Delayed atrial excitation following bifocal pacemaker stimulation

A patient with drug-resistant ventricular tachycardia due to ischemic heart disease with severe left ventricular failure was successfully treated by the implantation of a DDD pacemaker system pacing at a rate of 90 beats/min (overdrive suppression). Additional therapy with high doses of beta-blockers was necessary. The ECG demonstrated a delay of 100 ms between atrial spike and p-wave. The hemodynamic effects of this ineffective atrial contraction were assessed by jugular venous puls tracing, phonocardiography, echocardiography, and radionuclide-ventriculography. The desired positive effects of physiological pacing could only be achieved by further prolongation of the A-V interval by these 100 ms. This observation shows that, with DDD pacemakers, AV intervals of varying length may be necessary with VAT or VDD and DVI modes in individual cases.