Operative flow measurements and coronary bypass graft patency.

Early (one week) and late (one year) postoperative angiography was performed in 142 patients having 310 grafts (117 right coronary artery [RCA], 134 left anterior descending [LAD], and 59 circumflex coronary artery [CCA]) to assess the factors responsible for failure of aorta-coronary artery saphenous vein grafts. Early catheterization revealed an 85.5 per cent patency rate with similar rates for each artery (RCA 88 per cent, LAD 85 per cent, and CCA 81 per cent). At one year 238 grafts remained patent, for a cumulative patency rate of 76.8 per cent with a similar distribution for each vessel (RCA 75 per cent, LAD 78 per cent, and CCA 76 per cent). Intraoperative flow measurements were correlated with early and late patency. Grafts with a basal flow less than 20 ml. per minute have a 42 per cent early closure rate and a 21 per cent late closure rate (cumulative 63 per cent). A basal flow of less than 40 ml. per minute was associated with a 25 per cent early failure and an 11 per cent late failure rate (cumulative 36 per cent). Basal flow at levels greater than 40 ml. per minute was not associated with an increased probability of graft closure. Absence of reactive hyperemia (30 second graft occlusion) was associated with a 19 per cent probability of early closure and a 31 per cent probability of cumulative thrombosis. A papaverine-induced flow increase (15 mg. given into the graft) of less than 100 per cent over basal flow gave a 20 per cent probability of early failure and 30 per cent probability of cumulative closure. Thus intraoperative basal flow measurements are of predictive value in determining the fate of aorta-coronary artery vein bypass grafts, and vasodilatory maneuvers provide little additional information.     

Long-term (5 to 12 years) serial studies of internal mammary artery and saphenous vein coronary bypass grafts

Serial arteriograms were obtained in 501 patients after coronary bypass grafting. Study I within 5 years of operation (mean interval 15 months) and Study II more than 5 years after (mean interval 88 months, range 60 to 147 months). One hundred patients received both internal mammary artery and saphenous vein grafts: 37, mammary artery grafts only, and 364, vein grafts only. In Study I, 645 (82%) of 786 vein grafts were patent, 42 (5%) stenotic or irregular, and 99 (13%) occluded. Of 140 mammary artery grafts, 136 (97%) were patent, two (2%) stenotic, and two (2%) occluded. Of the 645 vein grafts patent in Study I, 357 (55%) remained patent in Study II, 119 (18%) were stenotic or irregular, and 169 (26%) were occluded. Of 136 mammary artery grafts patent in Study I, 130 (96%) were unchanged, one was stenotic, and five (4%) were occluded in Study II. Early vein graft patency was influenced by the coronary artery grafted and by angina. Progression of vein grafts patent at Study I to stenosis or occlusion at Study II was associated with increasing postoperative interval (p less than 0.00001), interval myocardial infarction (p less than 0.001), angina (p less than 0.001), diabetes (p less than 0.004), hypercholesterolemia (p less than 0.006), and hypertriglyceridemia (p less than 0.02); it was not influenced by the coronary artery grafted. Within 5 years of operation, mammary artery graft patency exceeded vein graft patency. Between 5 and 12 years after operation, the attrition rate of vein grafts greatly exceeded that of mammary artery grafts (p less than 0.0001).     

Composite Y internal thoracic artery-saphenous vein grafts: short-term angiographic results and vasoreactive profile

BACKGROUND: The angiographic patency of composite Y internal thoracic artery-saphenous vein grafts has not been investigated in detail. METHODS: Twenty-five patients who received composite Y internal thoracic artery-saphenous vein grafts had control angiography and vasoactive challenges with serotonin, acetylcholine, and isosorbide dinitrate at a mean of 2.5 +/- 1.2 years after surgery. RESULTS: The perfect patency rate of composite Y internal thoracic artery-saphenous vein grafts was 72% (18/25). The distal portion of the internal thoracic artery was stringed in 4 patients and occluded in 2. The saphenous branch of the composite Y internal thoracic artery-saphenous vein grafts was found patent in all patients except 1. No failures were reported in the proximal tract of the internal thoracic artery. The distal tract of the internal thoracic artery showed reduced capacity of endothelium-mediated relaxation. CONCLUSION: The short-term patency of composite Y internal thoracic artery-saphenous vein grafts is suboptimal and markedly influenced by distal runoff and native flow competition.     

Coronary graft patency after perioperative myocardial infarction: a study with multislice computed tomography

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.     

Thermal coronary angiography: a method for assessing graft patency and coronary anatomy in coronary bypass surgery

Thermal coronary angiography was evaluated in 50 patients undergoing 137 saphenous vein and 48 internal mammary artery bypass grafts. A total of 177 thermal coronary angiograms were performed after completion of the distal anastomoses by injection of cold cardioplegia into the vein or by reperfusion with warmer blood in the internal mammary artery grafts. These angiograms provided details of graft and anastomosis patency, flow directions, and presence of native coronary stenoses. Temperature differences between the injectant and the epimyocardium of greater than 4 degrees C resulted in high-contrast images. Thermal coronary angiograms were obtained in 173 of the 177 studied bypass grafts; 172 grafts were patent, and 1 internal mammary artery graft was occluded. Unsuspected stenoses were detected at the site of four distal anastomoses. Subsequently, two anastomoses were successfully revised and three additional grafts performed. Ninety-six native coronary stenoses were located in the recipient coronary arteries. In ten instances, the thermal coronary angiograms were obscured by excess fat or myocardium, thereby impeding correct image analysis. We conclude that thermal coronary angiography can be clinically relevant and helps improve decision making during coronary artery bypass operations.     

Fate of the graft and native vessel following endarterectomy of the left anterior descending coronary artery.

In 16 patients who underwent endarterectomy of the left anterior descending (LAD) coronary artery combined with saphenous vein bypass grafting between Aug. 1, 1976 and July 31, 1978, the results of preoperative and postoperative angiography were comparable. Most patients had obstruction or severe stenosis of the proximal LAD coronary artery together with a poor runoff as demonstrated angiographically. Eighteen vein grafts were placed in the LAD artery and 15 (83%) were satisfactorily patent. Six of 18 grafted arterial segments became occluded distal to the site of graft insertion, but in most cases there was sufficient proximal runoff to maintain graft patency. In this study intraoperative measurements of graft flow were predictive of graft or distal vessel patency, or both. Careful postoperative assessment of the results of this technique seems warranted.     

Internal mammary artery bypass graft--long-term patency rate and follow-up

Between December, 1968, and January, 1974, 814 internal mammary artery and 351 saphenous vein bypass graft procedures were performed in 628 patients. Operative mortality during the past 3 years has been 1.7%. Internal mammary artery bypasses were performed to the anterior descending, circumflex, obtuse marginal, distal right, and posterior descending right coronary arteries. Ninety-one patients having 137 internal mammary artery and 32 saphenous vein grafts were studied angiographically 12 to 36 months postoperatively. All but 2 internal mammary artery bypasses were patent, a patency rate of 98.5%; 27 of the 32 saphenous vein bypasses in this group were patent (84.3%). The majority of the internal mammary artery bypasses were to distal coronary arteries, while the saphenous veins were used primarily for proximal anastomosis. Cineangiographic volume/flow studies were also performed. The average flow in the more distal internal mammary artery bypasses was 61 ml. per minute as compared with 91 ml. per minute in the proximal saphenous vein grafts.     

Aorto-iliac reconstructions for intermittent claudication

Over a 12-year period, 290 aortofemoral reconstructions were performed for intermittent claudication involving 449 legs in 262 patients. The accumulative patency rate in surviving patients was 79 per cent at 5 years. The patency rate was significantly better in patients who stopped smoking after operation, and in men compared with women. Dacron grafts were significantly more successful than endarterectomy in men. If there was no associated superficial femoral artery occlusion, endarterectomy and Dacron bypass grafts were equally successful, but Dacron bypass grafts were significantly superior to endarterectomy if the superficial femoral artery was severely stenosed or occluded. The success rates for improving the patients' intermittent claudication were 90 per cent at 3 months and 72 per cent at 3 years. The success rate at 3 years was 80 per cent if the superficial femoral artery was patent but only 62 per cent if the superficial femoral artery was severely stenosed or occluded. Mortality and morbidity rates fell markedly in the last 6 years of the study.     

Fate of bypass grafts onto totally occluded coronary arteries.

BACKGROUND: Chronically occluded coronary arteries often develop good collateralisation, that leads to retrograde perfusion of these vessels, as regularly seen in coronary angiograms. Retrograde perfusion constitutes a form of competitive flow, which in turn is associated with an increased risk for early bypass graft failure. The aim of our study is to investigate the patency rate of bypass grafts onto totally occluded coronary arteries, in the presence of retrograde flow. METHODS: Two groups of patients were followed up by cardiac catheterisation. One month after undergoing coronary artery bypass grafting. Group 1 (n=33) had coronary three vessel disease, with one totally occluded coronary artery and evidence of retrograde flow in the preoperative coronary angiogram. Group 2 (n=30) was the control group, with coronary three vessel disease and without totally occluded coronaries. We used internal mammary arteries and saphenous vein grafts as conduits. RESULTS: Thirty-six point thirty-six per cent of bypass grafts onto totally occluded coronaries were occluded one month postoperatively (n=12). Graft failure in the control group was 13.3%. Significance p=0.03. CONCLUSIONS: In view of our findings we conclude, that there is a significantly increased incidence of early graft failure, when totally occluded coronary arteries are revascularised, that show retrograde flow in the preoperative coronary angiogram.     

Use of an aortic connector system for vein grafting

OBJECTIVE: The aortic connector system was used to minimize cerebrovascular complications when performing the proximal anastomosis of vein grafts during coronary artery bypass grafting (CABG). The goal of this study was to investigate the intermediate outcomes of patients undergoing CABG with the aortic connector system. METHODS: The aortic connector was used on nine patients undergoing CABG between November 2002 and July 2003. Intermediate outcomes of the patients were examined, and the results of coronary angiography, which were performed before patient discharge and at least 6 months after discharge, were evaluated. RESULTS: There were no operative deaths or cerebrovascular accidents. One patient died 9 months after discharge, one patient had angina, and the remaining seven patients were asymptomatic. When evaluating the results of angiography performed before patient discharge, two of the 21 distal vein graft anastomoses were occluded (patency rate, 90.5%), but there was no stenosis or occlusion at the proximal anastomoses sites that were performed using the aortic connector. When evaluating the results of the second angiography performed after patient discharge, four of the eight proximal anastomoses were patent, one was completely occluded, two had 90% stenosis and one had 75% stenosis. Further, four of the 18 distal anastomoses were occluded (patency rate, 77.8%). There was no significant difference in graft flow or device size when comparing patients with patent vein grafts and those with stenotic or occluded vein grafts. CONCLUSION: Intermediate outcomes of vein grafting using the aortic connector were suboptimal. Long-term outcome data are forthcoming.     

Does Mediastinitis Affect the Graft Patency?

As inflammation began to be recognized as a major contributor to the pathogenesis of atherosclerosis, we evaluated the patients that developed mediastinitis, a long-standing inflammatory process, after coronary artery bypass grafting. There are many studies that have focused on the graft patency. But, till now, no study has been done to detect the effects of mediastinitis to graft patency. So, we aimed to detect the effect of mediastinitis on the graft patency in patients who have undergone coronary artery bypass surgery. Sixteen of 45 patients who have been operated upon for coronary artery bypass surgery and developed mediastinitis, which was treated with open drainage and mediastinal irrigation with late wound closure, were included in the study. The mean age of the patients was 55 +/- 11 (range 35-69) and nine of the patients were male. The graft patency was evaluated with control coronary angiographies after a mean period of 30.42 +/- 43.17 months (range 1-132). The left internal thoracic artery was patent in all patients (100%). Right internal thoracic artery patency rate was 50% (1/2). One individual bypassed radial artery was patent, whereas the sequential bypassed graft was occluded. The patency ratio of radial artery anastomosis was 33% (1/3). Twelve of the 17 saphenous vein grafts were patent (70.58%). The total number of patent distal anastomosis was 30/38 (78.94%). When compared with the graft patency of patients without infection, it was found that mediastinitis does not affect the graft patency rates adversely.     

Femoropopliteal bypass in elderly diabetic patients.

The records of sixty-nine consecutive elderly diabetic patients over age 70 years who underwent femoropopliteal bypass at the New England Deaconess Hospital from 1966 to 1975 were reviewed and analyzed statistically. Grafts were classified as patent only if the patient had a palpable distal pulse postoperatively. No hospital deaths occurred. The patency rate declined with decreasing runoff below the knee. Patients receiving insulin had a patency rate of 7 per cent, compared with a rate of 35 per cent in patients treated with diet or oral agents (p < 0.05). Cross analysis disclosed no other significant difference between these two groups. No benefit from Dextran was demonstrable in our series. Graft closure carried a 36 per cent risk of above knee amputation. Life table analysis of patients who underwent autogenous vein graft (fifty-seven patients) showed one and three year patency rates of 72 and 56 per cent, respectively. Conversely, grafts of Dacron had one and three year patency rates of 48 per cent and less than 10 per cent, respectively. In a favorable subset of twenty-six patients who (1) were receiving insulin, (2) had either previously successful bypass or no previous vascular surgery, (3) had arteriographic evidence of one or more vessel runoff, and (4) had autogenous vein grafts, the one and three year patency rates were 91 and 82 per cent, respectively. Our experience shows that femoropopliteal bypass is safe and effective when patients are carefully selected. We strongly discourage the use of Dacron materials in elderly diabetic patients.     

Reliability of intraoperative flow measurements to determine early graft patency with simultaneous introduction of a new method for distal coronary artery run-off capacity

Intraoperative measurements of blood flow were made in 44 patients in whom a total of 112 venous bypass grafts were inserted. Blood flow through the graft was measured by a standard electromagnetic device as well as by a new method, consisting of a roller pump run-off system. At an average of 5 months after operation all patients underwent control coronaro-angiography. Overall patency-rate was 86.6%. Using the standard method mean flow in the patent grafts was 78 ml/min and 39 ml/min in the occluded grafts. Using the new run-off method mean flow in the patent grafts was 142 ml/min and 78 ml/min in the occluded grafts. It is concluded that measuring distal coronary artery run-off capacity provides a reliable index for predicting patency rate. For several reasons roller-pump run-off measurement has advantages over the generally used electromagnetic measurements.     

IMA-graft patency control by thermal coronary angiography during coronary bypass surgery.

Thermal coronary angiography (TCA) was evaluated for the intraoperative assessment of graft patency and flow in internal mammary artery (IMA) bypass grafts. TCA was performed in 210 patients undergoing 460 vein and 153 IMA bypass grafts after completion of the distal anastomoses. The IMA grafts and the recipient coronary arteries were delineated by the temperature differential between a cold epimyocardium and the perfusing warm blood after bulldog clamp release. TCA provided information about graft and anastomosis patency, initial flow patterns, and native coronary stenoses. TCA was performed in all studied IMA bypass grafts: 142 grafts were patent. Low flow but patency was observed in 24 IMA grafts and 11 IMA grafts showed no flow. Subsequently, 8 anastomotic failures and 3 proximal IMA graft occlusions were encountered. Based on these findings, 8 anastomoses were successfully revised and 7 additional vein grafts were added. One low flow IMA graft was not revised leading to postoperative ST elevation. Thirty-one distal native coronary stenoses were detected in the recipient LADs, 3 of which were not seen in the preoperative cineangiogram. In 20 instances, TCAs were obscured by an excess of fat or myocardium impeding image analysis. In 8 cases, TCA results were confirmed by conventional angiography postoperatively showing an excellent correlation in all cases. We conclude that intraoperative TCA demonstrates early IMA graft function and initial flow patterns. During our study, TCA documented a 7.2% IMA graft early failure rate. Intraoperative decision making was aided by TCA in 9.2% of all IMA grafts; this confirmed the clinical relevance of TCA.     

Noninvasive color Doppler inspection of small-diameter vascular grafts implanted in canine carotid and femoral arteries

To noninvasively evaluate a small-diameter vascular graft (approx. 4 mm in diameter) developed for coronary artery bypass application, a state-of-the-art color Doppler flow mapping system was applied to inspect various grafts implanted in 5 canines. The grafts, including Denaflex, Gore-Tex ePTFE, and Bioflow, were implanted interpositionally in the carotid and femoral arteries. Inspections were conducted with a 5 MHz linear vascular transducer at 6 weeks postimplantation and 12 weeks postimplantation, immediately prior to retrieval. In the carotid artery position, all 5 Denaflex grafts were patent throughout the implantation period while 2 of the 5 Gore-Tex grafts were occluded at 6 weeks, and 1 more was occluded at 12 weeks. In the femoral artery position, all 5 Denaflex grafts were patent at 6 weeks; however 2 were occluded at 12 weeks. For the Bioflow grafts at 6 weeks, 3 were patent, and 2 were occluded. The same results were observed at 12 weeks. The color Doppler inspection results indicated a higher patency rate in the carotid artery position than in the femoral artery position. Furthermore, the volumetric flow rate and the wall shear stress measured with the pulsed Doppler in the carotid artery were greater than in the femoral artery. These findings suggest that the hemodynamic "environment" in which the graft was implanted may affect the graft patency rate. The Doppler inspection results obtained at 12 weeks, identical with those observed after retrieval, demonstrated that color Doppler flow mapping is a reliable method to noninvasively inspect blood flow through small-diameter vascular grafts.     

Internal mammary artery grafts: technical factors influencing patency

Eight hundred fourteen patients with internal mammary artery (IMA) coronary artery bypass grafts have been restudied 961 times with coronary arteriography, primarily to evaluate the patency of the grafts in the setting of symptomatic coronary occlusive disease. Their records were reviewed to assess graft patency as related to the technical aspects of coronary artery bypass surgery. Patency was evaluated using life-table analysis of the data. The method of harvesting the IMA played no role in patency. The left anterior descending coronary artery was the recipient coronary artery with the highest patency rate. The left IMA had a significantly higher patency rate than the right IMA. As a group, the IMAs had a significantly higher patency rate than saphenous vein grafts. However, there was no difference between right IMA grafts and saphenous vein grafts. The mammary artery grafts that remained patent throughout the study had a significantly higher blood flow after bypass than did those that became occluded (43.0 +/- 0.9 versus 28.9 +/- 1.8 ml/min; p less than .001).     

Incidentally detected stenoses proximal to grafts originating below the common femoral artery: do they affect graft patency or warrant repair in asymptomatic patients?

OBJECTIVE: Stenoses in infrageniculate arteries proximal to a lower extremity vein graft may reduce flow velocity through the bypass graft and are thought to predispose to graft occlusion. Repair of these lesions has been recommended to preserve graft function. This study was undertaken to better define the natural history of grafts below inflow lesions and to evaluate the necessity of repair to preserve graft patency. METHODS: From 1994 through 1999, patients undergoing lower extremity vein grafts by a single surgeon at a university hospital and an affiliated teaching hospital were placed in a prospective protocol for proximal infrageniculate native artery and graft surveillance through use of duplex scanning. The records of those patients with grafts originating distal to the common femoral artery were evaluated; they form the basis for this report. Arteriograms were obtained before bypass grafting, and no patient had a stenosis greater than 50% diameter reduction proximal to the graft origin. Follow-up scans were obtained from the common femoral artery through the graft and outflow artery. The peak systolic velocity and velocity ratio in an infrageniculate native artery proximal to the graft origin were recorded, as were the location and the time interval since the bypass graft. Repair of these proximal lesions was not performed during the course of this study. Revision of the bypass graft or its anastomoses was undertaken according to preestablished duplex scan criteria. RESULTS: During this time, 288 autogenous infrainguinal bypass grafts were performed, of which 159 originated below the common femoral artery; of these, 74 were from the superficial femoral artery, 29 from the profunda femoris artery, 49 from the popliteal artery, and 7 from a tibial artery. The maximum peak systolic velocity proximal to the graft origin was more than 250 in 38 arteries (25%) and more than 300 in 26 arteries (16%). The velocity ratio was 3.0 or more in 32 arteries at the same location as the peak systolic velocity and 3.5 or more in 23 arteries (15%), confirming hemodynamically significant stenoses at these sites. The location of peak systolic velocity was the common femoral artery in 81 patients (51%), the superficial femoral artery in 50 (31%), the popliteal artery in 22 (14%), and a tibial artery in 6 (4%). Follow-up ranged from 8 to 60 months (mean, 35 months). During follow-up, 19 patients died, 18 with patent grafts. Overall, nine grafts occluded. One of the occluded grafts had a velocity ratio greater than 3.0; this may have contributed to graft thrombosis. The other occlusions resulted from an unrepaired graft lesion in 2 patients, graft infection in 2 patients, and graft ligation necessitated by below-knee amputation in 2 patients. No cause for the occlusion could be identified in two of the grafts (neither had evidence of proximal arterial stenosis). Assisted primary patency rates were 95% and 91% at 3 and 5 years, respectively. CONCLUSIONS: For grafts originating distal to the common femoral artery, stenoses proximal to the graft do not affect bypass graft patency and do not require repair to prevent graft occlusion. Surveillance of these lesions may therefore be unnecessary, inasmuch as the repair of proximal lesions should not be undertaken to preserve graft function.     

Nonanastomotic aneurysms in venous homologous grafts and bovine heterografts in femoropopliteal bypasses

In the absence of a suitable autologous vein for a long distal femoropopliteal bypass, the homologous vein appears to be a good substitute. However, the patency rate after one year is less than 50 per cent and nonanastomotic aneurysms occurred in one third of our patients followed for more than one year. These two complications may be related to an immune response which may be lessened by preservation of the graft in the frozen state.Bovine heterografts function well when placed subfascially for femoropopliteal bypasses ending above the knee. Failure rate is high when the distal end of the graft extends across the knee joint. In our experience nonanastomotic aneurysms have developed in 50 per cent of patent grafts followed for more than one year, although other surgeons have reported an incidence of only 3 to 20 per cent.In the follow-up of twenty-three venous homografts and twenty bovine heterografts placed as femoropopliteal bypasses, eight nonanastomotic aneurysms appeared and required replacement. This occurrence was noted in more than 33 per cent of grafts patent beyond one year. When an adequate autologous vein is not available, the composite Dacron-vein graft is the best substitute.     

The comparison of the graft patency after coronary artery bypass grafting using coronary angiography and multi-slice computed tomography.

OBJECTIVE: Coronary angiography (CAG) is the gold standard method in evaluating graft patency following coronary artery bypass grafting (CABG), even though there are several kinds of non-invasive methods. Recently developed multi-slice CT (m-CT), having effective scan times up to 0.25 s and multi-row detector array systems, enable rapid imaging of cardiac structures, including coronary arteries during one breath-hold. We compared m-CT with CAG for the evaluation of graft patency following CABG. METHODS: Forty-two patients having undergone m-CT and CAG within 3 months of CABG were studied. Twenty-three patients underwent conventional CABG and 19 off-pump CABG. A total of 125 grafts were used, including 42 left internal mammary arteries (LIMA), 25 radial arteries (RA), 3 right internal mammary arteries (RIMA) and 55 vein grafts. RESULTS: CAG showed a 96% (120/125) patency rate (1 LIMA, 2 RA and 2 vein grafts were occluded). m-CT showed a 98% (122/125) correct positive ratio with a sensitivity and specificity of 98 and 100%, respectively. The sensitivity in LIMA, RA, RIMA and vein grafts was 98, 91, 100 and 100%, respectively, with 100% specificity for all. There was an equivocal result in the competitive grafts with native coronary artery that were patent in the CAG, but faint opacification with no significant flow in the m-CT. CONCLUSIONS: This study showed that m-CT was very simple, useful and accurate in evaluating graft patency during the early post-operative period following CABG, even though there was an equivocal result in the competitive grafts with a native coronary artery.     

Clinical and angiographic assessment of complex mammary artery bypass grafting

The internal mammary artery has become the coronary bypass graft of choice in recent years because of enhanced long-term patency. Along with this trend, sequential, bilateral, and free mammary grafts have been employed more frequently in an effort to maximize the number of distal internal mammary anastomoses. This approach of maximally using the internal mammary artery (complex mammary grafting) seems logical, but at present little information about patency of the newer types of internal mammary artery grafts is available to justify the more complicated procedures. Over a 15 month period, 207 patients underwent bypass graft angiography from 1 to 32 weeks after operation. This is an 85% restudy rate for a consecutive series of coronary bypass procedures. Patency was defined as complete filling of the graft and distal vessel bypassed. A total of 841 distal vessels were grafted, or 4.1 per patient. The overall patency rate was 91% for 503 distal vein graft anastomoses and 99% for 338 internal mammary artery grafts. Individual patency rates of distal anastomoses, expressed as number patent/total (percent patent), were as follows: simple vein grafts, 262/285 (92%); sequential vein grafts, 196/218 (90%); left internal mammary artery to left anterior descending coronary artery, 109/110 (99%); left internal mammary to circumflex marginal artery, 14/14 (100%); right internal mammary to right coronary artery, 19/20 (95%); right internal mammary to left anterior descending coronary artery, 10/10 (100%); right internal mammary to circumflex marginal artery via transverse sinus, 18/20 (90%); sequential left internal mammary artery to left anterior descending system, 133/134 (99%); sequential left internal mammary to circumflex marginal system, 15/15 (100%); free internal mammary artery, 9/9 (100%); free sequential internal mammary artery, 6/6 (100%). Of the 18 patent transverse sinus right internal mammary grafts to the circumflex marginal artery, three exhibited very slow flow and probably were not functional. The hospital mortality associated with internal mammary revascularizations was 0.4% for nonemergency cases and 3.1% for emergency procedures. On the basis of clinical and postoperative graft patency data, expanded use of more complicated types of mammary grafts seems justified. Function of the right internal mammary graft to the circumflex marginal artery was suboptimal, and this method has been discontinued. All other complex mammary techniques had excellent patency rates as compared to vein grafts, and these differences may become even more significant in the late postoperative period.(ABSTRACT TRUNCATED AT 400 WORDS)