Recurrent Spasm of Radial Artery Graft Mimicking Fixed Stenosis

The radial artery is now frequently used as a conduit for coronary artery bypass grafting (CABG). Spasm of the radial artery conduit has been reported.1 We report a case in which spasm simulates the appearance of a fixed lesion. Case Report. A 56-year-old man presented with chest pain. He had CABG performed three months prior. This included a left internal mammary artery (LIMA) graft to the left anterior descending (LAD) coronary artery, a radial artery graft to the circumflex (CX) coronary artery, and a saphenous vein graft (SVG) to the right coronary artery (RCA). A thallium stress test demonstrated an area of lateral ischemia, which prompted coronary angiography. The catheterization revealed preserved left ventricular function with three-vessel coronary artery disease. The LIMA was open to the LAD. The SVG was open to the RCA. The radial artery was open to the obtuse marginal branch of the CX but displayed a tight proximal stenosis. A small lower circumflex marginal branch was 100% occluded and not bypassed. The radial artery stenosis was felt to be responsible for the patient’s symptoms and demonstrated lateral ischemia. The patient was brought to the catheterization lab on the following day for intervention on the radial artery graft. Initial angiography was unchanged from the previous day (Figure 1), showing a proximal stenosis in the radial graft. A 0.014´´ floppy guidewire was advanced down the graft into the CX artery, but was difficult to manipulate. Repeat angiography demonstrated diffuse spasm of a long segment of the proximal graft (Figure 2). The graft was treated with nitroglycerin and verapamil through the guide catheter. This resulted in complete resolution of the spasm including the original proximal area believed to be a fixed stenosis (Figure 3). Discussion. Review of this patient’s medical records revealed that several weeks prior to his catheterization he had been instructed to decrease both his nitrate (isorbide mononitrate 60 mg qd to 30 mg qd and then discontinue) and calcium blocker (360 mg qd to 180 mg qd). It is difficult to know if this medication change caused his symptoms, but there was a temporal relationship. Spasm of the radial graft may have been exacerbated by the medication change or may have been purely catheter-related. Likewise, it is difficult to know whether the thallium abnormality was due to spasm of the radial graft affecting the higher marginal branch or the ungrafted lower CX branch. Resumption of isorbide 60 mg qd and verapamil 240 mg qd resulted in resolution of most of the patient’s symptoms. The thallium stress imaging has not been repeated. As radial artery grafts are more frequently used as conduits for CABG, interventions are increasingly performed on patients with such grafts. Spasm of the radial artery in vitro and in situ as a graft has been reported.1–4 Such spasm has been shown to be responsive to combinations of nitroglycerin and calcium-channel blockers.1–4 Catheter-induced spasm of the native left and right coronary arteries is known to occur.5,6 Recognition of spasm as such is important since its misdiagnosis as a fixed stenosis can result in inappropriate referrals for revascularization procedures. Spasm of the same focal area of a native coronary during multiple different catheterizations has been reported.5,6 This situation is similar to our patient who had spasm of the radial artery graft on two different days, with the second on the day of a planned intervention. The radial artery seems more prone to spasm than a native coronary artery or internal mammary artery.7 This may be due to its more prominent muscular medial layers.7 Given this tendency, consideration might be given to the liberal use of intra-arterial nitroglycerin or calcium-channel blockers during diagnostic angiography of the radial artery to avoid confusion of spasm with a fixed stenosis and the subsequent attempt to perform an inappropriate intervention. Catheter-related spasm of native coronary arteries is not generally felt to have any particular prognostic significance or require any long-term treatment. Peri-operative calcium-channel blockers have been used after CABG to prevent spasm,8 but definitive data regarding their usefulness are lacking. Although a beneficial effect of peri-operatively administered diltiazem has been reported,9 a randomized six-month study of post-operative diltiazem demonstrated no clinical or angiographic differences.10 Whether catheter-induced spasm of the radial artery graft has any prognostic significance or correlates with any spontaneous spasm and whether it requires any long-term treatment is unclear. The possibility of such spasm should be kept in mind, however, when radial artery graft abnormalities are encountered.

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