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PubMed1977

Clinical judgement is not sufficient for the management of conduction defects (indications for diagnostic electrophysiologic studies).

Although analysis of the surface electrocardiograms is usually sufficient in the diagnosis and management of patients with cardiac arrhythmias, electrophysiologic studies can improve diagnostic, therapeutic, and prognostic decisions. Indications for electrophysiologic studies appear to include the following: (1) asymptomatic patients with chronic second degree AV block, both type I and type II with or without bundle branch block; (2) asymptomatic patients with complete AV block; (3) symptomatic patients with bundle branch block and 1:1 AV conduction; (4) patients with bundle branch block complicating acute myocardial infarction; (5) patients with electrocardiograms suggesting pseudo AV block; (6) symptomatic patients with sinus bradycardia, in whom the causal relationship is not clear enough to justify pacing therapy; (7) patients with frequent, troublesome paroxysmal supraventricular tachycardia; (8) patients with Wolff-Parkinson-White syndrome and frequent paroxysmal supraventricular tachycardia; (9) patients with recurrent paroxysmal ventricular tachycardia; (10) patients with syncope or severe dizziness in whom the causal mechanism is not defined.

Arrhythmia, Sinus↗
PubMed1977

Atypical 2nd degree AV block due to bilateral bundle branch block with Wenckebach phenomenon and concealed conduction in the bundle branch system.

A case of bilateral bundle branch block is described with the following features: -- 2nd degree infranodal AV block due to bilateral, intermittently synchronous "phase 3" bundle branch block; -- occasional AV conduction failure due to concealed His bundle extrasystoles; -- right bundle branch block pattern due to retrograde activation from the left bundle branch; -- QRS complexes having normal duration due to uniform slow conduction in both bundle branches; -- Wenckebach phenomenon in the right bundle branch; -- concealed conduction in both branches. The above interpretations are based on the use of His bundle recordings, results of right atrial stimulation and of pharmacological testing. Determinations of the lengths of all H--H intervals, whether H was followed by a ventricular response or blocked, permitted insight into the mechanism of 2nd degree AV block with varying (right and left) bundle branch block.

Aged↗
PubMed1977

Echo ICT.

Explore the source record for details and available documents.

Bundle-Branch Block↗
PubMed1977

His bundle electrograms in 51 patients requiring permanent transvenous pacemakers.

Fifty-one patients required the implantation of a Cordis Omnis-Stanicor permanent pacemaker. His bundle electrograms studies, which included right atrial pacing and sinoatrial (SA) node postsuppression recovery times, were performed prior to the implantations. Pacing and sensing thresholds were obtained in all patients. Syncope or episodes of dizziness were the presenting symptoms in virtually every patient. Twenty-eight of the 51 patients had the sick sinus syndrome. Only nine patients were in complete heart block, and an additional nine were in second-degree heart block. The His bundle electrogram technique was not particularly helpful in selecting the potential pacemaker candidate. The symptomatic patient with second- or third-degree heart block requires a pacemaker. In the sick sinus syndrome, the His bundle electrogram was a disappointing tool in detecting abnormalities. In chronic bundle branch block, the His bundle electrogram appears to play a major role. A prolonged H-V interval in a symptomatic patient, in whom a specific noncardiac cause cannot be identified, signifies that a pacemaker is required.

Adult↗
PubMed1979

[State of the heart conduction system in the sick sinus syndrome (according to the recording of the bundle of His potentials and the atrial stimulation test)].

It was established that the presence of Samoilov-Wenckebach's periods and prolongation of the H--V interval at low frequency of the imposed rhythm as well as periods of asystolia of more than 1,200 msec are most typical for these patients. An attempt was made to determine the type of cardiac stimulation indicated for such patients from the character of the disorders of rhythm observed in them and the initial frequency of their own cardiac contractions.

Action Potentials↗
PubMed1979

[Treatment of severe ventricular arrhythmia by means of repeated cardiac stimulation].

The overdrive pacing method is widely used now in clinical practice for prevention and treatment of severe ventricular disorders of the cardiac rhythm. The mechanisms of arrhythmia suppression by means of this stimulation is analysed. Indications are determined for the choice of the site of stimulation and optimal impulce frequency in ischemic heart disease, and overdosage with digitalis drugs, as well as in myocardiopathy.

Adult↗
PubMed1976

'Supernormal' phase in hemiblock conduction.

A case is described where the basic sinus rhythms is associated with an advanced degree of left anterior hemiblock. The rhythm is complicated by atrial extrasystoles, associated with a lesser degree of left anterior hemiblock. This paradox of 'supernormality' is explained on a critical interplay of differential refractoriness within the divisions of the left bundle-branch.

Adult↗
PubMed1978

Electrophysiological properties of intravenous metoprolol in man.

Electrophysiological changes produced by intravenous (0.1 mg/kg) metoprolol, a new selective beta 1-blocking agent devoid of intrinsic activity, were studied in 16 subjects with estimated normal impulse formation and conduction. The most important effects were sinus bradycardia, mild increase of sinoatrial conduction time, depression of intranodal conduction, and prolongation of AV node refractory periods. Sinus node recovery time and atrial refractory periods were unmodified. Infranodal conduction and the refractory periods of the His-Purkinje system, as well as of the bundle-branches, were unchanged. These effects are compared with those observed after intravenous propranolol, pindolol, and oxprenolol.

Adult↗
PubMed1978

Mahaim conduction producing left axis deviation and normal QRS.

An unusual patient is described in whom electrophysiological studies strongly suggest the occurrence of Mahaim conduction. The patient whose electrocardiogram previously showed a left anterior hemiblock pattern then developed advanced atrioventricular (AV) block (AH block). Beats conducted through the atrioventricular node always had a short HV interval (20 ms) and QRS complexes of left anterior hemiblock pattern. Junctional escape beats always had a normal HV interval (50 ms) with normal intraventricular conduction. His bundle pacing showed the StV interval and QRS contour of escape beats. These findings suggest the existence of an accessory pathway (Mahaim fibres) passing from the area of block, presumably the uppermost portion of the His bundle, to the posteroinferior division of the left bundle-branch. The surface electrocardiogram did not show the characteristic delta wave of the Wolff-Parkinson-White syndrome. Our observations suggest that patients in whom there is conduction along Mahaim fibres may show only the pattern of intraventricular conduction defect without a delta wave.

Cardiac Complexes, Premature↗