Evidence of a Dominant Backward-Propagating “Suction” Wave Responsible for Diastolic Coronary Filling in Humans, Attenuated in Left Ventricular Hypertrophy

Abstract

Coronary blood flow peaks in diastole when aortic blood pressure has fallen. Current models fail to completely explain this phenomenon. We present a new approach-using wave intensity analysis-to explain this phenomenon in normal subjects and to evaluate the effects of left ventricular hypertrophy (LVH). We measured simultaneous pressure and Doppler velocity with intracoronary wires in the left main stem, left anterior descending, and circumflex arteries of 20 subjects after a normal coronary arteriogram. Wave intensity analysis was used to identify and quantify individual pressure and velocity waves within the coronary artery circulation. A consistent pattern of 6 predominating waves was identified. Ninety-four percent of wave energy, accelerating blood forward along the coronary artery, came from 2 waves: first a pushing wave caused by left ventricular ejection-the dominant forward-traveling pushing wave; and later a suction wave caused by relief of myocardial microcirculatory compression-the dominant backward-traveling suction wave. The dominant backward-traveling suction wave (18.2+/-13.7 x 10(3) W m(-2)s(-1), 30%) was larger than the dominant forward-traveling pushing wave (14.3+/-17.6 x 10(3) W m(-2) s(-1), 22.3%, P =0.001) and was associated with a substantially larger increment in coronary blood flow velocity (0.51 versus 0.14 m/s, P <0.001). In LVH, the dominant backward-traveling suction wave percentage was significantly decreased (33.1% versus 26.9%, P =0.01) and inversely correlated with left ventricular septal wall thickness (r =-0.52, P <0.02). Six waves predominantly drive human coronary blood flow. Coronary flow peaks in diastole because of the dominance of a "suction" wave generated by myocardial microcirculatory decompression. This is significantly reduced in LVH.