title: Cardiovascular response to exercise in pacemaker implanted patients with fixed heart rate.
abstract: Cardiovascular response to supine exercise was studied in 11 patients with chronic ventricular pacing for complete atrioventricular block whose heart rate was fixed during exercise, and compared with 11 age- and sex-matched normal subjects. Oxygen uptake increased linearly with increasing work rate, and attained maximum values of 15.7 +/- 0.7 and 29.5 +/- 1.1 ml/min.kg, respectively. In both groups, cardiac output increased in association with oxygen uptake, although the maximum value in the patients was less than one half that in the controls (6.8 +/- 0.5 and 15.1 +/- 0.3 l/min). Stroke volume, however, could change in patients, as in the controls under similarly increased afterloads (maximum values were 96 +/- 7 and 93 +/- 3 ml/beat, respectively). During exercise, the systolic arterial pressure elevated to a similar extent in both groups (221 +/- 14 and 235 +/- 12 mmHg, respectively). The increase in stroke volume in the patients was achieved by complete systolic emptying and the Frank-Starling mechanism. It is considered that in patients with ventricular pacing, exercise can produce an increase in stroke volume when myocardial function is not impaired.
authors.affiliation: Department of Clinical Laboratory, Yamagata University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Miyazawa
authors.forename: I
authors.initials: I
authors.lastname: Yamaguchi
authors.forename: E
authors.initials: E
authors.lastname: Komatsu
authors.forename: S
authors.initials: S
authors.lastname: Kagaya
authors.forename: J
authors.initials: J
authors.lastname: Oda
mesh_terms: D000368:Aged; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006327:Heart Block / Q000628:therapy*; D006339:Heart Rate; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010138:Pacemaker, Artificial; D013318:Stroke Volume / Q000502:physiology