Cardiac size and function in pregnancy-induced hypertension.

The physiologic cardiac enlargement characteristic of normal pregnancy could result in important left ventricular dysfunction in the presence of elevated blood pressure. Using M-mode echocardiography, we measured left ventricular dimensions, fractional shortening, and radius-to-wall thickness ratio in 23 patients who had a diagnosis of pregnancy-induced hypertension at rest and during isometric exercise. Seventeen subjects with normal pregnancies were similarly studied and served as controls. The average gestation of patients with pregnancy-induced hypertension was 38 +/- 2 weeks, and that of control subjects was 37 +/- 1 weeks. The average age was 25 +/- 5 years for patients with pregnancy-induced hypertension, and that for control subjects was 29 +/- 4 years. The patients with pregnancy-induced hypertension did not show the normal eccentric cardiac enlargement observed during pregnancy; the average radius-to-wall thickness ratio was reduced in patients with pregnancy-induced hypertension. Fractional shortening, a reflection of ventricular performance, was maintained both at rest and during exercise in the hypertensive group. One patient, who did not show a reduced radius-to-wall thickness ratio, had marked reduction of left ventricular performance in the presence of severe pregnancy-induced hypertension. Left ventricular performance in most subjects with pregnancy-induced hypertension is normal. Preservation of left ventricular performance despite increased arterial pressure may be related to the absence of eccentric gestational cardiac enlargement.