RIGHT CORONARY BLOOD FLOW IN ACUTE PULMONARY EMBOLISM

Right coronary arterial blood flow was measured by means of an electromagnetic flowmeter during acute pulmonary embolism in open-chest anesthetized pigs. This study was undertaken in order to determine whether or not acute pulmonary embolism causes an impediment of right coronary flow which may be responsible for myocardial ischemia. Pulmonary embolism was induced with autologous blood clots in amounts sufficient to produce pulmonary hypertension, but not sufficient to produce shock. No reduction of right coronary blood flow after pulmonary embolization was observed. To the contrary, average right coronary mean flow increased from 27 to 61 ml. per minute (P < 0.001) following pulmonary embolizations in quantities sufficient to increase the average pulmonary arterial mean pressure from 12 to 42 mm. Hg. Smaller embolizations were associated with smaller increases or no change in right coronary mean flow. These observations are contrary to the theories of pulmonocoronary reflex spasm and right ventricular strain which had been proposed as possible causes of diminished coronary flow and subsequent myocardial ischemia after pulmonary embolism. The results suggest that myocardial ischemia in acute pulmonary embolism is not produced by an impediment of right coronary blood flow. © 1969.