Decreased Aortic Compliance Aggravates Myocardial Ischemia with Impaired Coronary Reserve Flow

Abstract

Although decreased aortic compliance has been reported in patients with coronary artery disease, the effects of this decrease on coronary circulation and myocardial function have not been investigated sufficiently. Accordingly, to elucidate the effects of decreased aortic compliance on myocardium perfused by a stenosed coronary artery, we measured regional segment length, subendocardial ECG, and myocardial tissue oxygen tension (PO²) in ten anesthetized open-chest dogs with coronary stenosis. A fixed coronary stenosis was made at the proximal portion of the left circumflex coronary artery (LCx). The grade of coronary stenosis was adjusted not to reduce the baseline LCx flow more than 10% but to eliminate LCx reactive hyperemia following a 10-s occlusion. To reduce aortic compliance, the thoracic aorta was sufficiently constricted with bandages without changing mean aortic pressure. Measurements were made at the baseline and in rapid pacing states to compare the two experimental conditions, with and without the bandages.