Aspects of pre-excitation and its elucidation by His bundle electrograms.

His bundle electrograms in two cases of Wolff-Parkinson-White (pre-excitation) syndrome.

Pre-excitation with normal PR intervals. A case secondary to slow Kent bundle conduction.

His bundle electrograms were recorded in a patient with pre-excitation and normal PR intervals to determine whether conduction was via anomalous A-V connection (Kent bundle) or infranodal bypass (Mahaim tract). During sinus rhythm (62/ min) both P-delta and P-H measured 155 msec. With atrial pacing at 70 and 75/min, P-H prolonged while P-delta remained constant. At 80/min, the anomalous pathway...

The differences in atrioventricular conduction of premature beats in young and adult goats.

Atrioventricular (AV) conduction was studied in anesthetized, open-chest, 1-35-day-old goats. Atrial, bundle of His, and ventricular bipolar electrograms were recorded, and the functional refractory periods of the AV conduction system and the ventricles were determined. Supraventricular premature excitation invaded the ventricles during their vulnerable period. This AV conduction property is di...

Mapping of ventricular tachycardia induced by programmed stimulation in canine preparations of myocardial infarction.

To investigate the mechanism of uniform ventricular tachycardia induced by programmed stimulation, we recorded His bundle electrograms and unipolar electrograms from 64 subepicardial, subendocardial, and intramural sites in dogs. Isochronal maps were generated off-line by computer. Two groups of dogs were studied 3 days after occlusion of their left anterior descending coronary arteries; one gr...

Arrival of excitation at right ventricular apical endocardium in Wolff-Parkinson-White syndrome type A, with and without right bundle-branch block.

Filtered bipolar right ventricular apical (RVA) and His bundle electrograms, using electrodes only i mm apart, were recorded in two patients with intermittent WPW type A with and without 'complete' right bundle-branch block. In beats with exclusive normal pathway conduction and 'complete' right bundle-branch block, the HV and V-RVA intervals represented His-to-left ventricular endocardial and l...