Effects of orthostatic postural changes on myocardial oxygen demands

The effects of orthostatic tilting were studied in 12 mongrel dogs anesthetized with sodium pentobarbital. Orthostasis produced significant decreases in cardiac output and left ventricular dimensions. Secondary decreases in coronary flow and myocardial oxygen consumption were also documented. These changes were attenuated when the animals were pretreated with propranolol. The upright posture may be of value in treatment of angina pectoris.