Cardiovascular response to exercise in pacemaker implanted patients with fixed heart rate.

概要

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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 sexmatched normal subjects. Oxygen uptake increased linearly with increasing work rate, and attained maximum values of 15.7±0.7 and 29.5±1.1ml/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±0.31/min). Stroke volume, however, could change in patients, as in the controls under similarly increased afterloads (maximum values were 96±7 and 93±3ml/beat, respectively). During exercise, the systolic arterial pressure elevated to a similar extent in both groups (221±14 and 235±12mmHg, 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.
International Heart Journal刊行会の論文