Missing atrial stimulus during DDD pacing.
D001281:Atrial Fibrillation / Q000628:therapy; D016275:Atrial Function; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography; D004867:Equipment Design; D006327:Heart Block / Q000628:therapy; D006801:Humans; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000628:therapy; D016276:Ventricular Function