A Pacemaker which Automatically Increases its Rate with Physical Activity

Summary

Although atrial synchronous pacemakers (VAT, VDD) are being used successfully to give some patients a physiologic heart rate increase with exercise, there are others who cannot benefit from these devices because of sinus node dysfunction. We constructed a novel pacemaker with an internal transducer which senses the quantity of physical activity and a special circuit which translates that quantity into a pacing rate. We initially tested the device in 5 normal subjects who wore the pacemaker on the chest surface while an ambulatory monitor recorded both the patient’s ECG and the stimulation rate of the pacemaker. The recordings demonstrated an excellent correspondence between two rates. The device was then implanted in two patients with sinus node dysfunction who subsequently demonstrated a physiological rate response with exercise and improved exercise tolerance.