BackgroundCoronary artery bypass graft (CABG) surgery is the standard of care in the treatment of advanced coronary artery disease, and its long-term results are affected by the failure of bypass grafts. The aim of the present study was to evaluate the early patency rate in coronary bypass grafts.MethodsA total of 107 consecutive patients who underwent CABG were included in this study. Early graft patency was evaluated via computed tomography (CT) angiography in the first week after surgery.ResultsThere were a total of 366 grafts, comprised of 250 venous grafts and 116 arterial grafts. Multi-slice CT detected acute graft occlusions in 32 (8.7%) of all the grafts, including 26 (10%) of the 250 venous grafts and 6 (5%) of the 116 arterial grafts. The patency rates obtained were 97.3% for the left internal mammary (IMA) grafts, 50% for the radial artery grafts, and 50% for the right IMA grafts. Additionally, 107 (96.4%) grafts to the left anterior descending artery (LAD) were classified as patent, whereas 1 (30%) of the 3 grafts in the left circumflex (LCX) region and 1 (50%) of the 2 grafts in the right coronary artery (RCA) territory were found to be occluded. In the venous category, 8 (13.7%) of the 58 grafts to LAD were found to be occluded. In the LCX region, 9 (8.5%) of the 106 grafts were classified as occluded, while the remaining 97 (91.5%) grafts were patent. The venous grafts to RCA were occluded in 9 (10.4%) of the 86 grafts. Amongst the multiple preoperative, intraoperative, and postoperative factors, pump time was significantly longer in the patients with occluded grafts than in those with patent grafts (P = 0.04).ConclusionThe IMA grafts had the highest early patency rate amongst the coronary bypass grafts. However, the other arterial grafts were associated with a high rate of acute occlusions.

A total of 55 consecutive patients who experienced perioperative myocardial infarction (MI) after coronary artery bypass grafting were studied using multislice computed tomography (MSCT) angiography to evaluate for graft patency. The MSCT detected acute graft occlusion in 23% grafts. Of the 55 patients, 40% patients had occluded grafts and perioperative MI in the area of the grafted vessels; remaining 60% had patent grafts with infarction in the area of the grafted vessels. Compared with the patients with patent grafts, those with occluded grafts had a higher blood sugar level. In addition, graft occlusion was higher in grafts with severe distal disease. Among the patients with patent grafts, luminal stenosis of the native vessels supplying the infarcted myocardium was higher than that in the native vessels supplying the non-infarcted myocardium. In conclusion, MSCT is feasible for the assessment of graft patency in the setting of perioperative MI. Graft occlusion is detected in less than half of the cases and usually occurs in the grafts with severe distal involvement and the patients with uncontrolled hyperglycemia. In patients with patent grafts, the severity of luminal stenosis of the native grafted vessel is the main predisposing factor for perioperative MI.

Use of topical sodium nitroprusside to relieve perioperative spasm of the internal mammary artery: A word of caution To the Editor: After reading with interest the article by Cooper, Wilkinson, and Angelini I concerning perioperative spasm of the internal mammary artery (IMA), we used sodium nitroprusside topically in two consecutive patients undergoing coronary artery bypass operation to relieve the spasm of the left IMA before closure of the sternotomy. The concentration of sodium nitroprusside used was that proposed by these authors, 2 mg in 4 ml of 5% dextrose in water. We report here the cases of these two consecutive patients, in whom significant drops in the arterial blood.pressure occurred immediately after the sodium nitroprusside was sprayed on the IMA pedicle. CASE I. A 61-year-old man underwent a coronary artery bypass operation with a left IMA graft to the left anterior descending artery and supplemental sequential saphenous vein grafts to the first and second marginal branches of the circumflexartery. The left IMA was dissected on a pedicle with the aid of electrocautery and titanium hemoclips. Papaverine at 6 mg in 0.9% normal saline solution was sprayed on the pedicle after dissection. After completion of proximal anastomoses, the patient was weaned from bypass with satisfactory hemodynamics and was decannulated. The left IMA was noticed to be spastic before closure of the sternotomy, and 2 mg sodium nitroprusside in 4 ml 5% dextrose in water was sprayed on the IMA pedicle. Systolic arterial blood pressure fell to 30 mm Hg within seconds after the vasodilator was sprayed on. This low blood pressure was not responsive to the infusion of fluids and necessitated the use of vasoactive agents. An intravenous injection of 500 f.l.g metaraminol was given. Despite volume infusion and metaraminol treatment, peripheral vascular collapse persisted and epinephrine was infused at a rate of 4 f.l.g/min. The patient's state of peripheral vascular collapse gradually resolved during the next 15 minutes, and the patient was transferred to the intensive care unit with stable hemodynamics. CASE 2. A 57-year-old woman underwent coronary artery bypass operation with a left IMA graft to the left anterior descending artery and a supplemental saphenous vein graft to the first diagonal artery. The left IMA was prepared as described in case I. The IMA was noted to be spastic after decannulation, and 2 mg sodium nitroprusside in 4 ml 5% dextrose in water was therefore sprayed on the IMA pedicle. Arterial blood pressure fell immediately after the vasodilator was sprayed on. Rapid fluid infusion and 500 ug metaraminol by intravenous injection were enough to reverse peripheral vascular collapse. The patient was transferred to the intensive care unit in stable condition. Early postoperative spasm of the IMA is a serious condition that can result in significant morbidity and mortality.v 3 Coo-Letters to the Editor 3 8 7 per, Wilkinson, and Angelini' recommended the topical use of sodium nitroprusside for immediate relief of IMA s...