Keishi Ueyama

Use of the Radial Artery Graft After Transradial Catheterization: Is It Suitable as a Bypass Conduit?

BACKGROUND The suitability of the radial artery after transradial catheterization as a bypass conduit has been of great concern to surgeons. METHODS A total of 67 patients underwent isolated coronary artery bypass grafting using the radial artery: 22 patients received preoperative transradial catheterization (group 1) and 45 patients did not receive transradial catheterization (group 2). Those patients were retrospectively reviewed. RESULTS Patient characteristics, operative procedures, and early clinical outcome were not different between groups. The stenosis-free graft patency rates in groups 1 and 2 were 88% (16 of 18 patients) and 90% (38 of 42 patients) in the left internal thoracic artery (p = 0.87); 77% (17 of 22 patients) and 98% (48 of 49 patients) in the radial artery (p = 0.017); and 87% (13 of 15 patients) and 84% (21 of 25 patients) in the saphenous vein (p = 0.42), respectively. Intimal hyperplasia of the radial artery was observed in 68% (11 of 16 patients) in group 1 and in 39% (14 of 34 patients) in group 2 (p = 0.046). CONCLUSIONS Transradial catheterization reduced early graft patency and caused intimal hyperplasia, although it did not affect early clinical outcomes. We suggest that the use of the radial artery as a bypass conduit after transradial catheterization should be undertaken cautiously.

Effect of low-dose aprotinin on coagulation and fibrinolysis in cardiopulmonary bypass.

To study the effect of low-dose aprotinin on hemostasis in patients undergoing cardiopulmonary bypass (CPB) for coronary artery bypass operations and to elucidate the mechanism of aprotinin action, we randomized 14 of 27 patients to receive 30,000 KIU/kg aprotinin in the CPB priming volume and 7,500 KIU/kg aprotinin intravenously each hour during CPB (1 patient was excluded from the aprotinin group because of protamine shock). Intraoperative and postoperative blood loss was significantly reduced in the aprotinin group. Antithrombin III level was significantly decreased, and the levels of thrombin-antithrombin III complexes were significantly increased during CPB in both groups, indicating activation of the clotting system. The marked increase in fibrin(ogen) degradation products during CPB in the control group, indicating enhanced fibrinolytic activity, was significantly reduced in the aprotinin group. alpha 2-Plasmin inhibitor was significantly reduced during CPB in the control group. The marked increase in alpha 2-plasmin inhibitor-plasmin complexes in the control group, indicating plasmin activity, was significantly reduced in the aprotinin group. A marked decrease in the platelet count was observed during CPB similarly in both groups. These findings demonstrated that low-dose aprotinin administration was effective in reducing intraoperative and postoperative blood loss and that activation of the clotting system during CPB was not followed by hyperfibrinolysis in aprotinin-treated patients. The improved hemostasis is mainly attributable to the prevention of hyperfibrinolysis during CPB.

Pressure characteristics in arterial grafts for coronary bypass surgery

The haemodynamic properties of arterial grafts were studied by measuring the pressure waveform at the tip of the grafts in 28 patients who underwent coronary artery bypass surgery (CABG). The internal thoracic and gastroepiploic arteries were harvested as pedicles for CABG. Pressure wave of the ascending aorta and arterial grafts were simultaneously recorded with an electrocardiogram under stable haemodynamic conditions before cardiopulmonary bypass. Systolic, diastolic and mean pressures were measured, and mean systolic and diastolic pressures calculated for systolic and diastolic areas divided by time. The ascending aorta showed high sustained diastolic pressure that decreased gradually. Pressures in the internal thoracic and gastroepiploic artery grafts had narrow contours and decreased rapidly. Pressure waveforms in the internal thoracic and gastroepiploic artery grafts had a notch between the systolic and diastolic contours. There was no difference in systolic pressure between the ascending aorta and internal thoracic and gastroepiploic artery grafts. Diastolic pressures were 64(9), 55(7), and 51(6) mmHg in the ascending aorta and internal thoracic and gastroepiploic artery, respectively. Mean(s.d.) pressures were 75(9), 65(9) and 59(7) mmHg in the ascending aorta and internal thoracic and gastroepiploic artery grafts, respectively. Diastolic and mean pressures in the internal thoracic artery grafts were significantly lower than in the ascending aorta but significantly higher than in the gastroepiploic artery grafts. The mean(s.d.) calculated diastolic pressure in the internal thoracic artery grafts was significantly lower than in the ascending aorta but significantly higher than in the gastroepiploic artery grafts. The inferior capacity of flow through the arterial grafts may be mainly attributable to reduced diastolic pressure, which is caused by anatomical characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiologic characteristics of coronary artery bypass grafts

To investigate the hemodynamic characteristics of arterial grafts for coronary artery bypass grafting, we measured phasic pressure and flow patterns in three types of grafts in a canine model (n = 18). A graft from the ascending aorta (AAG), a graft from the descending aorta at the first lumbar level (DAG), analogous to a right gastroepiploic artery, and an internal thoracic artery (ITA) were anastomosed to each other. The composite graft was anastomosed to the left anterior descending coronary artery, and then the left anterior descending coronary artery was ligated. Before grafting, the AAG showed high sustained diastolic pressure, but the ITA and DAG showed rapid fall of diastolic pressures. Mean diastolic pressures were 83 +/- 2, 72 +/- 3, and 57 +/- 2 mm Hg in the AAG, ITA, and DAG (p < 0.05). Free flow in the AAG was markedly greater than in the ITA or the DAG. After grafting to the left anterior descending coronary artery, no changes were observed in diastolic pressures compared with the pregrafting values. Total blood flows were 72 +/- 6, 80 +/- 7, 57 +/- 7, and 44 +/- 6 mL/min in the left anterior descending coronary artery, AAG, ITA, and DAG, respectively. There were no differences in systolic graft flow between the three types of grafts. Diastolic blood flow in the ITA (29 +/- 4 mL/min) and DAG (18 +/- 3 mL/min) was smaller than in the AAG (48 +/- 4 mL/min) (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Late patency of the left internal thoracic artery graft in patients with and without previous successful percutaneous transluminal coronary angioplasty

The aim of this study was to compare early and late graft patency in patients with and without previous successful PTCA. Of the 70 patients who received both early and late follow-up angiography, 13 patients who had received successful PTCA at the left anterior descending coronary artery (LAD) before CABG (group I) and 31 patients who had not received preoperative PTCA in any vessel (group II) were retrospectively reviewed. There were no significant differences in patient characteristics including major coronary risk factors. The mean duration between the operation and control angiography was 35+/-23 months in group I and 36+/-19 months in group II (P=0.90). Occlusions of the LITA graft were observed in four patients of group I and in four patients of group II. Cumulative patencies of the LITA graft were 54% in group I and 83% in group II (P=0.12). The late patency rate of the LITA graft bypassed to the LAD in patients that received previous successful PTCA in the coronary artery tended to be lower than in patients without previous PTCA. This result should be confirmed by further prospective studies.