Evaluation of Previously Cannulated Radial Arteries.

Abstract

To the Editor: I read with interest the article by Watson and colleagues1 on the evaluation of previously cannulated radial arteries. I have a number of queries. The paper fails to mention the time lapse between transradial artery coronary angiography and coronary artery bypass grafting (CABG). This is important, because the incidence of early radial artery (RA) occlusion after prior cannulation has been reported to be between 5% and 20%.2 Apart from occlusion, there can be damage to the arterial wall, endothelial disruption, damage to the tunica media, perivascular inflammation, and reactive hyperplasia with impaired vasodilatory capacity, which can occur within 3 months of transradial coronary angiography.3,4 The authors mention that “immediately after CABG, each patient had been given verapamil or diltiazem along with systemic heparinization.” Giving heparin after CABG is not a standard practice. What preparation of heparin was given (unfractionated or low-molecular-weight), in what dose, and for how long? The records inconsistently specified whether the right or left RA had been used for any particular graft. How then could the authors have known whether the RA under study had been cannulated? Hence their contention that they investigated patency in patients who had undergone transradial angiography is not totally true. Of the 3 occluded grafts, one was known to have been cannulated (and dissected) during coronary angiography. So why was this—a “known-to-have-been-dissected” radial artery—used? Of the 3 occluded grafts, the other 2 could also have been cannulated (or not). Either way, the percentage would be significantly affected. The authors also fail to mention whether the occluded grafts supplied native arteries that had critical stenosis. It has been documented that radial grafts to arteries with less than 80% stenosis are prone to blockage or will show a string sign.5 Kamiya and colleagues6 have shown that there is a substantially reduced patency rate for previously punctured RA grafts. We are strong proponents of the RA as a conduit but would advise against using a previously cannulated RA for at least 3 months. This time lapse is not absolute, and we always evaluate the RA by Doppler echocardiography (for size, calcification, and atherosclerosis), in addition, of course, to clinical evaluation with an Allen test.