Intracardiac electrophysiologic studies were performed in a patient having paroxysms of atrial flutter with 1:1 atrioventricular (A V) conduction. Although duration of conduction intervals was normal during sinus rhythm, the atrio His (A H) interval did not show the expected increase when the atria were stimulated at progressively higher rates. The results of pacing with the extrastimulus technique also indicated that the refractory periods of the A H tissues were shorter than normal. Yet, intravenously administered ouabain produced a significant increase in these refractory periods. The findings in this case are compatible with a partial A V nodal bypass with a shorter refractory period than the A V node or with an A V node with unusual capacity for rapid conduction. The response to ouabain therapy was that of A V nodal tissues.
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Critical Care and Intensive Care Medicine
- Cardiology and Cardiovascular Medicine