Postoperative Evaluation of Radial Artery Grafts for Coronary Artery Bypass Grafting by Transit-Time Doppler Flow Measurements[∗]

Due to the histological configuration of the vessel wall, the radial artery is prone to spasm as a result of handling or harvesting. Therefore, certain degrees of arterial wall spasm are unpreventable, even with appropriate pharmacologic treatment, while using the radial artery as a bypass graft in CABG. Consequently, the radial artery is only reluctantly used compared to saphenous vein grafts in CABG. In our clinical experience, the radial artery, if harvested carefully, has proved to be an excellent bypass graft. This investigation was undertaken to study the differences in blood flow measured directly after extracorporeal circulation in radial artery grafts and venous grafts. Both grafts were compared to the left internal mammarian artery anastomosed to the LAD. Methods: Between January 1998 and December 1999, 198 patients who were undergoing coronary artery revascularization with two grafts were retrospectively investigated. In all patients, the left internal mammarian artery (LIMA) was anastomosed to the left anterior descending branch (LAD). For the second graft, either the saphenous vein or the radial artery was used. Proximal anstomoses were performed as end-to-side into the ascending aorta. Patients were divided into four groups: Group 1: n = 79 IMA-LAD, vein to the circumflex artery; Group 2: n = 56 IMA-LAD, vein to the right coronary artery; Group 3: n = 34; IMA-LAD, radial artery to the circumflex artery; Group 4: n = 29 IMA-LAD, radial artery to the right coronary artery. Graft-flow measurements were performed using the transit-time method after extracorporeal circulation was terminated. The mean systolic, diastolic, and mean blood flow were measured, and the pulsatility index was calculated. Statistical analysis was performed using the of t-test analysis between the variables mean blood flow and pulsatility index. A p-value of < 0.05 was defined as statistically significant. Results: There were no statistically significant differences in mean blood flow or pulsatility index between radial artery and saphenous vein grafts to the right coronary artery and the circumflex artery, respectively. Also, there were no differences regarding vein grafts to the right coronary artery and to the circumflex artery, or regarding radial artery grafts to the two coronaries, respectively. In group 4, significantly lower blood flow to the LAD was found compared to group 1, and a significantly higher pulsatility index compared to groups 2 and 3. Conclusions: Radial artery grafts compared to saphenous vein grafts do not show significant differences early after operation in mean blood flow or pulsatility index. Further studies are needed to evaluate long-term performance of radial arteries as coronary bypass grafts and to compare the radial artery to the right mammarian artery and the standard saphenous vein graft.

Key words:

Transit-time doppler - Cardiovascular disease - Coronary disease - Coronary surgery - Radial artery - Revascularization

1 Presented as an oral presentation at the 3rd Joint Meeting of the German, the Austrian and the Swiss Societies for Thoracic and Cardiovascular Surgery, Lucerne, Switzerland, February 9-12, 2000

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1 Presented as an oral presentation at the 3rd Joint Meeting of the German, the Austrian and the Swiss Societies for Thoracic and Cardiovascular Surgery, Lucerne, Switzerland, February 9-12, 2000