Effect of dynamic cardiomyoplasty on phasic coronary arterial flow velocity in canine hearts

The usefulness of dynamic cardiomyoplasty has been demonstrated repeatedly, both experimentally and clinically. Although clinical applications of dynamic cardiomyoplasty to ischemic heart disease have been reported, its effect on the coronary blood flow has never been discussed. Therefore, we tested the hypothesis that dynamic cardiomyoplasty might adversely affect coronary arterial blood flow through compression of the coronary arteries during systolic skeletal muscular contraction and incomplete relaxation of the skeletal muscle flap during diastole. Dynamic cardiomyoplasty was performed in seven mongrel dogs with the use of a left latissimus dorsi-muscle flap, paced synchronously with the R wave of the electrocardiogram. A 3F Doppler catheter was placed in the left main trunk of the coronary artery to assess the instantaneous changes of coronary flow velocity by fast Fourier transformation analysis, We compared systolic and diastolic properties during assisted versus unassisted cardiac cycles by calculating the peak velocity and the time-velocity integral. During assisted cardiac cycles, a significant enhancement of coronary arterial blood flow velocity was demonstrated by significant increases in both systolic and diastolic peak velocity (26.9% +/- 6.5%, p0.005; 4.0% +/- 1.6%, p0.05, respectively) and time-velocity integral (20.9% +/- 4.8%, p0.05; 10.0% +/- 4.6%, p0.05, respectively). Enhancement of coronary arterial blood flow velocity was associated with an increase in mean aortic pressure (16.4% +/- 1.3%, p0.005) and descending aortic flow (67.5% +/- 5.3%, p0.005). Also, the improved systolic coronary arterial blood flow velocity was consistent with an increase in systolic aortic pressure (15.8% +/- 1.5%, p0.005), and enhancement of diastolic coronary arterial blood flow velocity was associated with an increase in diastolic aortic pressure (8.6% +/- 2.3%, p0.01). We concluded that coronary arterial blood flow velocity was increased by the enhancement of cardiac function as a result of dynamic cardiomyoplasty, leading to an increase of coronary perfusion pressure and cardiac output.