Atrial alternans: experimental echocardiographic and hemodynamic demonstration during programmed pacing.
Simultaneous hemodynamic and echocardiographic recordings were used to demonstrate mechanical atrial alternans during programmed atrioventricular (A-V) pacing in five open chest dogs. Each animal was studied in two stages, first with the A-V conduction system intact (phase I) and later after the experimental induction of complete A-V block (phase II). Atrial alternans was demonstrated during rapid atrial stimulation at cycle lengths ranging from 250 to 120 ms. During phase I, rapid atrial pacing resulted in complex combinations of variable A-V conduction disturbances with superimposed atrial and ventricular alternans. During phase II, atrial alternans could be observed during a programmed prolonged pause in ventricular activity. It is anticipated that this method will facilitate recognition of atrial alternans in various clinical situations and shed further light on its possible hemodynamic significance.
D000818:Animals; D016275:Atrial Function; D001283:Atrioventricular Node / Q000502:physiology; D002304:Cardiac Pacing, Artificial; D004285:Dogs; D004452:Echocardiography; D004562:Electrocardiography; D006327:Heart Block / Q000503:physiopathology; D006439:Hemodynamics; D009200:Myocardial Contraction; D011674:Pulse