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Query: UMLS:C0018799 (heart disease)
 34,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Indications for cardiac pacing in pediatric patients continue to expand. In addition to its traditional use in sinus and atrioventricular nodal disease, applications for cardiac pacing now include treatment of tachyarrhythmias after repair of congenital heart disease, reduction of left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and prevention of sudden death in the congenital long QT syndrome. Whereas many benefits have been well documented in adults, they remain anecdotal in children. Programmable features such as rate-response and antitachycardia pacing contribute to pacemaker versatility and facilitate the achievement of normal hemodynamics in children requiring long-term pacing therapy.
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PMID:Cardiac pacing in children. 955 56

Atrial fibrillation (AF) is the most common, sustained, symptomatic tachyarrhythmia that clinicians are called upon to manage. Management strategies include ventricular rate control coupled with anticoagulation, versus restoration and maintenance of sinus rhythm. Rate control may be achieved pharmacologically, with agents that impair AV nodal conduction directly and/or by increasing parasympathetic/sympathetic balance, or by modifying or ablating the AV nodal region anatomically. Rhythm control may be achieved by electrical or pharmacologic conversion followed by maintenance of sinus rhythm by pharmacologic (or occasionally ablative) therapies. This article will present current approaches to rate and rhythm control issues in atrial fibrillation. Parts 1 and 2, published previously, dealt with rate control and with the restoration of sinus rhythm. Part 3, the current article, details the selection process of choosing a therapy to maintain sinus rhythm, including the likelihood of success, the risks of therapy, and individualization of therapy as dependent upon the nature of the structural heart disease present. It also discusses nonpharmacologic approaches that have been recently developed or are undergoing development. One suggested drug selection algorithm is provided.
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PMID:Rhythm management in atrial fibrillation--with a primary emphasis on pharmacologic therapy: Part 3. 960 46

Antiarrhythmic drugs are known to affect the depolarization and repolarization time in a different fashion. The aim of the present study was to compare the effects of Sotalol, Flecainide and Propafenone on some common (QT, QTc, JT, JTc) or uncommon (QTc dispersion, T-peak to T-end interval) electrocardiographic parameters in order to evaluate the effects of these antiarrhythmic drugs on ventricular repolarization time both in terms of absolute values and of dispersion across the myocardium. The analysis of these antiarrhythmic drug effects was performed on the standard 12-lead electrocardiograms of 31 patients (17F and 14M, age 38.1+/-17 years, range 11-67 years) in the free-drug state and at the steady state after oral treatment with Sotalol (160 mg daily), Flecainide (200 mg daily) and Propafenone (450 mg daily). These drugs were prescribed, separately, to all the 31 patients, free of underlying structural heart disease, for the treatment of their atrio-ventricular nodal re-entry tachycardia. Data of the present study show that Sotalol, over the range prescribed, significantly prolongs ventricular repolarization index QT (P=0.001), JT (P=0.0001) and JTc (P=0.0001) values in an homogeneous fashion, as shown by the significant decrease in QTcD (P=0.019) and Tp-Te (P=0.01). On the contrary, Flecainide treatment was associated with an increase in QTcD (P=0.029), Tp-Te (0.0001), QT (P=0.001), QTc (P=0.0001) and QRS (P=0.0001), with no significant changes in JT and JTc. Propafenone, over the range prescribed, did not affect repolarization time, resulting only in a prolongation of depolarization time as expressed by the increase of QRS (P=0.0001).
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PMID:Compared effects of sotalol, flecainide and propafenone on ventricular repolarization in patients free of underlying structural heart disease. 982 29

Paroxysmal supraventricular tachycardia (SVT) may have numerous electro-physiologic mechanisms. The most common type of SVT is AV-nodal reentry tachycardia (60%) followed by the bypass tract-mediated SVT (preexcitation. 30%) and a smaller group (10%) comprising paroxysmal atrial flutter or fibrillation and atrial ectopic tachycardia. In persons with otherwise normal hearts symptoms are usually mild and include palpitations or an uneasy feeling in the chest. But some describe precordial pain. Weakness, dizziness, nausea, vomiting, and even syncope. Whenever possible a 12-lead-ECG during an episode of SVT should be obtained. If not possible the use of several Holter-ECG or of an event-recorder may be helpful. Conversion of a SVT can be accomplished by vagal maneuvers or intravenous adenosine (6-18 mg bolus injection). Further diagnostic procedures should prove or rule out a significant structural heart disease. Therapeutic options (expectative, pharmacological prophylaxis, invasive electrophysiologic testing and catheter-mediated modification or ablation) are chosen according to the objective threat (e.g. ventricular fibrillation due to 1:1 conducted atrial fibrillation in a preexcitation syndrome) and the subjective complaints. Definitive healing of the AV-nodal reentry tachycardia and the bypass tract-mediated SVT can be achieved by use of catheter-mediated modification or ablation in 95 to nearly 100%.
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PMID:[Modern therapy of paroxysmal supraventricular tachycardia]. 1009 47

With the introduction of radiofrequency energy, catheter ablation has become an established technique for managing many cardiac rhythm disturbances. High efficacy and safety have been reported for accessory pathway ablation, selective fast and slow atrioventricular nodal pathway ablation to eliminate atrioventricular nodal reentrant tachycardia (while preserving atrioventricular conduction), atrioventricular junctional ablation to control the ventricular response to atrial tachyarrhythmias, ablation of the right bundle branch to eliminate bundle branch reentrant ventricular tachycardia, and ablation of the site of tachycardia origin in patients with ventricular tachycardia unassociated with structural heart disease. In addition, there has been active investigation into ablation techniques for more complex arrhythmias such as atrial tachycardia, atrial flutter, and ventricular tachycardia associated with structural heart disease.
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PMID:Catheter ablation for cardiac arrhythmias. 1014 88

Paroxysmal atrial fibrillation is defined as an atrial fibrillation that terminates spontaneously. It is desirable that atrial fibrillation should be terminated immediately after onset, and should be prevented from re-initiation to avoid atrial electrical remodeling or atrial stunning after cardioversion. Antiarrhythmic agents are used for these reasons. The important factors for pharmacological cardioversion of atrial fibrillation are thought to be prolongation of atrial refractory and suppression of conduction time in the atrium. Therefore, class Ia and Ic antiarrhythmic drugs, including bepridil as class IV because of its characteristics of class Ia, are administered to restore sinus rhythm. Verapamil and diltiazem, or beta adrenergic blocker, or digitalis decreases the ventricular response during atrial fibrillation for disturbance of atrioventricular nodal conduction, and then cardioversion of atrial fibrillation may occur. Suppression of supraventricular extrasystoles and atrial conduction time, or prolongation of atrial refractoriness will be needed to maintain sinus rhythm. Class I, III, or bepridil as class IV excepting lidocaine and mexiletine are used to prevent paroxysmal atrial fibrillation. In general, sodium channel blocker is superior for defibrillation and potassium channel blocker is superior for prophylaxis of atrial fibrillation. Considering efficacy, antiarrhythmic agents should be selected depending on the following factors: cardiac function, renal or hepatic function, underlying heart disease, exercise-induced or enhanced mental condition, cholinergic induced, drug-resistant atrial fibrillation or not.
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PMID:[Pharmacological restoration and maintenance of sinus rhythm by antiarrhythmic agents]. 1034 38

We report our experiences with tachycardia-induced cardiomyopathy. Nine patients (3-56 years old) had incessant supraventricular tachycardia and congestive heart failure. The cardiac eco-Doppler evidenced a significant increase of cardiac volumes and mild tricuspid and mitral regurgitation. The ejection fraction (EF) was 0.31 +/- 0.12, the end diastolic volume was 162 +/- 48 cc and the end systolic volume, 116 +/- 54 cc. Four patients had accessory pathways, 3 atrial flutter, 1 A-V nodal reentrant tachycardia, and 1 ectopic atrial tachycardia. Two patients had Chagasic myocarditis. Only in one chagasic patient a decreased number of tachycardia episodes was achieved, this patient died. The autopsy revealed cerebellar and pulmonary emboli. In the other 8 patients the arrhythmia was well controlled. In these, the ventricular volumes decreased, the EF increased to 0.51 +/- 0.14 (p = 0.00006), and the congestive heart failure remitted. We conclude that incessant tachycardia produces a symptomatic dilated cardiomyopathy in patients with and without structural heart disease. The arrhythmia control is followed by an increase in cardiac function and a remission of heart failure symptoms.
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PMID:[Tachycardiomyopathy in patients with and without subacute cardiac pathology. Experiences at the Cardiovascular Center of Merida, Venezuela]. 1036 28

Atrial tachycardia (AT) originating in the triangle of Koch is reported rarely and presents a potential risk of atrioventricular (AV) block during radiofrequency (RF) catheter ablation. Eight patients with AT in the triangle of Koch undergoing RF ablation are presented. There were five women and three men, ranging in age from 32 to 74 years. One patient had bicuspid aortic valve disease, and the other seven patients had no structural heart disease. At electrophysiological study, AT was inducible in all eight patients. In one patient, AV nodal re-entrant tachycardia was also inducible. The site of AT was located by recording the earliest atrial activation during AT and successful RF ablation. Fluoroscopy confirmed the corresponding site to the region of the triangle of Koch. The earliest atrial activation was 35+/-9 ms before the surface P wave, and was recorded at the apex of the triangle of Koch near the bundle of His in six patients and midway between the bundle of His and coronary sinus os in two patients. At the successful RF application site, His potential was not recorded in any patient. The mean AV ratio was 5:1 (range 1:1 to 12:1). RF ablation at the successful site resulted in accelerated junctional rhythm in four of the eight patients and successfully terminated AT in all eight patients, with first-degree AV block in one patient. In conclusion, AT from the triangle of Koch is a distinct entity and RF ablation can be successfully performed; however, a potential risk of AV block remains.
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PMID:Radiofrequency ablation of atrial tachycardia originating from the triangle of Koch. 1065 32

From 1993 to 1998, a total of 100 consecutive pediatric patients with tachycardia (45 male and 55 female, aged 1 year 10 months to 17 years, 11+/-4 year) who underwent electrophysiological study were reviewed. Eleven of them were younger than 5 years. Two had tachycardia-related cerebrovascular accident. Congenital heart disease was found in 12 patients. After propofol anesthesia, the clinical tachycardia could not be induced in three (two atrial tachycardia and one AV nodal re-entrant tachycardia) and became nonsustained in five (atrial tachycardia). Mechanical ablation occurred in three and two had subsequent recurrences. Among the 85 cases who received radiofrequency ablation, the overall final success rate of RF ablation for all diagnoses was 94% with a diagnosis-specific success rate ranging from 100 to 57%. Tachycardia cardiomyopathy was noted in four (three atrial tachycardia and one junctional ectopic tachycardia) and all regressed after successful ablation. Success in two patients with left posterioseptal accessory pathway could only be achieved by delivering the energy at the middle cardiac vein. Two patients with right atrial isomerism had an 'AV nodal-to-AV nodal tachycardia' which was eliminated by ablation. Total recurrence rate was 13% but final success was achieved in all during re-study except the three patients who refused re-intervention. The atrial tachycardia developed in postoperative congenital heart disease was associated with the lowest success rate (57%) and highest recurrence rate (25%). Procedure-related complications occurred in four; two with transient brachial palsy, one with first-degree AV block and one with blood loss requiring blood transfusion. In conclusion, the experience of this single center confirmed the efficacy and safety of radiofrequency catheter ablation in treating pediatric arrhythmias, but the limitations in postoperative arrhythmias and the effects of propofol on tachycardia induction (especially the atrial tachycardia) need to be improved.
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PMID:Radiofrequency catheter ablation of tachycardia in children with and without congenital heart disease: indications and limitations. 1071 30

The purpose of this study was to examine the histopathological findings of right ventricular endomyocardial biopsies from ten patients less than 60 years of age (47 +/- 9.8 (mean +/- SD) years) with documented atrioventricular block but without apparent heart disease. They underwent electrophysiological testing, echocardiography, coronary angiography, and right ventricular endomyocardial biopsy. Biopsy specimens were assessed for morphologic changes in myocyte diameter, fibrosis, disarray, and degeneration. Electrophysiological testing demonstrated atrioventricular nodal block in 2, intra-His bundle block in 2, and infra-His bundle block in 6 patients. Histology revealed evidence of myocardial fibrosis with either myocyte hypertrophy or disarray in 7 of the 10 patients. The results of electrophysiological testing did not correlate with the histopathological findings or severity. In one patient, heart failure appeared during the follow-up period. We conclude that patients with atrioventricular block of unknown etiology have histological abnormalities of the ventricular endomyocardium in addition to the conduction system disturbances. We consider such cases as constituting one of the disease groups of cardiomyopathy, and suggest that it is necessary to follow up the clinical course in these patients.
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PMID:Endomyocardial biopsy findings in patients with atrioventricular block in the absence of apparent heart disease. 1077 20


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