Increased myocardial contractility following growth hormone administration in normal man. An echocardiographic study

Cardiac function was studied by echocardiography in 11 normal subjects before subcutaneous growth hormone administration (first control), after one week of subcutaneous growth hormone administration and at one week after stopping subcutaneous growth hormone administration (second control). Plasma growth hormone was 1.4 ng/ml and 4.5 ng/ml, respectively, at the first two examinations. Compared to the first and second control situations heart rate increased by 9% (p less than 0.1) and 15% (p less than 0.01), fractional shortening of the left ventricle by 8% (p less than 0.02) and 9% (p less than 0.01), and mean circumferential shortening velocity by 10% (p less than 0.05) and 14% (p less than 0.01) respectively. Mean arterial blood pressure was unchanged. Thus, in normal man an increase in plasma growth hormone up to levels comparable to those seen in type 1 diabetics during conditions of poor metabolic control seems to be followed by enhancement in myocardial contractility. Therefore we suggest that growth hormone might contribute to the increase of myocardial contractility earlier described in type 1 diabetic patients with no clinical signs of microvascular disease.