Left Ventricular Performance at Rest and during Exercise in Patients with Dual-Chamber Pacemakers

In 13 patients with an implanted dual-chamber atrioventricular (AV) demand pacemaker, left ventricular performance was elicited by pacing mode manipulation for study using gated cardiac pool scintigraphy at rest and during exercise. There was no significant difference between DDD and VVI at 70 and 90 beats/min with respect to cardiac output, peak ejection rate or peak filling rate. At 110 beats/min, the cardiac output was greater with DDD as compared to VVI. The peak filling rate was also significantly greater with DDD as compared to VVI (DDD : 3.6 vs VVI : 2.8 EDV/s, p<0.05). During exercise the cardiac output was greater with DDD as compared to VVI at the same rate. The peak filling rate during exercise was significantly greater with DDD as compared to VVI (DDD : 3.0 vs VVI : 2.5 EDV/s, p<0.01). We conclude that DDD is more beneficial than VVI in maintaining cardiac performance during exercise.(Internal Medicine 31 : 1-5, 1992)