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2,300 | Diabetic atrial fibrillation patients: mortality and risk for stroke or embolism during a 10-year follow-up. | To compare in atrial fibrillation patients with and without diabetes, (1) baseline characteristics, (2) additional risk factors for stroke or peripheric or visceral embolism (hypertension, previous stroke, age >75 years), (3) mortality, (4) stroke or embolism, and (5) oral anticoagulation in the year 2000.</AbstractText>Included were 409 outpatients with nonrheumatic atrial fibrillation (62 +/- 12 years, 36% female). All underwent transthoracic and transesophageal echocardiography. Patients with thrombi received oral anticoagulation; patients without thrombi received aspirin until the follow-up in 1995; afterwards, oral anticoagulation according to risk factors for stroke or embolism was recommended. Patients were contacted during the year 2000.</AbstractText>Type 2 diabetes was diagnosed in 73 patients (18%). Sixteen (22%) diabetic and 169 (50%) nondiabetic patients had no other risk factors for stroke or embolism (p < 0.0001). Diabetic patients were older, had more frequent heart failure, hypertension, myocardial infarction, left ventricular dysfunction, valvular abnormalities, left atrial or appendage thrombi, larger left atria, and left atrial appendages than nondiabetic patients. Mean follow-up was 115 months. Diabetic patients had a higher mortality than nondiabetic patients (7%/year versus 4%/year, p < 0.0001). The rate of stroke or embolism of diabetic (3%/year) and nondiabetic patients (2%/year) was similar. The rate of oral anticoagulation was higher in diabetic than in nondiabetic patients (p = 0.0066).</AbstractText>Diabetic patients with atrial fibrillation frequently have additional risk factors for stroke or embolism, and thus should be treated with oral anticoagulation. Whether in the rare cases of atrial fibrillation, in whom diabetes is the only clinical risk factor, oral anticoagulation is indicated cannot be answered by the present study.</AbstractText>Copyright 2003 John Wiley & Sons, Ltd.</CopyrightInformation> |
2,301 | Overcoming ACLS dogma: how quickly should we change? | The ECC Guidelines 2000 considered interesting new evidence about a pre-defibrillation period of prescribed CPR to increase the probability that the postshock rhythm would be perfusing rather than asystole. If victims of out-of-hospital cardiac arrest have not received bystander CPR before the arrival of the defibrillator, a period of preshock CPR could enhance the value of the shocks. At the end of the year 2000 there was insufficient evidence to recommend any other approach than shock as soon as possible and perform CPR at all other times. |
2,302 | R wave undersensing caused by an algorithm intended to enhance sensing specificity in an implantable cardioverter defibrillator. | This article reports on a case of ventricular undersensing despite normal R wave amplitudes during sinus rhythm in an ICD patient. Undersensing of ventricular signals was noted without any evidence of lead dislocation or variation in signal amplitude. Undersensing was due to an exceptionally small R wave signal width and a feature of the Biotronik sensing algorithm designed to avoid oversensing. This algorithm, intended to enhance the sensing specificity of the device, requires registration of two consecutive points above the maximum programmed sensitivity for a ventricular sense event. After modifying the algorithm to a single point registration undersensing disappeared. |
2,303 | Atrial fibrillation with a very rapid ventricular response as the first clinical arrhythmia in a 76-year-old man. | The interest of electrohysiological study for the prognostic evaluation of asymptomatic Wolff-Parkinson-White (WPW) syndrome remains controversial. We report the case of an asymptomatic 67-year-old man without heart disease in whom a type A WPW syndrome was noted. Because the WPW was unchanged during exercise testing, transesophageal EPS was performed. In basal state, 1/1 conduction through the Kent bundle was noted up to a rate of 210 beats/min. After infusion of 30 microg of isoproterenol, atrial pacing was associated with a 1/1 conduction throughout the Kent bundle at a rate at 300 beats/min and induced rapid atrial fibrillation which was stopped by flecainide. No treatment was indicated. Nine years later, at age 76, the patient developed syncope related to rapid atrial fibrillation requiring cardioversion. In conclusion, the occurrence of a potentially lethal supraventricular tachyarrhythmia in a previously asymptomatic patient with WPW syndrome might be encountered in elderly patients. Transesophageal electrophysiological evaluation is a useful means to predict this risk. |
2,304 | Incidence and rate characteristics of atrial tachyarrhythmias in patients with a dual chamber defibrillator. | Atrial tachyarrhythmias play an important role in the treatment of patients with malignant ventricular tachyarrhythmias not only with respect to inappropriate discharges but also to left ventricular function and stroke risk. A combined dual chamber defibrillator provides separate therapies for atrial and ventricular tachyarrhythmias. To assess the incidence of atrial tachyarrhythmias in patients with this dual chamber implantable defibrillator, 40 patients with ventricular tachyarrhythmias and concomitant atrial tachyarrhythmias and/or AV conduction disturbances were included in a prospective study. During a mean follow-up of 25 +/- 11 months, 26 of 40 patients had a total of 1,430 recurrences of atrial tachyarrhythmias. The vast majority of the atrial tachyarrhythmias with regular atrial cycles had a mean median atrial cycle length of 235 +/- 37 ms and a mean duration of 34 +/- 144 minutes. Atrial tachyarrhythmias with irregular atrial cycles exhibited a median atrial cycle length of 198 +/- 31 ms and had a mean duration of 246 +/- 1,264 minutes. In addition, 67% of 375 tachyarrhythmias, in which the median ventricular cycle length during the ongoing episode could be documented, had a ventricular rate <100 beats/min. Continuous atrial arrhythmia detection with a dual chamber ICD reveals a high incidence of atrial tachyarrhythmias with a predominantly short duration of paroxysmal recurrences <1 hour in the vast majority of episodes. |
2,305 | A randomized prospective study of single coil versus dual coil defibrillation in patients with ventricular arrhythmias undergoing implantable cardioverter defibrillator therapy. | ICD implantation is standard therapy for malignant ventricular arrhythmias. The advantage of dual and single coil defibrillator leads in the successful conversion of arrhythmias is unclear. This study compared the effectiveness of dual versus single coil defibrillation leads. The study was a prospective, multicenter, randomized study comparing a dual with a single coil defibrillation system as part of an ICD using an active pectoral electrode. Seventy-six patients (64 men, 12 women; age 61 +/- 11 years) were implanted with a dual (group 1, n = 38) or single coil lead system (group 2,n = 38). The patients represented a typical ICD cohort: 60% presented with ischemic cardiomyopathy as their primary cardiac disease, the mean left ventricular ejection fraction was 0.406 +/- 0.158. The primary tachyarrhythmia was monomorphic ventricular tachyarrhythmia in 52.6% patients and ventricular fibrillation in 38.4%. There was no significant difference in terms of P and R wave amplitudes, pacing thresholds, and lead impedance at implantation and follow-up in the two groups. There was similarly no difference in terms of defibrillation thresholds (DFT) at implantation. Patients in group 1 had an average DFT of 10.2 +/- 5.2 J compared to 10.3 +/- 4.1 J in Group 2, P = NS. This study demonstrates no significant advantage of a dual coil lead system over a single coil system in terms of lead values and defibrillation thresholds. This may have important bearing on the choice of lead systems when implanting ICDs. |
2,306 | High resolution mapping of the pulmonary vein and the vein of Marshall during induced atrial fibrillation and atrial tachycardia in a canine model of pacing-induced congestive heart failure. | The study examined the activations in the pulmonary veins (PVs) and the vein of Marshall (VOM) during atrial fibrillation (AF) in dogs with congestive heart failure (CHF).</AbstractText>The patterns of activation within the PVs and the VOM during AF in CHF are unclear.</AbstractText>We induced CHF in nine dogs by rapid ventricular pacing. The patterns of activation during induced AF were studied one week after ceasing ventricular pacing.</AbstractText>The duration of induced AF averaged 80.7 +/- 177.3 s. The termination of low-amplitude fractionated activity in the PVs preceded the termination of AF in 25 of 29 episodes. High-density mapping (1-mm resolution) showed that the PV was activated by a focal wave front independent of left atrial (LA) activation in 22 AF episodes. Frequent intra-PV conduction blocks and multiple wave fronts in the PVs were recorded during 10 AF episodes. Focal activations were observed within the VOM in 4 of 12 episodes of AF. Three atrial tachycardia (AT) episodes originated from a focus within a PV. Histological studies showed extensive fibrosis in the PVs and in the atria. The PVs in five normal dogs did not have focal or fractionated activity during induced AF.</AbstractText>Atrial fibrillation in canine CHF is associated with independent focal activations in the PVs and the VOM, and with complex wave fronts within the PVs. The PVs may also serve as the origin of AT. These findings suggest that electrical and anatomical remodeling of the PVs and the VOM are important in the maintenance of AF and AT in dogs with CHF.</AbstractText> |
2,307 | Fibrosis of the left atria during progression of heart failure is associated with increased matrix metalloproteinases in the rat. | The purpose of this study was to determine the pathogenic factors and molecular mechanisms involved in fibrosis of the atria.</AbstractText>Fibrosis is an important component of the pathophysiology of atrial fibrillation, especially when the arrhythmia is associated with heart failure (HF) or atrial dilation.</AbstractText>We used a rat model of myocardial infarction (MI) complicated by various degrees of left ventricular dysfunction and atrial dilation to study fibrosis and matrix metalloproteinase (MMP) activity in the left atrial (LA) myocardium by means of histologic, Western blot, zymographic, and immunohistologic techniques.</AbstractText>Three months after surgical ligature of the left coronary artery, 27 rats had a large MI, 12 were in mild HF, and 15 in severe HF. Both groups had LA enlargement at the echocardiography. Masson's trichrome and picrosirius staining of tissue sections revealed marked fibrosis at the periphery of trabeculae and also surrounding myolytic myocytes, in both mild and severe HF. In mild HF, the activity and expression of the matrilysin MMP-7 were increased (122%), whereas in severe HF, both MMP-7 (211%) and the gelatinase MMP-2 (187%) were up-regulated. There were no changes in the expression or activity of MMP inhibitors, TIMP-1, -2, and -4. Immunostaining of cryosections showed that MMP-2 was present in the interstitial spaces, whereas MMP-7 accumulated in myolytic myocytes.</AbstractText>Hemodynamic overload of the atria is an important pathogenic factor of fibrosis; MMP-7 appears to be involved in the early stage of this tissue remodeling process.</AbstractText> |
2,308 | Complete heart block: determinants and clinical impact in patients with hypertrophic obstructive cardiomyopathy undergoing nonsurgical septal reduction therapy. | The purpose of this paper is to examine the incidence and determinants of permanent complete heart block (CHB) after nonsurgical septal reduction therapy (NSRT), and to evaluate the clinical impact of permanent pacemaker (PPM) placement.</AbstractText>Nonsurgical septal reduction therapy with ethanol improves the clinical and hemodynamic parameters in patients with symptomatic hypertrophic obstructive cardiomyopathy. Complete heart block is a common complication after NSRT.</AbstractText>The database of 261 consecutive patients who underwent NSRT at Baylor College of Medicine was reviewed. Clinical variables that were considered as possible determinants for CHB after NSRT were: age, gender, New York Heart Association (NYHA) functional class, left ventricular outflow tract (LVOT) gradient at rest or with provocation, septal thickness, and baseline exercise duration. For electrocardiographic (ECG) variables, the presence of first-degree atrioventricular (AV) block, bifascicular block, left bundle branch block, atrial fibrillation, and left ventricular hypertrophy were analyzed. In addition, the volume of ethanol injected, the method of administration of ethanol (i.e., bolus vs. slow injection [over 30 to 60 s]), number of septal arteries occluded, use of myocardial echocardiography, and infarct size as determined by peak creatine kinase level.</AbstractText>Of 261 consecutive patients, 37 had PPM or automatic implantable cardiac defibrillator placed before NSRT. Of the remaining 224 patients, 31 (14%) developed CHB after the procedure. Multivariate logistic regression analysis showed that female gender (odds ratio [OR] 4.3; P = 0.02), bolus injection of ethanol (OR 51; P = 0.004), injecting more than one septal artery (OR 4.6; P = 0.016), the presence of left bundle branch block (OR 39; P = 0.002), and first-degree AV block (OR 14; P = 0.001) on the baseline ECG are independent predictors of CHB after NSRT. Patients requiring PPM placement had a similar improvement in their NYHA functional class, septal thickness reduction, LVOT gradient reduction, and improvement of exercise capacity when compared with patients who did not require pacing.</AbstractText>Multiple demographic, electrocardiographic, and technical factors seem to increase the risk of CHB after NSRT. Patients with CHB after NSRT derive similar clinical and hemodynamic benefit to patients who did not require permanent pacing.</AbstractText> |
2,309 | Blockade of the inward rectifying potassium current terminates ventricular fibrillation in the guinea pig heart. | Stable high-frequency rotors sustain ventricular fibrillation (VF) in the guinea pig heart. We surmised that rotor stabilization in the left ventricle (LV) and fibrillatory conduction toward the right ventricle (RV) result from chamber-specific differences in functional expression of inward rectifier (Kir2.x) channels and unequal IK1 rectification in LV and RV myocytes. Accordingly, selective blockade of IK1 during VF should terminate VF.</AbstractText>Relative mRNA levels of Kir2.x channels were measured in LV and RV. In addition, LV (n = 21) and RV (n = 20) myocytes were superfused with BaCl2 (5-50 micromol/L) to study the effects on IK1. Potentiometric dye-fluorescence movies of VF were obtained in the presence of Ba2+ (0-50 micromol/L) in 23 Langendorff-perfused hearts. Dominant frequencies (DFs) were determined by spectral analysis, and singularity points were counted in phase maps to assess VF organization. mRNA levels for Kir2.1 and Kir2.3 were significantly larger in LV than RV. Concurrently, outward IK1 was significantly larger in LV than RV myocytes. Ba2+ decreased IK1 in a dose-dependent manner (LV change > RV change). In baseline control VF, the fastest DF domain (28-40 Hz) was located on the anterior LV wall and a sharp LV-to-RV frequency gradient of 21.2 +/- 4.3 Hz was present. Ba2+ significantly decreased both LV frequency and gradient, and it terminated VF in a dose-dependent manner. At 50 micromol/L, Ba2+ decreased the average number of wavebreaks (1.7 +/- 0.9 to 0.8 +/- 0.6 SP/sec x pixel, P < 0.05) and then terminated VF.</AbstractText>The results strongly support the hypothesis that IK1 plays an important role in rotor stabilization and VF dynamics.</AbstractText> |
2,310 | [Myocardial infarction in women: risk factors and clinical features]. | The course of myocardial infarction (MI) in women, especially 60 years of age and older, is characterized by such severe complications as cardiorrhexis, hypovolemic cardiogenic shock, asystole, recurrent ventricular fibrillation and electromechanic dissociation responsible for the majority of lethal outcomes. Especially high MI lethality is in women at the age 70-79 years who have also the highest incidence of recurrent macrofocal MI while small-focal MI occurs in women over 80 years of age (80-89) more frequently than in 60-year-olds and younger. Dominating MI risk factors in women were the following: arterial hypertension detected in 81% patients under 60 and 90.8% cases over 60 years; abnormal lipid spectrum of blood including hypercholesterolemia (HCE), hypertriglyceridemia (HTE) and low concentration of HDLP cholesterol. HCE and HTE closely correlated with abdominal obesity irrespectively of age. Early menopause in women under 60 and diabetes mellitus of type 2 in older women, accumulation of two and more factors of risk contribute to development of coronary heart disease and MI, in females. |
2,311 | The effect of short-term coronary perfusion using a perfusion apparatus on canine heart transplantation from non-heart-beating donors. | We investigated the effects of briefly perfusing hearts from non-heart-beating donors (NHBDs) with a Celsior solution before cardiac transplantation.</AbstractText>Donor hearts were left in situ for 20 minutes after cardiac arrest was induced by rapid exsanguination. Twelve donor-recipient pairs of mongrel dogs were divided into 2 groups, the simple immersion (SI, n = 6) group and the coronary perfusion (CP, n = 6) group. Both groups underwent coronary flushing with Celsior, after which hearts from the SI group were stored using simple immersion for 4 hours and hearts from the CP group underwent 1 hour of further perfusion followed by storage for 3 hours. Orthotopic transplantation was then performed. We measured cardiac output, end-systolic maximal elastance (E(max)), left ventricular pressure, and rate pressure product 1 and 2 hours after weaning from cardiopulmonary bypass (CPB). Two hours after weaning from CPB, the hearts were harvested for histopathologic study and to determine the percentage of water content.</AbstractText>The cardiac output (CO) recovery rate was significantly higher in the CP group than in the SI Group 1 hour after weaning from CPB (p < 0.05). The CO recovery rate, E(max), and rate pressure product were significantly higher and the percentage of water content was significantly lower in the CP group than in the SI Group 2 hours after weaning from CPB (p < 0.05). Histopathologic damage was more severe in the SI group.</AbstractText>The results of this study suggest that short-term coronary perfusion with a Celsior solution may be useful for heart transplantation from NHBDs.</AbstractText> |
2,312 | Hypertension and concurrent arrhythmias. | Hypertension and cardiac arrhythmias commonly coexist in many patients. In this review, we will initially discuss arrhythmogenesis in hypertension, with particular emphasis on atrial and ventricular tachyarrhythmias and sudden cardiac death, whilst in the final part, we will focus our attention on the effects of anti-hypertensive therapies on supra-ventricular and ventricular arrhythmias and on sudden cardiac death prevention. Many patients with atrial fibrillation or frequent premature ventricular contractions have hypertension, and both need to be managed appropriately. Furthermore, hypertensive left ventricular hypertrophy could cause a wide variety of ventricular arrhythmias, which could end in sudden cardiac arrest. Most anti-hypertensive therapies, such as the beta blockers or ACE inhibitors, by slowing or interrupting the progression towards atrial and ventricular remodelling might exert some anti-arrhythmic effect, thus reducing the risk of sudden cardiac death in these patients. |
2,313 | Radiofrequency catheter ablation for various tachyarrhythmias: experience in the Bangkok Heart Institute. | Radiofrequency catheter ablation (RFCA) is the first-line therapy for various tachyarrhythmias. The authors reports experience of RFCA for various types of tachyarrhythmia in 80 consecutive patients, 85 tracts of ablation, from May 2001 to October 2002. The mean age was 40 years, range 6-81 years. Seventy four and 13 tracts of ablation were supraventricular and ventricular arrhythmia, respectively. The results are shown below. [table: see text]</AbstractText>RFCA is an effective method to cure various types tachyarrhythmia. Long-term follow-up should be evaluated in patients with paroxysmal atrial fibrillation.</AbstractText> |
2,314 | Life threatening ventricular arrhythmias with transient or correctable causes. | Traditionally, myocardial ischemia, electrolyte disorders, and proarrhythmic drug reactions have been considered transient and correctable causes of life threatening ventricular tachyarrhythmias. Recent evidence suggests that patients whose ventricular tachyarrhythmias are attributed to these "causes" have a poor outcome. This overview reviews the available literature examining ischemia, electrolyte disorders and pro-arrhythmic drug reactions as potentially reversible causes of ventricular tachycardia (VT) and ventricular fibrillation (VF). While all 3 are undoubtedly involved in the genesis of these tachyarrhythmias, and all 3 deserve particular clinical attention (outlined in the text), difficulties in the identification and/or reversal of their influences exist. Proarrhythmic drug reaction may be a reversible cause of VT/VF, hypokalemia and hypomagnesemia should be considered risk factors for VT/VF, and the role of ischemia is complex. Accordingly, physicians should use extreme caution in attributing life-threatening ventricular tachyarrhythmias to these 3 conditions. Further research is required to identify "truly reversible" causes of VT/VF. |
2,315 | Nineteen years' experience of out-of-hospital cardiac arrest in Gothenburg--reported in Utstein style. | To describe the outcome in the Utstein style for out of hospital cardiac arrest in Gothenburg, over a period of 19 years.</AbstractText>All consecutive cases of cardiac arrest between 1980 and 1999 in which the emergency medical service (EMS) system responded and attempted resuscitation were reported and followed up for 1 year.</AbstractText>In all, there were 5270 attempts. 3871 (73%) of which were regarded as being of a cardiac aetiology. In these cases, information on witnessed status was missing in 782 cases (20%). Of the remaining 3089 cases, 2066 (67%) were bystander witnessed, 791 (26%) were unwitnessed and 232 (8%) crew witnessed. The median interval between a call for the ambulance and the arrival of the first ambulance was 5 min. Thirteen percent of the bystander-witnessed cases were discharged from hospital. Of the unwitnessed cases, only 2% were discharged from hospital, whereas 22% of the crew-witnessed cases were discharged. Of the patients with a bystander-witnessed cardiac arrest of a cardiac aetiology found in ventricular fibrillation (VF), 20% were discharged from hospital.</AbstractText>In this large Utstein style study of out of hospital cardiac arrest stretching over almost 19 years, we report high survival rates both for patients suffering a bystander-witnessed cardiac arrest, and for the subgroup suffering a bystander-witnessed cardiac arrest with VF as the first recorded rhythm. These high survival rates can in part be explained by the short time intervals from calls being received by the emergency dispatch centre (EDC) to the arrival of the emergency medical service at the scene.</AbstractText> |
2,316 | Success changes the problem: why ventricular fibrillation is declining, why pulseless electrical activity is emerging, and what to do about it. | Programs for research and practice in resuscitation have focused on identification and reversal of ventricular fibrillation (VF). While substantial progress has been achieved, evidence is accumulating that clinical death is less likely to be caused by fibrillation now than in the 1960s and 1970s. Pulseless electrical activity (PEA) has emerged as the most common rhythm found in arrests in the hospital and is rapidly rising in pre-hospital reports.</AbstractText>To identify the magnitude of changes occurring, search for potential explanations from population and clinical epidemiology and present the data available regarding etiology and treatment of PEA.</AbstractText>Synthesis of material from population epidemiology, clinical epidemiology, animal and human research on VF and PEA.</AbstractText>VF is a manifestation of severe, undiagnosed coronary artery disease (CAD). Rates of death from CAD increased from rare in 1930 to become the most common cause of death in the US. CAD death rates peaked in the early 1960s and had declined over 50% by the late 1990s. Primary and secondary prevention, early diagnosis and aggressive, successful treatment have contributed to this decline. PEA is a brief phase in clinical death that occurs after losses in consciousness, ventilatory drive and circulation but before decay to asystole; survival rates are poor. PEA is a common stage in clinical death from any of a variety of tissue hypoxic/anoxic insults. Research on PEA is needed; 50 years of attention to CAD and VF have resulted in improved survival and changed the disease spectrum. Similar attention to animal and clinical research on PEA may have the potential to improve survival.</AbstractText> |
2,317 | A prospective, randomised and blinded comparison of first shock success of monophasic and biphasic waveforms in out-of-hospital cardiac arrest. | Evidence suggests that biphasic waveforms are more effective than monophasic waveforms for defibrillation in out-of-hospital cardiac arrest (OHCA), yet their performance has only been compared in un-blinded studies.</AbstractText>We compared the success of biphasic truncated exponential (BTE) and monophasic damped sine (MDS) shocks for defibrillation in OHCA in a prospective, randomised, double blind clinical trial. First responders were equipped with MDS and BTE automated external defibrillators (AEDs) in a random fashion. Patients in ventricular fibrillation (VF) received BTE or MDS first shocks of 200 J. The ECG was recorded for subsequent analysis continuously. The success of the first shock as a primary endpoint was removal of VF and required a return of an organized rhythm for at least two QRS complexes, with an interval of <5 s, within 1 min after the first shock. The secondary endpoint was termination of VF at 5 s. VF was the initial recorded rhythm in 120 patients in OHCA, 51 patients received BTE and 69 received MDS shocks. The success rate of 200 J first shocks was significantly higher for BTE than for MDS shocks, 35/51 (69%) and 31/69 (45%), P=0.01. In a logistic regression model the odds ratio of success for a BTE shock was 4.01 (95% CI 1.01-10.0), adjusted for baseline cardiopulmonary resuscitation, VF-amplitude and time between collapse and first shock. No difference was found with respect to the secondary endpoint, termination of VF at 5 s (RR 1.07 95% CI: 0.99-1.11) and with respect to survival to hospital discharge (RR 0.73 95% CI: 0.31-1.70).</AbstractText>BTE-waveform AEDs provide significantly higher rates of successful defibrillation with return of an organized rhythm in OHCA than MDS waveform AEDs.</AbstractText> |
2,318 | Biphasic and monophasic shocks for transthoracic defibrillation: a meta analysis of randomised controlled trials. | Biphasic waveforms are routinely used for implantable defibrillators. These waveforms have been less readily adopted for external defibrillation. This study was performed in order to evaluate the efficacy and harms of biphasic waveforms over monophasic waveforms for the transthoracic defibrillation of patients in ventricular fibrillation (VF) or haemodynamically unstable ventricular tachycardia.</AbstractText>Studies included randomised controlled trials comparing monophasic and biphasic external defibrillation for participants with VF or hemodynamically unstable ventricular tachycardia. Seven trials (1129 patients) were included in the analysis. All trials were conducted during electrophysiology procedures or implantable cardioverter/defibrillator testing.</AbstractText>Compared with 200 J monophasic shocks, 200 J biphasic shocks reduced the risk of post-first shock asystole or persistent VF by 81% (relative risk (RR) 0.19; 95% confidence intervals (CI) 0.06-0.60) for the first shock. Reducing the energy of the biphasic waveform to 115-130 J resulted in similar effectiveness compared with the monophasic waveform at 200 J (RR 1.07, CI 0.66-1.74). Low energy biphasic shocks produce less myocardial injury than higher energy monophasic shocks as determined by ST segment deflection after shock.</AbstractText>Biphasic waveforms defibrillate with similar efficacy at lower energies than standard 200 J monophasic waveforms, and greater efficacy than monophasic shocks of the same energy. Available data suggests that lower delivered energy and voltage result in less post-shock myocardial injury.</AbstractText> |
2,319 | [Drug therapy of atrial fibrillation]. | The authors summarize the up-to-date knowledge relating to the pharmacological treatment of atrial fibrillation. They emphasize that drug treatment continues to be in the forefront of the therapy of the arrhythmia, which can now be considered to constitute a cardiovascular epidemic. In the era following the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AF-FIRM) trial, the strategy of pharmacological treatment will certainly change: in place of "rhythm control", which in recent decades has been overforced in patients identical with the elderly, cardiac patients with an impaired left ventricular function who were enrolled into AFFIRM, there will be a more frequent use of ventricular "rate control". Naturally, this does not mean that, in certain patient groups, an effort should not be made to restore and maintain the sinus rhythm. In cases involving congestive heart failure and structural heart disease complicated by a depressed left ventricular systolic function, atrial fibrillation is currently treated with antiarrhythmic drugs possessing low proarrhythmic activity that prolong refractory period (Class 3), and with the even safer mortality-reducing beta-receptor blockers. The classical antiarrhythmic drugs (quinidine, procainamide, disopyramide) are being increasingly forced into the background, and the areas of indication of the novel Na(+)-channel blocker antiarrhythmics (propafenone, flecainide) have also narrowed: they are administered only in the event of atrial fibrillation in patients with a structurally intact heart or left ventricular hypertrophy. After a brief survey of the more important aspects of ventricular rate control, and of the drugs available, the research trends aimed at the progression of the pharmacological treatment of atrial fibrillation are outlined. The clinical introduction of procedures based on myocardial gene therapy is now a realistic therapeutic approach as concerns atrial fibrillation too. |
2,320 | Digoxin in heart failure and cardiac arrhythmias. | Digoxin therapy has no effect on mortality in heart failure. Digoxin may be useful for maintaining clinical stability and exercise capacity in patients with symptomatic heart failure. Digoxin appears to be of most benefit in patients with severe heart failure, cardiomegaly and a third heart sound. Digoxin should be used as a second-line drug after diuretics, angiotensin-converting enzyme inhibitors and beta-blockers in patients with congestive heart failure who are in sinus rhythm. Digoxin should be used as a first-line drug in patients with congestive heart failure who are in atrial fibrillation. ARRHYTHMIAS: Digoxin has a limited, but useful, role, either alone or in combination with other agents such as beta-blockers, diltiazem or verapamil, in achieving satisfactory resting ventricular rate control in patients with chronic atrial fibrillation. In patients who lead a predominantly sedentary lifestyle (perhaps particularly in those who are elderly), digoxin alone may be the agent of choice. |
2,321 | Clinical and transthoracic echocardiographic predictors of abnormal transesophageal findings in patients with suspected cardiac source of embolism. | Approximately 20% of cerebral infarctions are caused by a cardiac source of embolism. Although transesophageal echocardiography (TEE) is a valuable tool for evaluating patients with suspected cardioembolism, its use should be more selective.</AbstractText>We attempted to determine whether risk factors derived from the clinical, ECG, and transthoracic echocardiogram (TTE) would make TEE use more selective and increase its yield.</AbstractText>We retrospectively reviewed the records of 108 patients with suspected embolic stroke who had undergone TEE evaluation. We defined the presence of left atrial appendage spontaneous contrast (LAASC), left atrial appendage thrombus (LAAT), patent foramen ovale (PFO), or intraatrial septal aneurysm (IASA) as TEE endpoints suggestive of cardioembolism. We evaluated the association between the TEE endpoints and (1) age greater than 60 years, (2) the presence of atrial flutter (AFl) or atrial fibrillation (AF) on ECG, (3) left ventricular (LV) dysfunction by TTE (mild, LVEF < 40%; severe, LVEF < 25%), and (4) left atrial (LA) size > 4 cm also determined by TTE. The statistical analysis performed was one-way analysis of variance controlling for interactions between different risk factors and the endpoints. RESULTS The strongest independent predictors for the presence of LAASC or LAAT were age greater than 60 years, presence of AFl/AF, and LV systolic dysfunction. There was no association between any of the risk factors with the presence of PFO or IASA.</AbstractText>This study demonstrates that clinical characteristics, ECG, and TTE findings can help to better select stroke patients for TEE. Future larger studies are needed to provide more supporting data.</AbstractText> |
2,322 | Tissue discontinuities affect conduction velocity restitution: a mechanism by which structural barriers may promote wave break. | The mechanism by which structural barriers promote wave break and fibrillation is unclear. Conduction velocity (CV) restitution is an important determinant of wave break. Abnormal CV restitution is associated with ventricular fibrillation in patients with heart disease and arises preferentially in fibrotic myocardium. We hypothesize that tissue discontinuities imposed by structural barriers cause abnormal CV restitution.</AbstractText>Tissue discontinuities were simulated in cultures of neonatal rat heart cells grown in 8-armed star patterns. Premature stimulation was applied at the extremity of 1 arm (n=12) while extracellular electrograms were recorded at 24 sites throughout the star. Action potentials were recorded at the following 3 sites: in the stimulated arm and at the discontinuity both proximal to and distal from the star center. Extracellular recordings revealed progressive increases in activation delay (indicative for abnormal CV restitution) only at the discontinuity from arms proximal to the star center. The mean increase in delay was 0.81+/-0.41 ms/10 ms for recording sites proximal to and 3.13+/-0.58 ms/10 ms for sites distal from this discontinuity. Depolarizing currents were determined in single cells during premature stimulation and for voltage configurations similar to those arising at the discontinuity. Both voltage-clamp measurements and computer simulations showed that delay at the discontinuity was associated with biphasic, prolonged activation and delayed inactivation of depolarizing current.</AbstractText>Tissue discontinuities cause abnormal CV restitution. Rapid increase in activation after an initial slow activation and delayed inactivation at the discontinuity lengthen the duration of depolarizing current and cause the abnormal restitution.</AbstractText> |
2,323 | Colour tissue velocity imaging can show resynchronisation of longitudinal left ventricular contraction pattern by biventricular pacing in patients with severe heart failure. | To quantify ventricular resynchronisation by biventricular pacing using colour tissue Doppler velocity imaging (c-TVI).</AbstractText>c-TVI shows regional tissue velocity profiles with a very high time resolution (10 ms). Eighteen patients were studied from an apical four chamber view at baseline and after a one month follow up of biventricular pacing. Regional left ventricular peak tissue velocities and regional time differences during the cardiac cycle were compared in the basal and mid interventricular septal segments of the left ventricle, and in the corresponding segments in the left ventricular free wall.</AbstractText>From baseline to follow up, mean peak tissue velocities changed only during isovolumic contraction in the basal interventricular septum and the left ventricular free wall. At baseline the peak main systolic tissue velocities in the left ventricular free wall were typically delayed by an average of 42 ms in the basal left ventricular site and by 14 ms in the mid left ventricular site compared with the corresponding sites in the interventricular septum. After resynchronisation by biventricular pacing those regional movements were separated by an average of only 7 ms at the basal site, but there was still a 21 ms earlier movement of the left ventricular free wall in the mid left ventricular site. The diastolic movement pattern remained unchanged from baseline to follow up.</AbstractText>c-TVI showed a significant asynchronous regional longitudinal movement of basal left ventricular sites at baseline. A change to a more synchronous longitudinal left ventricular movement pattern during biventricular pacing was demonstrated.</AbstractText> |
2,324 | Acute myocardial infarction: clinical and epidemiological profile and factors associated with in-hospital death in the municipality of Rio de Janeiro. | To study the factors associated with the risk of in-hospital death in acute myocardial infarction in the Brazilian public health system in Rio de Janeiro, Brazil.</AbstractText>Sectional study of a sample with 391 randomly drawn medical records of the hospitalizations due to acute myocardial infarction recorded in the hospital information system in 1997.</AbstractText>The diagnosis was confirmed in 91.7% of the cases; 61.5% males; age = 60.2 +/- 2.4 years; delta time until hospitalization of 11 hours; 25.3% were diabetic; 58.1% were hypertensive; 82.6% were in Killip I class. In-hospital mortality was 20.6%. Thrombolysis was used in 19.5%; acetylsalicylic acid (ASA) 86.5%; beta-blockers 49%; angiotensin-converting enzyme (ACE) inhibitors 63.3%; calcium channel blockers 30.5%. Factors associated with increased death: age (61-80 years: OR=2.5; > 80 years: OR=9.6); Killip class (II: OR=1.9; III: OR=6; IV: OR=26.5); diabetes (OR=2.4); ventricular tachycardia (OR=8.5); ventricular fibrillation (OR=34); recurrent ischemia (OR=2.7). The use of ASA (OR=0.3), beta-blockers (OR=0.3), and ACE inhibitors (OR=0.4) was associated with a reduction in the chance of death.</AbstractText>General lethality was high and some interventions of confirmed efficacy were underutilizated. The logistic model showed the beneficial effect of beta-blockers, and ACE inhibitors on the risk of in-hospital death.</AbstractText> |
2,325 | Simultaneous use of bilateral subthalamic nucleus stimulators and an implantable cardiac defibrillator. Case report. | Bilateral electrical stimulation of the subthalamic nucleus is being used with increasing frequency as a treatment for severe Parkinson disease (PD). Implantable cardiac defibrillators improve survival in certain high-risk patients with coronary artery disease and ventricular arrhythmias. Because of concern about possible interaction between these devices, deep brain stimulation (DBS) systems are routinely disconnected before defibrillators are implanted in patients with PD and arrhythmia. The authors report on a patient with bilateral subthalamic stimulators who underwent successful placement of an implantable defibrillator. Testing of the devices over a wide range of settings revealed no interaction. The patient subsequently underwent multiple episodes of cardioversion when the ventricular lead became dislodged. There was no evidence of adverse neurological effects, and interrogation of the DBS devices after cardioversion revealed no changes in stimulus parameters. The outcome in this case indicates that DBS systems may be safely retained in selected patients who require implantable cardiac defibrillators. |
2,326 | [Coronary vasospasm during off-pump coronary artery bypass grafting; report of two cases]. | Coronary vasospasm is one of the most dangerous and fatal complications of coronary artery bypass grafting (CABG) operation. Our experiences in recent 2 cases happened during off-pump CABG (OPCAB) are presented. Case 1: A 63-year-old male who had 3 vessels disease underwent OPCAB using left internal thoracic artery (LITA) and the radial artery. When the sternotomy was going to be closed, ST elevation of electrocardiogram (ECG) occurred and was followed by ventricular fibrillation. Intra-aortic balloon pumping (IABP) and percutaneous cardiopulmonary support (PCPS) were applied immediately and an additional grafting to first diagonal artery (D 1) was carried out using a saphenous vein. Case 2: A 67-year-old male underwent OPCAB using LITA and the radial artery. ST elevation of ECG suddenly occurred and was followed by complete atrio-ventricular (AV) block when the sternum was closed. IABP and the ventricular pacing were applied immediately. While OPCAB may be less invasive operating method than conventional CABG, we should pay more attention to the coronary vasospasm. |
2,327 | A case series of sotalol-induced torsade de pointes in patients with atrial fibrillation--a tale with a twist. | Sotalol is a potent antiarrhythmic often used in patients with atrial fibrillation. However, it has been associated with a risk of provoking other potentially dangerous arrhythmias, especially if used in high doses and in patients with uncorrected electrolyte imbalance or impaired renal and cardiac function.</AbstractText>We present 4 patients with atrial fibrillation treated with sotalol who developed torsade de pointes due to marked prolongation of the QT interval. While 1 patient had renal failure, all had normal left ventricular function. One patient had been treated with sotalol for more than 10 months before developing torsade de pointes precipitated by hypokalaemia, while another had tolerated sotalol for a 3-month period before the drug was discontinued, and only developed torsade de pointes when the drug was restarted 2 years later. Significantly, the doses used in all patients were relatively low, in contrast to most other reported cases where higher doses were used.</AbstractText>As with all antiarrhythmic therapy, these cases illustrate the need for close follow-up of patients treated with sotalol, even if relatively low doses are used. In addition, patients who had previously tolerated the drug well are still susceptible to its proarrhythmic effects.</AbstractText> |
2,328 | [Treatment with implantable defibrillator]. | About 20 years ago the first patient received an implantable cardioverter defibrillator (ICD), and since then the number of implants have increased dramatically. The ICD can terminate ventricular fibrillation and ventricular tachycardia. Studies of secondary prophylaxis show that ICD treatment can improve the prognosis of patients who have survived cardiac arrest. Prophylactic ICD treatment in patients who have not had cardiac arrest is only recommended for selected groups. Patients with poor left ventricular function seem to benefit the most and ongoing trials should elucidate the possible benefit from prophylactic ICD treatment in heart failure patients. The purpose of this article is to describe the development in ICD treatment and give a survey of the present indications for ICD treatment. |
2,329 | [Diagnosis of narrow QRS complex tachycardias]. | Tachycardias with normal QRS complexes (less than 0.12 seconds) may have multiple origins which may be classified in 4 groups: sinusal, atrioventricular nodal, atrioventricular junctional and finally, some ventricular tachycardias arising from near the conduction pathways. The electrocardiographic diagnosis requires analysis of the QRS complexes to detect an eventual irregularity which would suggest atrial fibrillation. When the tachycardia is regular, analysis of the P waves is fundamental (position in the ventricular cycle and morphology). The relationship of the P waves and the QRS complexes enables identification of those forms independent of the AV node and some rare types of tachycardia. Finally, the response to vagal stimulation is essential whether the tachycardia stops, slows down or persists unchanged. |
2,330 | Incident cases of heart failure in a community cohort: importance and outcomes of patients with preserved systolic function. | The clinical presentation and outcomes of patients with heart failure and preserved systolic function have not been well characterized in the outpatient setting.</AbstractText>This was a retrospective cohort study of 403 patients with new-onset heart failure in a large regional health maintenance organization between July 1996 and December 1996. The clinical characteristics and treatment of patients with preserved ejection fractions (PrEF; >45%) were compared with those of patients with with reduced left ventricular function (Low EF) after excluding patients with terminal comorbidities. The main outcome measure was the combination of death, cardiovascular (CV) hospitalization, or both, which was assessed for as long as 24 months (mean, 22 months) with proportional hazards models.</AbstractText>Sixty-five patients (16%) did not have an assessment of left ventricular (LV) function. Of the remaining 338 patients, 191(57%) had an EF <45% (Low EF group) and 147 (44%) had preserved LV function (PrEF group). Patients with PrEF tended to be older, more frequently women, have less coronary disease and myocardial infarction, and have more atrial fibrillation and other comorbid conditions. They had higher systolic blood pressures and pulse pressures and slower heart rates than the patients with reduced LV function on initial presentation. Overall, mortality and CV hospitalization rates were similar in the 2 groups; however, on multivariate analysis, which took into account baseline differences between groups, low EF was a significant independent predictor of the combined end point (hazard ratio, 1.9; 95% CI, 1.3-2.9).</AbstractText>Patients with preserved LV function constitute a significant portion of incident outpatient patients with heart failure and carry a better prognosis than patients with reduced LV function.</AbstractText> |
2,331 | Mechanisms of sodium channel inactivation. | Rapid inactivation of sodium channels is crucial for the normal electrical activity of excitable cells. There are many different types of inactivation, including fast, slow and ultra-slow, and each of these can be modulated by cellular factors or accessory subunits. Fast inactivation occurs by a 'hinged lid' mechanism in which an inactivating particle occludes the pore, whereas slow inactivation is most likely to involve a rearrangement of the channel pore. Subtle defects in either inactivation process can lead to debilitating human diseases, including periodic paralyses in muscle, ventricular fibrillation and long QT syndrome (delayed cardiac repolarization) in the heart, and epilepsy in the CNS. |
2,332 | Are lipid-lowering drugs also antiarrhythmic drugs? An analysis of the Antiarrhythmics versus Implantable Defibrillators (AVID) trial. | This study sought to evaluate the antiarrhythmic effects of lipid-lowering drug therapy as assessed by ventricular tachyarrhythmia (ventricular tachycardia [VT]/ventricular fibrillation [VF]) recurrences recorded by an implantable cardioverter defibrillator (ICD) in patients with atherosclerotic heart disease (ASHD).</AbstractText>Randomized trials of lipid-lowering drugs suggest reduction of sudden death (SD) in patients with ASHD. Because SD is usually secondary to VT/VF, this observation suggests that lipid-lowering therapy has antiarrhythmic effects.</AbstractText>The probability of VT/VF recurrence in patients with ASHD treated with an ICD in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial who did not receive lipid-lowering drug therapy (n = 279) was compared with that in patients who received early and consistent lipid-lowering therapy (n = 83). In addition, all-cause mortality and cardiac mortality of all patients in the AVID trial with ASHD who did not receive lipid-lowering therapy (n = 564) were compared with that of those who received early and consistent lipid-lowering therapy (n = 149).</AbstractText>Using multivariate analyses, lipid-lowering therapy was associated with a reduction in the relative hazard for VT/VF recurrence of 0.40 (95% confidence interval [CI] 0.15 to 0.58) (adjusted p = 0.003) in the ICD subgroup. Lipid-lowering therapy was also associated with a reduction in the relative hazard for all-cause mortality of 0.36 (95% CI 0.15 to 0.68) (adjusted p = 0.03) and a reduction in the relative hazard for cardiac mortality of 0.39 (95% CI 0.16 to 0.78) (adjusted p = 0.04) in the larger study population.</AbstractText>In patients with ASHD who have received an ICD, lipid-lowering therapy is associated with reduction in the probability of VT/VF recurrence, suggesting that part of the benefit of lipid-lowering therapy may be due to an antiarrhythmic effect.</AbstractText> |
2,333 | Relationship between ST-segment morphology and conduction disturbances detected by signal-averaged electrocardiography in Brugada syndrome. | Although arrhythmogenesis of Brugada syndrome is still unknown, it has been reported to be associated with conduction disturbances. Two ST-segment morphologies (coved and saddle-back patterns) have been described in this syndrome. No study has sought to determine which morphology has stronger conduction disturbances, thereby associating with life-threatening events.</AbstractText>Forty-six patients who presented the Brugada-type ECG with either of a characteristic coved (n = 25) or saddle-back (n = 21) pattern of ST-segment morphology underwent signal-averaged ECG (SAECG). SAECG parameters, and the history of life-threatening events defined as syncope or aborted sudden death, were compared between groups.</AbstractText>Although filtered QRS duration did not differ between groups, the incidence of late potentials in the coved group was higher than in the saddle-back group (22 patients (88%) versus 4 patients (19%); P < 0.01), showing lower RMS40 and longer LAS40. Life-threatening events occurred in 17 patients (68%) in the coved group and 7 patients (33%) in the saddle-back group (P = 0.02).</AbstractText>The coved pattern of ST segment was more closely related to conduction disturbances than the saddle-back pattern in patients with Brugada-type ECG. Life-threatening events were more common in patients with the coved ST-segment elevation. Conduction disturbances in the coved pattern of ST segment may reflect a substrate of arrhythmogenesis in Brugada syndrome.</AbstractText> |
2,334 | Increased p-wave duration and p-wave dispersion in patients with aortic stenosis. | P-wave dispersion (PWD), defined as the difference between the maximum and minimum P-wave duration, has been proposed as being useful for the prediction of paroxysmal atrial fibrillation (AF). AF is the most common arrhythmia and an important prognostic indicator for clinical deterioration in patients with aortic stenosis (AS). The aim of the present study was to evaluate PWD in patients with AS.</AbstractText>The study population consisted of two groups: Group I consisted of 98 patients with AS (76 men, 22 women; aged 63 +/- 8 years) and group II consisted of 98 healthy subjects (same age and sex) without any cardiovascular disease. A 12-lead electrocardiogram was recorded for each subject. The P-wave duration was calculated in all leads of the surface electrocardiogram. The difference between the maximum and minimum P-wave duration was calculated and was defined as the PWD. All patients and control subjects were also evaluated by echocardiography to measure the left atrial diameter, left ventricular ejection fraction, left ventricular wall thicknesses, and the maximum and mean aortic gradients. Patients were also evaluated for the presence of paroxysmal AF.</AbstractText>Maximum P-wave duration and PWD of group I were found to be significantly higher than those of group II. In addition, patients with paroxysmal AF had significantly higher PWD than those without paroxysmal AF. There was no significant difference between the two groups regarding minimum P-wave duration. In addition, there was no significant correlation between echocardiographic variables and PWD.</AbstractText>PWD, indicating increased risk for paroxysmal AF, was found to be significantly higher in patients with AS than in those without it. Further assessment of the clinical utility of PWD for the prediction of paroxysmal AF in patients with severe AS will require longer prospective studies.</AbstractText> |
2,335 | Noninvasive risk stratification in arrhythmogenic right ventricular cardiomyopathy. | The natural history of arrhythmogenic right ventricular cardiomyopathy is determined by the electrical instability of the dystrophic myocardium, which can precipitate arrhythmic cardiac arrest any time during the course of the disease and by the progressive myocardial loss that results in ventricular dysfunction and heart failure. Sudden death accounts for the majority of the fatal events but its occurrence is mostly unpredictable. There are no prospective and controlled studies assessing clinical markers that can predict the occurrence of life-threatening ventricular arrhythmias. However, the noninvasive risk profile, which emerges from retrospective analysis of clinical and pathologic series, is characterized by history of syncope, physical exercise, spontaneous ventricular tachycardia or ventricular fibrillation, right ventricular dysfunction, left ventricular involvement, right precordial negative T wave, right bundle branch block, QT-QRS dispersion, right precordial ST-segment elevation and late potentials. At present only QRS dispersion, history of syncope and right and/or left ventricular abnormalities at radionuclide angiography proved to be independent noninvasive predictors of sudden death. |
2,336 | Effects of right coronary artery PTCA on variables of P-wave signal averaged electrocardiogram. | P-wave signal averaged ECG has been used to detect atrial late potentials that were found in paroxysmal atrial fibrillation. Ischemia is supposed to trigger ventricular late potentials, which indicate an elevated risk for ventricular tachycardia. Preexistent ventricular late potentials measured by ventricular signal averaged ECG is supposed to be eliminated by successful PTCA.</AbstractText>We examined the incidence of atrial late potentials in patients with a proximal stenosis of the right coronary artery and new onset of atrial fibrillation. Furthermore, we investigated the anti-ischemic effect of a successful percutaneous transluminal coronary angioplasty.(PTCA) of the right coronary artery. P-wave signal averaged ECG from 23 patients who had a PTCA of the right coronary artery (group A) were compared to age, sex, and disease-matched control subjects (group B) one day before, one day after, and one month after PTCA.</AbstractText>A new appearance of paroxysmal atrial fibrillation was presented in eight patients before PTCA (group A1) of group A. Patients with a stenosis of the right coronary artery had a significantly higher incidence of supraventricular extrasystoles in a 24-hour-Holter ECG (131.1 +/- 45.4 vs 17.1 +/- 18.9, P < 0.0002). The duration of the filtered P wave was longer (124.8 +/- 11.9 vs 118.5 +/- 10.1 ms, P < 0.04) and the root mean square of the last 20 ms (RMS 20) was significantly lower in group A than in group B (2.87 +/- 1.09 vs 3.97 +/- 1.12 micro V, P < 0.01). A successful PTCA caused an increase in RMS 20 (2.87 +/- 1.11 vs 4.19 +/- 1.19 microV, P < 0.02) and a decrease in filtered P-wave duration (124.8 +/- 11.9 vs 118.4 +/- 10.4 ms, P < 0.04). Preexistent atrial late potentials were found among 15 patients before PTCA. After successful PTCA only 3 out of 15 patients were affected (P < 0.0004) after one day, as well as after one month. All patients with a history of atrial fibrillation did not suffer from an arrhythmic recurrence within the following six months after successful PTCA.</AbstractText>A stenosis of the right coronary artery is associated with atrial late potentials. A successful PTCA of the right coronary artery eliminates preexistent atrial late potentials and may reduce the risk of atrial fibrillation.</AbstractText> |
2,337 | Effects of P-wave dispersion on atrial fibrillation in patients with acute anterior wall myocardial infarction. | P-wave dispersion (P dispersion), defined as the difference between the maximum and the minimum P-wave duration (P minimum), and maximum P-wave duration (P maximum) have been used to evaluate the discontinuous propagation of sinus impulse and the prolongation of atrial conduction time respectively. The aim of this study was to investigate whether early assessment of P dispersion predicts paroxysmal atrial fibrillation (AF) in patients with acute anterior wall myocardial infarction (MI).</AbstractText>We prospectively evaluated 147 consecutive patients (45 women, 102 men; aged 55 +/- 9 years) with a first acute anterior wall MI. All patients were evaluated by echocardiography to measure the left atrial diameter and left ventricular ejection fraction (LVEF). Electrocardiography was recorded from all patients on admission and every day during hospitalization.</AbstractText>AF occurred in 25 patients. In 122 patients, AF did not occur. P maximum was found to be significantly higher in patients with AF than in patients without AF (115 +/- 17.3 ms vs 101 +/- 14.7 ms, P = 0.001). P dispersion also was significantly higher in patients with AF than in patients without AF (50 +/- 12.5 ms vs 43 +/- 10.1 ms, P = 0.01). There was no significant difference between the two groups in P minimum (64 +/- 12.5 ms vs 59 +/- 11.7 ms, P = 0.057). The echocardiographically left atrial diameters were not significantly higher in the patients with AF than those without (25 +/- 3.38 mm and 23 +/- 3.36 mm, respectively, P = 0.76). LVEF was found to be significantly different in the patients who developed AF and in those who did not (37.96 +/- 6.18% vs 47.70 +/- 6.01%, P = 0.0001).</AbstractText>Although P maximum and P dispersion are significant predictive factors of AF in patients with acute anterior wall MI in the univariate analysis, on the basis of multivariate analysis, only age and LVEF were independent predictive parameters for AF.</AbstractText> |
2,338 | Optimal timing for electrical defibrillation after prolonged untreated ventricular fibrillation. | It currently is recommended that electrical shocks be delivered immediately on recognition of ventricular fibrillation. However, decreased effectiveness of this approach has been reported after prolonged intervals of untreated ventricular fibrillation. We investigated the optimal strategy for successful defibrillation after prolonged untreated ventricular fibrillation by using a rat model of ventricular fibrillation and closed-chest resuscitation.</AbstractText>Controlled, randomized, laboratory study.</AbstractText>Research laboratory at a VA hospital.</AbstractText>Seventy pentobarbital anesthetized Sprague-Dawley rats.</AbstractText>After 10 mins of untreated ventricular fibrillation, four groups of rats were randomized to receive electrical shocks (which we designated as "experimental shocks") immediately before or at 2, 4, or 6 mins of chest compression. Unsuccessfully defibrillated rats received additional shocks (which we designated as "rescue shocks") after 8 mins of chest compression.</AbstractText>The number of rats that restored spontaneous circulation after the experimental shocks increased with increasing duration of the predefibrillatory interval of chest compression (0 of 8, 0 of 8, 2 of 8, and 7 of 8, respectively, p <.005). Two additional groups then were randomized to receive repetitive experimental shocks at 2, 4, and 6 mins or a single attempt at 6 mins of chest compression. Although a comparable number of rats restored spontaneous circulation in each group, rats subjected to repetitive defibrillation attempts had more intense postresuscitation ectopic activity and worse survival. Two final groups were used to investigate whether inhibition of the sarcolemmal sodium-hydrogen exchanger isoform-1 (NHE-1) could facilitate return of spontaneous circulation during repetitive defibrillation attempts. Although spontaneous circulation was restored earlier in more rats subjected to NHE-1 inhibition, the differences were statistically insignificant. NHE-1 inhibition, however, replicated previously reported resuscitation and postresuscitation benefits. The optimal predefibrillation interval of chest compression was approximately 6 mins, and this coincided with partial return of the amplitude and frequency characteristics of the ventricular fibrillation waveform to those present immediately after induction of ventricular fibrillation.</AbstractText>Improved outcome after prolonged untreated ventricular fibrillation may result from strategies that provide chest compression before attempting defibrillation and avoid early and repetitive defibrillation attempts. The amplitude and frequency characteristics of the ventricular fibrillation waveform could help identify the optimal timing for attempting electrical defibrillation.</AbstractText> |
2,339 | Analysis of incidence of atrial fibrillation after implantation of VVI pacemaker--long-term observation of 154 patients. | Incidence of occurrence of atrial fibrillation (Af) after implantation of VVI was examined and the possible mechanism was explored. Eighty cases of atrioentricular block (AVB) and 74 cases of sick sinus syndrome (SSS) were studied and followed up for 1-14 years after implantation of VVI. The endpoint was the occurrence of permanent Af. The results showed that the incidence of Af among the 154 patients was 14.3% (22/154). And the incidence was 2.5% among patients with AVB (2/80), and 27% among patients with SSS (20/74). Significant significance was found between patients with AVB and those with SSS (P < 0.01). Among the patients with SSS, the incidence was 33.3% (9/27) in type I, 38.1% (8/21) in type III and 11.5% (3/26) in type II. Significant differences were revealed among patients with I, III and II type SSS (P < 0.05). It is concluded that retrograde conduction of pure ventricular pacing may play the chief role of occurrence of Af. |
2,340 | Ibutilide for pharmacological cardioversion of atrial fibrillation and flutter: impact of race on efficacy and safety. | To evaluate the racial differences in the efficacy and safety of ibutilide in patients with recent-onset (<2 weeks) atrial fibrillation and atrial flutter.</AbstractText>This study included 58 consecutive patients with recent-onset atrial fibrillation (n = 34) and atrial flutter (n = 24). The mean age was 65.7 +/- 14.6 years (range, 37-86 years), 47% were women (n = 27) and 34% (n = 20) were African Americans. The duration of arrhythmia ranged from 3 hours to 2 weeks. All patients had echocardiography, were on therapeutic anticoagulation, had a fairly well controlled ventricular rate, normal QTc interval on 12-lead electrocardiography, and normal serum electrolytes. Ibutilide was administered as an intravenous infusion with a maximal dose of 2 mg.</AbstractText>The overall conversion rate to sinus rhythm was 66% (n = 38), with 62% (n = 21) with atrial fibrillation and 71% (n = 17) of atrial flutter. Most conversions (84%) occurred within 45 minutes of ibutilide infusion. The mean time to arrhythmia conversion was 37.4 +/- 59.8 minutes. Race had a significant impact on efficacy, with increased conversions seen in African Americans (P = 0.004) and increased nonconversion seen in whites (P = 0.02). Successful conversion was not affected by the left atrial size or the presence of valvular heart disease, hypertension, heart failure, coronary heart disease, and diabetes mellitus. QTc intervals were prolonged after drug administration, with a mean change of 24.6 milliseconds for all patients. The QTc prolongation after drug administration was greater in African Americans than in whites (27.4 vs. 23.3 milliseconds). Torsade de pointes occurred in 4 patients (3 African Americans) and was treated with intravenous magnesium sulfate and electrical cardioversion.</AbstractText>Ibutilide used for pharmacological cardioversion of atrial fibrillation and atrial flutter is more effective in African Americans but carries a higher risk of torsade de pointes.</AbstractText> |
2,341 | Dofetilide: A new antiarrhythmic agent approved for conversion and/or maintenance of atrial fibrillation/atrial flutter. | Dofetilide is a new antiarrhythmic agent recently approved for the conversion of and maintenance of sinus rhythm in patients with atrial fibrillation (AF) and atrial flutter (AFl). Dofetilide is a selective class III antiarrhythmic drug which works by selectively blocking the rapid component of the delayed rectifier outward potassium current (I(kr)). Dofetilide has been shown to prolong the effective refractory period which is accompanied by a dose-dependent prolongation of the QT and QTc intervals, with parallel increases in ventricular refractoriness. Approximately 80% of dofetilide is excreted in the urine which requires dose adjustments in renal insufficiency. The elimination half-life is approximately 10 h in patients with normal renal function. The therapeutic blood level range of dofetilide is presently unknown and monitoring of dofetilide blood levels is not available at this time. Clinical trials have shown dofetilide to be superior to flecainide in converting AFl patients to normal sinus rhythm (NSR) (70% vs. 9%; p<0.01). It also was more effective than sotalol in converting AF and AFl patients to NSR (29% vs. 6%; p<0.05) and maintaining these patients in NSR for up to 1 year (p<0.05). Most patients convert to NSR within 24-36 h. Torsade de pointes is the most serious side effect occurring in 0.3-10.5% of patients and is dose related. Other common side effects include headache, chest pain and dizziness. To minimize the risk of induced arrhythmia, patients initiated or reinitiated on dofetilide should be hospitalized for a minimum of 3 days where continuous electrocardiographic monitoring, evaluation of renal function and serum electrolytes and cardiac resuscitation can be provided. |
2,342 | Characteristics of Chinese patients with symptomatic Brugada syndrome in Taiwan. | Since 1992, the Brugada syndrome has been increasingly recognized worldwide, although its incidence and distribution remain unclear. In Asia, several cases have been reported in Japan, Thailand, Singapore, and Vietnam. However, little information is available from the Chinese population. Since June 1997, we have identified 10 patients with the diagnosis of the Brugada syndrome from six hospitals in Taiwan. All patients were male with the mean age of 46 +/- 7 years (range 36-61). They all had a normal chemistry profile, coronary angiography and echocardiography. Clinical presentations varied from seizure and syncope to sudden cardiac death. MRI and ultrafast CT of the heart did not show any abnormalities. Sustained ventricular tachycardia/ventricular fibrillation (VF) was induced in 7 of 8 patients who underwent an electrophysiologic study. The pharmacological provocation test was positive in 4 of 5 patients. One of the 4 patients who had a genetic study showed SCN5A gene mutation. An implantable cardioverter defibrillator (ICD) was implanted in 8 patients. During a mean follow-up of 29 +/- 17 months (range 2-54), 3 of 8 patients who had an ICD received appropriate ICD discharges after implantation. These 3 patients who were subsequently treated with antiarrhythmic agents have had no further recurrent ICD discharges. Two patients who refused ICD implantation are alive and well without taking antiarrhythmic agents. Our study showed that the clinical characteristics of our patients are similar to those described in the literature and that ICD is an effective treatment modality for patients with recurrent VF. However, antiarrhythmic agents may be beneficial for suppressing arrhythmia recurrences in selected patients. |
2,343 | Unexplained syncope in patients with structural heart disease and no documented ventricular arrhythmias: value of electrophysiologically guided implantable cardioverter defibrillator therapy. | To evaluate electrophysiologically guided implantable cardioverter defibrillator (ICD) therapy in patients with syncope, structural heart disease and no documented sustained ventricular tachycardia (sVT).</AbstractText>Programmed ventricular stimulation (PVS) was performed in 52 patients (age 62+/-10 years): 40 patients had ischaemic and 12 patients had idiopathic dilated cardiomyopathy. On PVS sVT and ventricular fibrillation were induced in seven and four patients, respectively, and two patients spontaneously experienced symptomatic sVT. These patients received an ICD (ICD group, n=13). Non-inducible patients were left on conventional therapy (non-ICD group, n=39). During 5+/-2.8 years five ICD patients received therapies, all appropriate. There were seven non-sudden deaths and overall survival analysis revealed no significant difference. Recurrent syncope occurred in five ICD and four non-ICD patients and did not correlate well with sVT. The positive and negative predictive values of PVS for tachyarrhythmias or sudden death were 36 and 98%, respectively.</AbstractText>Syncope per se does not necessarily herald a bad prognosis. PVS identifies high-risk patients. Induction of ventricular fibrillation with double or triple extrastimuli is of limited value. Patients with poor left ventricular function and bad clinical condition benefit most from an ICD. Syncope and sVT are not necessarily correlated during follow-up, which may merit consideration.</AbstractText> |
2,344 | Transplantation of lungs from non-heart-beating donors after functional assessment ex vivo. | If lungs from patients dying of heart attacks are to serve as donor organs in a safe way, their function should be properly assessed before transplantation. The aim of this study was to investigate donor lung function evaluation in a realistic large animal model.</AbstractText>Twelve 60-kg pigs were used. Five minutes after ventricular fibrillation was induced, cardiopulmonary resuscitation was initiated and maintained for 20 minutes. After a 10-min hands-off period, heparin was administered through a central venous catheter followed by 20 chest compressions. Intrapleural cooling was initiated after 65 minutes of warm ischemia. Cooling proceeded for 6 hours within the cadaver, after which lung function was assessed ex vivo. Recipient pigs underwent left lung transplantation followed by right pneumonectomy, thus making these animals 100% dependent for their survival on the function of the donor lungs.</AbstractText>The assessment showed that all lungs had adequate function to serve as donor lungs. All recipient animals were in good condition during the 24-hour observation period after the operation. The blood gas function did not differ significantly from that in the healthy donor animals before induction of ventricular fibrillation; pulmonary vascular resistance was within normal range.</AbstractText>Lungs from non-heart-beating donors topically cooled in situ for 6 hours after 65 minutes of warm ischemia were assessed ex vivo and found to have normal function. They were then transplanted and retained normal function during a 24-hour observation period.</AbstractText> |
2,345 | Significant effects of atrioventricular node ablation and pacemaker implantation on left ventricular function and long-term survival in patients with atrial fibrillation and left ventricular dysfunction. | Control of ventricular rate by atrioventricular node ablation and pacemaker implantation in patients with drug-refractory atrial fibrillation (AF) is associated with improved left ventricular (LV) function. The objective of this study was to determine the effect of atrioventricular node ablation on long-term survival in patients with AF and LV dysfunction. Survival was determined by the Kaplan-Meier method for 56 study patients with LV ejection fraction (EF) < or =40% who underwent atrioventricular node ablation and pacemaker implantation and 56 age- and gender-matched control patients with AF and LVEF >40%, and age- and gender-matched control subjects from Minnesota. Groups were compared using the log-rank test. In study patients (age 69 +/- 10 years; 45 men), LVEF was 26% +/- 8% and 34% +/- 13% (p <0.001) before and after ablation, respectively. During follow-up (40 +/- 23 months), 23 patients died. Observed survival was worse than that of normal subjects (p <0.001) and control patients (p = 0.005). After ablation, LVEF nearly normalized (> or =45%) in 16 study patients (29%), in whom observed survival was comparable to that of normal subjects (p = 0.37). Coronary artery disease, hyperlipidemia, chronic renal failure, previous myocardial infarction, and coronary artery operation were independent predictors for mortality. Near normalization of LVEF occurred in 29% of study patients, suggesting that AF-induced EF reduction is reversible in many patients. Normal survival in patients with reversible LV dysfunction highlights potential survival benefits of rate control. Poor survival in patients with persistent LV dysfunction confirms the importance of optimal medical therapy. |
2,346 | Effect of elevated heart rate preceding the onset of ventricular tachycardia on antitachycardia pacing effectiveness in patients with implantable cardioverter defibrillators. | The incorporation of antitachycardia pacing (ATP) into implantable cardioverter defibrillators (ICDs) has provided a better tolerated alternative to shocks. ATP has been shown to be effective in terminating approximately 80% to 90% of spontaneous ventricular tachycardia (VT) episodes. Although ATP is routinely used, little is known about predictors of ATP failure. Based on the evaluation of stored electrograms, we aimed to prospectively follow patients with ICDs, and to analyze parameters affecting ATP effectiveness. One hundred eighteen consecutive patients received ICDs for standard indications. Before discharge, empirical, standardized ATP therapy was programmed in all patients within VT zones. A total of 1,218 spontaneous tachycardia episodes occurred in 51 patients during a mean follow-up of 24.5 +/- 12 months. Among these, 888 VTs were diagnosed. One hundred four fast VTs were detected in the ventricular fibrillation zone and treated with primary shock delivery. ATP was attempted 881 times in the remaining 784 VT episodes. ATP terminated 640 VTs successfully, ATP failed in 55 VTs finally reverted by shocks, and 89 VTs converted to a slower VT outside the VT zone. Fifty-one of these slower VTs reverted spontaneously, and 38 were redetected and treated. Finally, in primary intention-to-treat basis, ATP was successful in 691 VTs (88%) and unsuccessful in 93 VTs (12%). There was no influence of VT cycle length on ATP success rate. Furthermore, ATP efficacy was similar between patients with left ventricular ejection fraction < or =35% or >35%, between daytime and nighttime, as well as between patients with ischemic or nonischemic cardiomyopathy. A faster heart rate immediately preceding the onset of VT (103 +/- 19 vs 78 +/- 14 beats/min, respectively, hazard ratio 4.08, 95% confidence interval 2.11 to 7.89, p <0.001), and absence of beta-blocker therapy (82% vs 93%, respectively, hazard ratio 2.71, 95% confidence interval 1.72 to 4.29, p = 0.02) were found, by Cox proportional-hazard analysis, to be the sole independent predictors of ATP ineffectiveness in ICD recipients. Thus, the present study identified both preceding sinus tachycardia (reflecting an increased sympathetic tone) and lack of beta-blocker use as independent risk factors for reduced success of ATP therapy in terminating VT. Therefore, modification of sympathetic tone may be beneficial for patients with ICDs. |
2,347 | [Value of genetic testing in the management of the congenital long QT syndrome]. | The congenital long QT syndrome (LQTS) is a variable clinical and genetic entity characterised by prolongation of the QT interval on the ECG associated with the risk of serious ventricular arrhythmias (torsades de pointe, ventricular fibrillation) which may cause syncope and sudden death in patients with otherwise normal hearts. To date, 6 loci have been identified with the genes responsible for the forms LQT1, LQT2, LQT5 and LQT6, coding for the potassium channels (KCNQ1, HERG, KCNE1 and KCNE2, respectively) which, in the heterozygote state, are responsible for the main forms of LQTS without deafness and, in the homozygote state (KCNQ1 and KCNE1) for the recessive forms of LQTS with or without deafness. The gene for the LQT3 form codes for the cardiac sodium channel (SCN5A). The genetic variability observed in the LQTS corresponds to the diversity of cardiac ionic channels implicated in the genesis of the action potential, so making the LQTS a disease of the ionic channels or a "channelopathy". The potential severity of the prognosis justifies testing of subjects with long QT intervals on the ECG and Holter recording. In order to identify subjects with the genetic abnormality who are asymptomatic, these investigations associated with genetic testing should be made in all close members of the family of an affected person. The major problem remains the evaluation of the risk of sudden death in asymptomatic subjects with a genetic abnormality. At present, in the absence of clearly proven prognostic factors and in the knowledge that effective treatment without major secondary effects is available, all patients should be given prophylactic betablocker therapy. |
2,348 | Role of nonsustained ventricular tachycardia and programmed ventricular stimulation for risk stratification in patients with idiopathic dilated cardiomyopathy. | The prognostic role of asymptomatic nonsustained ventricular tachycardia (NSVT) and programmed ventricular stimulation (PVS) in patients with idiopathic dilated cardiomyopathy (IDC) remains controversial.</AbstractText>The prognostic significance of ventricular arrhythmias, ejection fraction, NYHA class, atrial fibrillation and age for overall and sudden death mortality was prospectively studied in 157 patients with IDC (group 1) free of documented sustained ventricular arrhythmia and syncope. In 99 patients with asymptomatic NSVT (group 2), PVS with 2 - 3 extrastimuli was performed. Non-inducible patients were discharged without specific antiarrhythmic therapy, whereas those with inducible monomorphic ventricular tachycardia were implanted with an ICD.</AbstractText>In group 1, 48% of patients had NSVT. Overall and sudden death mortality were significantly higher in patients with NSVT (34.2 vs. 9.8%, p = 0.0001 and 15.8 vs. 3.7%, p = 0.0037; follow-up 22 +/- 14 months). Multivariate analysis revealed that NSVT independently predicts both overall and sudden death mortality (p = 0.0021 and.0221, respectively; adjusted for EF, NYHA class and age). In group 2, inducibility of sustained ventricular tachyarrhythmia was 7%, but sustained monomorphic VT occurred in 3% only. Two of 7 inducible patients experienced arrhythmic events during a follow-up of 25 +/- 21 months (positive predictive value 29%). Overall and sudden death mortality were 29% and 0% in the inducible group vs. 17 and 4% in the non-inducible group. Both overall and sudden death mortality were significantly lower in non-inducible patients from group 2 as compared to patients from group 1 with NSVT (p = 0.0043 and 0.0048), most likely due to a more common use of betablockers and a higher EF in the former group (p < 0.001, respectively).</AbstractText>In patients with IDC, NSVT independently predicts both overall and sudden death mortality. Due to a low inducibility rate and a poor positive predictive value, PVS seems inappropriate for further arrhythmia risk assessment. However, in spite of documented NSVT, the incidence of SCD in patients on optimized medical treatment including betablockers seems to be very low, questioning the need for specific arrhythmia risk stratification.</AbstractText> |
2,349 | Single-beat determination of Doppler-derived aortic flow measurement in patients with atrial fibrillation. | The clinical assessment of left ventricular systolic function in patients with atrial fibrillation is unreliable and difficult because of beat-to-beat variation. We initially evaluated an index that is on the basis of the ratio of preceding R-R (RR1) to pre-preceding R-R (RR2) intervals (RR1/RR2) for the measurement of Doppler aortic flow (peak flow velocity [Vp] and time-velocity integral [TVI] proportional to stroke volume) in 20 patients (aged 65 +/- 9.6 years) with atrial fibrillation. We obtained each parameter for >13 cardiac cycles, and the relationship between each parameter at a given cardiac beat and the RR1/RR2 ratio were evaluated by linear regression analysis. The value of each parameter at RR1/RR2 = 1 was calculated from the equation of linear regression line and compared with measured average value over all cardiac cycles. Both parameters showed a significant positive correlation with the RR1/RR2 ratio (Vp, r = 0.98, y = 1.01x + 0.61; TVI, r = 0.99, y = 1.01x + 0.26). The calculated value of each parameter at RR1/RR2 = 1 was quite similar to the average value (Vp, 97.4 +/- 30.8 vs 95.7 +/- 29.8 cm/s; TVI, 17.7 +/- 6.8 vs 17.3 +/- 6.7 cm, respectively). In the additional 20 patients (aged 77.4 +/- 15.2 years), Doppler aortic flow parameters of a single beat with identical RR1 and RR2 intervals were compared with measured average value over all cardiac cycles and showed similar results (Vp, r = 0.99, y = 0.99x + 3.4, P <.0001, bias -0.5 cm/s; TVI, r = 0.99, y = 0.92x + 1.5, P <.0001, bias 0.1 cm). In conclusion, the Doppler aortic flow at RR1/RR2 = 1 allows the left ventricular systolic parameters to be accurately evaluated during atrial fibrillation and obviates the less reliable process of averaging multiple irregular beats. |
2,350 | Proarrhythmic effect of pacemaker stimulation in patients with implanted cardioverter-defibrillators. | We sought to determine the potential of right ventricular VVI backup pacing to induce ventricular tachyarrhythmias in patients with implanted cardioverter-defibrillators.</AbstractText>All consecutive patients presenting exclusively with pacemaker-induced tachycardias (PITs) were included in a prospective study using a crossover protocol. Patients were randomized to either group 1 (augmentation of the baseline frequency of the pacemaker to 60 bpm) or group 2 (pacemaker turned off) and were followed up for 1 year and then crossed over to the other programming, looking for reoccurrence of PIT. Of 150 consecutive patients, 39 (26%) had PIT, 13 of them exclusively (8.6%). Forty of 1063 analyzed tachyarrhythmias of all the patients were PIT (3%). Before inclusion in the study, the patients had 2.7+/-0.9 PITs in 11+/-6.5 months with their pacemakers programmed empirically at 42.3 bpm. During the study phase, no PIT occurred while the pacemaker was turned off, whereas programming to 60 bpm led to the recurrence of PIT in 5 of 6 patients (1.4+/-0.6 per patient). At the end of the study, 9 patients underwent a prolonged follow-up with their pacemakers turned off, resulting in spontaneous episodes of ventricular tachycardia/fibrillation in 5 patients, but PITs were no longer observed.</AbstractText>This crossover protocol proves the potential proarrhythmic effect of pacemaker stimulation in implantable cardioverter-defibrillator patients. Resulting PITs led to clinical symptoms and antitachycardia therapy by the implantable cardioverter-defibrillator. Thus, in patients presenting with PIT but without a pacemaker indication, the pacemaker feature should be turned off, or, alternatively, the longest possible escape interval should be programmed.</AbstractText> |
2,351 | Spatial distribution of phase singularities in ventricular fibrillation. | Multiple excitation wavelets are present during ventricular fibrillation (VF). The underlying wavelet organization of VF is unclear. Phase singularities (PSs)-locations of ambiguous activation state-underlie reentry and wavelet splitting and represent the sources of VF. Understanding the mechanisms of PS formation might be important in the development of effective therapies for sudden death.</AbstractText>We performed voltage, phase, and PS mapping in fibrillating ventricles, applying an automated PS detection algorithm to optically recorded fibrillation signals. PS clustering was noted along epicardial vessels, ridges of endocardial trabeculae, and papillary muscle insertions. Microscopically, these locations correlated with areas of apposition of fibers with different angulations and intramural vessels. A total of 83.2% of PSs were formed at and meandered about these anatomic structures, which acted as stabilizers: PSs colocalizing at anatomic substrates had longer life spans than nonanatomic PS (82.46+/-60.8 versus 40.5+/-31.9 ms, P<0.01). The RV endocardium had a higher PS incidence than the epicardium (42.3+/-9.2 versus 23.5+/-11.6 PS/s, P<0.01). Autocorrelation showed that irregular behavior was spatially restricted to anatomic heterogeneities compared with other areas, which had nearly periodic behaviors. Simple spatial PS distributions underlay complex and variable activation patterns attributable to variable PS behaviors, life spans, and inter-PS interactions.</AbstractText>PSs occur in a nonrandom spatial distribution and colocalize with normal anatomic heterogeneities. Varying PS behaviors and life spans but stable PS spatial distributions cause ever-changing activation patterns that characterize VF.</AbstractText> |
2,352 | Altered atrial electrical restitution and heterogeneous sympathetic hyperinnervation in hearts with chronic left ventricular myocardial infarction: implications for atrial fibrillation. | The substrates for the increased incidence of atrial fibrillation (AF) in hearts with chronic left ventricular myocardial infarction (MI) remain poorly defined. We hypothesized that chronic MI is associated with atrial electrical and neural remodeling that enhances AF vulnerability.</AbstractText>We created MI in 8 dogs by permanent occlusion of the left anterior descending (LAD) coronary artery. Seven dogs (3 with thoracotomy) that had no LAD occlusion served as controls. Eight weeks after surgery, the incidence and duration of pacing-induced AF in the open chest anesthetized state were significantly (P<0.05) higher in the MI than in control dogs. Multisite biatrial monophasic action potential (MAP) recordings showed increased heterogeneity of MAP duration (MAPD) and MAPD restitution slope. AF in the MI groups was preceded by significantly higher MAPD (P<0.01) and MAP amplitude (P<0.05) alternans in both atria compared with controls. Epicardial mapping using 1792 bipolar electrodes (1-mm spatial resolution) showed multisite wavebreaks of the paced wavefronts leading to AF in MI but not in control dogs. Multiple wavelets in MI dogs were associated with significantly higher incidence and longer duration of AF compared with control. The density of biatrial tyrosine hydroxylase (TH) and growth-associated protein43 (GAP43) nerves were 5- to 8-fold higher and were more heterogeneous in MI compared with control dogs.</AbstractText>Chronic ventricular MI with no atrial involvement causes heterogeneous alteration of atrial electrical restitution and atrial sympathetic hyperinnervation that might provide important substrates for the observed increased AF vulnerability.</AbstractText> |
2,353 | Cardiac Resynchronization Therapy for Advanced Heart Failure. | Cardiac resynchronization therapy (CRT) represents a new class of heart failure therapy that provides symptom relief and decreased need of hospitalization in a significant number of patients already receiving maximal medical intervention. Patients with ischemic or nonischemic dilated cardiomyopathy, coupled with interventricular conduction delays, who have New York Heart Association class III or IV symptoms, are currently candidates for CRT. This device-based intervention reverses adverse ventricular remodeling, decreases the severity of mitral regurgitation, and increases cardiac efficiency and output. New selection criteria are being considered in an attempt to identify patients who have a high chance of responding, and possibly, to identify patients that have a high chance of not responding to CRT. These efforts are in response to the 20% to 25% "nonresponder" rate observed when the currently accepted inclusion criteria are used. Other patient populations may also benefit from CRT, including those in need of antibradycardia pacing, patients with atrial fibrillation, and some who meet the criteria for prophylactic implantation of a cardiac defibrillator. This review focuses on the current strategies to refine patient selection criteria and addresses some of the practical issues in prescribing CRT. |
2,354 | Rate control in atrial fibrillation: choice of treatment and assessment of efficacy. | The clinical relevance and high social costs of atrial fibrillation have boosted interest in rate control as a cost-effective alternative to long-term maintenance of sinus rhythm (i.e. rhythm control). Prospective studies show that rate control (coupled with thromboembolic prophylaxis) is a valuable treatment option for all forms of atrial fibrillation. The rationale for rate control is that high ventricular rates, frequently found in atrial fibrillation, lead to haemodynamic impairment, consisting of a variable combination of loss of atrial kick, irregularity in ventricular response and inappropriately rapid ventricular rate, depending on the type of underlying heart disease. Long-term persistence of tachycardia at a high ventricular rate can lead to various degrees of ventricular dysfunction and even to tachycardiomyopathy-related heart failure. Identification of this reversible and often concealed form of left ventricular dysfunction can permit effective management by rate (or rhythm) control. Although acute rate control (to reduce ventricular rate within hours) is still often based on digoxin administration, for patients without left ventricular dysfunction, calcium channel antagonists or beta-adrenoceptor antagonists (beta-blockers) are generally more appropriate and effective. In chronic atrial fibrillation, long-term rate control (to reduce morbidity/mortality and improve quality of life) must be adapted to patients' individual characteristics to grant control during daily activities, including exercise. According to current guidelines, the clinical target of rate control should be a ventricular rate below 80-90 bpm at rest. However, in many patients, assessment of the appropriateness of different drugs should include exercise testing and 24h-Holter monitoring, for which specific guidelines are needed. In practice, rate control is considered a valid alternative to rhythm control. Recent prospective trials (e.g. the Pharmacological Intervention in Atrial Fibrillation [PIAF] and the Atrial Fibrillation Follow-up Investigation of Rhythm Management [AFFIRM] trials) have shown that in selected patients, rate control provides similar benefits, more economically, in terms of quality of life and long-term mortality. The choice of a rate control medication (digoxin, beta-blockers, calcium channel antagonists or possibly amiodarone) or a non-pharmacological approach (mainly atrioventricular node ablation coupled with pacing) must currently be based on clinical assessment, which includes assessing the presence of underlying heart disease and haemodynamic impairment. Definite guidelines are required for each different subset of patients. Rate control is particularly tricky in patients with heart failure, for whom non-pharmacological options can also be considered. The preferred pharmacological options are beta-blockers for stabilised heart failure and digoxin for unstabilised forms. |
2,355 | Resection of bronchopulmonary cancers invading the left atrium--benefit of cardiopulmonary bypass. | Cardiopulmonary bypass (CPB) for extended lung resections involving great vessels and other mediastinal organs remains controversial, especially due to CPB-related haemorrhagic and immunological issues. Here, we will retrospectively analyse the results obtained with such procedure.</AbstractText>Between January 1994 and February 2001, four patients underwent surgery under CPB for lung carcinoma in our department. Three patients were male and one female; mean age was 58.8 +/- 6.3 years. The patients suffered from malignant pulmonary lesions involving the left atrium (T4 or stage IIIb) - two epidermoid carcinoma, one adenocarcinoma and one large-cell carcinoma. Procedures were performed under complete CPB with aortic cross-clamping in all but one patient who underwent hypothermic ventricular fibrillation. Mean CPB duration was 86.7 +/- 26.5 min.</AbstractText>There were no hospital mortalities (D30). Mean duration for assisted ventilated support was 9.5 +/- 2.5 hours, 2.5 +/- 1 days for ICU stay and 14.3 +/- 1 days for hospital stay. Operation-related complications were rare. Two patients presented with transient postoperative atrial fibrillation. Only one patient had to undergo reoperation for compressive haemopericardium drainage at D23. The mean quantity of transfused packed red blood cell packs was 2.7 +/- 1.7. Two patients survived over three years after surgery and one patient is still alive at 72 months without any recurrent symptom.</AbstractText>In some cases of T4 lung cancer considered inoperable, CPB permits extended lung resections offering significant hope for survival at an acceptable operative risk.</AbstractText> |
2,356 | Effects of irradiation on the components of implantable pacemakers. | The purpose of this study was to examine the effects of irradiation on implantable pacemaker components. The pacemaker was divided into three components: lead wire and electrode, battery, and electrical circuit, and each component was irradiated by X-ray and electron beams, respectively. The pacemaker parameters were measured by both telemetry data of the programmer and directly measured data from the output terminal. The following results were obtained. For the lead wire and electrode, there was no effect on the pacemaker function due to irradiation by X-ray and electron beams. In the case of battery irradiation, there was no change in battery voltage or current up to 236Gy X-ray dose. In the electrical circuit, the pacemaker reverted to the regular beating rate (fixed-rate mode) immediately after the start of X-ray irradiation, and it continued in this mode during irradiation. In patients with their own heartbeat rhythm, changing to the fixed-rate mode may cause dangerous conditions such as ventricular fibrillation. When the accumulated irradiation dose is increased, another failure can be seen in the output voltage of the pacemaker. The pacing output voltage dropped rapidly by about 40 % at 30-88Gy. Decreasing the output voltage results in pacing disorders, and heart failure may occur. In the telemetry data of the programmer, no change in output voltage could be detected, highlighting the difference between telemetry data and actual pacing data. |
2,357 | Utility of B-type natriuretic peptide (BNP) as a screen for left ventricular dysfunction in patients with diabetes. | Routine screening of diabetic patients with echocardiography is not feasible due to its limited availability and high cost. B-type natriuretic peptide (BNP) is secreted from the left ventricle in response to pressure overload and is elevated in both systolic and diastolic dysfunction.</AbstractText>BNP levels were compared to echocardiographic findings in 263 patients. Patients were divided into two groups: clinical indication for echocardiography (CIE) (n = 172) and those without clinical indication for echocardiography (no-CIE) (n = 91). Cardiologists making the assessment of left ventricular function were blinded when measuring plasma levels of BNP.</AbstractText>The 91 patients with no-CIE with echoes had similar BNP levels (83 +/- 16 pg/ml) to the 215 patients with no-CIE without echoes (63 +/- 10, P = 0.10). Patients with CIE and subsequent abnormal left ventricular function (n = 112) had a mean BNP concentration of 435 +/- 41 pg/ml, compared with those with no-CIE, but had abnormal left ventricular function on echo (n = 32) (161 +/- 40 pg/ml). Twenty-one of 32 patients with no-CIE but with abnormal left ventricular function had diastolic dysfunction (BNP 190 +/- 60 pg/ml). A receiver-operating characteristic (ROC) curve revealed that the area under the curve was 0.91 for CIE patients and 0.81 for no-CIE patients (P < 0.001). For those with no congestive heart failure (CHF) symptoms, BNP levels showed a high negative predictive value (91% for BNP values <39 pg/ml), while in those patients who had a CIE, BNP levels showed a high positive predictive value for the detection of left ventricular dysfunction (96% with BNP levels >90 pg/ml).</AbstractText>BNP can reliably screen diabetic patients for the presence or absence of left ventricular dysfunction.</AbstractText> |
2,358 | Risk factors for recurrence of atrial fibrillation in patients undergoing hybrid therapy for antiarrhythmic drug-induced atrial flutter. | Catheter ablation of the inferior vena cava-tricuspid annulus isthmus and continuation of antiarrhythmic drug therapy have been shown to be an effective hybrid therapy for atrial flutter which results from antiarrhythmic drug treatment of atrial fibrillation. The aim of this study was to determine the risk factors for recurrence of atrial fibrillation in patients undergoing hybrid therapy for antiarrhythmic drug-induced atrial flutter.</AbstractText>90 patients with paroxysmal (n=46) or persistent atrial fibrillation (n=44) developed atrial flutter due to the administration of amiodarone (n=48), flecainide (n=22), propafenone (n=14) or sotalol (n=6). Recurrence of atrial fibrillation after ablation was assessed during follow-up on continued antiarrhythmic drug therapy and during long-term follow-up, irrespective of the initial antiarrhythmic medication. During the follow-up on continued antiarrhythmic drug therapy (16+/-13 months), recurrence of atrial fibrillation was documented in 24 of 90 patients (27%). The presence of accompanying pre-ablation episodes of atrial fibrillation on antiarrhythmic treatment (Odds ratio 7.1, 95% confidence interval 2.3 to 25, p=0.001) and decreased left ventricular ejection fraction (Odds ratio 3.7, 95% confidence interval 1.01 to 12.5, p=0.048) were significant and independent predictors of post-ablation atrial fibrillation. Antiarrhythmic medication was discontinued during long-term follow-up due to adverse drug effects (amiodarone, n=12; flecainide, n=1) in 13 patients (14%). During the long-term follow-up, irrespective of the initial antiarrhythmic medication (21+/-15 months), stable sinus rhythm was maintained in 60 of 90 patients (67%). CONCLUSION Hybrid therapy can be considered as the first line therapy for patients with antiarrhythmic drug-induced atrial flutter but patients should be carefully evaluated for accompanying pre-ablation episodes of atrial fibrillation and possible adverse drug effects before initiation of hybrid therapy.</AbstractText> |
2,359 | Cardiac arrhythmias in the athlete: the evolving role of electrophysiology. | Arrhythmia management has undergone a revolution in the past decade. The diagnosis and treatment of arrhythmias in the athlete can be complicated by the need to compete and exercise. Some arrhythmias may be benign and asymptomatic, but others may be life threatening. Sinus bradyarrhythmias are common and even expected in athletes; these are rarely a cause for concern. Heart block is unusual and merits a thorough work-up. Atrial fibrillation may be more common in the athlete, and supraventricular tachycardias other than atrial fibrillation warrant consideration of radiofrequency ablation for cure. Ventricular arrhythmias in the athlete generally occur in the setting of structural heart disease that is genetically determined (hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia, anomalous coronary arteries), or acquired (coronary artery disease, myocarditis, idiopathic dilated cardiomyopathies). In these conditions the arrhythmia is life threatening. Ventricular arrhythmias that occur in the athlete without structural heart disease are not thought to be life threatening. Athletes with structural heart disease and those with exertional syncope merit a complete evaluation. |
2,360 | Event and sideline management of sudden cardiac death. | The increasing use of automated external defibrillators (AEDs), coupled with methods to improve cardiopulmonary resuscitation and implementation of early defibrillation, have significantly improved survival from sudden cardiac death (SCD) in the prehospital setting. This article reviews the evidence and principles of management of SCD in the sports setting. It is noted that ventricular fibrillation is the most common arrhythmia causing SCD in athletes. When it occurs, survival is reduced by 7% to 10% per minute pending defibrillation. This statistic is true for athletes as well as nonathletes, and underscores the critical need for a rapid defibrillation response. Use of the AED in the sports setting and suggestions on whether to implement an AED program are reviewed. Despite increasing application of this technology, outcomes data on the use of AEDs in the sports arena are lacking, partly due to the relatively rare occurrence of SCD therein. New evidence on pharmacotherapy in SCD is also reviewed. Although drug administration in SCD is unlikely to be required in the sports setting, clinicians are updated on some of the newer considerations. Finally, selected articles from the recent literature on advanced cardiac life support are provided to guide the team physician in using the most current approach to the management of SCD. |
2,361 | Is timing everything? Therapeutic potential of modulators of cardiac Na(+) transporters. | Sodium ion (Na(+)) transporters have roles in the modulation of cardiomyocyte pH and Na(+) and Ca(2+) handling. Activation of the cardiac Na(+)-H(+) exchanger 1 (NHE1) during ischaemia induces arrhythmias, myocardial stunning and irreversible cell injury. As the benefits of NHE1 inhibitors (e.g., amiloride, cariporide) in models of myocardial infarction are usually much greater when used as pretreatment, rather than during or after ischaemia, it is probably not surprising that clinical trials with cariporide in ischaemia have shown little shortterm benefit. NHE1 inhibitors have been shown to be beneficial in animal models of ventricular fibrillation and resuscitation, cardioplegia, hypertrophy and heart failure, and their therapeutic potential in these conditions should be further developed. The Na(+)-HCO(3)(-) cotransporter (NBC) is also stimulated by intracellular acidification, and part of the benefit of angiotensin-converting enzyme inhibitors after myocardial infarction may be due to inhibition of the NBC. Selective inhibitors of the NBC are required to determine the therapeutic potential of this mechanism. The Na(+)-Ca(2+) exchanger (NCX) has a major role in cardiac Na(+) and Ca(2+) homeostasis and influences cardiac electrical activity. The NCX also has a role in ischaemia/infarction, arrhythmias, hypertrophy and heart failure. NCX inhibitors may have beneficial effects in animal models of ischaemia and reperfusion injury and the therapeutic benefit of these should be further studied in animal models. |
2,362 | Sodium-hydrogen exchange inhibition preserves ventricular function after ventricular fibrillation in the intact swine heart. | We tested the hypothesis that sodium-hydrogen exchange inhibition attenuates ventricular dysfunction after ischemia-reperfusion injury in the intact porcine heart.</AbstractText>Twelve pigs (weight, 30-45 kg) were evenly divided into 2 groups. Baseline ventricular function studies were based on echocardiography, conductance, aortic flow, and left ventricular pressure. Animals were given vehicle (control) or benzamide-N-(aminoiminomethl)-4-(4-[2-furanylcarbonyl]-1-piperazinyl)-3-(methylsulfonyl)methanesulfonate (BIIB 513; 3 mg/kg administered intravenously). Ten minutes later, hearts were subjected to 75 seconds of ventricular fibrillation. After reperfusion for 40 minutes, function studies were repeated. Hearts were arrested and excised. Postmortem data included passive pressure-volume curves and myocardial water content.</AbstractText>Preload recruitable stroke work was significantly decreased from baseline after ischemia and reperfusion in the control group (27.7 +/- 2.5 vs 48.0 +/- 5.6 mm Hg [+/- SEM], P =.001) but not in the BIIB 513 group (43.0 +/- 5.8 vs 45.5 +/- 4.1 mm Hg, P = not significant). In vivo diastolic and postmortem passive left ventricular compliance were reduced after ischemia and reperfusion for control animals but remained unchanged for animals receiving BIIB 513. Time required to recover baseline blood pressure after ventricular fibrillation was significantly longer for control animals (159 +/- 15 vs 88 +/- 14 seconds [+/- SEM], P =.008). Myocardial water content (78.97% +/- 0.94% vs 77.86% +/- 0.46% [+/- SEM]) and normalized left ventricular mass (137.24 +/- 6.17 vs 128.41 +/- 1.96 g [+/- SEM]) were insignificantly increased in control animals.</AbstractText>Sodium-hydrogen exchange inhibition attenuates ventricular dysfunction after 75 seconds of ventricular fibrillation and 40 minutes of reperfusion. This family of agents might prove useful in patients with severe left ventricular dysfunction undergoing ventricular fibrillation for implantable cardioverter defibrillator testing.</AbstractText> |
2,363 | Amiodarone reduces the incidence of atrial fibrillation after coronary artery bypass grafting. | The purpose of this study was to evaluate the safety and efficacy of postoperative administration of prophylactic amiodarone in the prevention of new-onset postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting.</AbstractText>In this prospective study 157 patients were randomly divided into two groups: 77 patients (amiodarone group) received intravenous amiodarone in a dose of 10 mg/kg/d for postoperative 48 hours. On postoperative day 2 oral amiodarone was started with a dose of 600 mg/d for 5 days, 400 mg/d for the following 5 days, and 200 mg/d for 20 days, and 80 patients received placebo (control group).</AbstractText>Preoperative patient characteristics and operative variables were similar in the two groups. Postoperative atrial fibrillation occurred in 8 patients (10.4%) receiving amiodarone and in 20 (25.0%) patients receiving placebo (P =.017). Duration of atrial fibrillation was 12.8 +/- 4.8 hours for the amiodarone group compared with 34.7 +/- 28.7 hours for the control group (P =.003). The maximum ventricular rate during atrial fibrillation was slower in the amiodarone group than in the control group (105.9 +/- 19.1 beats per minute and 126.0 +/- 18.5 beats per minute, respectively, P =.016). The two groups had a similar incidence of complication other than rhythm disturbances (20.8% vs 20.0%, P =.904). Amiodarone group patients had shorter hospital stays than that of control group patients (6.8 +/- 1.7 days vs 7.8 +/- 2.9 days, P =.014). The in-hospital mortality was not different between two groups (1.3% vs 3.8, P =.620).</AbstractText>Postoperative intravenous amiodarone, followed by oral amiodarone, appears to be effective in the prevention of new-onset postoperative atrial fibrillation. It also reduces ventricular rate and duration of atrial fibrillation after coronary artery bypass grafting. It is well tolerated and decreases the length of hospital stay.</AbstractText> |
2,364 | Transmyocardial laser revascularization: epicardial ECG detection provides efficient R-wave triggering during mobilization of the heart. | In order to achieve an accurate intraoperative ECG detection, a new technique in detecting the trigger-signal was developed. In contrast to the traditional three-lead ECG-configuration, the left leg electrode was connected to a transient epicardial pacemaker electrode on the left-ventricular surface.</AbstractText>The Holmium:YAG-Laser for Transmyocardial Laser Revascularization (TMLR) is R-wave-triggered, providing the release of energy only during the refractory period of the heart cycle. However, an exact ECG-triggering during mobilization of the apex and/or posterior wall is difficult to achieve by using conventional ECG-configuration, therefore increasing the risk for mistriggering and induction of arrhythmias during TMLR.</AbstractText>Two groups of patients, all undergoing stand alone TMLR-procedures via left minithoracotomy, were compared. Ten patients were operated with the conventional ECG configuration (group 1) and ten patients with the modified epicardial ECG configuration (group 2).</AbstractText>In patients of group 1, as a result of a loss of the trigger signal or due to the triggering of artifacts, the incidence of correctly triggered QRS-complexes was 56% of all documented QRS-complexes. In contrast, an excellent triggering was observed in 98% (p < 0.001) in group 2, resulting in a reduction of laser operative time by 35% (p < 0.001) and a decrease in the incidence of intraoperative ventricular fibrillation (0 vs. 3).</AbstractText>In conclusion, this new ECG configuration is a simple but effective method in achieving an excellent ECG signal during all stages of TMLR. As a consequence, a reduction in operative time and incidence of ventricular fibrillation can be achieved.</AbstractText> |
2,365 | Long-term outcomes of out-of-hospital cardiac arrest after successful early defibrillation. | Mortality after out-of-hospital cardiac arrest from ventricular fibrillation is high. Programs focusing on early defibrillation have improved the rate of survival to hospital discharge. We conducted a population-based analysis of the long-term outcome and quality of life of survivors.</AbstractText>All patients who had an out-of-hospital cardiac arrest between November 1990 and January 2001 who received early defibrillation for ventricular fibrillation in Olmsted County, Minnesota, were included. The survival rate was compared with that of an age-, sex-, and disease-matched (2:1) control population of residents who had not had an out-of-hospital cardiac arrest and with that of age- and sex-matched controls from the general U.S. population. The quality of life was assessed with use of the Medical Outcomes Study 36-item Short-Form General Health Survey (SF-36) and compared with U.S. population norms.</AbstractText>Of 200 patients who presented with an out-of-hospital cardiac arrest with ventricular fibrillation, 145 (72 percent) survived to hospital admission (7 died in the emergency department) and 79 (40 percent) were neurologically intact (good overall capability or moderate overall disability) at discharge. The mean (+/-SD) length of follow-up was 4.8+/-3.0 years. Nineteen patients died after discharge from the hospital. The expected five-year survival rate (79 percent) was identical to that among age-, sex-, and disease-matched controls (P=0.68) but lower than that among the age- and sex-matched U.S. population (86 percent, P=0.02). Fifty patients completed SF-36 surveys at the end of follow-up, and the majority had a nearly normal quality of life, with the exception of reduced vitality.</AbstractText>Long-term survival among patients who have undergone rapid defibrillation after out-of-hospital cardiac arrest is similar to that among age-, sex-, and disease-matched patients who did not have out-of-hospital cardiac arrest. The quality of life among the majority of survivors is similar to that of the general population.</AbstractText>Copyright 2003 Massachusetts Medical Society</CopyrightInformation> |
2,366 | [Frequency and predictors of atrial fibrillation in severe mitral regurgitation]. | The aim of this study was to assess the frequency and the predictive factors for atrial fibrillation (AF) in patients with severe mitral regurgitation (MR).</AbstractText>This study is a retrospective evaluation involving of 199 patients (100 females, 99 males, mean age 53.8+/-18.5) with severe MR who had been admitted to our clinic between 1997 and 2001. Etiologies of MR were; rheumatic heart disease (n=132), ischemic heart disease (n=44), mitral valve prolapsus (n=14) and mitral annular calcification (n=9). Patients who had AF (n=95), sinus rhythm (n=98) or recurrent AF (n=6) were determined according to ECG. Age, gender, smoking, hypertension, diabetes mellitus, electrocardiographic left ventricular hypertrophy (LVH), echocardiographic left atrial (LA) diameter, left ventricular end-systolic dimension (LVESD), left ventricular end-diastolic dimension (LVEDD), ejection fraction (EF), right atrial size, pulmonary artery pressure and presence or absence of mitral stenosis were recorded.</AbstractText>Atrial fibrillation was observed in 50.8% of the patients. Female gender (60% vs. 40%, p=0.009), LA diameter (5.6+/-1.0 cm vs. 4.8+/-0.6 cm, p<0.001) and right atrium size (30.7% vs. 11.2%, p=0.001) were found as the predictive factors of AF in univariate analysis. Multiple logistic regression analysis showed that advanced age (p<0.014), female gender (p=0.02), LA size (p<0.001) and coexistence of MR with mitral stenosis (p<0.013) were independent risk factors for AF in patients with rheumatic MR. None of variables could be predictive for AF in patients with ischemic MR. Atrial fibrillation was found more frequently in patients with rheumatic MR than that of ischemic MR (p<0.001). In rheumatic MR, left atrium cut-off value for AF was found to be 5.5 cm (sensitivity: 52.1%, specificity: 90.7%).</AbstractText>Atrial fibrillation is a common arrhythmia in severe MR (50.8%). Left atrial size is a powerful independent predictor for AF.</AbstractText> |
2,367 | A case of electrical storm in a liver transplant patient. | Electrical storm has not been well described in liver transplant patients. We present a case of sympathetically mediated recurrent ventricular fibrillation in a young patient transplanted for acute Wilson's disease. This case highlights the role of the sympathetic nervous system in causing electrical storm and it demonstrates the ability of beta-blocking agents to terminate the event. In young liver transplant patients, beta-blocking agents should be considered for therapy of perioperative electrical storm if there is no known structural or coronary heart disease and when there are no risk factors for, or evidences of, torsades de pointes. |
2,368 | Retinal evaluation of patients on chronic amiodarone therapy. | To determine whether retinal electrophysiologic changes can be detected and correlated with funduscopic findings in patients with the long-term use of amiodarone.</AbstractText>Eleven patients ranging in age from 52 to 67 years were recruited from the Stanford University Medical Center Department of Cardiology for ophthalmologic examination. Patients had received amiodarone at various dosages ranging from 100 to 800 mg daily for at least 15 months. Clinical indications for the use of amiodarone included atrial fibrillation, ventricular arrhythmias, and congestive heart failure. All patients underwent retinal electrophysiology studies (full-field and multifocal electroretinograms) in addition to a complete ophthalmologic examination and fluorescein angiography.</AbstractText>No patients were found to have significant vision loss. Funduscopic examination and fluorescein angiography showed mild age-related changes in four patients, three of whom had nonspecific foveal pigmentary alterations. Multifocal and full-field electroretinograms were mostly unremarkable, and the mildly subnormal findings in a few patients showed no consistent pattern to suggest a toxic cause. Dosage, duration of amiodarone exposure, patient age, and underlying cardiac disease did not appear to correlate with these findings.</AbstractText>No significant adverse retinal funduscopic changes or electrophysiologic effects could be correlated with amiodarone exposure in this small series of patients. Routine electrophysiologic and funduscopic screening of patients receiving amiodarone does not seem warranted, although future prospective controlled studies may be required to exclude the possibility of progressive abnormalities in patients with preexisting age-related macular degeneration.</AbstractText> |
2,369 | Predictors of residual tricuspid regurgitation after mitral valve surgery. | Whether preoperative tricuspid regurgitation (TR) will regress or progress late after surgery is unknown. The aim of this study was to evaluate predictors of significant TR late after mitral valve surgery.</AbstractText>A retrospective analysis was performed on a total of 174 patients who underwent mitral valve surgery without tricuspid valve surgery. Preoperatively, 46 patients (26%) had 2+ TR, and 128 patients (74%) had 1+ or less TR. Postoperative 3+ TR was considered significant TR. Variables were used to evaluate predictors of TR development by univariate or multivariate analysis.</AbstractText>The mean follow-up was 8.2 years (range 1.0 to 14.5 years) after surgery. There was progressive TR (3+ or more) in 28 patients (16%) during the follow-up period. In univariate analysis, atrial fibrillation, rheumatic etiology, huge left atrium, left ventricular dysfunction, and preoperative 2+ TR were significant risk factors for TR development. Multivariate analysis identified preoperative 2+ TR, atrial fibrillation, and huge left atrium as statistically significant predictors for late TR after surgery.</AbstractText>Aggressive repair of accompanying TR should be undertaken at the time of initial surgery in patients with huge left atrium or atrial fibrillation, even if preoperative TR is 2+.</AbstractText> |
2,370 | Conversions in off-pump coronary surgery. | There have been 784 coronary artery bypass grafting (CABG) procedures performed at a new center for treating cardiovascular disease in Tuzla, Bosnia and Herzegovina, and the surgical team has been fully trained in offpump coronary artery bypass (OPCAB) surgery. All surgical patients were considered for on-pump CABG (ONCAB) and OPCAB surgical procedures. Minimally invasive direct coronary artery bypass grafting and robotic procedures were done as OPCAB. For multivessel median sternotomy cases, the selection criteria were arbitrary (approximately 50% were performed as ONCAB for perfusionist training). Patients who were scheduled for and began their operations as OPCAB but who were then placed on cardiopulmonary bypass during the surgical procedure were counted as conversions. The outcomes of converted patients were studied and are the subject of this report.</AbstractText>Of the 784 CABG procedures, 391 (49.6%) were scheduled and performed as ONCAB operations; 357 (45.5%) were performed as OPCAB; and 36 (9.2% of the originally scheduled OPCAB patients or 4.6% of the total number of CABG surgeries) were originally scheduled as OPCAB operations but were converted to ONCAB. Reasons for conversions were hemodynamic instability (21 patients), difficult revision of grafts (8), ventricular fibrillation (5), and poor native vessel (2). Outcomes of patients undergoing conversions were analyzed with respect to the conversion cause. When the cause of the conversion was mild-to-moderate hemodynamic instability or difficult graft revision (n = 27), no adverse ischemic effects were seen; however, when the cause of conversion was severe hemodynamic instability, ventricular fibrillation, or cardiac arrest (n = 9), 6 patients (66.6%) had severe ischemic complications involving the central nervous system or the myocardium.</AbstractText>Myocardial ischemia must be monitored and treated aggressively in OPCAB surgery. In patients with mild hemodynamic instability, conversion did not adversely affect outcome. In patients with severe hemodynamic compromise and cardiac arrest, serious complications of cerebral and myocardial ischemia were observed. The appropriate timing of conversion is essential.</AbstractText> |
2,371 | Usefulness of microvolt T-wave alternans for prediction of ventricular tachyarrhythmic events in patients with dilated cardiomyopathy: results from a prospective observational study. | This study was designed to evaluate the ability of microvolt-level T-wave alternans (MTWA) to identify prospectively patients with idiopathic dilated cardiomyopathy (DCM) at risk of ventricular tachyarrhythmic events and to compare its predictive accuracy with that of conventional risk stratifiers.</AbstractText>Patients with DCM are at increased risk of sudden death from ventricular tachyarrhythmias. At present, there are no established methods of assessing this risk.</AbstractText>A total of 137 patients with DCM underwent risk stratification through assessment of MTWA, left ventricular ejection fraction, baroreflex sensitivity (BRS), heart rate variability, presence of nonsustained ventricular tachycardia (VT), signal-averaged electrocardiogram, and presence of intraventricular conduction defect. The study end point was either sudden death, resuscitated ventricular fibrillation, or documented hemodynamically unstable VT.</AbstractText>During an average follow-up of 14 +/- 6 months, MTWA and BRS were significant univariate predictors of ventricular tachyarrhythmic events (p < 0.035 and p < 0.015, respectively). Multivariate Cox regression analysis revealed that only MTWA was a significant predictor.</AbstractText>Microvolt-level T-wave alternans is a powerful independent predictor of ventricular tachyarrhythmic events in patients with DCM.</AbstractText> |
2,372 | Effects of angiotensin II type 1 receptor antagonist on electrical and structural remodeling in atrial fibrillation. | The purpose of the present study was to evaluate the effect of angiotensin II type 1 receptor (AT1R) antagonist on chronic structural remodeling in atrial fibrillation (AF).</AbstractText>We previously reported that an AT1R antagonist, candesartan, prevents acute electrical remodeling in a rapid pacing model. However, the effect of candesartan on chronic structural remodeling in AF is unclear.</AbstractText>Sustained AF was induced in 20 dogs (10 in a control group and 10 in a candesartan group) by rapid pacing of the right atrium (RA) at 400 beats/min for five weeks. Candesartan was administered orally (10 mg/kg/day) for one week before rapid pacing and was continued for five weeks. The AF duration, atrial effective refractory period (AERP) at four sites in the RA, and intra-atrial conduction time (CT) from the RA appendage to the other three sites were measured every week.</AbstractText>The mean AF duration in the control group after five weeks was significantly longer than that with candesartan (1,333 +/- 725 vs. 411 +/- 301 s, p < 0.01). The degree of AERP shortening after five weeks was not significantly different between the two groups. The CT from the RA appendage to the low RA after five weeks with candesartan was significantly shorter than that in the control (43 +/- 14 vs. 68 +/- 10 ms, p < 0.05). The candesartan group had a significantly lower percentage of interstitial fibrosis than the control group (7 +/- 2% vs. 16 +/- 1% at the RA appendage, p < 0.001).</AbstractText>Candesartan can prevent the promotion of AF by suppressing the development of structural remodeling.</AbstractText> |
2,373 | Familial atrial fibrillation is a genetically heterogeneous disorder. | The aims of this study were to identify and characterize familial cases of atrial fibrillation (AF) in our clinical practice and to determine whether AF is genetically heterogeneous.</AbstractText>Atrial fibrillation is not generally regarded as a heritable disorder, yet a genetic locus for familial AF was previously mapped to chromosome 10.</AbstractText>Of 2,610 patients seen in our arrhythmia clinic during an 18-month study period, 914 (35%) were diagnosed with AF. Familial cases were identified by history and medical records review. Four multi-generation families with autosomal dominant AF (FAF 1 to 4) were tested for linkage to the chromosome 10 AF locus.</AbstractText>Fifty probands (5% of all AF patients; 15% of lone AF patients) were identified with lone AF (age 41 +/- 9 years) and a positive family history (1 to 9 additional relatives affected). In FAF 1 to 3, AF was associated with rapid ventricular response. In contrast, AF in FAF-4 was associated with a slow ventricular response and, with progression of the disease, junctional rhythm and cardiomyopathy. Genotyping of FAF 1 to 4 with deoxyribonucleic acid markers spanning the chromosome 10q22-q24 region excluded linkage of AF to this locus. In FAF-4, linkage was also excluded to the chromosome 3p22-p25 and lamin A/C loci associated with familial AF, conduction system disease, and dilated cardiomyopathy.</AbstractText>Familial AF is more common than previously recognized, highlighting the importance of genetics in disease pathogenesis. In four families with AF, we have excluded linkage to chromosome 10q22-q24, establishing that at least two disease genes are responsible for this disorder.</AbstractText> |
2,374 | [Detection of left ventricular ischemia at rest by tissue Doppler echocardiography]. | A 53-year old woman without a previous history of cardiac disease was successfully resuscitated from ventricular fibrillation. Despite a normal two dimensional echocardiogram, tissue Doppler analysis of left ventricular long-axis contraction revealed marked postsystolic contractions in the territory of the left coronary artery suggesting ischemia as the underlying pathogenetic mechanism. This was confirmed by coronary angiography which revealed a high-grade ostial stenosis of the left main stem. After coronary artery bypass surgery, the tissue Doppler findings normalized.</AbstractText>Assessment of regional long axis function by tissue Doppler echocardiography may yield important additional findings even if two-dimensional echocardiography is apparently normal.</AbstractText> |
2,375 | The effects of nifedipine on ventricular fibrillation mean frequency in a porcine model of prolonged cardiopulmonary resuscitation. | We assessed the effects of a calcium channel blocker versus saline placebo on ventricular fibrillation mean frequency and hemodynamic variables during prolonged cardiopulmonary resuscitation (CPR). Before cardiac arrest, 10 animals were randomly assigned to receive either nifedipine (0.64 mg/kg; n = 5) or saline placebo (n = 5) over 10 min. Immediately after drug administration, ventricular fibrillation was induced. After 4 min of cardiac arrest and 18 min of basic life support CPR, defibrillation was attempted. Ninety seconds after the induction of cardiac arrest, ventricular fibrillation mean frequency was significantly (P < 0.01) increased in nifedipine versus placebo pigs (mean +/- SD: 12.4 +/- 2.1 Hz versus 8 +/- 0.7 Hz). From 2 to 18.5 min after the induction of cardiac arrest, no differences in ventricular fibrillation mean frequency were detected between groups. Before defibrillation, ventricular fibrillation mean frequency was significantly (P < 0.05) increased in nifedipine versus placebo animals (9.7 +/- 1.2 Hz versus 7.1 +/- 1.3 Hz). Coronary perfusion pressure was significantly lower in the nifedipine than in the placebo group from the induction of ventricular fibrillation to 11.5 min of cardiac arrest; no animal had a return of spontaneous circulation after defibrillation. In conclusion, nifedipine, but not saline placebo, prevented a rapid decrease of ventricular fibrillation mean frequency after the induction of cardiac arrest and maintained ventricular fibrillation mean frequency at approximately 10 Hz during prolonged CPR; this was nevertheless associated with no defibrillation success.</AbstractText>This study evaluates the effects of a calcium channel blocker on ventricular fibrillation mean frequency, hemodynamic variables, and resuscitability during prolonged cardiopulmonary resuscitation (CPR) in pigs. Nifedipine, but not saline placebo, prevented a rapid decrease of ventricular fibrillation mean frequency after the induction of cardiac arrest and maintained ventricular fibrillation mean frequency at approximately 10 Hz during prolonged CPR but did not improve resuscitability.</AbstractText> |
2,376 | The relative toxicity of amitriptyline, bupivacaine, and levobupivacaine administered as rapid infusions in rats. | Intravascular injection of local anesthetics carries the risk of cardiovascular (CV) and central nervous system (CNS) toxicity. Amitriptyline, a tricyclic antidepressant, has local anesthetic potency that is more than that of bupivacaine. In this study, we compared the CV and CNS toxicity of the local anesthetics bupivacaine and levobupivacaine with that of amitriptyline. Twenty-nine Sprague-Dawley rats had their right external jugular vein and carotid artery cannulated under general anesthesia. On Day 2, rats were sedated with midazolam (0.375 mg/kg intraperitoneally) and received rapid infusions of either 1) bupivacaine, levobupivacaine, or amitriptyline at 2 mg x kg(-1) x min(-1) (5 mg/mL concentration) or 2) normal saline (400 micro L x kg(-1) x min(-1)) through an external jugular vein cannula. Electrocardiogram and arterial blood pressure were measured until the dose to cause impending death was reached (heart rate 50 bpm/asystole or apnea for >30 s). The mean dose required to cause apnea and impending death was significantly larger for amitriptyline (74.0 +/- 21 mg/kg and 74.5 +/- 21 mg/kg, respectively) than for levobupivacaine (32.2 +/- 20 mg/kg and 33.9 +/- 22 mg/kg, respectively) or bupivacaine (21.5 +/- 7 mg/kg and 22.7 +/- 7 mg/kg, respectively) (P < 0.05). A significantly larger dose of amitriptyline, given by rapid infusion, is required to cause CV and CNS toxicity in rats, when compared with bupivacaine and levobupivacaine.</AbstractText>Amitriptyline, a tricyclic antidepressant, has local anesthetic properties and is more potent than bupivacaine. Significantly larger doses of amitriptyline, given by rapid infusion, are required to cause cardiovascular and central nervous system toxicity in rats, when compared with bupivacaine and levobupivacaine.</AbstractText> |
2,377 | [Wolff-Parkinson-White syndrome in the child. A case report with associated atrial fibrillation]. | In children, Wolff-Parkinson-White (WPW) syndrome is often revealed by reentrant tachycardia episodes. Rarely, this syndrome can be the cause of syncope or of sudden death, resulting from rapid conduction of atrial fibrillation to the ventricles through the accessory pathway.</AbstractText>The authors report the case of a child, who had a WPW syndrome diagnosed after birth because of a supraventricular tachycardia and who was later asymptomatic. At ten years of age, he was admitted because of palpitations due to atrial fibrillation and rapid conduction through the accessory pathway.</AbstractText>In a child with WPW syndrome, tachycardia with wide and irregular QRS complexes should evoke the involvement of atrial fibrillation, with rapid conduction to the ventricle. Drugs blocking conduction through the atrio-ventricular node are contra-indicated and the condition is an indication for radiofrequency ablation.</AbstractText> |
2,378 | [Risk factors for stroke in Chinese with non valvular atrial fibrillation: a case-control study]. | The aim of this study is to identify the risk factors in Chinese with nonvalvular atrial fibrillation and stroke, using case-control methodology.</AbstractText>A total of 4 511 adult patients diagnosed with atrial fibrillation were identified from 18 hospitals over a 2-year period. There were 1 086 patients with rheumatic valvular atrial fibrillation and 3 425 patients with nonvalvular atrial fibrillation. Among the nonvalvular atrial fibrillation patients, 827 had ischemic stroke. The data of the patients having nonvalvular atrial fibrillation with stroke was compared with those having nonvalvular atrial fibrillation without stroke (n = 2 598). The effect of each variable on stroke was assessed with a logistic regression analysis.</AbstractText>The studied cases with stroke and controls without stroke were similar in terms of percentage with sex, a past history of congestive heart failure, myocardial infarction, and mean left atrial size. Cases were significantly older than controls (73.3 +/- 9.2 vs. 68.2 +/- 12.3, P < 0.001) and more likely to have a history of hypertension (71.0% versus 51.6%, P < 0.001) and diabetes (17.9% vs. 11.1%, P = 0.001). There is strong evidence that left atrial (LA) thrombi make AF patients highly risky for stroke. In multivariate analysis, age > or = 75 (OR 1.76; 95% CI 1.08 approximately 2.98), history of hypertension (OR 1.52; 95% CI 1.28 approximately 1.80), diabetes (OR 1.39; 95% CI 1.11 approximately 1.76), high systolic blood pressure (OR 1.71; 95% CI 1.21 approximately 2.28), LA thrombi (OR 2.77; 95% CI 1.25 approximately 6.13) were independently associated with stroke. The lack of the association between left ventricular dysfunction and stroke is due to the relatively incorrect diagnosis of heart failure in the context of atrial fibrillation.</AbstractText>Our analysis suggests that old age, hypertension, diabetes, high systolic blood pressure and LA thrombi detected with echocardiography are independent risk factors, which should be considered when decision of long-term anticoagulation therapy to prevent stroke with nonvalvular atrial fibrillation is to be made.</AbstractText> |
2,379 | Prospective randomized comparison of 65%/65% versus 42%/42% tilt biphasic waveform on defibrillation thresholds in humans. | The waveform tilt of biphasic shocks yielding the lowest defibrillation threshold (DFT) is not well defined. Some evidence indicates that tilts less than 65% may improve DFTs.</AbstractText>In 57 patients undergoing ICD implantation, DFTs were determined with truncated exponential biphasic waveform tilts at 65%/65% and at 42%/42%. An external defibrillator with custom software was used for testing. The effective capacitance of the defibrillator was 132-microF for both waveforms. DFTs were determined using a binary search method starting with 12 Joules (J). Patients were randomly assigned to initial testing with either one of the two tilts. Thirty patients (Group 1) were tested with a two electrode (active can to RV coil, or SVC coil to RV coil) and 27 patients (Group 2) were tested with a three electrode system (subcutaneous patch or active can + SVC coil to RV coil).</AbstractText>Groups 1 and 2 did not differ in age, ejection fraction or antiarrhythmic medications. Group 1 delivered energy DFTs were 10.1 +/- 5.5 J with the 65%/65% tilt and 10.1 +/- 5.9 J for the 42%/42% tilt (p = 0.92). In group 2 the average DFT for the 65%/65% tilt was 8.4 +/- 5.7 J and for the 42%/42% tilt was 8.1 +/- 5.3 J (p = 0.70). There were no significant differences in DFTs for either group. The system impedance for Group 1 was 64 +/- 12 ohms and for Group 2 was 39 +/- 6 ohms (p < 0.0001).</AbstractText>We found no differences in DFTs between 65%/65% tilt and 42%/42% tilt using either 2- or 3-electrode defibrillation systems. Further research is needed to optimize waveforms in order to minimize DFTs, which will result in smaller ICDs and/or greater safety margins for defibrillation.</AbstractText> |
2,380 | Is inappropriate implantable defibrillator shock therapy predictable? | To identify implantable cardioverter defibrillator (ICD) patients who are at risk of receiving inappropriate shock.</AbstractText>Inappropriate ICD shock, usually from atrial fibrillation (AF) or sinus tachycardia (ST), is a common problem. We hypothesized that clinical variables would predict which patients with single chamber ICDs would be more likely to receive inappropriate therapy and be candidates for more accurate discriminators such as those available in dual chamber ICDs.</AbstractText>The ICD registry at St. Michael's Hospital has it's clinical information and demographic data updated after each clinic visit. Inappropriate shock was considered as the outcome variable. Possible predictors considered were age, gender, ejection fraction, NYHA class, prior CABG and prior history of AF. Univariate predictors were identified using t-test for continuous variables and Chi-square test for categorical variables. Multivariate predictors were identified using stepwise logistic regression analyses.</AbstractText>Of 299 patients, 261 had complete data for analysis. In this population 78% were male, mean age was 60 +/- 13 years, mean ejection fraction was 37 +/- 15% and mean follow up was 53 +/- 36 months. One hundred and sixteen of the 261 patients (44%) received one or more inappropriate therapies (73% within 2 years of receiving their device), and 140 (51%) received one or more appropriate therapies. Significant predictors of inappropriate therapy by multivariate model were prior AF (OR 2.6, 95% CI 1.5-4.5) and NYHA class 1 vs. classes 2-4 (OR 2.2, 95% CI 1.2-3.7).</AbstractText>Clinical characteristics of ICD patients can predict those at risk for inappropriate shock and should be considered for interventions to decrease such shocks.</AbstractText> |
2,381 | Feasibility of atrial sensing via a free-floating single-pass defibrillation lead for dual-chamber defibrillators. | Detection and misclassification of rapidly conducted atrial fibrillation (AF) and marked sinus tachycardia by implantable cardioverter defibrillators (ICD) can result in the delivery of inappropriate therapies. Continuous atrial sensing may improve the differentiation between supraventricular and ventricular tachycardia. The present approach is to implant a separate atrial pacing lead connected to a dual-chamber defibrillator. We hypothesized that a free-floating single-pass defibrillation lead reliably senses the atrial electrical activity. The aim of the study was to assess during implantation the efficacy of a custom-built free-floating single-pass defibrillation lead and to record sinus rhythm (SR), induced AF, and atrial flutter (Afl).</AbstractText>The free-floating single-pass defibrillation lead (Biotronik, Berlin, Germany) had an atrial bipole with 10 mm spacing and a distance between the atrial bipole and the electrode tip of 13.5, 15 or 17-cm. The lead was temporarily implanted in 15 patients during an ICD implantation. Fifteen seconds recordings were made during SR and after the induction of AF and Afl as well as during induced ventricular fibrillation. The amplitude and the time that the amplitude was less than 0.3 mV were assessed.</AbstractText>The amplitude during SR (2.1 +/- 1.4 mV) was significantly higher compared with the amplitudes for Afl (1.3 +/- 0.5 mV; p < 0.02) and AF (0.7 +/- 0.5 mV; p < 0.001). Low amplitudes were not observed during SR and rarely during Afl (1.6 +/- 3.1%), but they were observed 19.9 +/- 15.9% of the time during AF (p < 0.05). The correlation coefficients between SR and AF amplitudes were r = 0.25, between SR and Afl amplitudes r = 0.31, and between AF and Afl amplitudes r = 0.41. During the ventricular fibrillation conversion test 9 patients were in continuous SR. The P-wave amplitude before the induction of ventricular fibrillation was 2.1 +/- 1.4 mV. The signal during ventricular fibrillation decreased to 1.1 +/- 0.7 mV and increased immediately after the termination of ventricular fibrillation to 1.6 +/- 0.8 mV.</AbstractText>The recorded unfiltered signals indicate that SR as well as AF and Afl can immediately be detected after the implantation of the new free-floating single-pass defibrillation lead. High signal amplitude during SR did not predict high amplitude during AF or Afl. During induced ventricular fibrillation the P-wave amplitude decreased intermittently.</AbstractText> |
2,382 | Ablation of typical atrial flutter using a three-dimensional ultrasound mapping system. | The aim of the study was to test the feasibility of the new Realtime Position Management mapping system for ablation of typical atrial flutter.</AbstractText>The ultrasound multi-transducer catheters of the RPM Mapping System are placed in the coronary sinus and at the right ventricular apex. Position and movement of the ablation catheter can be depicted on the monitor at any time. Several guiding marks are set in the right atria and thus, define the subsequent lesion lines. A total of 15 patients were treated. In 13 patients complete bi-directional block was established after the ablation. In two patients only significant conduction delay was measured after the end of the procedure. A total of 10.2 +/- 6.3 cooled RF-applications were needed to reach the end-point of the procedure. The total energy was 18.76 +/- 13.23 J. The fluoroscopy time for ablation was 22.2 +/- 8.34 min. During a mean follow-up of 8.4 +/- 3.2 months no recurrence of atrial flutter occurred. One patient developed atypical flutter and another patient had atrial fibrillation. Both patients were treated with antiarrhythmic drugs. There was one ablation related complication, a pericardial effusion.</AbstractText>The Realtime Position Management system is easy to manage and control. The precision of anatomical linear lesions is improved and fluoroscopic exposure time considerably reduced after learning curve.</AbstractText> |
2,383 | [Update cardiology 2001/2002-part II. From unstable coronary syndrome to terminal heart failure]. | The cardiovascular continuum describes the way from risk factors to atherosclerosis, acute cardiovascular events (unstable angina and myocardial infarction), and development of terminal heart failure and its complications. Following this way, advances are reported in the therapy of acute coronary syndrome, heart failure, ventricular and supraventricular tachyarrhythmias, and stroke in patients with patent foramen ovale. The following issues are reported in detail: (1) significance of statins and statin withdrawal, glycoprotein IIb/IIIa receptor blocker, acute coronary interventions, aspirin and clopidogrel in unstable coronary syndromes, (2) pathogenesis of acute pulmonary edema associated with hypertension, (3) cardiac regeneration capability after transplantation and myocardial infarction, (4) beta-blocker therapy, efficacy of additional angiotensin receptor blocker therapy and multisite biventricular pacing in symptomatic (advanced) heart failure, (5) prognosis after ablation of the atrioventricular node in patients with atrial fibrillation, (6) primary prevention with an implantable defibrillator and resumption of driving after implantation, and (7) therapeutic options after cryptogenic stroke and patent foramen ovale. |
2,384 | Determination of the upper limit of vulnerability using implantable cardioverter-defibrillator electrograms. | The upper limit of vulnerability (ULV) correlates with the defibrillation threshold and can be determined with 1 episode of ventricular fibrillation (VF). To automate the ULV in an implantable cardioverter-defibrillator (ICD), the most vulnerable intervals must be identified from an ICD electrogram rather than the latest-peaking surface T wave (Tpeak). We hypothesized that the recovery time (TR), defined as the maximum derivative (dV/dt) of the T wave of the shock electrogram, correlates with the most vulnerable intervals.</AbstractText>We determined ULV, defibrillation threshold, and the most vulnerable intervals in 25 patients at ICD implantation. The ULV was the weakest T-wave shock that did not induce VF. The most vulnerable intervals were the ones associated with the strongest shocks that induced VF. Telemetered shock electrograms were stored on digital tape and differentiated offline to measure TR. Tpeak and TR were highly correlated (Tpeak-TR=-2+/-11 ms; rho=0.80, P<0.001). At least 1 most vulnerable interval timed between -20 ms and +20 ms relative to Tpeak in all patients and between -40 ms and +20 ms relative to TR in 96% of patients.</AbstractText>The recovery time of shock electrograms provides accurate information about global repolarization. TR closely approximates Tpeak. The ULV method may be automated in an ICD by timing T-wave shocks relative to TR.</AbstractText> |
2,385 | Increased severity of reperfusion arrhythmias in mouse hearts lacking histamine H3-receptors. | We had previously reported that activation of histamine H(3)-receptors (H(3)R) on cardiac adrenergic nerve terminals decreases norepinephrine (NE) overflow from ischemic hearts and alleviates reperfusion arrhythmias. Thus, we used transgenic mice lacking H(3)R (H(3)R(-/-)) to investigate whether ischemic arrhythmias might be more severe in H(3)R(-/-) hearts than in hearts with intact H(3)R (H(3)R(+/+)). We report a greater incidence and longer duration of ventricular fibrillation (VF) in H(3)R(-/-) hearts subjected to ischemia. VF duration was linearly correlated with NE overflow, suggesting a possible cause-effect relationship between magnitude of NE release and severity of reperfusion arrhythmias. Thus, our findings strengthen a protective antiarrhythmic role of H(3)R in myocardial ischemia. Since malignant tachyarrhythmias cause sudden death in ischemic heart disease, attenuation of NE release by selective H(3)R agonists may represent a new approach in the prevention and treatment of ischemic arrhythmias. |
2,386 | A critical evaluation of results of partial left ventriculectomy. | Because of the variation in the surgical procedures designed to reduce ventricular radius, along with differences in hospital care, it is difficult to disentangle the factors that may contribute to the success or failure of the partial left ventriculectomy.</AbstractText>We undertook partial left ventriculectomy in 18 patients, 10 suffering from idiopathic dilated cardiomyopathy and 8 from ischemic heart disease. We assessed the amount of reduction in wall stress, the systolic thickening of the ventricular wall, and the extent of connective tissue in the excised segment of the wall. Of the overall group, six patients died, three from infarction, one of stroke, one with asystole, and one with ventricular fibrillation. The mean decrease in measured mesh tension was 40% (p < 0.001). Most patients exhibited improvements postoperatively in terms of the systolic thickening of the posterior and superior free walls of the left ventricle. In those in whom the events could be monitored, life-threatening arrhythmias posed complications in three of four patients with ischemic heart disease, and in two of six patients suffering from idiopathic dilated cardiomyopathy. In one patient, death was associated with a transmural alignment of fibrous tissue.</AbstractText>Our measured reductions in myocardial mesh tension were in keeping with the anticipated theoretical reduction in wall stress expected from partial ventriculectomy. The basic concept underscoring surgical maneuvers to reduce ventricular radius, therefore, is sound. A potential trap is the resection of the marginal artery. Critical myofibrosis was a rare complication. Arrhythmias, which are common, can successfully be treated by implantation of antitachycardic and defibrillatory devices.</AbstractText> |
2,387 | Partial left ventriculectomy (Batista's Procedure) case report: 40 months follow-up. | Partial left ventriculectomy (PLV) (also known as Batista's Procedure) is a surgical procedure for treatment of dilated cardiomyopathy when cardiac transplant is contraindicated. Mitral valve replacement is needed because of mitral regurgitation as a consequence of annulus enlargement and papillary muscle resection. Bleeding and arrythmias are the main complications.</AbstractText>We considered for this operation a 60-year-old male patient. He suffered from valvular dilating cardiomyopathy as a consequence of mitral and aortic valve regurgitation. Furthermore, a severe peripheral vascular disease treated with aortic-bifemoral prosthesis contraindicated heart transplantation. He needed frequent hospital admissions for pulmonary edema and his quality of life was very poor. Batista's procedure was performed in March 1998, successfully. Mitral and aortic valves were replaced by use of mechanical prosthesis. The postoperative period was characterized by early weaning from ventilator and drugs; atrial fibrillation, reversed by Amiodaron; a little bilateral pleural effusion; and pacemaker implantation following advanced heart conduction block. No bleeding episodes were observed. In March 2001 the progression of the vascular disease forced the patient to undergo to a femoro-femoral bypass and endoarterectomy of the right branch of the vascular prothesis. The patient tolerated the procedure very well. He had no complications during the postoperative period with early weaning from ventilator and drugs.</AbstractText>At the end of the procedure ejection fraction raised from 15% to 30%. Echocardiographic data demonstrated a slow but progressive improvement of the cardiac diameters and volumes with a preserved left ventricular function.</AbstractText>Even if a larger number of cases and longer follow-up are necessary, our report demonstrated that Batista's procedure should be considered as a surgical alternative to heart transplantation, in well-selected patients with absolute contraindication to heart transplantation and left ventricular assist device implantation.</AbstractText> |
2,388 | [Anticoagulation--control of heart rate--cardioversion. Therpeutic algorithm in ventricular tachycardia]. | The first therapeutic step in the emergency situation absolute tachyarrhythmia in underlying atrial fibrillation is the immediate initiation of anticoagulation treatment with heparin, followed by control of the ventricular frequency. Cardioversion promises success when: atrial fibrillation < 48 hours, transesophageal echocardiography excludes a thrombus, > 3 weeks effective anticoagulation, left ventricle < 50 mm, and atrial fibrillation not longer than one year. In the emergency situation electric cardioversion is to be preferred to drug-induced cardioversion. If the pumping function is reduced, amiodarone is a safe agent for rhythm stabilization. Care must be exercised with verapamil, digitalis and adenosine in irregular broad QRS complex tachycardia and suspected WPW syndrome. |
2,389 | Heart failure complicated by atrial fibrillation: mechanistic, prognostic, and therapeutic implications. | Atrial fibrillation and congestive heart failure are two distinct clinical entities that are responsible for significant morbidity and mortality in the Western world. Hypertension, coronary artery disease, and nonischemic cardiomyopathy represent the most prevalent underlying pathologies of both diseases, implying a coincidence of both in many patients. The prevalence of atrial fibrillation with a progressive degree of congestive heart failure is increasing, as judged by New York Heart Association functional class. Moreover, the presence of congestive heart failure has been identified as one of the most powerful independent predictors of atrial fibrillation, with a sixfold increase in relative risk of its development. On the other hand, atrial fibrillation can cause or significantly aggravate symptoms of congestive heart failure in previously asymptomatic or well-compensated patients. In some patients, symptomatic dilated cardiomyopathy may develop over time entirely due to atrial fibrillation with rapid ventricular rates. Upon restoration of sinus rhythm, this type of "tachymyopathy" has been shown to be often reversible. Recent investigations of the physiologic and structural changes of the atrial myocardium ("electrical and structural remodeling") have shown that neurohumoral activation, fibrosis, and apoptosis are demonstrable with both diseases. On the other hand, experimental data suggest that the substrates of atrial fibrillation in congestive heart failure are different from those of pure atrial tachycardia-related forms of atrial fibrillation. This review highlights the clinical and pathophysiologic similarities and differences of atrial fibrillation and congestive heart failure relevant to the understanding, treatment, and prevention of these diseases in the population at risk. |
2,390 | Sudden death of a case of hypertrophic obstructive cardiomyopathy 19 months after successful percutaneous transluminal septal myocardial ablation. | A 56-year-old male with hypertrophic obstructive cardiomyopathy complicated with medically refractory paroxysmal atrial fibrillation and congestive heart failure was treated with percutaneous transluminal septal myocardial ablation. The resting left ventricular outflow tract gradient decreased from 70 mmHg to 0 mmHg after the procedure, and clinical symptoms improved dramatically. However, the patient died suddenly 19 months later and autopsy revealed nontransmural myocardial fibrosis with an irregular border in the interventricular septum. |
2,391 | Autonomic imbalance as a property of symptomatic Brugada syndrome. | The autonomic properties in 27 patients with the electrocardiographic morphology of Brugada syndrome were investigated using 24-h Holter monitoring: 10 patients had a history of ventricular fibrillation (VF; Br-VF group) and 17 did not (Br-N group); there were 26 healthy subjects enrolled in this study. All subjects underwent normal Holter data monitoring and power spectral analysis. Few extrasystoles were observed in either group, and the mean heart rate (HR), maximum HR, and total heart beats over 24 h were obtained. All of these measurements were significantly lower in the Br-VF group than in the Br-N and healthy subject groups. The RR interval variability was analyzed over 512 beats every 10 min. The high-frequency component (0.15-0.40 Hz; HF), low-frequency component (0.04-0.15 Hz; LF) and the LF/HF ratio were analyzed over 24 h. The HF was significantly higher and LF/HF ratio lower in the Br-VF group than in the healthy subjects. The HF was also significantly higher than in the Br-N group. During the night (00.00-05.00 h), the HF was significantly higher in the Br-VF group, and the LH/HF lower. During the day (12.00-17.00 h), the HF was significantly higher in the Br-VF group, but there was no difference in the LF/HF. These results indicate that high vagal tone and low sympathetic tone are specific properties of symptomatic Brugada syndrome. |
2,392 | Adrenomedullin gene delivery attenuates myocardial infarction and apoptosis after ischemia and reperfusion. | Adrenomedullin (AM) has been shown to protect against cardiac remodeling. In this study, we investigated the potential role of AM in myocardial ischemia-reperfusion (I/R) injury through adenovirus-mediated gene delivery. One week after AM gene delivery, rats were subjected to 30-min coronary occlusion, followed by 2-h reperfusion. AM gene transfer significantly reduced the ratio of infarct size to ischemic area at risk and the occurrence of sustained ventricular fibrillation compared with control rats. AM gene delivery also attenuated apoptosis, assessed by both terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay and DNA laddering. The effect of AM gene transfer on infarct size, arrhythmia, and apoptosis was abolished by an AM antagonist, calcitonin gene-related peptide [CGRP(8-37)]. Expression of human AM significantly increased cardiac cGMP levels and reduced superoxide production, superoxide density, NAD(P)H oxidase activity, p38 MAPK activation, and Bax levels. Moreover, AM increased Akt and Bad phosphorylation and Bcl-2 levels, but decreased caspase-3 activation. These results indicate that AM protects against myocardial infarction, arrhythmia, and apoptosis in I/R injury via suppression of oxidative stress-induced Bax and p38 MAPK phosphorylation and activation of the Akt-Bad-Bcl-2 signaling pathway. Successful application of this technology may have a protective effect in coronary artery diseases. |
2,393 | The prevalence of heart failure and asymptomatic left ventricular systolic dysfunction in a typical regional pacemaker population. | To assess the prevalence of heart failure and asymptomatic left ventricular systolic dysfunction in the chronically paced population.</AbstractText>Three hundred and seven patients were identified from attendance at routine pacemaker follow-up clinic. Subjects underwent a medical history and examination, 6-minute walk test and echocardiography. 94 (31%) had a left ventricular ejection fraction (LVEF) <40%, of whom 83 had symptoms of heart failure (70% NYHA II, 26% NYHA III and 4% NYHA IV). Heart failure was more prevalent in patients with single chamber compared to dual chamber pacemakers, (DDD(R) 18% vs 35% VVI(R), p<0.008), and those with chronic atrial fibrillation (AF) compared to those with sinus rhythm (42% vs 21%, p=0.003). Decreasing 6-minute walk distance, history of ischaemic heart disease and years of pacing were independently associated with the presence of heart failure (combined R=0.572, p<0.001).</AbstractText>Heart failure due to left ventricular systolic dysfunction is common in the paced population. Only a minority of these had a pre-existing diagnosis and a smaller proportion were on 'optimal' therapy. Echocardiographic screening of this high-risk population is justified to improve rates of diagnosis and treatment of heart failure.</AbstractText> |
2,394 | Increased cortical cerebral blood flow by continuous infusion of adrenaline (epinephrine) during experimental cardiopulmonary resuscitation. | To study the effects of continuously administered adrenaline (epinephrine), compared to bolus doses, on the dynamics of cortical cerebral blood flow during experimental cardiopulmonary resuscitation (CPR), and after restoration of spontaneous circulation (ROSC).</AbstractText>Ventricular fibrillation was induced in 24 anaesthetised pigs. After a 5-min non-intervention interval, closed-chest CPR was started. The animals were randomised into two groups. One group received three boluses of adrenaline (20 microg/kg) at 3-min intervals. The other group received an initial bolus of adrenaline (20 microg/kg) followed by an infusion of adrenaline (10 microg/kg x min). After 9 min of CPR, defibrillation was attempted, and if spontaneous circulation was achieved the adrenaline infusion was stopped. Cortical cerebral blood flow was measured continuously using Laser-Doppler flowmetry. Jugular bulb oxygen saturation was measured to reflect global cerebral oxygenation. Repeated measurements of 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) in jugular bulb plasma were performed to evaluate cerebral oxidative injury.</AbstractText>During CPR mean cortical cerebral blood flow was significantly higher (P=0.009) with a continuous adrenaline infusion than with repeated bolus doses. Following ROSC there was no significant difference in cortical cerebral blood flow between the two study groups. No differences in coronary perfusion pressure, rate of ROSC, jugular bulb oxygen saturation or 8-iso-PGF(2alpha) were seen between the study groups.</AbstractText>Continuous infusion of adrenaline (10 microg/kg x min) generated a more sustained increase in cortical cerebral blood flow during CPR as compared to intermittent bolus doses (20 microg/kg every third minute). Thus, continuous infusion might be a more appropriate way to administer adrenaline as compared to bolus doses during CPR.</AbstractText> |
2,395 | Reverse CPR: a pilot study of CPR in the prone position. | Cardiopulmonary resuscitation (CPR), as described in 1960, remains the cornerstone of therapy for cardiopulmonary arrest. Recent case reports have described CPR in the prone position. We hypothesized rhythmic back pressure on a patient in the prone position with sternal counter-pressure (termed reverse CPR here) would increase intra-thoracic pressure and in turn systolic blood pressure (SBP) during cardiac arrest versus standard CPR.</AbstractText>Six patients from Columbia Presbyterian Medical Center's Cardiac and Medical Intensive Care Units (CICU and MICU) were enrolled. Eligible patients had suffered circulatory arrest and failed standard CPR for at least 30 min. After enrollment the patients received 15 additional min of standard CPR and then reverse CPR for 15 min. The study's primary endpoint, mean SBP, significantly improved from 48 mmHg during standard CPR to 72 mmHg during reverse CPR (mean improvement=23+/-14 mmHg). Mean calculated mean arterial pressure (MAP) was also improved significantly from 32 mmHg during standard CPR to 46 mmHg during reverse CPR (mean improvement=14+/-11 mmHg). The mean diastolic blood pressure (DBP) improved from 24 mmHg during standard to 34 mmHg during reverse CPR (mean improvement=10+/-12 mmHg). This difference did not meet statistical significance. No patients had return of spontaneous circulation.</AbstractText>Reverse CPR generates higher mean SBP and higher mean MAP during circulatory arrest than standard CPR. These novel findings justify further research into this technique.</AbstractText> |
2,396 | Safety and feasibility of a clinical pathway for the outpatient initiation of antiarrhythmic medications in patients with atrial fibrillation or atrial flutter. | We sought to establish the safety and feasibility of a clinical pathway for the outpatient initiation of antiarrhythmic medications (AAMs) for the maintenance of sinus rhythm in patients with atrial fibrillation (AF) or atrial flutter (AFl). AAMs are frequently utilized to maintain sinus rhythm in patients with AF or AFl. Although they are often initiated in an outpatient setting, there is little prospective evidence for the safety of this approach. Patients with a history of AF or AFl were prospectively monitored with an event recorder during 409 AAM initiation trials. All AAMs were initiated in sinus rhythm. Patients transmitted a recording (30 seconds) once daily for 10 consecutive days. Amiodarone was used for 212 patients (51.8%), 127 (31.1%) received a type 1C AAM, 37 (9.0%) received sotalol, and 33 (8.1%) received a type 1A AAM. Adverse events occurred in 17 patients (3 died, 3 had bradycardia that required permanent pacemaker implantation, and 11 had bradycardia requiring a decrease in the dose of antiarrhythmic or rate-controlling medication). Most events were due to bradycardia in patients who received amiodarone. There was a significant association between amiodarone-associated bradycardia and women. The only event that occurred during the first 48 hours was an episode of bradycardia in a patient who received amiodarone and was managed as an outpatient. The outpatient initiation of AAMs for patients with a history of AF or AFl while in sinus rhythm is associated with significant risk. Most adverse events occurred beyond the usual time period for in-hospital monitoring of the initiation of AAMs. |
2,397 | The psychosocial impact of the implantable cardioverter defibrillator: a meta-analytic review. | The implantable cardioverter defibrillator (ICD) has become the treatment of choice for ventricular arrhythmia (VA; abnormal heart rhythms) and the prevention of sudden cardiac death (SCD). Recent clinical trials have shown the ICD to be superior to anti-arrhythmic medication in reducing mortality; however, research has suggested that ICD recipients experience poor psychosocial adjustment following implantation of the device. This aim of this study was to identify the key psychological characteristics associated with ICD implantation and to establish whether poor psychosocial outcome can be attributed directly to the device and its therapy.</AbstractText>Studies which reported valid and reliable measures of psychological functioning in ICD patients and appropriate comparison groups were considered for inclusion in a meta-analytic review. A systematic search of electronic databases and reference lists identified 20 studies which fulfilled the inclusion criteria.</AbstractText>There were no significant differences in psychosocial outcome between ICD patients and drug-maintained VA patients or between pre- and post-implant ICD patients. However, ICD patients reported significantly worse psychological functioning and physical functioning than other cardiac controls.</AbstractText>These findings suggest that poor psychosocial outcome in ICD patients may occur as a result of variables associated with the underlying VA condition, rather than as a direct response to implantation of the device and its therapy. This holds important implications for the development and implementation of psychological interventions for patients experiencing VA, in preference to ICD-specific programmes.</AbstractText> |
2,398 | Decreased plasma brain natriuretic peptide levels after a successful maze procedure. | Previous reports indicate that plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) increase in atrial fibrillation (AF), but decrease after successful direct current (DC) cardioversion. Although the maze procedure is the only curative therapy for AF, the effects on atrial and left ventricular function remain unclear. The study aim was to determine whether plasma ANP and BNP levels decrease after the maze procedure in patients with mitral valve disease.</AbstractText>Twenty-seven patients either with (n = 23) or without (n = 4) AF underwent mitral valve surgery; of these patients, 13 underwent a maze procedure for chronic AF. Blood samples and echocardiographic data were obtained before and at one year after surgery.</AbstractText>Ten patients with AF achieved sinus rhythm (SR) or junctional rhythm after the maze procedure. In patients subjected to mitral valve surgery, mean plasma levels of ANP and BNP were 59.8 +/- 11.9 and 139.2 +/- 53.7 pg/ml, respectively. ANP and BNP plasma levels fell significantly after surgery (to 32.1 +/- 4.1 and 46.7 +/- 10.2 pg/ml, respectively; p = 0.04 and p = 0.004). In patients with successful maze procedure, plasma levels of BNP and left ventricular end-diastolic dimension (LVDd) were significantly decreased by 35.7% and 82.7% compared with preoperative values (BNP, 35.7 +/- 4.9% for SR versus 83.4 +/- 9.6% for AF, p = 0.008; LVDd, 82.7 +/- 3.7% for SR versus 97.0 +/- 3.2% for AF, p = 0.0159).</AbstractText>A successful maze procedure significantly decreased LVDd and plasma levels of BNP after surgery. These results show that the maze procedure is effective in improving left ventricular diastolic dysfunction for a mid-term period in patients with mitral valve disease.</AbstractText> |
2,399 | Effect of thyrotropin-releasing hormone on the development of cardiac arrhythmias during stimulation of sensorimotor cortex in cats. | Preliminary intravenous injection of thyrotropin-releasing hormone in a dose of 20 g/kg to cats with developing myocardial ischemia during stimulation of the cerebrocortical sensorimotor zone had a pronounced antiarrhythmic effect. |
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