Direct and noninvasive evaluation of the cardiovascular response to isometric exercise

One method for testing cardiac reserve is to increase arterial pressure by isometric handgrip exercise (IHE) which increases the afterload against which the left ventricle must eject blood. In previous invasive studies in patients with cardiac disease, decreased ventricular reserve during IHE was manifest by a marked rise in LVEDP and a fall in cardiac output and stroke work index. To avoid the limitations of invasive techniques, we used M-mode echocardiography and other noninvasive measurements to evaluate the response to IHE in 11 normals and four patients with varying degrees of adriamycin cardiotoxicity. The normal response to IHE was manifest by an increase in heart rate (38%), arterial pressure (40%), cardiac output %53%), left ventricular end-diastolic diameter (12%), and endsystolic diameter (6%). There was no essential change in systemic vascular resistance, fractional shortening, or ejection fraction. In five normal subjects, 2 hours after 80 mg of oral propranolol, the response to IHE was altered as follows. Although the rise in arterial pressure was the same, the heart rate increase was blunted, and there was no significant rise in cardiac output. In the adriamycin-treated group the resting heart rate was higher, but the blood pressure response to IHE was the same. Compared to the normals, the adriamycin group had a fall in VCF and a rise in fractional shortening and ejection fraction, together with a rise in end-systolic diameter. Although further studies must be performed, noninvasive characterization of IHE may be helpful in evaluating ventricular reserve.