A STUDY OF CORONARY FLOW UNDER CONDITIONS OF HEMORRHAGIC HYPOTENSION AND SHOCK

Abstract

Changes in coronary flow and flow resistance were estimated during standardized hemorrhagic hypotension and shock in dogs by use of a perfusion type flowmeter. Coronary flow decreased to 30-60% of control flow during the 50 and 30 min. hypotensive periods and flow resistance was greatly decreased. Following reinfusion of all withdrawn blood and restoration of mean aortic pressure to control level, the coronary flow increased to 121-420% of control flow. The augmented coronary flow was maintained until some time after circulatory failure had intervened and almost invariably was greater than the coronary flow at equivalent aortic pressure in the pre-shock state. Flow resistance during circulatory failure was always less than control resistance. Vasodilata-tion appeared to play a prominent part in the decrease in resistance. It is concluded that circulatory failure following hemorrhagic hypotension is not precipitated by an inadequate coronary flow following restoration of aortic pressure by reinfusion.