The importance of vasodilator therapy for early radial artery string signs identified by intraoperative angiography during coronary artery bypass surgery

Introduction: Long term graft patency is the major factor for survival in patients after coronary artery bypass grafting (CABG). When using radial arteries as a graft the occurrence of spasm (strings) may be of concern. We determined the presence of radial artery string signs immediately after completion of the grafts and, if diagnosed, investigated the effects of intra-graft vasodilator therapy. Methods: 36 consecutive patients underwent CABG with the use of the left internal mammary artery to the LAD, and the radial artery to the second target vessel. A proximal and distal segment of the radial artery was harvested for histologic examination. Blood flow measurement (ml/min) and resistance index (PI) was performed with a doppler flow probe, followed by intraoperative angiography. Results: Average RA blood flow was 71±23ml/min and flow and resistance index was 2.4±1.1. Intraoperative angiography identified in 4 of the patients (11.1%) string signs despite excellent flow pattern. Intracoronary nitric oxide reduced strings significantly in three out of four. In one patient strings remained despite vasodilator therapy and the graft was replaced. Histologic examination revealed low grade atherosclerotic changes in nearly all grafts. Conclusion: The present study demonstrates that in 11% of the radial arteries strings are present despite the presence of atherosclerotic changes which should be treated with intra-graft vasodilator therapy. We suggest to perform introperative radial artery angiography whenever possible to exclude early string signs or to treat those to avoid early graft failure.