Regional myocardial perfusion and function after coronary bypass surgery: evaluation using handgrip exercise Doppler echocardiography]

To evaluate myocardial perfusion and function of the interventricular septum after coronary artery bypass surgery, 29 patients with internal mammary artery grafts (IMAG) were examined using handgrip exercise Doppler echocardiography. IMAG flow was measured by color flow Doppler. Septal excursion and percent thickening of the interventricular septum during systole were measured as indicators of regional left ventricular function by M-mode echocardiography. Myocardial perfusion was estimated by thallium-201 exercise myocardial scintigraphy using a treadmill. 1. At rest, there were no significant correlations between IMAG flow and septal excursion and percent thickening or myocardial perfusion. 2. After the isometric handgrip exercise test, IMAG flow increased 20.0 +/- 3.9% from at rest, and the percentage of change in IMAG flow correlated significantly with changes in septal excursion (r = 0.63) and percent thickening (r = 0.72). It was found that a response of bypass graft flow to exercise has a correlation with contractility of cardiac muscle. 3. The rate of increase in IMAG flow in patients with normal myocardial scintigraphic findings (31.8 +/- 6.2%) was higher than that in patients with ischemia (15.3 +/- 5.6%) or infarction (15.0 +/- 11.3%). 4. A greater increase of percent thickening was observed in patients with normal exercise myocardial scintigraphic findings. These results suggest that the responses of the bypass graft flow to handgrip exercise may reflect viability and contractility of cardiac muscles perfused by the graft. Thus, exercise Doppler echocardiography is useful for evaluating regional myocardial perfusion and function of the interventricular septum after coronary artery bypass surgery.