Abstract
Background and Purpose. It is not easy to evaluate blood inflow into the myocardial microvasculature. The purposes of this study were to visualize inflow to the microvasculature using real-time myocardial contrast echocardiography (MCE) and to examine the effects of cardiac phase on the replenishment curve.
Methods and Results. Real-time MCE was performed during Definity® infusion in 6 open- canines. The timing of termination for the burst technique was set at end-diastolic or end-systolic phase, and the initial inflow of contrast after destruction of bubbles into the myocardium was evaluated. The video intensity at ventricular septum was also measured until myocardial opacification reached a plateau after the burst technique and was fitted to the replenishment curve: y=A(1-e -βt).
Results. Myocardial opacification at diastolic phase just after destruction of bubbles significantly increased, however, it did not increase in the initial systolic phase. The A value did not change regardless of timing of termination to burst bubbles. The β value at diastolic phase was lower than that at systolic phase (0.91±:0.18 vs. 0.67±0.14).
Conclusions. The flow into coronary arterioles is dominant at diastolic phase similar to epicardial coronary flow. Timing of termination to burst bubbles influences parameters of replenishment curve.
