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Phasic blood flow recorded in five unobstructed dog aortocoronary bypass grafts to the left coronary artery was similar to that of normal coronary arteries, with a high diastolic-to-systolic flow ratio which averaged 2.7 +/- 0.4. With an average of 52 +/- 7% and 72 +/- 6% stenosis in the coronary artery distal to the graft, the phasic graft-flow pattern was altered, with a decrease in the diastolic-to-systolic flow ratio to 1.9 +/- 0.4 and 1.2 +/- 0.4, respectively. Phasic patterns recorded in 42 human saphenous vein grafts to branches of the left coronary artery subsequently shown to be patent by postoperative coronary arteriography were similar to those of a normal coronary artery, with an average diastolic-to-systolic flow ratio of 2.3 +/- 0.83 and an average flow of 76 +/- 48 ml/min. Phasic flow measured in 20 grafts shown to be occulded at restudy had an average diastolic-to-systolic flow of 1.3 +/- 0.45, with an average flow of 72 +/- 33 ml/min and a phasic graft flow which was similar to that obtained from partially obstructed coronary arteries. We conclude that partial obstruction of the graft or the distal coronary artery alters the flow pattern, and this partial obstruction may lead to closure of the graft.

The histochemical and ultrastructural effects of extracorporeal circulation and aortic cross-clamping during coronary heart surgery have been examined in drill biopsy samples of the left ventricle in 22 patients. The biopsies were obtained before and after bypass with a DeSoutter drill. Histochemical studies indicated definite differences between control and experimental biopsies, with increased succinic dehydrogenase, cytochrome oxidase, and LDH activity, while phosphorylase A and myosin ATPase activities declined. Furthermore, free phospholipid levels increased, as determined by the acid hematein reaction. Ultrastructural examination demonstrated loss of glycogen, intracellular swelling, and mitochondrial damage, which included loss of matrix density, loss of cristae, and eventual disruption in the postbypass biopsy. These results, which closely resemble the effects of ischemia and reperfusion observed in animal experiments, suggest that the initial insult is a change in membrane permeability regulation.

A routine chest X-ray taken four months after blunt chest trauma revealed a left ventricular aneurysm in a totally asymptomatic patient. At surgery a thin-walled, clot-filled aneurysm was successfully removed. This case demonstrates the need for careful follow-up of all patients sustaining blunt chest trauma even though the initial cardiac evaluation may be negative. Our feeling that all such aneurysms should be treated surgically is further reinforced by our operative findings.