Two patients who had an endocardial cushion type of ventricular septal defect underwent electrophysiologic studies for detection of specialized conduction tissue during operative repair. In one patient, with an inferior leftward frontal plane QRS axis on the ECG, we recorded an intraventricular His bundle electrogram anterior and superior to the ventricular septal defect. In the other patient, ...

Coronary artery disease, which involves a wide range of conditions, including narrowed or blocked coronary arteries, has remained the leading cause death in United States for over 50 years. The majority cardiovascular disorders are preventable, identified through risk factors. Electrocardiogram (ECG), routinely available test that provides information about one’s electrophysiologic health, may ...

The electrophysiologic properties of tocainide were evaluated by electrophysiologic studies in 11 patients before, during and after a constant intravenous infusion of the drug for 15 minutes. Peak plasma tocainide concentrations averaged 11.0 +/- 1.7 microgram/ml (SEM), range 3.7 to 22.7. AH, HV, QRS, QTc and RR intervals were measured every 5 minutes during sinus and atrial-paced rhythms and s...

Various electrocardiographic and vectorcardiographic (ECG-VCG) patterns of ventricular conduction disturbances are inducible by premature right atrial stimulation (PRAS). These patterns are a consequence of different degrees of refractoriness in the specialized ventricular conduction system. We observed that the intermediate phases of left bundle branch block (LBBB) induced by PRAS in 20 subjec...

Waldo and his colleagues at the University of Alabama (1-3) observed that a critical rate of pacing was required to terminate atrial flutter. At the lower rates of pacing, continuation of the arrhythmia occurred immediately after cessation of pacing. Their observations had important clinical implications, including the recommendation for systematic prophylactic implantation of electrodes during...