THE VELOCITY OF BLOOD FLOW IN ARTERIES IN ANIMALS

Abstract

The hot wire principle of A. V. Hill can be used to indicate and to measure accurately rapid changes occurring in the blood flow, if the wire be inserted directly in the blood stream. An enamelled nickel wire 63u in diameter is threaded through an artery and used as one of the arms of a Kelvin Thompson bridge. The method does not require the use of an anticoagulant, except in standardization and in employment of special cannulae, as for recording simultaneous blood pressures. The velocity pulse curve resembles the pressure pulse curve in the femoral, carotid and aorta. Respiratory waves in blood flow can be recorded. Systolic velocities of 50 to 100 cm. per sec. have been found for dogs under dial-morphine anaesthesia. Velocity curves in the anterior descending branch of the left coronary artery indicate that the maximum flow occurs in diastole and minimum toward the end of systole in this vessel.