title: The effect of heart rate on the working capacity of patients with complete heart block and physiological pacemaker.
abstract: The effect of heart rate (HR) on maximum working capacity was studied in 18 patients (mean age 55 years) with a physiological pacemaker implanted for chronic complete heart block of different aetiology. Exercise testing was performed by bicycle ergometry in 3 pacing protocols in randomized sequence, and without the patients knowing the preprogrammed pacing mode: 1) VVI pacing at a rate of 30 beats/min--exercise on heart block; 2) VVI pacing at a rate of 70 beats/min; 3) physiological DDD or QT pacing. While patients with heart block had a mean HR of 54 +/- 16 beats/min and working capacity of 81 +/- 31 W, on VVI 70 pacing the values were 73 +/- 9 beats/min (+35%, p < 0.002) and 100 +/- 45 W (+24%, p < 0.008), respectively. Exercise during physiological pacing led to an increase in HR to 140 +/- 15 beats/min (+169%, p < 0.002) and in working capacity to 130 +/- 52 W (+61%, p < 0.002). Thus, the increment in working capacity was 2.5 times higher on physiological than standard ventricular pacing (p < 0.005) if compared with the working capacity of patients with heart block.
authors.affiliation: First Medical Clinic, Medical School, Olomouc, Czechoslovakia.
authors.forename: J
authors.initials: J
authors.lastname: Lukl
authors.forename: P
authors.initials: P
authors.lastname: Heinc
mesh_terms: D000368:Aged; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006327:Heart Block / Q000503:physiopathology* / Q000628:therapy; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D010807:Physical Endurance / Q000502:physiology*