GROWTH-HORMONE AND HEART PERFORMANCE - A NOVEL MECHANISM OF CARDIAC WALL STRESS REGULATION IN HUMANS

Objectives This study was designed to assess systolic wall stress and ventricular function in patients with deranged growth hormone secretio n, in an attempt to elucidate the mechanisms of growth hormone interac tion with heart performance. Design A case-control study. Subjects Thi rty patients with active acromegaly, free of diabetes mellitus and cor onary artery disease, and 25 subjects with congenital growth hormone d eficiency were studied. Twelve growth hormone-deficient subjects were reevaluated after 12 months of recombinant human growth hormone therap y. Two groups of 30 normal subjects each were used as controls for the acromegalic and growth hormone-deficient patients, respectively. Resu lts In the acromegalics, end-systolic wall stress was reduced (-20%; P <0.01) due to ventricular wall thickening (+26%, P<0.001), whereas car diac output was significantly increased (+20%; P<0.01). The velocity o f fibre shortening was unchanged. In growth hormone-deficient subjects , end-systolic wall stress was markedly increased (+38%, P<0.001) due to a significant reduction of ventricular wall thickness (28%; P<0.001 ), whereas cardiac output was significantly decreased (-44%; P<0.001). Replacement therapy with recombinant human growth hormone produced a partial correction of wall thickness and stress. Consequently, systoli c performance and cardiac out put improved significantly. Conclusion T his study demonstrates that growth hormone plays a role in the control of cardiac wall stress and performance through a mechanism mediated b y the effect of growth hormone on myocardial tissue growth. The data m ay have therapeutic implications in cardiac diseases that lead to hear t failure.