title: Effects of atrioventricular intervals on right atrial monophasic action potential duration during pacing or reciprocating tachycardia.
abstract: We evaluated the relationship between changes in the atrioventricular (AV) intervals and right atrial monophasic action potential duration at 90% repolarization (RA-MAPD90) in humans. In 4 patients, RA-MAPD90 was measured during AV reciprocating tachycardia (AVRT, n = 2) or AV node reentrant tachycardia (AVNRT, n = 2) and atrial or ventricular pacing at similar cycle lengths. In 10 patients, RA-MAPD90 was measured during continuous atrioventricular sequential pacing at AV intervals of 0, 50, 100, 150, 200, 250, 300, 350 msec for 90 sec at a cycle length of 333-400 msec. In patients with AVRT, the RA-MAPD90 during tachycardia was shorter than RA-MAPD90 during RA or RV pacing. In patients with AVNRT, RA-MAPD90 during tachycardia was similar or longer than RA-MAPD90 during RA or RV pacing. As the AV interval was increased from 0 msec to 150 msec, the peak right atrial pressure decreased from 8-12 mmHg to 2-3 mmHg. RA-MAPD90 decreased to its minimal value at an AV interval of 150 msec. The maximal difference in the RA-MAPD90 obtained by changing the AV interval was 22.5 +/- 3.0 msec. We conclude that 1) a very short AV or VA interval causes an increase in RA-MAPD90 which correlates with an increase in RA pressure, and 2) RA-MAPD90 during supraventricular tachycardia is different from RA-MAPD90 during atrial or ventricular pacing. Thus, a contraction-excitation feedback mechanism may exist in the human atrium.
mesh_terms: D000200:Action Potentials; D000293:Adolescent; D000328:Adult; D016280:Atrial Function, Right; D001283:Atrioventricular Node / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D002648:Child; D005246:Feedback; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D011312:Pressure; D011930:Reaction Time; D013617:Tachycardia, Supraventricular / Q000503:physiopathology*