as compared with nonobese patients, which was attributed mainly to an 86% increase in the risk of appropriate ICD shocks (P = 0.006). Consistent with these results, the risk of the combined endpoint of appropriate VT/VF therapy or sudden cardiac death (SCD) was also significantly increased among obese patients (Hazard Ratio 1.59; P = 0.01).</AbstractText>Our findings suggest that in nondiabetic patients with ischemic left ventricular dysfunction, a BMI > or =30 kg/m(2) is an independent risk factor for ventricular tachyarrhythmias.</AbstractText> |
8,862 | Atrial fibrillation and plasma troponin I elevation after cardiac surgery: relation to inflammation-associated parameters. | Recent studies have demonstrated correlation between inflammation to plasma troponin (cTnI) levels elevation and atrial fibrillation (AF) in noncardiac surgery settings. The goal of this prospective study was to examine the relation between inflammation associated parameters (IAPs) to post cardiac surgery cTnI elevation and AF.</AbstractText>A single post CABG cTnI measurement was assessed in 156 consecutive patients. Clinical, operative and postoperative data, IAPs (hypophosphatemia, preoperative statin treatment, immediate postoperative fever, and prolonged mechanical ventilation) and in-hospital AF episodes were prospectively recorded.</AbstractText>Mean cTnI level was 14.4 +/- 12.4 ng/mL. In the two in-hospital deaths (1.2%) cTnI concentration was less than 12 ng/mL. Cardiac troponin-I levels were significantly higher in patients not preoperatively treated with statins (21.6 +/- 4.1 vs. 13.3 +/- 0.9, p = 0.05), in patients who needed intraoperative cardioversion (16.7 +/- 2.2 vs. 12.2 +/- 0.9, p = 0.07), in patients with postoperative hypophosphatemia (16.9 +/- 10.0 vs. 11.1 +/- 13.7, p = 0.04), postoperative fever (18.6 +/- 3.0 vs. 13.7 +/- 1.0, p = 0.07) and postoperative respiratory complications (23.9 +/- 4.3 vs. 13.5 +/- 1.0, p = 0.04). Step-wise logistic regression analysis revealed the following parameters as independently associated with elevated cTnI levels: preoperative statin treatment (CI 95%-15.9; -1.7, p = 0.02), intraoperative ventricular arrhythmia (CI 95%-0.7; 13.8, p = 0.08), hypophosphatemia (CI 95% 0.9; 8.6, p = 0.02), postoperative fever (CI 95% 0.9; 11.0, p = 0.02), and postoperative respiratory complications (CI 95% 0.1; 0.5, p = 0.01). Of the 156 patients, 50 (32.1%) had postoperative AF. The first episode of AF occurred between postoperative day 1 and 6 (mean-day 2). Mean duration of AF was 21.8 +/- 8.1 hours. Postoperative AF was significantly associated with age above 75 (50% vs. 29.4%, p = 0.01), hypertension (37% vs. 18%, p = 0.02), preoperative calcium channel blockers treatment (44% vs. 26%, p = 0.02), furosemide treatment (58% vs. 30%, p = 0.05), and preoperative left atrial diameter above 40 mm (56% vs. 29%, p = 0.01). Postoperatively, AF was significantly associated with postoperative renal failure (70% vs. 29%, p = 0.01), respiratory complications (61% vs. 29%, p = 0.02), and prolonged hospital stay (OR 1.1; CI 1.0-1.3; p < 0.05). No association was found between troponin levels and postoperative AF. Multivariable analysis found only left atrial enlargement and prolonged hospital stay independently associated with AF.</AbstractText>A significant correlation between clinical IAPs and cTnI plasma level elevation was found after cardiac surgery. There was no correlation between these parameters and postoperative AF, and there was no correlation between postoperative plasma cTnI levels and the occurrence of AF. Preoperative treatment with statins may be beneficial in reducing postoperative inflammatory response but further study has to be carried out.</AbstractText> |
8,863 | Using the upper limit of vulnerability to assess defibrillation efficacy at implantation of ICDs. | The upper limit of vulnerability (ULV) is the weakest shock strength at or above which ventricular fibrillation (VF) is not induced when the shock is delivered during the vulnerable period. The ULV, a measurement made in regular rhythm, provides an estimate of the minimum shock strength required for reliable defibrillation that is as accurate or more accurate than the defibrillation threshold (DFT). The ULV hypothesis of defibrillation postulates a mechanistic relationship between the ULV-measured during regular rhythm-and the minimum shock strength that defibrillates reliably. Vulnerability testing can be applied at implantable cardioverter defibrillator (ICD) implant to confirm a clinically adequate defibrillation safety margin without inducing VF in 75%-95% of ICD recipients. Alternatively, the ULV provides an accurate patient-specific safety margin with a single fibrillation-defibrillation episode. Programming first ICD shocks based on patient-specific measurements of ULV rather than programming routinely to maximum output shortens charge time and may reduce the probability of syncope as ICDs age and charge times increase. Because the ULV is more reproducible than the DFT, it provides greater statistical power for clinical research with fewer episodes of VF. Limited evidence suggests that vulnerability testing is safer than conventional defibrillation testing. |
8,864 | Effect of programmed number of intervals to detect ventricular fibrillation on implantable cardioverter-defibrillator aborted and unnecessary shocks. | Detection of self-terminating arrhythmias by implantable cardioverter-defibrillators (ICDs) causes unnecessary battery depletion and unnecessary shocks. Our goal was to estimate the effect of the programmed number of intervals to detect (NID) ventricular fibrillation (VF) on ICD temporal episode rate, unnecessary shocks, and delay in detection of VF.</AbstractText>We analyzed 773 ICD-detected VF episodes in 875 patients. The number of intervals to detect VF was programmed to 12 of 16 (NID 12) in 305 patients and 18 of 24 (NID 18) in 570 patients. For patients with NID 12, we estimated the increase of mean cumulative episode rate at 6 months since implant and decrease in detection time for VF compared with a hypothetical NID 18. For patients with NID 18, we estimated the decrease of mean cumulative episode rate and unnecessary shocks compared with a hypothetical NID 12. Patients with NID 12 had a 17% increased episode rate resulting in unnecessary capacitor charging for self-terminating arrhythmias. Patients with NID 18 had a 22% decreased episode rate. In patients with NID 12, hypothetical NID 18 would have delayed detection of 273 VF episodes in 1.8 seconds. In patients with NID 18, hypothetical NID 12 would have resulted in inappropriate delivery of 14 aborted shocks in 10% of patients with episodes.</AbstractText>In patients with self-terminating device-detected VF, increasing the number of intervals to detect VF from 12/16 to 18/24 results in a clinically significant decrease in ICD detections and fewer unnecessary shocks with minimal incremental delay in VF detection.</AbstractText> |
8,865 | Ineffectiveness of precordial thump for cardioversion of malignant ventricular tachyarrhythmias. | The Precordial Thump (PT) is commonly used for cardiopulmonary resuscitations both in and out of hospitals. However, the support for its efficiency relies mainly on sporadic cases. In this current prospective large study, we tested the effectiveness and safety of PT in a wide range of malignant ventricular tachyarrhythmias.</AbstractText>The study included 80 patients who underwent electrophysiological study and/or implantation of a cardiodefibrillator device. During these procedures, once a malignant ventricular tachyarrhythmia was induced, PT was used as the first treatment option. If the PT failed, other means were used to discontinue the arrhythmia.</AbstractText>Polymorphic ventricular tachycardia occurred in 32 (40%) patients, ventricular fibrillation in 28 (35%) patients, and 20 (25%) patients had sustained monomorphic ventricular tachycardia. Except in one patient with monomorphic ventricular tachycardia, the PT was unsuccessful in terminating any of the other malignant tachyarrhythmias, and internal or external defibrillation was eventually required in all other 79 (99%) patients. The PT was not associated with any damage either to the sternal bone, ribs, or to the cardiodefibrillator device.</AbstractText>PT is not effective in terminating malignant ventricular tachyarrhythmia and should be reserved to a situation in which a defibrillator is not available.</AbstractText> |
8,866 | Atrial, SA nodal, and AV nodal electrophysiology in standing horses: normal findings and electrophysiologic effects of quinidine and diltiazem. | Although atrial arrhythmias are clinically important in horses, atrial electrophysiology has been incompletely studied.</AbstractText>Standard electrophysiologic methods can be used to study drug effects in horses. Specifically, the effects of diltiazem on atrioventricular (AV) nodal conduction are rate-dependent and allow control of ventricular response rate during rapid atrial pacing in horses undergoing quinidine treatment.</AbstractText>Fourteen healthy horses.</AbstractText>Arterial blood pressure, surface electrocardiogram, and right atrial electrogram were recorded during sinus rhythm and during programmed electrical stimulation at baseline, after administration of quinidine gluconate (10 mg/kg IV over 30 minutes, n = 7; and 12 mg/kg IV over 5 minutes followed by 5 mg/kg/h constant rate infusion for the remaining duration of the study, n = 7), and after coadministration of diltiazem (0.125 mg/kg IV over 2 minutes repeated every 12 minutes to effect).</AbstractText>Quinidine significantly prolonged the atrial effective refractory period, shortened the functional refractory period (FRP) of the AV node, and increased the ventricular response rate during atrial pacing. Diltiazem increased the FRP, controlled ventricular rate in a rate-dependent manner, caused dose-dependent suppression of the sinoatrial node and produced a significant, but well tolerated decrease in blood pressure. Effective doses of diltiazem ranged from 0.125 to 1.125 mg/kg.</AbstractText>Standard electrophysiologic techniques allow characterization of drug effects in standing horses. Diltiazem is effective for ventricular rate control in this pacing model of supraventricular tachycardia. The use of diltiazem for rate control in horses with atrial fibrillation merits further investigation.</AbstractText> |
8,867 | Atrial fibrillation after non-cardiac surgery: P-wave characteristics and Holter monitoring in risk assessment. | We investigated the role of 12-lead ECG P-wave duration and dispersion and of Holter monitoring as predictors of post-thoracic surgery atrial fibrillation.</AbstractText>One hundred and five consecutive patients (88 males-17 females; age 60+/-9), undergoing thoracic surgery at National Cancer Institute between 2001 and 2003, were enrolled and both standard ECG and Holter monitoring were obtained from each patient. P-wave study was made on a magnified ECG paper copy. Holter monitoring was performed 1-3 days before surgery; patients were divided into three classes according to number and complexity of premature supra ventricular complexes (0: <30/h and no repetitive forms; 1: >30/h or couplets; 2: run of supraventricular tachycardia or atrial fibrillation).</AbstractText>Atrial fibrillation was detected in 12 patients (11%) within 96 h from surgery. In univariable logistic model, P-wave duration was not associated with postoperative atrial fibrillation while P-wave dispersion and Holter monitoring demonstrated a statistically significant association with the occurrence of atrial fibrillation (OR of 30 vs 20 ms=2.06; CI: 1.17-3.64; p=0.012, OR of class 1-2 vs class 0=8.16; CI: 2.04-35.59; p=0.003, respectively). In the multivariable model, both P-wave dispersion and Holter were shown to be significantly associated with the end-point. Holter monitoring enhanced the predictive ability of P-wave dispersion (area under the ROC curve increased from 0.64 to 0.80).</AbstractText>P-wave dispersion, but not duration, was associated with atrial fibrillation after thoracic surgery. Preoperative Holter monitoring adds further information and could be used to enhance the P-wave predictive power.</AbstractText> |
8,868 | Medical management of atrial fibrillation: future directions. | Atrial fibrillation is the most common arrhythmia that requires treatment, and although ablation is appropriate in many cases, anti-arrhythmic drug therapy remains the first and most appropriate therapy in most patients. Currently available antiarrhythmic drugs are limited by modest efficacy and significant toxicity. Cardiac toxicity relates to effects on the ventricle, especially in prolonging the QT interval and causing torsades de pointes. Amiodarone, an agent with multiple antiarrhythmic effects, is unique in its relative lack of pro-arrhythmia, although its non-cardiac toxicities limit its use. Some investigational agents are directed at multiple ion channels, or are designed to be analogs of amiodarone. The other line of investigation focuses on the antiarrhythmic action of agents that affect novel ion channel targets. Basic and early clinical studies show promise for drugs that provide atrial antiarrhythmic effects without ventricular pro-arrhythmia by affecting the atrium preferentially or selectively (inhibiting the I(TO) and I(Kur) currents, respectively). Future drugs may possess preferential effects on the remodeled atrium (and as such would be selective for patients with atrial fibrillation). It is hoped that efforts to develop new drugs, including those with preferential effects on the atrium, will provide therapy with greater efficacy and safety. |
8,869 | Pacing therapy for prevention of atrial fibrillation. | The role of permanent pacing for the prevention of atrial fibrillation is reviewed. A moderate decrease in the incidence of acute and chronic atrial fibrillation has been seen with atrial pacing compared with ventricular pacing, especially in patients with sinus node dysfunction based on a meta-analysis of clinical trials. A variety of different pacing algorithms have been studied in small numbers of patients for only short durations of time and have shown an inconsistent effect on different measures of atrial fibrillation burden. The interatrial septum or Bachmann's bundle has been shown in some, but not all, studies to have a beneficial effect on reducing the incidence of atrial fibrillation. Less well studied is the combined benefit of alternate site atrial pacing combined with atrial fibrillation prevention pacing algorithms. Device measurement of the duration of atrial fibrillation appears to be an accurate measure of disease burden, and preliminary evidence suggests that atrial fibrillation burden is associated with an increased risk of stroke and death. Future studies are needed to demonstrate the long-term efficacy of device algorithms for the prevention or termination of atrial fibrillation. |
8,870 | Mapping and ablation of left atrial tachycardias occurring after atrial fibrillation ablation. | Regular left atrial tachycardias are a frequent complication of atrial fibrillation ablation procedures. The arrhythmia mechanism appears to be due to focal pulmonary vein reentry in patients who undergo only electrically guided pulmonary vein isolation. The most common site of origin is the septal and inferior aspect of the right pulmonary veins. Attention to avoiding gaps when ablating along this region will minimize the occurrence of these tachycardias. In patients who also undergo linear left atrial ablation lesions and in patients with significant left atrial disease, macroreentry around the mitral annulus or ipsilateral pulmonary veins is frequently observed. Confirming electrical block across any prophylactic linear lesions (mitral isthmus line, left atrial roof line) likely is important for preventing gap-related proarrhythmic tachycardias. When tachycardias do occur, temporizing with ventricular rate control and cardioversion is initially indicated, as approximately one third of these atrial tachycardias may resolve with time. For tachycardias persisting after ablation, detailed three-dimensional activation and entrainment mapping can facilitate localization of the atrial tachycardia and guide the approach to eliminating the arrhythmias. This review provides a systematic approach to the evaluation, diagnosis, localization, and elimination of left atrial tachycardias occurring after atrial fibrillation ablation. |
8,871 | Intracardiac atrial defibrillation. | Intravascular ventricular defibrillation and intravascular atrial defibrillation have many similarities. An important factor influencing the outcome of the shock is the potential gradient field created throughout the ventricles or the atria by the shock. A minimum potential gradient is required throughout the ventricles and probably the atria in order to defibrillate. The value of this minimum potential gradient is affected by several factors, including the duration, tilt, and number of phases of the waveform. For shock strengths near the defibrillation threshold, earliest activation following failed shocks arises in a region in which the potential gradient is low. The defibrillation threshold energy can be decreased by adding a third and even a fourth defibrillation electrode in regions where the shock potential gradient is low for the shock field created by the first two defibrillation electrodes and giving two sequential shocks, each through a different set of electrodes. However, the addition of more electrodes and sequential shocks complicates both the device and its implantation. Because patients are conscious when the atrial defibrillation shock is given, they experience pain during the shock, which is one of the main drawbacks of intravascular atrial defibrillation. Unfortunately, the pain threshold for defibrillation shocks is so low that a shock less than 1 J is uncomfortable and is not much less painful than shocks several times stronger. Therefore, even though electrode configurations exist that have lower atrial defibrillation threshold energy requirements than the atrial defibrillation threshold with standard defibrillation electrode configurations used in implantable cardioverter-defibrillators (ICDs) for ventricular defibrillation, they are not clinically practical because their shocks are almost as painful as with the standard ICD electrode configurations. Such electrode configurations would make the ICD more complicated, leading to greater difficulty and longer time required for implantation. |
8,872 | Isolated left ventricular noncompaction in association with rheumatic mitral stenosis. | Fifty year old man with a known case of chronic rheumatic heart disease with atrial fibrillation was presented with severe mitral stenosis. He was incidentally detected to have noncompaction of left ventricle on echocardiography and Doppler examination. He underwent successful percutaneous trans-luminal mitral commissurotomy (PTMC) for severe mitral stenosis. This is the first reported case of isolated ventricular noncompaction (IVNC) associated with acquired chronic rheumatic mitral stenosis. |
8,873 | The role of gender and sex hormones in ischemic-reperfusion injury in isolated rat hearts. | To establish potential anti-ischemic effects of testosterone and estradiol on myocardium we used isolated rat hearts in accordance with Langendorff, exposed to 40 min of ischemia and reperfusion. Rats were pretreated for 10 days, males with testosterone and females with estradiol and injuries from those hearts were compared to the hearts where both drugs were applied to the isolated hearts directly. The myocardial injuries were determined by changes in coronary flow, incidence and duration of arrhythmias and lactate dehydrogenase release rates used as markers for level of cardiac injury during reperfusion. Coronary flow in the hearts of animals pretreated with estradiol during reperfusion increased by 68.7+/-3.6% (P<0.001) and in those pretreated with testosterone by 50.1+/-2.1% (P<0.05) vs. control hearts. Lactate dehydrogenase release rates decreased in the hearts of animals pretreated with estradiol by 55.7+/-1.9% (P<0.01) vs. controls and by 58.8+/-3.0 (P<0.01) vs. directly applied estradiol. Duration of ventricular fibrillation decreased after 10 days application of drugs, from 9.42+/-0.81 min to 4.58+/-0.93 min (P<0.05) with estradiol and from 9.19+/-1.05 min to 4.65+/-0.51 min (P<0.05) with testosterone. The duration of heart arrest decreased in 10 days application of testosterone from 2.42+/-0.16 min to 20.0+/-12.26 s (P<0.01). Hearts from animals pretreated for 10 days with estradiol showed more cardioprotective effects during reperfusion than those pretreated with testosterone. Testosterone pretreatment, despite being less effective in cardioprotection than estradiol, improved coronary flow and decreased arrhythmias as effectively as estradiol. |
8,874 | Open source model for generating RR intervals in atrial fibrillation and beyond. | Realistic modeling of cardiac inter-beat (RR) intervals is highly desirable for basic research in cardiac electrophysiology, clinical management of heart diseases, and developing signal processing tools for ECG analysis.</AbstractText>We present an open source computer model that is capable to generate realistic time series of RR intervals in both physiologic and pathologic conditions. Detailed model structure and the software implementation are described.</AbstractText>Examples are provided on how to use this model to generate RR intervals in atrial fibrillation with ventricular pacing, normal sinus rhythm with heart rate variability, and typical atrial flutter with atrioventricular block. The extensibility of the model is also discussed.</AbstractText>The present computer model provides a unified platform wherein various types of ventricular rhythm can be simulated. The availability of this open source model promises to support and stimulate future studies.</AbstractText> |
8,875 | Ventricular fibrillation frequency characteristics are altered in acute myocardial infarction. | Future automated external defibrillators are being designed to direct rescue efforts (chest compressions first vs. defibrillation) by inferring the duration of ventricular fibrillation based on its waveform characteristics such as frequency content. This approach assumes that the ventricular fibrillation waveform is an appropriate surrogate for ventricular fibrillation duration and is not affected by structural heart disease. We hypothesized that an acute myocardial infarction may alter the frequency content of ventricular fibrillation.</AbstractText>Animal intervention study with comparison to control group.</AbstractText>University animal laboratory.</AbstractText>Twenty-seven swine.</AbstractText>Acute myocardial infarction was induced by occlusion of the mid-left anterior descending artery. Ventricular fibrillation was induced in swine with acute myocardial infarction and control swine.</AbstractText>Ventricular fibrillation was induced in 11 swine with an acute myocardial infarction and in 16 control swine. Ventricular fibrillation waveforms were analyzed for mean, median, and dominant frequency, as well as bandwidth and amplitude. All frequency characteristics were significantly (p < .001) altered in swine with acute myocardial infarction compared with controls. Specifically, these characteristics were significantly depressed and varied little over time in swine with acute myocardial infarction compared with controls.</AbstractText>These data establish that ventricular fibrillation during an acute myocardial infarction has an altered frequency content and time evolution compared with ventricular fibrillation without coronary obstruction. Frequency characteristics such as mean, median, dominant, and bandwidth show little variation in time after an acute myocardial infarction and are not suitable surrogates for ventricular fibrillation duration. These findings have important implications for the development of "smart" automated external defibrillators designed to determine duration of ventricular fibrillation from the waveform characteristics.</AbstractText> |
8,876 | [Time-frequency analysis of ventricular fibrillation and the effects of amiodarone]. | This study is to quantify time-varying dominant frequencies in electrocardiogram (ECG) during the ventricular fibrillation (VF). Orthogonal ECG (sagittal, x; transverse, y; and longitudinal, z) and the transvenous two-leads defibrillation systems were set in 19 dogs. Time-frequency analysis was used to assess changes in the dominant frequency within ECG recorded in dogs during trials of 10-30 s of VF. In 4 additional dogs, the dominant frequencies were compared during 10 s of VF before and after administration of amiodarone. Results showed that in the 427 trials of 10 s VF and 335 trials of 30 s VF, average variation in the dominant frequency was considerable, between +/- 12%-18%. The frequencies orthogonal ECG during 10 s VF were distributed symmetrically above and below the mean frequency like a normal distribution. In the 79 trials with administration of amiodarone during 10 s VF in all three ECG, the mean frequencies decreased from 6.5 (x), 7.4 (y) and 7.0 Hz (z) to 6.1, 6.4 and 6.3 Hz (P < 0.01), respectively, and the variation in dominant frequencies decreased from 1.18, 1.38 and 1.19 to 0.98, 1.11 and 1.02 Hz (P < 0.05) respectively. The results confirmed that the frequencies of 10-30 s VF in ECG vary considerably and continuously, and amiodarone decreases this variation. |
8,877 | Outcome of pharmacological rhythm control for new-onset persistent atrial fibrillation in patients with systolic heart failure: a comparison with patients with normal left ventricular function. | To compare outcome of a serial cardioversion strategy in atrial fibrillation (AF) patients with and without systolic heart failure (HF).</AbstractText>In patients with new-onset persistent AF and systolic HF [left ventricular ejection fraction (LVEF) <0.40] outcome of a serial electrical cardioversion (ECV) and serial antiarrhythmic drug strategy was compared with a control group of patients without HF. Follow-up was 18 months. Sixty-four consecutive patients with systolic HF (mean age 64 +/- 12 years, 50% coronary artery disease, LVEF 0.30 +/- 0.07) were enrolled and compared with 48 consecutive patients without HF (mean age 66 +/- 8 years, all LVEF >0.50, 40% lone AF). Success of ECV and occurrence of subacute and late recurrences in patients with and without HF were comparable. After the first relapse, AF was accepted in significantly more HF patients (23 vs. 4%, P < 0.01). Significantly less HF patients underwent serial ECV and antiarrhythmic drug approach (42 vs. 71%, respectively, P < 0.001). At the end of follow-up more HF patients were in permanent AF (45 vs. 29%, P = 0.03).</AbstractText>Recurrence pattern after ECV is comparable between patients with and without systolic HF, but outcome of a serial cardioversion strategy is worse in HF patients, possibly related to a less stringent use of this approach.</AbstractText> |
8,878 | Examination of research trends on patient factors in patients with implantable cardioverter defibrillators. | The implantable cardioverter defibrillator (ICD) is the most effective treatment available for terminating potentially life-threatening ventricular tachycardia and ventricular fibrillation and reducing the risk of mortality. Despite its established health benefits, ICD therapy is accompanied by a unique array of patient and psychological factors meriting ample research attention. The purpose of this paper is to examine research trends and results regarding patient factors in cardiac and ICD research and to discuss key areas for future research.</AbstractText>: An increase in articles associated with patient factors in cardiac and ICD research will be shown over time.</AbstractText>: The Medical Subject Heading (MeSH) system in PubMed was used to index articles under a range of psychosocial headings for both cardiovascular disease and ICDs to quantify the frequency of articles published across time, the journals most frequently utilized, the most productive institutions, and the most common areas of inquiry.</AbstractText>: A significant positive relationship was revealed between patient factors in cardiac research (r=0.96, p<0.01) and ICD research (r=0.88, p<0.01) over time. Research is limited by the small number of investigations and institutions. Of the 178 articles on patient factors in ICD research, the most frequent areas of inquiry were psychosocial treatment (70.79%), anxiety (33.15%), quality of life (32.02%), and depression (29.78%).</AbstractText>: Future research examining positive adjustment is warranted, especially in light of increased prophylactic ICD implantation and possible decreased treatment burden associated with decreased shocks.</AbstractText> |
8,879 | A phase II study of capecitabine and irinotecan in combination with concurrent pelvic radiotherapy (CapIri-RT) as neoadjuvant treatment of locally advanced rectal cancer. | We sought to evaluate the efficacy and safety data of a combination regimen using weekly irinotecan in combination with capecitabine and concurrent radiotherapy (CapIri-RT) as neoadjuvant treatment in rectal cancer in a phase-II trial. Patients with rectal cancer clinical stages T3/4 Nx or N+ were recruited to receive irinotecan (50 mg m(-2) weekly) and capecitabine (500 mg m(-2) bid days 1-38) with a concurrent RT dose of 50.4 Gy. Surgery was scheduled 4-6 weeks after the completion of chemoradiation. A total of 36 patients (median age 62 years; m/f: 27:9) including three patients with local recurrence were enclosed onto the trial. The median distance of the tumour from the anal verge was 5 cm. The main toxicity observed was (NCI-CTC grades 1/2/3/4 (n)): Anaemia 23/9/-/-; leucocytopenia 12/7/7/2, diarrhoea 13/15/4/-, nausea/vomiting 9/10/2/-, and increased activity of transaminases 3/3/1/-. One patient had a reversible episode of ventricular fibrillation during chemoradiation, most probably caused by capecitabine. The relative dose intensity was (median/mean (%)): irinotecan 95/91, capecitabine 100/92). Thirty-four patients underwent surgery (anterior resection n=25; abdomino-perineal resection n=6; Hartmann's procedure n=3). R0-resection was accomplished in all patients. Two patients died in the postoperative course from septic complications. Pathological complete remission was observed in five out of 34 resected patients (15%), and nine patients showed microfoci of residual tumour (26%). After a median follow-up of 28 months one patient had developed a local recurrence, and five patients distant metastases. Three-year overall survival for all patients with surgery (excluding three patients treated for local relapse or with primary metastatic disease) was 80%. In summary, preoperative chemoradiation with CapIri-RT exhibits promising efficacy whereas showing managable toxicity. The local recurrence and distant failure rates observed after a median 28 months are low compared with standard 5-fluorouracil based therapy. |
8,880 | Subclinical atherosclerosis and risk of atrial fibrillation: the rotterdam study. | Myocardial infarction is an important risk factor for atrial fibrillation, but the role of subclinical atherosclerosis is unknown. This longitudinal study evaluates whether atherosclerosis affects the risk of atrial fibrillation in persons without overt coronary disease.</AbstractText>This investigation was part of the Rotterdam Study, a population-based cohort study among persons 55 years or older. Participants with atrial fibrillation at baseline, with a history of myocardial infarction, or with angina pectoris and those who had undergone cardiac operative procedures were excluded, leaving 4407 subjects for the analyses. Baseline intima-media thickness of the common carotid artery and the presence of carotid plaques were used as indices of generalized atherosclerosis. During a median follow-up of 7.5 years, 269 cases of incident atrial fibrillation were identified. Relative risks were calculated with 95% confidence intervals, adjusted for age and sex, using the Cox proportional hazards model. Additional adjustments were made for body mass index, hypertension, systolic blood pressure, serum cholesterol level, smoking, diabetes mellitus, left ventricular hypertrophy on the electrocardiogram, and the use of cardiac medication.</AbstractText>The risk of atrial fibrillation was associated with carotid intima-media thickness (relative risk, 1.90; 95% confidence interval, 1.20-3.00, highest vs lowest quartile) and severity of carotid plaques (relative risk, 1.49; 95% confidence interval, 1.06-2.10, severe vs absence). Risk estimates were stronger in women than in men.</AbstractText>Atherosclerosis in participants without manifest atherosclerotic disease is an independent risk factor for atrial fibrillation. These results suggest that aggressive treatment of asymptomatic atherosclerosis may help to prevent atrial fibrillation.</AbstractText> |
8,881 | Resuscitation from transfusion-associated hyperkalaemic ventricular fibrillation. | Evidence to guide resuscitation from transfusion-related hyperkalaemic ventricular fibrillation is sparse. This case report describes a 29 kg patient undergoing scoliosis surgery who developed hyperkalaemic ventricular tachycardia/fibrillation following the replacement of over two blood volumes with banked blood in 90 minutes. Rapid reversion to sinus rhythm followed administration of 1.4 mmol of calcium chloride and two units of insulin (Actrapid, Novo Nordisk). The relevant literature is reviewed, indicating that an elevated serum ionised calcium level protects against hyperkalaemia, by an intracellular mechanism. Evidence supports the use of lignocaine, but not amiodarone, as additional treatment. |
8,882 | Development of congestive heart failure in Japanese patients with atrial fibrillation. | Atrial fibrillation (AF) and congestive heart failure (CHF) are frequently coexistent, but their temporal relationship in Japanese patients is unclear.</AbstractText>248 AF patients (63.6+/-10.0 years old) without a history of CHF were enrolled for analysis of the development of CHF during the follow-up period of 49.7+/-29.8 months. Of them, 195 did not have structural heart disease, 22 had dilated or hypertrophic cardiomyopathy, 18 had an old myocardial infarction, and 15 had valvular heart disease. During the follow-up period, 16 patients (6.5%) developed CHF requiring hospitalization (2.0% per patient-year). Although age, gender, fractional shortening, left atrial diameter, hypertension and diabetes mellitus were not associated with CHF development, existence of structural heart disease and left ventricular hypertrophy by Cornell voltage criteria on ECG were significantly associated with CHF development. Cox-Hazard regression analysis revealed that the existence of structural heart disease was the only independent risk factor (hazard ratio 3.50, 95% confidence interval 1.21-10.1).</AbstractText>In the present group of Japanese AF patients, CHF requiring hospitalization occurred at a rate of 2% per year. The existence of structural heart disease was the only independent risk factor in this population.</AbstractText> |
8,883 | Dose-response effect of flecainide in patients with symptomatic paroxysmal atrial fibrillation and/or flutter monitored with trans-telephonic electrocardiography: a multicenter, placebo-controlled, double-blind trial. | A double-blind, randomized, parallel-group, placebo-controlled trial was conducted in patients with paroxysmal atrial fibrillation or flutter (PAF/PAFL) experiencing 2 or more episodes of symptomatic PAF/PAFL during a 28-day observation period to determine the dose-response effect and safety of flecainide.</AbstractText>A total of 143 patients at 30 centers were randomized to receive 25, 50, or 100 mg of flecainide or placebo twice daily (BID). In 123 patients (per protocol set), those remaining free from PAF/PAFL after the treatment were 3.1% on placebo, 7.7% on 25 mg/BID, 9.4% on 50 mg/BID, and 39.4% on 100 mg/BID of flecainide. As a whole group, a significant linear dose-response (p<0.001) was observed and a significant difference between placebo and 100 mg/BID was observed (p<0.001). A similar dose-response between the present study and Caucasian study was demonstrated. Although there were 5 patients who needed cardioversion or ablation because of frequent episodes of PAF/PAFL (2 in 25 mg/BID, 1 in 50 mg/BID, and 2 in 100 mg/BID of flecainide), neither death nor ventricular proarrhythmic event was reported.</AbstractText>This study indicated that flecainide exerted a significant dose-dependent effect on the prevention of symptomatic PAF/PAFL recurrence and showed that there was no inter-ethnic difference in the clinical effect of flecainide in patients with PAF/PAFL.</AbstractText> |
8,884 | Blood pressure and estimated risk of stroke in the elderly population of Spain: the PREV-ICTUS study. | The objective of this study was to estimate the high blood pressure values and the 10-year risk of stroke in the Spanish general population aged 60 years or older using the Framingham scale.</AbstractText>This was a multicenter, population-based, cross-sectional study performed in Spanish primary care centers. A randomized selection of centers and recruitment population was used. We collected clinical, biochemical, and electrocardiographic data.</AbstractText>We analyzed 7343 subjects (mean age, 71.6 years; standard deviation, 7.0; 53.4% females, 34.4% obese subjects, and 27.1% diabetic subjects). Electrocardiographic-left ventricle hypertrophy was present in 12.9% of the subjects, atrial fibrillation in 8.4%, and established cardiovascular disease in 28.9%; 73.0% already had hypertension diagnosed, and 12.8% showed high blood pressure without a prior diagnosis of hypertension. Among hypertensive subjects, 29.1% had high blood pressure on therapeutic objective, and of the total population 35.7% had high blood pressure under control. Those with hypertension already diagnosed showed a higher prevalence of other stroke risk factors (left ventricle hypertrophy, atrial fibrillation, diabetes, or established cardiovascular disease). The estimated 10-year stroke risk was 19.6% (standard deviation, 17.3%), and was greater in hypertensive patients (23.7%; standard deviation, 18.5) than in patients with high blood pressure without known hypertension (12.4%; standard deviation, 9.2), or in normotensive subjects (5.3%; standard deviation, 0.2; P<0.001).</AbstractText>The 10-year estimated stroke risk was 19.6%, and it was greater in hypertensive patients as compared with the remainder people at any blood pressure range. The concomitant stroke risk factors are more prevalent in patients with hypertension already diagnosed, which implies an important additional estimated risk of stroke.</AbstractText> |
8,885 | Co-ordinated intra-abdominal and intra-thoracic pressures regulate cough assisted cardiac circulatory support. | Periodically case studies emerge that demonstrate voluntary and forced coughing in ventricular fibrillation or asystole can maintain consciousness for up to 100 s. Forced cough is effective in producing co-ordinated abdominal muscle contraction and increases in intra-abdominal and thoracic pressures. These co-ordinated pressure changes are likely to be responsible for assisted circulation. In this short communication we discuss some of the possible abdominal physiological mechanisms for cough assisted circulatory support. |
8,886 | Beneficial effects of carbon monoxide-releasing molecules on post-ischemic myocardial recovery. | There is increasing evidence corroborating a protective role of carbon monoxide releasing molecules (CORMs) in injured tissues. Carbon monoxide (CO) carriers have been recently developed as a pharmacological tool to simulate the effect of heme oxygenase-1-derived CO. The effects of CORM-3, a water-soluble CO releaser, on the incidence of reperfusion-induced ventricular fibrillation (VF) and tachycardia (VT) were studied in isolated rat hearts. Hearts were treated with different doses of CORM-3 before the induction of 30 min global ischemia followed by 120 min reperfusion. We found that at concentrations of 25 microM and 50 microM of CORM-3 promoted a significant reduction in the incidence of VF and VT. Thus, the incidence of VF was reduced by 67% (p<0.05) and 92% (p<0.05) with 25 microM and 50 microM of CORM-3, respectively. The protective effect of CORM-3 on the incidence of VT followed the same pattern. The antiarrhythmic protection was associated with a marked attenuation in infarct size, significant decreases in cellular Na(+) and Ca(2+) gains and K(+) loss. Consequently, the recovery of post-ischemic function was significantly improved. In conclusion, CORM-3 exerts beneficial effects against ischemia/reperfusion-induced injury through its abilities to release CO which mediates a cardioprotective action by regulating tissue Na(+), K(+), and Ca(2+) levels. |
8,887 | Causes of errors in the electrocardiographic diagnosis of atrial fibrillation by physicians. | The emphasis of most large studies has been placed on the treatment and prevention of atrial fibrillation (AF) and its complications. Little is known about the accuracy of physicians in the electrocardiographic (ECG) diagnosis of AF and the possible causes of the diagnostic errors.</AbstractText>Over a period of 10 months, a total of 35508 ECGs (28356 patients) were overread in a 385-bed community hospital within 24 hours of the initial reading. Corrected ECGs were returned to the patient file. The gold standard for the final diagnosis was based on the consensus by the cardiologist readers.</AbstractText>In all, 35508 ECGs were reviewed. A total of 2809 cases of AF were studied. Incorrect diagnoses related to AF were found in 219 cases. Type I errors (overdiagnosis) occurred in 137 cases. Rhythms with irregular R-R intervals (sinus rhythm with premature atrial contractions and atrial tachycardia or flutter with variable atrioventricular conduction) were misdiagnosed as AF. The presence of low-amplitude atrial activity and/or baseline artifact significantly increased the likelihood of the erroneous diagnosis, whereas ventricular rates of 130 beats/min did not influence the rate of error. Type II errors (missed AF) occurred in 82 cases where AF was either missed or confused with atrial tachycardia/flutter. Finally, ventricular pacing significantly increased the likelihood of type II errors.</AbstractText>In our institution, about 900 ECGs are read each week and 5 of them carry a wrong interpretation related to AF. More attention to common sources of errors as reinforced by an ongoing quality improvement program may reduce the rate of mistakes and thus prevent serious consequences.</AbstractText> |
8,888 | Irregularity test for very short electrocardiogram (ECG) signals as a method for predicting a successful defibrillation in patients with ventricular fibrillation. | A significant proportion of patients with ventricular fibrillation (VF) can only be defibrillated after a period of chest compressions and ventilation before the defibrillation attempt. In these patients, unsuccessful defibrillations increase the duration of heart arrest and reduce the possibility of a successful resuscitation, which could be avoided if a reliable prediction for the success of defibrillation could be made. A new method is presented for estimating the irregularity in very short electrocardiographic (ECG) recordings that enables the prediction of a successful defibrillation in patients with VF. This method is based on a recently developed determinism test for very short time series. A slight modification shows that the method can be used to determine relative differences in irregularity of the studied signals. In particular, ECG recordings of VF from patients who could be successfully defibrillated are characterized by a higher level of irregularity, indicating a chaotic nature of the dynamics of the heart, which is in agreement with previous studies on long ECG recordings showing that cardiac chaos was prevalent in healthy heart, whereas in severe congestive heart failure, a decrease in the chaotic behavior was observed. |
8,889 | Valsartan in the treatment of heart attack survivors. | Survivors of myocardial infarction (MI) are at high risk of disability and death. This is due to infarct-related complications such as heart failure, cardiac remodeling with progressive ventricular dilation, dysfunction, and hypertrophy, and arrhythmias including ventricular and atrial fibrillation. Angiotensin (Ang) II, the major effector molecule of the renin-angiotensin-aldosterone system (RAAS) is a major contributor to these complications. RAAS inhibition, with angiotensin-converting enzyme (ACE) inhibitors were first shown to reduce mortality and morbidity after MI. Subsequently, angiotensin receptor blockers (ARBs), that produce more complete blockade of the effects of Ang II at the Ang II type 1 (AT1) receptor, were introduced and the ARB valsartan was shown to be as effective as an ACE inhibitor in reducing mortality and morbidity in high-risk post-MI survivors with left ventricular (LV) systolic dysfunction and and/or heart failure and in heart failure patients, respectively, in two major trials (VALIANT and Val-HeFT). Both these trials used an ACE inhibitor as comparator on top of background therapy. Evidence favoring the use of valsartan for secondary prevention in post-MI survivors is reviewed. |
8,890 | [Sudden cardiac death: epidemiology and modern therapy]. | Sudden Cardiac Death (SCD) has become an important public health challenge in the Western World. In Switzerland near 10,000 people suffer each year from SCD. The survival from SCD to hospital discharge is discouraging (near 5%). Large majority of events occur unexpectedly in the out-of-hospital environment and are not predicted with great accuracy by risk profiling. Because the majority of SCD occur by the mechanism of ventricular fibrillation, community-based defibrillation strategies have emerged as one approach to SCD problem. Newer strategies of defibrillation designed to respond faster to out-of-hospital cardiac arrest, including public access defibrillation, as well as aggressive primary and secondary prevention of coronary artery disease appears as the best approach for successful management of SCD. |
8,891 | Transvenous cardioverter-defibrillator implantation in a patient with tricuspid mechanical prosthesis. | A 64-year-old woman was referred to our center because of poorly tolerated ventricular tachycardia (VT) at 210 bpm due to an old myocardial infarction. The patient had been operated on at age of 20 for mitral valve commissurolysis, at age of 49 for ductal carcinoma, at age of 56 for mitral valve replacement, and at age of 61 for tricuspid valve replacement. Left ventricular EF was 31%. The patient was in permanent atrial fibrillation (AF) since the age of 53. She had undergone three cardiac surgery procedures, ending with two prosthetic mechanical valves. The cardiac surgery team advised against an epicardial ICD implantation.</AbstractText>We achieved a fully transvenous implant, with a screw-in defibrillation coil in the low right atrium and a bipolar pacing/sensing lead in a posterolateral branch of the coronary sinus. Pacing/sensing parameters were reliable, and effective defibrillation occurred at 20 J by a stepdown protocol. During 16-month follow-up, three VT episodes at 210 bpm were terminated by antitachycardia pacing (ATP) therapy. Left ventricular pacing/sensing was stable at long term.</AbstractText>Thanks to technologic improvements, transvenous ICD implantation is feasible and safe in patients with a tricuspid mechanical prosthesis.</AbstractText> |
8,892 | Fatal inappropriate ICD shock. | Inappropriate implantable cardioverter defibrillator (ICD) therapy carries a low but relevant risk of ventricular proarrhythmia. In the present case, the extremely rare event of a fatal arrhythmia caused by inappropriate therapy is reported. Dislodgement of the ventricular lead to the level of the tricuspid annulus led to additional sensing of the atrial signal during sinus tachycardia. Spuriously, ventricular fibrillation was sensed and induced inappropriate ICD shocks. The fourth inappropriate shock caused ventricular fibrillation, which was subsequently undersensed by the dislodged lead due to low ventricular amplitudes. The ICD started antibradycardic pacing during ventricular fibrillation. After initial successful resuscitation, the patient died 1 week later due to severe hypoxic brain damage. Although not preventable in the present case, it underlines the necessity of immediate interrogation of the ICD after ICD therapy and deactivation of the ICD in the setting of a dislodged endocardial lead and intensive care monitoring of the patient until revision. |
8,893 | Enterovirus-associated hemophagocytic syndrome in children with malignancy: report of three cases and review of the literature. | Enteroviruses can cause severe manifestations in children with malignancy. Infection-associated hemophagocytic syndrome (IAHS) due to enterovirus is a rare entity in children. Patients with malignancy and IAHS due to enterovirus were retrospectively evaluated at the University of Athens' Hematology-Oncology pediatric unit within a 6-year period (2000-2006). IAHS occurred in three cases among 56 patients with documented enteroviral infection. The diagnosis of IAHS was confirmed by bone marrow aspiration and biopsy. Nested reverse transcriptase-polymerase chain reaction (RT-PCR), sequencing of the amplified alleles, and immunohistochemistry were performed to document the presence of enterovirus. The type of enterovirus was specified by indirect immunofluorescence assay. At the early phase of the disease, patients presented mild, non-specific viral symptoms, persistent unexplained fever, and pancytopenia. At the late phase, patients had more severe manifestations, such as persistent high fever, diarrhea, weight loss, hepatosplenomegaly, and hepatic dysfunction. The therapeutic approach consisted of supportive care, administration of immunoglobulin (400 mg/kg or 2 g/kg), and pleconaril. All patients had fatal outcome; two patients succumbed to multiorgan failure (MOF), while one patient succumbed to ventricular fibrillation. IAHS usually has fulminant course and leads to severe and life-threatening complications, such as liver failure and MOF. IAHS should always be included in the differential diagnosis of viral syndrome or unexplained fever. The therapeutic approach for IAHS should be administered as early as possible, before the progression to irreversible tissue damage. Early therapeutic intervention involving high doses of immunoglobulin might be beneficial for the patient's outcome. |
8,894 | The use of protamine after radiofrequency catheter ablation: a pilot study. | Evaluate the effect of administering intravenous protamine immediately post-radiofrequency catheter ablation (RFCA) on thrombotic and bleeding complications in heparinized patients.</AbstractText>Heparinized patients that had RFCA for atrial or ventricular arrhythmias at our institution between January 2001 and March 2006 and had a complete data set were included in this cohort evaluation. Patients receiving at least one dose of protamine within 15 min of RFCA were deemed the prophylactic group while those not receiving protamine within 15 min were the control group. Thrombotic (cerebrovascular event, transient ischemic attack, pulmonary embolism, deep vein thrombosis, or myocardial infarction) and bleeding events (blood loss requiring transfusion, hematoma requiring intervention, or intracranial hemorrhage) were compared between groups.</AbstractText>Overall, 158 patients (74% male, 55 +/- 13.5) met inclusion criteria. Of these, 73.4% received prophylactic protamine (average dose = 39 mg +/- 17). Only one patient (0.9%) in the prophylactic protamine group and zero patients in the control group experienced a thrombotic event (p > 0.99). Only two patients (1.7%) in the protamine group (n = 2 blood transfusions) and zero patients in the control group experienced bleeding events (p = 0.839).</AbstractText>Administering prophylactic intravenous protamine to allow for quicker catheter removal following RFCA in heparinized patients did not markedly impact thrombotic or bleeding complication rates in our population. The perceived benefit in our institution to protamine administration in this population is a reduction in postoperative patient immobilization and discomfort, reduced PACU nursing care, and earlier time to discharge. Given the low rate of thrombotic and bleeding events, a study of several thousand patients would be needed to fully evaluate the impact on these events.</AbstractText> |
8,895 | Prognostic value of location and type of myocardial infarction in the setting of advanced left ventricular dysfunction. | Location (anterior) and type (Q wave) of myocardial infarction (MI) might be considered of prognostic significance when predicting mortality. However, there are limited data regarding the prognostic significance of type and location of MI in patients with severely depressed left ventricular function. In 1,221 patients in the MADIT II, Q-wave MI was observed in 763 patients (62%), 115 (10%) had non-Q-wave MI, and 343 (28%) had conduction abnormalities. In patients with Q-wave MI, anterior MI was present in 430 (57%), inferior in 155 (20%), and combined in 178 (23%) patients. Study end points included all-cause mortality, hospitalization or death due to worsening congestive heart failure, and episodes of ventricular tachycardia or ventricular fibrillation requiring implantable cardioverter-defibrillator therapy. In a multivariate Cox proportional hazard model predicting mortality, the following clinical variables entered the predictive model at a p value <0.10: treatment (implantable cardioverter-defibrillator vs conventional therapy), age dichotomized at 65 years, angina pectoris, ejection fraction dichotomized at 25%, serum urea nitrogen dichotomized at 25 mg/dl, and beta-blocker use. After adjustment for these covariates, risk of mortality was not significantly different in non-Q-wave MI versus Q-wave MI. However, when analyzing location of MI, inferior wall MI was associated with a significantly (hazard ratio 1.58, p = 0.048) higher risk of mortality than anterior wall MI. In addition, patients with conduction abnormalities had a higher risk of mortality (hazard ratio 1.36, p = 0.088) than patients with anterior wall MI. In conclusion, in the setting of severely depressed ejection fraction (< or =30%), inferior wall MI was associated with a significantly higher risk of mortality than anterior wall MI. |
8,896 | Different roles of nitric oxide synthase isoforms in cardiopulmonary resuscitation in pigs. | The purpose of the present study was to identify the roles of the three nitric oxide synthase (NOS) isoforms on whole body ischemia-reperfusion injury during cardiopulmonary resuscitation (CPR) with periodic acceleration (pGz) in pigs. Thirty-two anesthetized pigs (27.6+/-3.4 kg) were monitored for hemodynamics and selected echocardiographic variables. Twenty minutes after NOS inhibition or placebo administration, ventricular fibrillation (VF) was induced and remained untreated for 3 min, followed by CPR with pGz for 15 min, plus 3 min of manual chest compressions and defibrillation attempt. Four groups were studied: (1) saline control; (2) L-NAME (non-selective NOS inhibitor); (3) aminoguanidine (inducible NOS inhibitor); (4) TRIM (neuronal NOS inhibitor). Return of spontaneous circulation (ROSC) to 180 min occurred in 6/8 controls, 4/8 L-NAME, 7/8 aminoguanidine, and 2/8 TRIM animals. The L-NAME group had significantly lower organ blood flow, impaired cardiac function, but higher vascular tone than control group. The aminoguanidine group had the highest organ blood flows and survival rate. Six out of eight TRIM treated animals had initial return of heartbeat; however, with impaired heart contractility and could not survive more than 20 min of ROSC. This study reveals the differential role of endogenous NO produced from the three NOS isoforms during pGz-CPR. Both endothelial and neuronal NOS derived NO show predominantly protective effects while inducible NOS derived NO plays a detrimental role in pGz-CPR. The present study has shown that cardiac arrest and resuscitation appears to be associated with a different expression of NOS isoforms which appear to affect resuscitation outcomes differently. |
8,897 | Management of dofetilide overdose in a patient with known cocaine abuse. | Dofetilide, a class III antiarrhythmic agent, is prescribed for conversion to and maintenance of normal sinus rhythm in patients with persistent atrial fibrillation or atrial flutter. Most antiarrhythmics have significant toxicities such as torsade de pointes, and patients should be closely monitored while receiving antiarrhythmic therapy. However, we know of no reports concerning management of intentional overdose of dofetilide that have been published. We report the case of a 33-year-old man who was treated for ingestion of approximately 5 mg of dofetilide as a suicide attempt. In addition, he had a known history of cocaine abuse. He came to the emergency department approximately 45 minutes after the ingestion; examination revealed a QTc interval of approximately 570 msec. He was treated with activated charcoal and sorbitol by nasogastric tube and received aggressive supplementation with potassium and magnesium. The patient was monitored by telemetry for several days and responded well. Cardiac toxicity is the utmost concern when treating dofetilide overdose. The mainstay of treatment focuses on supportive care and prevention of drug absorption. Ventricular dysrhythmias or torsade de pointes should be treated according to advanced cardiac life support guidelines. |
8,898 | Improvement of quality of life after percutaneous balloon mitral valvulotomy in patients with mitral stenosis: does rhythm matter? | Limited data are available on the effect of percutaneous balloon mitral valvulotomy (PBMV) on quality of life (QoL) in patients with mitral stenosis (MS), and whether the effect is similar between patients in sinus rhythm (SR) and with atrial fibrillation (AF). The study aim was to determine the effect of PBMV on the QoL of such patient groups.</AbstractText>A total of 130 patients with symptomatic MS and scheduled for PBMV was studied. Patients with AF were predominantly male, and had more severe symptoms, a larger left atrial size and a lower left ventricular ejection fraction (LVEF). Baseline characteristics were collected together with PBMV outcomes. QoL was assessed using the SF-36 questionnaire at baseline, and at one and six months after PBMV. The QoL assessment included eight aspects: physical functioning; role physical; bodily pain; general health; vitality; social functioning; role emotional; and mental health. The raw scale was transformed into a transformed scale from 0 (worst) to 100 (best). Physical and mental subscales were calculated.</AbstractText>The cardiac rhythm was AF in 65 patients (50%). QoL on physical and mental scales was significantly improved after PBMV. There was no difference in the effect of PBMV on QoL improvement in patients with AF and SR. QoL improvement was demonstrated in all aspects, except for bodily pain. PBMV also improved NYHA functional class and mitral valve area, but decreased left atrial diameter and right ventricular systolic pressure in both groups. An increase in LVEF was observed in patients with AF CONCLUSION: PBMV was shown to improve QoL in patients with MS, irrespective of their baseline cardiac rhythm.</AbstractText> |
8,899 | Postoperative outcome after coronary artery bypass grafting in chronic obstructive pulmonary disease. | It is uncertain if the presence and severity of airflow obstruction in chronic obstructive pulmonary disease (COPD) is predictive of surgical morbidity and mortality after coronary artery bypass grafting (CABG).</AbstractText>Retrospective study of patients who underwent CABG between 1998 and 2003 in a university-affiliated hospital for whom a preoperative spirometry was available. COPD was diagnosed in smokers or ex-smokers 50 years of age or older in the presence of irreversible airflow obstruction. Patients were divided into three groups depending on the spirometry: controls (forced expiratory volume in 1 s [FEV1] 80% or more, FEV1/forced vital capacity [FVC] greater than 0.7), mild to moderate COPD (FEV1 50% or more and FEV1/FVC 0.7 or less) and severe COPD (FEV1 less than 50% and FEV1/FVC 0.7 or less).</AbstractText>Among the 411 files studied, 322 (249 men, 68+/-8 years of age) were retained (controls, n=101; mild to moderate COPD, n=153; severe COPD, n=68). The mortality rate (3.0%, 2.6% and 0%, respectively) was comparable among the three groups. Patients with severe COPD had a slightly longer hospital stay than controls (mean difference 0.7+/-1.4 days, P<0.05). Pulmonary infections were more frequent in severe COPD (26.5%) compared with mild to moderate COPD (12.4%) and controls (12.9%), P<0.05. Atrial fibrillation tended to be more frequent in severe COPD than in the other two groups.</AbstractText>Mortality rate associated with CABG surgery is not influenced by the presence and severity of airflow obstruction in patients with COPD. The incidence of pulmonary infections and length of hospital stay were increased in patients with severe COPD.</AbstractText> |
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