Direct myocardial revascularization: saphenous vein bypass grafts to the distal coronary artery. Technical details and postoperative hemodynamics

Simplified circular aortotomy in aortocoronary bypass operations

Adaptation of a rongeur technique facilitates aortotomy in aortocoronary bypass operations. A single motion with a double-action duckbilled rongeur produces a smooth-walled, symmetrical aortotomy which varies in shape predictably according to the angle at which the rongeur is held relative to the axis of the aorta.

Effects of surgery on angina (pre- and postinfarction) and myocardical function (failure)

With the advent of direct bypass surgery, the dramatic clinical responses in some patients has been followed by enormous enthusiasm in many centers. Surgical technics have advanced to such a point that nearly all patients with obstructive coronary disease could have the obstructions bypassed to one or many areas. Criteria for evaluating surgery include mortality, operative infarction rate, patency of grafts, clinical response, and stress testing. Many reports fail to correlate results with angiographic studies of vein function and with completeness of revascularization. When cine studies are performed, a good correlation exists between patent veins and relief of angina and improved stress response. Different patterns of response to stress, sometimes independent of relief of angina, are obtained depending on the completeness of revascularization. Predictable relief of angina is found if revascularization is complete. At times dramatic, but much less predictable, relief of failure (improved ventricular function) follows revascularization. Angina is a valuable aid in selecting some patients for surgery. Stress testing (bicycle ergometry) can now define general groups of patients who are likely, and who are not likely, to show improved myocardial response to stress after surgery. These studies also demonstrate the need for the surgeon to provide complete revascularization whenever possible. The criteria for selection for surgery of patients with symptoms of gross heart failure remain unclear. While revascularization technics could be technically applied to nearly all coronary patients, present methods are unable accurately to define who really needs the surgery and, equally important, which hearts will respond once revascularization is completed.

Myocardial blood flow in man: effects of coronary collateral circulation and coronary artery bypass surgery

The effects of coronary artery bypass graft (CAB) and coronary collaterals (CC) on myocardial blood flow (MBF) were studied in 24 patients undergoing 29 CAB's. MBF after CAB was compared to preexisting MBF by intraoperatively injecting (133)xenon via distal CAB with proximal CAB first occluded then open. Pressure gradients across bypassed obstructions were measured. The results were correlated with preoperative coronary arteriograms to determine the effects of CC on MBF and postobstructive perfusion pressures. Mean MBF was increased by CAB from 32+/-6 (se) ml/min per 100 g (CAB occluded) to 118+/-13 ml/min per 100 g (CAB open). The (133)Xe clearance curves with CAB open were resolved into slow (19+/-2 ml/min per 100 g) and rapid (133+/-12 ml/min per 100 g) phases, suggesting that MBF remained heterogeneous after CAB. Vessels with less than 80% stenosis by angiography had pressure gradients less than 20 mm Hg across obstructions, high postobstructive perfusion pressures (75+/-7 mm Hg), and normal MBF (87+/-6 ml/min per 100 g) even with CAB occluded. Vessels with greater than 80% stenosis or total occlusion by angiography had significant pressure gradients with marked reduction of postobstructive MBF. No significant difference in postobstructive MBF was found when vessels with CC (21+/-4 ml/min per 100 g) were compared to those without CC (17+/-4 ml/min per 100 g) (P > 0.4). These studies demonstrate that (a) mean MBF increased 268% after CAB, (b) heterogeneous MBF persisted after CAB, (c) CC were not associated with significant increases in MBF, and (d) vessels with less than 80% stenosis had less than 20 mm Hg gradient with minimal effect on resting MBF.

Aortocoronary bypass graft. Initial blood flow through the graft, and early postoperative patency

Intraoperative measurements of blood flow were made in 70 patients in whom a total of 103 venous bypass grafts had been inserted from the aorta to the right, the left anterior descending, or the circumflex coronary artery. Cineangiographic evaluation of graft patency was performed in all patients. Overall patency rate was 90.3%. Flow in all bypass grafts averaged 68 ml/min. All grafts with flow of 20 ml or less or which failed to respond to the injection of 20 mg of papaverine became occluded. All grafts with flow greater than 45 ml/min remained open.

Progressive and late obstruction of an aorto-coronary venous bypass graft

Progressive late obstruction of an aorto-coronary venous bypass graft is reported in a 44-year-old man who died of bi-ventricular failure 114 days after surgery. The first portion of the vein graft had a residual lumen of one mm. Histology showed marked intimal fibrosis. Mechanism for this occlusion and fibrosis is unclear. This representsc the first documented case of late obstruction of an aorto-coronary bypass graft with angiographic evidence of early postoperative patency.