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

The authors present a case of permanent atrial standstill with syncopal attacks, in a patient with chronic Chagas' Heart Disease. The recognition of this dysrhythmia was based upon the conventional and intracavity electrocardiographic tracings in addition to phonomecanographic and hemodynamic data. The recording of the His Bundle electrogram demonstrated the absence of atrial activity, with the His potential preceding all ventricular complexes and an advanced conduction defect distal to the bundle of His. A diffuse type of atrial involvement was suggested by the lack of response to pacemaker stimulation. An increase in ventricular rate following intravenous atropine administration, led to the diagnosis of an a-v junctional rhythm with a widened QRS complex due to an associated right bundle branch block. Following the implantation of an epicardial ventricular pacemaker, the patient became completely asymptomatic despite the persistence of electrical and mechanical atrial standstill.
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PMID:Persistent atrial standstill. 108 60

Five patients with bidirectional tachycardia due to digitalis toxicity associated with severe organic heart disease were studied. The origin of the abnormal rhythm was established with the aid of His bundle recordings in three cases and by indirect clues in the others two. In three cases the origin of bidirectional tachycardia was suprahisian while in two patients it was infrahisian. In one patient the transition from junctional to ventricular tachycardia could be observed. Bidirectional tachycardia appears to be a complex arrhythmia in which similar electrocardiographic configuration can be due to different mechanism. Digitalis toxicity was often a causal factor.
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PMID:Bidirectional tachycardia a study of five cases. 108 15

Bipolar electrode catheter recordings of His bundle electrograms with three simultaneously recorded surface electrocardiographic leads were obtained from 30 pediatric and adolescent patients (aged 3 to 18 years). In 14 patients, cardiac murmurs were proved to be innocent by cardiac catheterization. The control conduction intervals were compared to those of 13 patients with congenital heart disease, and three with acquired heart disease (myocardiopathy, rheumatic valvular disease, and Friedreich's ataxia). P-R, intra-atrial (P-A), A-V nodal (A-H), and intraventricular (H-V) conduction intervals were measured to the nearest 5 msec. Conduction delays were analyzed in each of the three components of the P-R interval. These delays occurred both in single components of the system as well as in combined conduction delays and were not always demonstrable by surface electrocardiograms. The Wenckebach phenomenon induced by atrial pacing was localized to the A-V node as well as the His-Purkinje system. This technique of intracardiac electrogram recordings is safe, does not significantly prolong cardiac atheterization time, and often yields unique and useful data concerning A-V conduction.
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PMID:A His bundle electrocardiographic analysis of cardiac conduction in the pediatric and adolescent patient. 111 61

His bundle electrograms were performed in ten patients with organic heart disease. Recordings were made at various rates using right atrial pacing. Two grams of methylprednisolone were infused intravenously over a 20-minute period. The PI-A, A-H, H-Q, and H-S intervals were obtained before and up to 1 hour after the infusion of the steroid. The maximum effect was seen at 1 hour. All patients showed a significant prolongation in the A-H interval with negligible effects on other intervals. At the atrial pacing rate of 120 beats/minute, the average A-H interval increased from control of 119 milliseconds to 159 milliseconds after steroids (P smaller than 0.01). Second-degree heart block occurred at lower pacing rates after steroids in six patients as compared with the control state. The postsuppressive sinoatrial node recovery time was increased in seven cases after steroid infusion. Pharmacologic doses of steroids can impair conduction through the atrioventricular node.
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PMID:The effect of pharmacologic doses of steroids on atrioventricular conduction in man. 112 32

We reviewed 144 consecutive patients with symptomatic high grade atrioventricular block. Cases due to congenital heart disease, acute myocardial infarction, cardiac surgery or digitalis toxicity were excluded. Of the remaining, we chose 71 patients in whom atrioventricular conduction was observed either intermittently during complete heart block (CHB) or in electrocardiograms taken within two years prior to documentation of CHB. The mean age was 69 years, with the peak incidence in the seventh decade in 43 men and eight decade in 28 women. Bundle branch block (BBB) was present in 76% of patients as follows: 47% had right BBB (20% with normal QRS axis, 20% with left axis deviation and 7% with right axis deviation), 17% had left BBB (11% with normal QRS axis and 6% with left axis deviation) and 12% had either alternating BBB, right BBB with alternating axis deviation or atypical BBB. "Trifascicular block" patterns accounted for 21% of the total group of CHB. We also studied the prevalence of various patterns of BBB in a group of 2000 random hospital patients of comparable age and sex exclusive of those with acute myocardial infarction and heart surgery. The risk of CHB for the various patterns of BBB was calculated relative to normal intraventricular conduction. All patterns of BBB carried a considerably increased relative risk of CHB, (P smaller than .01). The relative risk was highest for RBBB with left axis deviation and lowest for LBBB with normal or left axis deviation. In the men, 74% had QRS patterns of "bifascicular" or "trifascicular" block during atrioventricular conduction. By contrast, 71% women had atrioventricular beats showing either no BBB or right BBB with normal QRS axis. QRS pattern during CHB was unchanged from that during atrioventricular conduction in 52% if cases (rabge 38%-76% with different QRS patterns) suggesting idiojunctional pacemaker. CHB in these cases was thought to be due probably to coexistent disease in the AV node or His bundle. Although the concept of uni-, bi- and trifascicular block patterns has been useful in identifying patients at greater risk of CHB, the predictability of the electrocardiogram has obvious limitations, particularly in women.
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PMID:The relative risk of spontaneous complete atrioventricular block in elderly patients with impaired intra-ventricular conduction. 115 Dec 1

Electrophysiological and histopathological examinations were carried out in 2 patients with persistent atrial standstill. Intracardiac studies revealed that atrial standstill was due to atrial inexcitability. It was demonstrated in both patients that prolongation of the H-V interval and the duration of H deflection was associated with complete right bundle branch block and that the escape rhythm was an A-V junctional origin. Histologically, marked fibrosis of the right atrium and fibrous strands in the right ventricle were demonstrated in a 69-year-old man with idiopathic cardiomyopathy. In another female patient with peripartum heart disease aged 40 years, there was moderate degeneration of the myocardium in the right ventricle. The results of electron microscopic observations are also presented. The importance of the examination of His bundle electrography in persistent atrial standstill and the diagnostic criteria and treatment of this lesion are discussed.
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PMID:Persistent atrial standstill due to atrial inexcitability. An electrophysiological and histological study. 118 87

In three patients with congenital heart disease the site of atrioventricular (A-V) block was localized within the His bundle with the aid of His bundle electrograms. In one patient with first degree A-V block and normal QRS configuration, electrophysiologic studies revealed "split" His potentials. The other two patients had complete A-V block, and their His bundle electrograms revealed His spikes both proximal and distal to the site of block. One of the two patients, who had a pattern of left bundle branch block in the electrocardiogram, had surgically induced complete A-V block after repair of an ostium primum atrial septal defect. The other patient with congenital A-V block had a narrow QRS complex and, in addition to complete block within the His bundle, prolonged A-V nodal conduction time but no associated cardiac anomaly. Both patients with complete heart block required pacemaker insertion. The natural history of intra-H-is bundle block is not known, and it is difficult to recommend appropriate therapy. More electrophysiologic studies are needed in patients with A-V block to determine the prognostic significance of such block or conduction delay in the His bundle.
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PMID:Congenital and surgical atrioventricular block within the His bundle. 119 47

In nine patients without clinical or laboratory evidence of heart disease, premature atrial depolarization (PAB) induced a complete block of conduction in the intraventricular conducting system. In these patients the functional refractory period AV (FRPav)) gave short and very similar results to the effective refractory period of the His-Purkinje system (ERPhp), and the effective refractory period AV (ERPAV) was found to be shorter than the ERPhp in all cases. A linear correlation between the ERPhp and the basic cycle length (BCL) was also observed. These special functional properties of the AV node justify the occurrence of intraventricular block after PAB. In fact, the stimulus, rapidly conducted through the AV node, finds a complete or incomplete refractoriness in the ventricular conducting system, and therefore bundle branch or complete intraventricular block occurs. The linear correlation between the ERPHP and the BCL explains why the atrial pacing is not always useful for pointing out intraventricular conducting defects.
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PMID:[Functional block in the His-Purkinje system (author's transl)]. 123 12

His bundle electrograms were performed in eight patients with organic heart disease. Recordings were made at various rates utilizing right atrial pacing. A solution of 100 cc of iced cold 5% glucose and water was infused through a cardiac catheter placed at the level of the tricuspid valve. The P-A, A-H, H-Q and H-S intervals were determined before and immediately after the cold water infusion. A significant prolongation of the A-H interval occurred with negligible effects on the P-A, H-Q and H-S intervals. At the atrial pacing rate of 100/min the average A-H interval increased from the control value of 116 to 125 msec after the infusion (P less than 0.02); at the pacing rate of 140/min, the A-H interval increased from 147 to 158 msec (P less than 0.01). This represents an impairment in conduction through the atrioventricular node.
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PMID:Effect of cold isotonic glucose infusion on A-V nodal conduction. 124 7

His bundle electrograms were recorded in 308 adults with chronic bundle branch block. The A-H interval was normal in 249 patients and prolonged in 59. Comparison of patients with normal and prolonged A-H intervals revealed a greater incidence of demonstrable organic heart disease in the latter (P less than 0.01). Dyspnea, cardiomegaly and congestive heart failure were more frequent in patients with A-H prolongation. These patients also had longer P-R intervals and atrioventricular (A-V) nodal effective refractory periods, lower paced rates producing second degree A-V block proximal to the His bundle and a greater frequency of H-V prolongation. All patients were prospectively followed up in a conduction disease clinic with mean follow-up periods (+/- standard error of the mean) of 523 +/- 23 and 588 +/- 47 days in the patients with normal and prolonged A-H intervals, respectively. Seven (3 percent) of the patients with a normal A-H interval had A-V block with probable or definite site of block proximal to the His bundle in three and distal to the His bundle in four. In five of the six patients with a prolonged A-H interval who experienced A-V block (10 percent), the probable or definite site of block was proximal to the His bundle. Mortality (both sudden and nonsudden) was not significantly different in the patients with normal and prolonged A-H intervals. In summary, A-H prolongation was associated with increased incidence of organic heart disease and myocardial dysfunction. The risk of development of A-V nodal block was greater in patients with a prolonged A-H interval but appeared to be of minimal clinical significance.
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PMID:Significance of A-H interval in patients with chronic bundle branch block. Clinical, electrophysiologic and follow-up observations. 124 55


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