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Protective effect of Crataegus oxyacantha against reperfusion arrhythmias after global no-flow ischemia in the rat heart.

The protective effect against reperfusion arrhythmias of a 3-month oral pretreatment with a dried extract of Crataegus oxyacantha (LI 132)(standardized to 2.2% flavonoids) was studied with the Langendorff heart of the rat after global no-flow ischemia. The heart was perfused with a modified Krebs-Henseleit solution in which the K+ content was reduced to 3.4 mmol/l in order to lower the fibrillation threshold. According to pilot experiments which considered various durations of global no-flow ischemia ranging from 10 to 20 minutes, two durations were chosen for the present study: 20 minutes (group 20) in which ventricular fibrillation (VF) was the predominant form of arrhythmias, and 18 minutes (group 18) in which the prevalence of VF was markedly lower despite the small difference in the duration of ischemia. Crataegus pretreatment significantly (p = 0.02) reduced the average prevalence of malignant arrhythmias (VF + Flutter) as observed during the 20-min-period of reperfusion as follows: group 20: from 89% (control, n = 9) to 51% (LI 132, n = 7), group 18: from 48% (control, n = 8) to 8% (LI 132, n = 8). In group 20, ventricular tachycardia (VT) could be observed only in the treated group, because of the predominance of VF in the control group. LI 132 pretreatment reduced the average prevalence of VT in group 18 in spite of the identical percentage of occurrence (6 out of 8 rats, with and without treatment) due to a shorter duration of the VT episodes. Thus, under the conditions of our experiments, effective prevention against reperfusion arrhythmias by Crataegus pretreatment was evident.

Animals↗

Performance of a new single-chamber ICD algorithm: discrimination of supraventricular and ventricular tachycardia based on vector timing and correlation.

AIMS: Interval- and morphology-based algorithms have been used in modern implantable cardioverter defibrillators (ICDs) to discriminate supraventricular tachycardia (SVT) from other rhythms. A newly developed ICD discrimination algorithm, Rhythm ID (Guidant Corporation, St Paul, MN, USA), uses both interval-based metrics and an electrogram vector timing and correlation (VTC) algorithm in a dual-chamber ICD. In a single-chamber ICD, Rhythm ID contains only the VTC component. This study conducted a retrospective analysis of the performance of Rhythm ID for the detection of induced and spontaneous rhythms in a single-chamber ICD. METHODS AND RESULTS: This study gathered the data from a prospective, multicentre clinical trial. Ninety-six patients were implanted with a dual-chamber ICD. For this study, each episode was analysed to determine the performance of the single-chamber ICD Rhythm ID algorithm. The mean age of the patients implanted with the device was 67+/-11 years. Seventy-eight patients were male. The primary cardiovascular disease was coronary artery disease and the primary tachyarrhythmia was monomorphic ventricular tachycardia (VT). The mean follow-up time was 11.4 months. A total of 369 induced and spontaneous ventricular arrhythmias was analysed. The algorithm detected 100% of ventricular arrhythmias. Four hundred and forty-two SVT episodes were analysed, including 145 induced and 297 spontaneous. The SVTs were atrial fibrillation (n=199), atrial flutter (n=135), and 1:1 SVT (n=108). The single-chamber ICD Rhythm ID algorithm successfully discriminated 403 SVT episodes and achieved a specificity of 91%. CONCLUSION: The single-chamber version of Rhythm ID demonstrated high specificity without compromising sensitivity.

Aged↗

[Endocavitary percutaneous ablation of tachyarrhythmias].

The indication and result of catheter ablation for supraventricular and ventricular arrhythmias are reviewed, with special emphasis on the need to inform the patient undergoing this type of procedure, the possible complications and our center's results.

Atrial Flutter↗

Atrial arrhythmias in adults after repair of tetralogy of Fallot. Correlations with clinical, exercise, and echocardiographic findings.

BACKGROUND: The long-term success of intracardiac repair of tetralogy of Fallot is hampered by the occurrence of arrhythmias. Numerous studies have stressed the potential role of ventricular arrhythmias. However, the importance of other arrhythmias in the morbidity of these patients appears to be underestimated. Furthermore, most follow-up studies have been limited to children or adolescents, whereas many patients have reached adulthood after earlier repair of tetralogy of Fallot. The aim of the present study was to determine the incidence of atrial fibrillation, atrial flutter, and other supraventricular arrhythmias in adult patients after intracardiac repair for tetralogy of Fallot and their correlation with surgical and clinical findings. METHODS AND RESULTS: The study group consisted of 53 consecutive patients referred to the Thoraxcenter adult congenital heart disease clinic. They underwent repair at a mean age of 9.1 years (range, 0.7 to 55 years). The median age at the time of study was 23.2 years (range, 15 to 57 years; mean age, 26.6 years), and the mean duration of follow-up of 17.5 years (range, 1.4 to 32 years) after surgery. Records were reviewed extensively for evidence of arrhythmias. The follow-up study included routine 12-lead ECG, 24-hour continuous ambulatory monitoring, and echocardiography, and 46 patients underwent exercise testing. Sinus node dysfunction was recorded in 19 patients (36%), of whom 4 required a permanent pacemaker. Atrial fibrillation or flutter was found in 12 patients, and other supraventricular tachycardias were found in 6. The former were more frequently of older age at follow-up. Antiarrhythmic therapy and cardioversion were typically directed at control of atrial (and not ventricular) tachyarrhythmias. Ten patients (19%) showed nonsustained ventricular tachycardia; they were older at initial surgery and older at follow-up and had more intracardiac repairs and longer cardiopulmonary bypass times. CONCLUSIONS: Despite an emphasis on ventricular ectopy in past series, the main sources of morbidity in adult patients after surgical correction of tetralogy of Fallot emanated from atrial arrhythmias, which were present in one third of the patients.

Adult↗

Rhythm discrimination by rate branch and QRS morphology in dual chamber implantable cardioverter defibrillators.

Morphology Discrimination is a discriminator based on QRS morphology analysis that has been recently implemented in dual chamber implantable cardioverter defibrillators (ICDs). Detected events are initially classified according to median atrial and ventricular rates (Rate Branch). Then, a series of discriminators (Morphology Discrimination, Stability, Sudden Onset) analyze the rhythm according to specific criteria and the number of discriminators required for VT diagnosis (i.e., requiring "any" or "all" of the specific discriminators to indicate VT). The discriminating accuracy of the algorithm was evaluated in 645 detections recorded during the follow-up of 25 patients. The overall specificity for 397 supraventricular arrhythmias was 73.5% (292/397) with the tachycardia diagnosis criteria set to "any" and 90.9% (361/397) with the tachycardia diagnosis criteria set to "all." Sensitivity for VT was 100% and 98.7% (231/234) with the tachycardia diagnosis criteria set to "any" and "all," respectively. With the tachycardia diagnosis criteria set to "any," specificity for atrial fibrillation was 88.6%, for atrial flutter 40.3%, for atrial tachycardia 0%, and for sinus tachycardia 97.0%. With the tachycardia diagnosis criteria set to "all," specificity for atrial fibrillation was 92.40%, for atrial flutter 93.5%, for atrial tachycardia 54.7%, and for sinus tachycardia 99.0%. The contribution of Morphology Discrimination was crucial to improve the specificity of the Rate Branch algorithm. The implementation of Morphology Discrimination in a dual chamber ICD with Rate Branch rhythm classification allows the attainment of high specificity and high sensitivity for ventricular tachyarrhythmias.

Aged↗

Enalapril decreases the incidence of atrial fibrillation in patients with left ventricular dysfunction: insight from the Studies Of Left Ventricular Dysfunction (SOLVD) trials.

BACKGROUND: Atrial fibrillation (AF) is frequently encountered in patients with heart failure (HF) and is also a predictor of morbidity and mortality in this population. Recent experimental studies have shown electrical and structural atrial remodeling with increased fibrosis in animals with HF and have suggested a preventive effect of ACE inhibitors (ACEi) on the development of AF. To verify the hypothesis that ACEi prevent the development of AF in patients with HF, we conducted a retrospective analysis of the patients from the Montreal Heart Institute (MHI) included in the Studies Of Left Ventricular Dysfunction (SOLVD). METHODS AND RESULTS: Clinical charts were reviewed and serial ECGs interpreted by a single cardiologist blinded to drug allocation. Patients with AF or flutter on the baseline ECG were excluded. Baseline characteristics were obtained from the SOLVD databases. The mean follow-up was 2.9+/-1.0 years. Of the 391 patients randomly assigned at MHI, 374 were in sinus rhythm at the time of random assignment, with 186 taking enalapril and 188 taking placebo. Baseline characteristics were similar in the two groups except for a higher incidence of previous myocardial infarction in the enalapril group. Fifty-five patients had AF during the follow-up: 10 (5.4%) in the enalapril group and 45 (24%) in the placebo group (P<0.0001). By Cox multivariate analysis, enalapril was the most powerful predictor for risk reduction of AF (hazard ratio, 0.22; 95% CI, 0.11 to 0.44; P<0.0001). CONCLUSIONS: Treatment with the ACEi enalapril markedly reduces the risk of development of atrial fibrillation in patients with left ventricular dysfunction.

Angiotensin-Converting Enzyme Inhibitors↗

Electrical management of arrhythmias with emphasis on the tachycardias.

Information from stimulation studies in human beings with tachycardia has resulted in the application of cardiac pacing in the treatment of such patients. Short-term pacing is especially useful in patients with atrial flutter. Long-term pacing with use of chronically implanted units can be applied to patients with different types of supraventricular and ventricular tachycardia. In these patients careful electrophysiologic studies are required before the pacing device is implanted. New developments enabling automatic and more individually designed modes of pacing are urgently needed.

Cardiac Pacing, Artificial↗

Effectiveness of surgical management of the Wolff-Parkinson-White syndrome.

In this report, the surgical experience with the treatment of Wolff-Parkinson-White syndrome in 190 patients who had 210 Kent bundles has been summarized. The patients with reentry tachycardia caused by the Kent bundle were relieved by Kent division or by His division, the latter being used only in 10 percent of the patients. A malignant ventricular arrhythmia was found in 25 percent of the patients and was due to a Kent bundle that conducted an atrial flutter-fibrillation 1:1 to the ventricle. This arrhythmia was corrected by Kent interruption, since the Kent bundle alone participated in the arrhythmia. Other unusual manifestations of Kent bundles were found, such as multiple pathways, unidirectional conducting pathways, and pathways causing incessant junctional tachycardia. Other cardiac problems were frequently present, such as hypertrophic cardiomyopathy and Ebstein's anomaly. Even in such a multifaceted problem caused by a minute congenital abnormality, careful application of sophisticated electrophysiologic measurements followed by appropriate surgical methods have proved to be effective in correcting the two arrhythmias associated with Wolff-Parkinson-White syndrome.

Arrhythmias, Cardiac↗

[Heart diseases as a cause of cerebral symptoms and syndromes].

The causes, clinical indications and diagnosis and differential diagnosis of cardiac disorders which may lead to cerebral symptoms are illustrated on the basis of a review of the present day level of scientific research. Principally involved are cerebral ischaemias arising from cerebral embolisms or from reduction of cardiac output in cardiovalvular and myocardial disorders. The incidence of all embolisms of cardiac origin makes up 10% of all ischaemic cerebral infarcts, with auricular fibrillation, irrespective of its origin, mitral stenosis, myocardial infarct, mitral insufficiency and combined mitral valve defects, and, in younger patients, mitral valve prolapse, being, in this order of frequency, of primary clinical significance. The other cardiovalvular and myocardial disorders have, in comparison, a relatively low incidence of cerebral embolisms. Haemodynamically induced cerebral ischaemias frequently occur in the form of complications following acute cardiac arrest, in myocarditis and in case of primary cardiomyopathies resulting from cardiac insufficiency or complicating bradyarrhythmia. They are clinically apparent in the form of syncope, and other impairments of consciousness of various levels of seriousness with and without indications of cerebral origin, extending up to coma. In view of the high incidence of 25% of acute cerebral ischaemias in cases of cardiac disease, not only neurological but also detailed cardiological investigation is vital in all cases for a correct diagnosis and for the selection of a suitable course of treatment. Cerebral complications in bradyarrhythmia and endocarditis are discussed in the context of a review of the relevant literature together with consideration of their epidemiology, aetiology, pathophysiology and clinical profile. Pathological sinus-bradycardia, bradyarrhythmia absoluta, sinu-atrial and atrio-ventricular blockages, carotid-sinus and sick-sinus node syndrome, paroxysmal atrial tachycardia, AV-node tachycardias, and auricular fibrillation and flutter, taken as a whole, lead to cerebral complications affected patients in 5 to 10% of afflictions of the central nervous system occur in 50% of patients suffering from complete AV blockage and, at a not precisely definable frequency, in patients suffering from other bradyarrhythmias. In addition to transitory, uncharacteristic symptoms such as dizziness, vertigo, impairment of vision and balance, presyncope, syncope and Adams-Stokes syndrome dominate the clinical profile. Endocarditis, with an incidence of 0.01 to 0.05% in the overall population, results in central nervous system complications in 12 to 25% of cases on average.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain Ischemia↗

Clinical, electrophysiological, and histopathological observations in supraventricular tachycardia.

Fifty patients with supraventricular tachycardia (SVT) underwent clinical electrophysiological studies (EPS), endomyocardial biopsies and cardiac catheterizations. EPS revealed AV nodal reentrant tachycardia (AVNRT) in seven patients, AV reentrant tachycardia utilizing concealed AV bypass tracts (AVR-CBT) in nine patients, AV reentrant tachycardia utilizing AV bypass tracts with ventricular preexcitation (manifest WPW) in 13 patients, sinus nodal or intra-atrial reentrant tachycardia (SNRT or IART) in three patients, atrial flutter (AF) in nine patients, automatic atrial tachycardia (AAT) in five patients, and multifocal atrial tachycardia (MAT) in four patients. According to the clinical observations, three patients with AVNRT (43%), six with AVR-CBT (67%), six with manifest WPW (46%), two with SNRT or IART (67%), eight with AF (89%), two with AAT (40%), and two with MAT (50%) showed other accompanying clinical abnormalities. In all patients who were studied histologically, changes in the myocardium were seen; myocarditic changes, postmyocarditic changes and nonspecific abnormalities were present in six (12%), 15 (30%), and nine (18%) respectively. Myocardial changes were observed in four out of seven cases with AVNRT (57%), in six out of nine with AVR-CBT (67%), in five out of 13 with manifest WPW (38%), in two out of three with SNRT or IART (67%), in six out of nine with AF (67%), in all five cases of AAT (100%), and in two out of four with MAT (50%). Nineteen out of 32 without clinical abnormalities except for arrhythmias (59%) had myocardial changes (six had myocarditic changes, ten had postmyocarditic changes, and three had nonspecific abnormalities). On the other hand, nine out of 21 with myocarditic or postmyocarditic changes were accompanied with various arrhythmias other than SVT (two had SSS, five had AV block or rBBB, and two had VT). Elevated LVEDP was present in 36% of the group with normal myocardium and in 53% of the group with myocardial changes. However, the low EF was shown in no patients with normal myocardium but in 21% of the group with myocardial changes. The low CI was also shown in only 9% of the group with normal myocardium but in 28% of the group with myocardial changes. These results suggest that patients with SVT may exhibit several histopathological changes in the myocardium, even in the absence of any clinical organic heart disease.

Adult↗

Indications for and complications of temporary transvenous cardiac pacing.

A prospective survey was conducted of the indications for and complications of 153 temporary transvenous cardiac pacing lead insertions in 148 patients. Pacing for bradyarrhythmias or potential bradyarrhythmias (Group I) accounted for 105 insertions, wide complex tachycardia (Group II) 17, and narrow complex tachycardia (Group III) 31 pacing electrode insertions respectively. The infraclavicular subclavian vein approach was used in 73%. The median insertion time was 20 minutes. Group I: 77% were undertaken because of severe symptoms. On 64 occasions (61%) the patient had complete heart block or ventricular asystole. Group II: The lead was inserted to treat and often assist in the diagnosis of the wide complex tachycardia. Ventricular 'burst' pacing reverted ventricular tachycardia in 13 (76%). Group III: Rapid atrial 'burst' pacing was used to treat supraventricular tachyarrhythmias (paroxysmal supraventricular tachycardia and atrial flutter) resistant to medical therapy. Pacing was successful in reverting 28 (90%). A complication occurred in 27 (18%) of 153 lead insertions, 11 (7%) were serious. No complication resulted in the death of a patient. Temporary transvenous pacing is safe and effective for the treatment of bradyarrhythmias and certain tachyarrhythmias.

Adolescent↗

Arrhythmia control by selective lengthening of cardiac repolarization: role of N-acetylprocainamide, active metabolite of procainamide.

In recent years, data has become available to support the concept that a selective lengthening of the cardiac action potential (a Class III antiarrhythmic action) by whatever mechanism with an attendant increase in the effective refractory period constitutes a distinct antiarrhythmic mechanism. Such an action is exemplified clinically by hypocalemia and hypothyroidism and pharmacologically by amiodarone, sotalol and bretylium, all of which have other associated features. The N-acetylation of procainamide leads to the pharmacologically active compound, N-acetylprocainamide (NAPA). The loss of propensity to block depolarization with the preservation of the effect on repolarization in the case of NAPA makes the compound a class III antiarrhythmic agent. The process of N-acetylation has also led to longer elimination half-life and predominantly renal excretion with linear kinetics but with the preservation of the antiarrhythmic properties of the parent compound. The electrophysiologic data are consistent with the results of studies which have demonstrated that NAPA has the potential to suppress premature ventricular contractions and prevent spontaneously occurring as well inducible ventricular tachycardia in patients with heart disease. The effects on atria indicate that the drug has the potential to electively reverse atrial flutter and fibrillation to normal rhythm and maintain stability of sinus rhythm. The overall experimental and clinical data warrant further evaluation of NAPA as an antiarrhythmic agent.

Acecainide↗

[Trial of the clinical use of Ritmilen].

The clinical analysis of the rhythmilene efficacy was performed in 247 patients receiving the drug for various arrhythmias. Due to its anticholinergic properties rhythmilene somewhat increased the sinus rhythm and improved atrioventricular conduction. These properties of the drug often caused urination retention, largely in males over 55 years. The drug was highly active in ventricular paroxysmal tachycardia and extrasystole. The scheme of an interrupted administration of rhythmilene and cordaron for preventing attacks of atrial fibrillation and flutter was worked out. The necessity of the systematic control of the duration of the Q-T interval is emphasized.

Adult↗