MITRAL-VALVE PROLAPSE AND BORDERLINE HYPERTENSION

Systemic hemodynamics, plasma volume and circulating catecholamlne levels were measured under baseline conditions in 21 patients with idiopathic mitral valve prolapse (IMVP), 13 with and eight without borderline hypertension, and compared with two control populations comprised of 34 normotensive and 15 borderline hypertensive subjects without mitral valve prolapse. The IMVP population had a faster heart rate (73 ± 2 vs 67 ± 2 beats/minute; p < 0.05) and a greater cardiac index (3.5 ± 0.1 vs 3.0 ± 0.1 liters/min/m2p < 0.025) than the normotensive controls. However, heart rate and cardiac index were similar in IMVP and borderline hypertensive patients. The IMVP patients showed an increased responsiveness of heart rate and systolic arterial pressure during beta-adrenergic receptor stimulation (isoproteretiol infusion) when compared to the second control group of patients with borderline hypertension who had similar hyperdynamic circulation. Responses to upright tilt, Valsalva maneuver, and handgrip, however, did not differ between the IMVP and the two control groups. Circulating catecbolamine levels were slightly higher in IMVP patients. It is concluded that some IMVP patients (with or without hypertension) demonstrate increased betaadrenergic receptor responsiveness associated with a hyperkinetic circulation. Therefore, a hyperbetaadrenergic state could possibly account for the observed abnormal left ventricular contraction pattern and clinical symptoms in the mitral valve prolapse syndrome. © 1979 American Heart Association, Inc.