The design of atrial synchronous, ventricular inhibited (VDD) pacemakers has been improved. Physiologic long-term benefit has now been established, although this mode of pacing accounts for approximately one percent of implanted devices. With the ultimate control of pacemaker-mediated tachycardia through atrial refractory programming close at hand or already available, one might expect an increase in VDD pacing in patients with exercise-induced high degree heart block and stable sinus node function.