Response to isometric exercise in children and young adults with aortic regurgitation.

We studied the hemodynamic response to isometric exercise in 28 children and young adults with aortic regurgitation (AR). Results were compared with those of 18 control subjects without heart disease. Sustained isometric exercise at 33% maximal handgrip capability produced similar increase in heart rate in the two groups. Systolic blood pressure rose to a greater extent in patients with AR than in controls (mean rise 33 mm Hg vs 13 mm Hg). Thirteen of 28 patients with AR had elevated left ventricular end-diastolic diameters at rest. During isometric exercise, left ventricular end-diastolic diameter remained constant in both groups. However, end-systolic diameter increased in patients with AR, resulting in a fall in shortening fraction. The mean left ventricular shortening fraction of the patients with AR fell from 36.0 +/- 1.0% to 32.8 +/- 1.2% (p less than 0.001), but did not change in controls. The fall in shortening fraction was most marked in patients with severe AR. We conclude that patients with AR have an abnormal cardiovascular response to isometric exercise consisting of greater increase in blood pressure and a decrease in left ventricular fractional shortening.