AbstractThe purpose of the study was to evaluate the functional changes which may occur in the human hypertensive heart following treatment with beta-blocking agents. In 54 primary hypertensive men investigated in the control state and after three weeks of treatment with propranolol (320 mg/day) it was seen that: (a) beta-adrenergic blockade depresses the pre-ejection, and probably the ejection left ventricular function; (b) the former effect is unrelated to changes in peripheral circulation, while the latter result may be either potentiated or overcome, depending on the direction to which treatment shifts the vascular resistance; (c) variations of impedance, rather than of blood pressure, influence the ejection left ventricular function; and (d) withdrawal of the adrenergic support to the heart, due to beta-blockade, is probably the primary factor responsible for the abnormal ventricular adaptation to an augmented impedance.