Adjunct endarterectomy of the left anterior descending coronary artery

During a three-year period, complete revascularization of diffusely diseased left anterior descending (LAD) coronary arteries was accomplished by extensive endarterectomy in conjunction with bypass grafting in 37 patients in whom conventional bypass was not feasible. This group constituted 7.0% of all patients undergoing nonemergency coronary revascularization during this period. The left internal mammary artery was used to bypass the endarterectomized LAD artery in 22 patients. There was 1 (2.7%) operative death and 1 perioperative myocardial infarction. At follow-up, which was 100% with a mean of 41.4 months, all endarterectomy patients were in New York Heart Association Functional Class I or II. Twenty-four endarterectomy patients underwent first-pass radionuclide angiographic stress testing 20 months after operation. Twenty patients (83%) had excellent postoperative exercise tolerance, achieving 5 to 7 mets on treadmill testing. Left ventricular functional reserve was preserved, as evidenced by an increase of global ejection fraction from 48 +/- 15% at rest to 59 +/- 18% (p less than 0.005) with exercise. A similar increase was measured in the proximal and distal anterior wall segmental ejection fractions. No difference in response to exercise was found between the internal mammary artery and the vein graft groups. Thus, complete revascularization of the diffusely diseased LAD artery can be accomplished by adjunct endarterectomy without added morbidity or mortality and with excellent functional results.     

Expanded use of internal mammary artery graft for myocardial revascularization

To improve the early and late benefits of coronary artery bypass grafting, use of internal mammary artery grafts was expanded. The first 60 patients to receive two mammary artery-coronary artery anastomoses and supplemental saphenous vein grafts are reviewed. Altogether 210 grafts (3.5/patient) were performed, including 54 mammary artery grafts in situ, six of them as free grafts. In 12 patients the right internal mammary artery was placed through the transverse sinus to revascularize the circumflex artery, and the left mammary artery was placed to the left anterior descending artery. In the remaining 48 patients both internal mammary arteries were used to revascularize the left anterior descending and the right coronary artery. There were no perioperative deaths and no sternal infections. Postoperative complications included re-exploration for bleeding and diaphragmatic dysfunction. Late follow-up was complete. Of 60 patients observed for 1/2 to 4 years, 57 were asymptomatic. Exercise stress tests were performed in 58 cases and were normal in 56.     

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)     

Bilateral Internal Mammary Artery Grafts in Patients with Left Main Coronary Artery Disease

The use of the internal mammary artery (IMA) in myocardial revascularization has been expanded with bilateral and sequential grafting. However, its application in the presence of left main coronary artery stenosis (LMCAS) has not been well established. From September 1983 through December 1990, 280 patients with LMCAS greater than 50% were revascularized (3.4 mean grafts per patient) with bilateral IMA and saphenous vein grafts. Eighty-one were sequential IMA grafts. There were 234 males (83.6%) and 46 females (16.4%) with a mean age of 64.4 years (range 39 to 84 years). Preoperatively, there were six patients (2.1%) in New York Heart Association (NYHA) Class I, 30 patients (10.7%) in Class II, 130 patients (46.4%) in Class III, and 114 patients (40.7%) in Class IV. Fifty-six patients (20.0%) had an ejection fraction less than 50%. In-traaortic balloon counterpulsation was used preoperatively in 26 patients (9.3%) and intraoperatively in 11 patients (3.9%). There were four hospital deaths (1.4%). Hospital complications included: reoperation for bleeding, 7 patients (2.5%); pulmonary insufficiency, 21 patients (7.5%); perioperative infarction, 14 patients (5.0%); and stroke, 4 patients (1.4%). Follow-up was obtained in 276 hospital survivors (100.0%) with a mean of 33.4 months. There were 20 late deaths (7.1%): seven cardiac related and 12 noncardiac related. Postoperative assessment reveals substantial functional improvement. These results furnish evidence that bilateral IMA grafts can be accomplished with a low operative risk and can provide excellent functional results in patients with LMCAS.     

非体外循环冠状动脉旁路移植术围手术期心肌梗死发生率与移植血管血流量的关系

目的探讨冠状动脉旁路移植术（CABG）中移植血管血流量与围手术期心肌梗死（MI）发生率之间的关系,为临床提供借鉴。方法采集2010年1～6月在北京大学第一医院连续58例因冠心病接受单纯择期非体外循环冠状动脉旁路移植术（（）PcAB）患者的临床资料。术中均采用左乳内动脉（I,IMA）吻合于左前降支（I．AD）,其他靶血管则以大隐静脉（SV）作为旁路移植血管,在关胸前循环状态稳定条件下,应用瞬时流量测定技术测量各移植血管的血流量,并计算移植血管总血流量。根据术后是否发生围手术期MI,将患者分成两组：MI组11例,其中男7例,女4例;年龄67．4±10．3岁;非MI组,47例,其中男38例,女9例;年龄63．3±9．9岁。分析两组患者术前及术中的相关危险因素。结果MI组与非MI组的手术时间差异无统计学意义（205．44±59．6rainVS．183．4±32．4min,t=1．69l,P=0．096）。MI组与非MI组移植血管数量（3．00±1．oo支VS．2．96±0．78支,t=0．154,P=0．878）、LIMA-LAD移植血管血流量（15．40±）1．37mi／minVS．16．50±10．83mJ／min,f=0．301,P=0．764）差异均无统计学意义;MI组与非MI组移植血管总血流量（41．03土19．50ml／minVS．64．09±32．44ml／min,t=2．254,P=0．028）差异有统计学意义。移植血管总血流量〈48．5ml／min为发生MI的危险因素EoR：4．706,95％CI（1．099,20．147）]。结论移植血管总血流量可在一定程度上预测CABG后急性心肌缺血事件的发生,总血流量〈48．5ml／min的患者术后发生围手术期MI的概率将明显增加。     

Coronary artery operation in radiation-associated atherosclerosis: long-term follow-up.

Radiation-associated coronary atherosclerosis is a potential problem for patients who have had mediastinal irradiation for malignant tumors. This study identified 14 patients with radiation-associated coronary atherosclerosis, defines unique population characteristics, and analyses postsurgical problems and long-term outcome. Fourteen patients with radiation-associated coronary atherosclerosis and class III and IV New York Heart Association symptoms were identified because of mediastinal or chest wall irradiation (30 Gy) associated with anterior epicardial discoloration or fibrosis, aortitis with adventitial thickening, and inflammatory process over a proximal coronary artery. Two distinct treatment groups were analyzed. Coronary artery operation resulted in one hospital death, with vein grafts being used predominantly. The internal mammary artery could only be used in 3 patients because of vessel friability and mediastinal fibrosis. Postoperative right ventricular dysfunction and pulmonary problems were frequent. Severe pericardial inflammatory complications (fibrosis with graft closure, and constrictive pericarditis) present in 2 early patients resulted in routine anterior pericardiectomy after coronary artery operation without further problems. Long-term follow-up (100%) (range, 11 to 74 months) revealed that 1 patient died late and of the remainder (12 patients), 11 were in New York Heart Association class I and 1 in class II, experiencing three myocardial events. Thus, patients with radiation-associated coronary atherosclerosis have a low operative mortality but have risk of early right ventricular and pulmonary dysfunction. The routine use of internal mammary artery may not be possible and anterior pericardiectomy is recommended. Long-term results are excellent and no evidence of accelerated disease has been noted.     

Multivessel coronary revascularization without saphenous vein: long-term results of bilateral internal mammary artery grafting

When the saphenous vein is absent or inadequate, options for multivessel coronary revascularization include bilateral mammary artery grafting and the use of conduits of unproven durability (arm vein, homologous umbilical vein, prosthetic graft). To evaluate the long-term effectiveness of bilateral mammary artery grafting, we reviewed the cases of 76 consecutive patients with multivessel disease (33 with two-vessel disease, 43 with three-vessel disease) who underwent revascularization with bilateral mammary artery grafts only during the period from 1971 to 1980. No hospital deaths occurred. Thirty-three free and 119 in situ grafts were used. Late follow-up was complete, ranging from 12 to 132 months (mean interval, 67 months) and revealed improvement by at least one New York Heart Association functional class in 59 of 71 survivors. Postoperative arteriograms (mean interval, 26 months) of 55 grafts in 28 patients showed that 49 grafts were patent (89%). Five late deaths (2 noncardiac) occurred. Actuarial survival was 97.2% to seven years and 90.2% at nine years after operation. Bilateral mammary artery grafting yielded excellent graft patency, relief of symptoms, and long-term survival. When saphenous vein is unsuitable for grafting, bilateral mammary artery grafts should be utilized before other conduits are considered.     

Evaluation of postoperative flow reserve in internal mammary artery bypass grafts

The internal mammary artery has been advocated for use in bypass grafting owing to its superior long-term patency when compared to saphenous vein grafts. Concern exists that the flow through the internal mammary artery may be inadequate during periods of peak myocardial demand. This flow was investigated in 24 consecutive patients with a mean proximal left anterior descending artery stenosis of 87.5% who were selected for coronary bypass using the internal mammary artery. Within 8 weeks of operation, all were evaluated by exercise thallium 201 scintigraphy. Thallium activity, expressed as a ratio of anteroseptal activity to posterolateral wall activity (or inferior wall activity if the posterolateral wall was deemed abnormal), was 0.97 +/- 0.15. A second group of 25 patients, with normal coronary arteries, was similarly evaluated. The mean septal to posterolateral wall thallium activity ratio for these control patients was 1.0 +/- 0.15. A third group of 26 patients who underwent single-vessel percutaneous transluminal coronary angioplasty of the left anterior descending artery and a fourth group of 28 saphenous vein graft recipients were compared by stress thallium scintigraphy. Thallium 201 activity for the vein graft group (0.96 +/- 0.19) was not significantly different from that for the mammary artery group, whereas the flows obtained with a single attempt at angioplasty were significantly inferior (p less than 0.05). The internal mammary artery provides excellent coronary flow at peak myocardial demand and compares favorably to angioplasty and saphenous vein grafting.     

The effects of coronary revascularization on left ventricular function in ischemic heart disease

Although it is well established that coronary revascularization can reverse exercise-induced ischemic dysfunction, the effects on resting ventricular performance are controversial. From a group of 183 patients receiving surgical therapy for ischemic heart disease, 166 underwent bypass graft arteriography at an average of 7 to 14 days postoperatively. In 149 patients, satisfactory preoperative and postoperative biplane left ventriculograms were obtained. Regional wall motion was assessed by the 100 segment method of Sheehan and Dodge, and a perioperative change in shortening greater than 2 standard deviations of normal variability over 20 or more adjacent segments was considered significant. Ninety-five patients had stable or progressive angina, 88 had medically refractory unstable angina, 155 were in New York Heart Association Class IV, and 37 had a preoperative left ventricular ejection fraction of less than 0.4. Myocardial integrity was preserved with crystalloid cardioplegia and topical hypothermia. Seven hundred ninety-eight bypass grafts were performed (522 vein grafts and 276 mammary artery grafts), and 13 patients had concomitant left ventricular aneurysmectomy. Hospital mortality was 2.2%. The overall early graft patency rate was 95.9% (93.7% for vein grafts and 100% for mammary arteries). Only one patient had a decrement in regional wall motion, and 51 (37%) had significant postoperative improvement (27 in the unstable angina group and 24 in the stable angina group); in the patients with improved regional wall motion, ejection fraction increased by an average of 0.18 (p less than 0.01). Ejection fraction also improved after aneurysmectomy, and the increment seemed to result from both a reduction in end-diastolic volume and improved regional wall motion. Thus, reversible ischemic myocardial dysfunction appears to be common in the general population of patients undergoing coronary artery bypass grafting; 40% of patients with unstable angina and 34% of those with stable angina can be expected to have improved regional wall motion after successful revascularization. Finally, ventricular aneurysm resection significantly enhances left ventricular performance as assessed by ventriculographic ejection fraction.     

Coronary artery bypass grafting with the right gastroepiploic artery

The excellent results of coronary artery bypass with the internal mammary artery and the increasing numbers of patients who need coronary reoperations, but for whom conventional bypass conduits are not available, have prompted us to evaluate alternative arterial bypass conduits. The right gastroepiploic artery has been used as a coronary bypass graft in 36 patients (32 men), whose ages ranged from 29 to 71 years. Twenty-two patients had had previous coronary bypass grafting and six of these were undergoing their third bypass operation. The right gastroepiploic artery was used as an in situ graft to the right coronary artery or circumflex branches for 17 patients and as an aorta-coronary ("free") graft in 19 patients, six to the left anterior descending or diagonal, six to the circumflex, and seven to the right coronary artery. In conjunction with right gastroepiploic artery grafting, 16 patients received bilateral internal mammary artery grafts and 17 received one internal mammary artery graft. Histologically, right gastroepiploic artery segments from 18 patients could not be distinguished from internal mammary artery segments, and no evidence of atherosclerosis was found. Two patients died in the hospital, one intraoperatively and one 3 months after the operation, of a perioperative stroke. Perioperative morbidity included wound complication in three and reexploration for bleeding in two. At late follow-up 1 to 38 months after operation, two late deaths had occurred and 21 patients were free of symptoms. Postoperative angiography (postoperative interval 1 week to 13 months) was performed in nine grafts, three in situ grafts to the right coronary artery and six free grafts that included two to the left anterior descending, three to the circumflex, and one to the right coronary artery. All right gastroepiploic artery grafts were patient. The right gastroepiploic artery is an arterial conduit that can be used as an in situ graft to posterior coronary vessels and as a free graft to any coronary arterial system. Early graft patency has been excellent, and the histologic similarity between the right gastroepiploic artery and the internal mammary artery suggest that the long-term results will be favorable.     

Twelve-year experience with bilateral internal mammary artery grafts

A 12 1/2-year experience with 227 patients who underwent coronary revascularization with bilateral internal mammary artery (IMA) and supplemental saphenous vein grafts is presented. There were 725 coronary grafts performed (3.2 per patient). Forty-four IMA grafts were sequential. In 42 patients, the right IMA was placed through the transverse sinus to revascularize the circumflex artery. Operative mortality was 4% (9 of 227 patients). Postoperative complications included sternal infection (4 patients), reexploration for bleeding (5), and diaphragmatic dysfunction (10). Postoperative arteriography in 30 patients (mean interval, 4 1/4 years) revealed that 92% (34/37) of the left IMA and 87% (26/30) of the right IMA grafts were patent. Late follow-up was complete in 207 surviving patients. Eighteen late deaths (9 cardiac and 9 noncardiac) occurred. Actuarial survival was 83% at 10 years after operation. Of 68 patients followed from 8 to 12 1/2 years (mean interval, 10 1/2 years), 69% were asymptomatic, and 28% were in New York Heart Association Functional Class II. We conclude that bilateral IMA grafting can be accomplished with low operative risk and provides excellent long-term results.     

Internal mammary artery revascularization in the patient on long-term renal dialysis

Twenty-six patients on long-term renal dialysis underwent coronary artery bypass grafting. The patients were divided into two groups: group 1, (16 patients) saphenous vein bypass grafts, and group 2, (10 patients) internal mammary artery in combination with saphenous vein bypass grafts. Both groups were similar in terms of cardiac hemodynamics and previous number of myocardial infarctions, though more group 1 patients were in New York Heart Association class III or IV. Patients in group 1 received 2.9 bypass grafts per patient; patients in group 2 received 4.0 bypass grafts per patient (4 with bilateral mammary arteries). No wound healing problems occurred in either group. Blood replacement was similar for both groups (group 1, 5.5 units/patient; group 2, 5.3 units/patient). More platelets were given to group 1 patients (16.2 units/patient) than group 2 patients (3.1 units/patient). We conclude that use of the internal mammary artery in patients on long-term renal dialysis does not alter wound healing or increase blood loss in this subset of patients.     

Triple sequential grafts using the internal mammary artery. An angiographic and short-term follow-up study.

Between December 1984 and December 1988, coronary artery bypass operations, involving the use of 119 sequential internal mammary artery grafts with three or more anastomoses per conduit, were performed in 116 patients. Patients included 14 women and 102 men, with a mean age of 60 years. They received a total of 629 anastomoses; 373 anastomoses were used in multiple sequential arterial bypass grafts; 116 sequential left and three right internal mammary artery jump grafts were performed. There were 27 patients with bilateral internal mammary artery grafts, but only 17 had completely arterial revascularizations. Perioperative infarction occurred in 3.4% of the patients; 1.7% of infarctions were related to sequential internal mammary artery grafts. There were no hospital deaths. Control angiography was performed within a month of the operation in 72 patients (with 371 anastomoses, of which 229 were in sequential arterial bypass grafts). The overall patency rate was 94.6%, and for the internal mammary artery sequential graft with three or more anastomoses it was 96.1%. The mean follow-up period was 13 months; 110 patients were in New York Heart Association class I; there was one non-cardiac-related death, and three patients (2.6%) had a late myocardial infarction. One was related to the area revascularized by the sequential internal mammary artery graft. Multiple sequential internal mammary artery bypass grafts in coronary artery disease are feasible, with a high short-term patency and a low perioperative morbidity and mortality.     

Seventeen-year experience with bilateral internal mammary artery grafts

The internal mammary artery (IMA) is being recognized as the conduit of choice for myocardial revascularization. From January 1972 through June 1988, 1,087 patients received bilateral IMA and supplemental vein grafts. There were 917 men (84.4%) and 170 women (15.6%) with a mean age of 62.4 years (range, 29 to 84 years). Three hundred ninety-four patients (36.2%) had unstable angina, and 194 (17.8%) had left main coronary artery stenosis greater than 50%. In all, 3,741 coronary grafts were performed, with a mean of 3.4 per patient. Hospital mortality was 2.7% (29 patients). Hospital complications included reoperation for bleeding, 19 patients (1.7%); sternal infection, 16 patients (1.5%); respiratory failure, 35 patients (3.2%); perioperative myocardial infarction, 22 patients (2.0%); and stroke, 20 patients (1.8%). Post-operative arteriography in 53 patients (mean postoperative time, 53.0 months) showed that 92.1% (58/63) of the left IMA and 84.9% (45/53) of the right IMA grafts were patent. Follow-up was completed on 1,058 hospital survivors. There were 82 late deaths (7.8%). The actuarial survival for patients discharged from the hospital was 80.0 +/- 3.2% (plus or minus standard error of the mean) at 10 years and 60.0% +/- 5.0% at 15 years. At follow-up, 866 patients (90.3%) were asymptomatic and in New York Heart Association class I and 68 (7.1%) were in class II. This longitudinal analysis demonstrates that bilateral IMA grafting has a low operative risk and provides excellent long-term functional improvement and survival.     

Off-pump redo coronary artery bypass grafting

BACKGROUND: Conventional redo coronary artery bypass grafting is associated with significant morbidity. The danger of reoperation is mainly in reopening the sternum and in the manipulation of the heart and the old grafts. Therefore, off-pump redo coronary artery bypass grafting with a patient-specific approach in selected cases seems an ideal technique. METHODS: Between October 1995 to September 1999, 50 patients with mean age of 61.8+/-8 years underwent reoperative coronary artery bypass grafting without cardiopulmonary bypass. Isolated left internal mammary artery (LIMA) to left anterior descending artery (LAD) anastomosis was carried out in 25 cases through left anterior minithoracotomy. In 1 patient LIMA was grafted on a previous vein graft to LAD, which was critically stenosed proximally but distal anastomosis was patent. In another case LIMA was grafted to Ramus intermedius branch. Midsternotomy approach was used to carry out LAD and right coronary artery grafting in 21 cases. In 2 patients a posterolateral thoracotomy approach was used to bypass obtuse marginal branches without cardiopulmonary bypass; in these cases proximal anastomosis was performed on the descending aorta. RESULTS: Mortality rate was 4% (2 deaths). Two patients sustained perioperative myocardial infarction. No patient was reexplored for hemorrhage and 38 patients did not require homologous blood transfusion. Sixteen patients underwent check angiogram and all of them were found to have patent redo grafts. Cardiac recovery room stay was 22+/-7 hours and hospital stay 5+/-2 days. CONCLUSIONS: In selected patients, reoperative coronary artery bypass grafting can be performed without cardiopulmonary bypass with a low perioperative morbidity and mortality and satisfactory graft patency.     

Advantage of internal thoracic artery for coronary arterial bypass surgery in patients over 70 years of age]

Between April 1988 and September 1991, 16 among 23 patients over 70 years of age underwent coronary bypass grafting (CABG) with at least one arterial graft. The age ranged from 70 to 77 years (mean, 72.1 years) and involved coronary lesions were two vessels in two patients and three vessels in 14 patients. Seven patients with unstable angina received emergency CABG. The number of distal anastomosis with arterial graft was mean of 1.3 per patient and left internal thoracic artery (ITA) was used as a pedicled graft in all patients. Sequential grafting with left ITA arterial graft was performed in two and right gastroepiploic artery was concomitantly used in three patients. No atherosclerosis was seen in left ITA, however, poor quality saphenous vein graft (SVG) was in five and atherosclerosis of ascending aorta was in five patients. After operation deep vein thrombosis of leg after harvesting SVG occurred in one patient. The angiogram performed within one month of operation in nine patients showed that the patency rate of arterial graft was 100% and that of SVG was 94.4%. The longest follow-up period was 42 months and New York Heart Association Functional Class improved to Class I or II in all patients. The use of pedicled ITA in elderly patient showed advantage for diseased ascending aorta and it seemed to prevent the postoperative complication due to the use of SVG.     

Fifteen-year results of coronary artery bypass for isolated left anterior descending coronary artery disease

During 1971 through 1975, 266 patients underwent primary coronary artery bypass grafting for occlusive disease confined to the left anterior descending coronary artery. Actuarial survival at 15 years was 72.7% with 60% of survivors being free from angina. Although the cause of death was cardiac related in 50% of the patients who died, survival was comparable with that of an age-matched and sex-matched general population. During follow-up, 48 secondary or tertiary repeat coronary artery bypass as well as 44 percutaneous transluminal coronary angioplasty procedures were performed. Acute event-free status (freedom from acute myocardial infarction, repeat coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, or death) persisted at 15 years in 43.2% of patients. The differences in survival when patients were segregated according to age, sex, number of grafts performed, or graft conduit (internal mammary artery versus vein) were not significant. However, comparison of graft conduits revealed a significantly better (p = 0.02) overall acute event-free survival when the internal mammary artery was used.     

Endarterectomy of the LAD and internal mammary artery grafting. A reliable association

Endarterectomy of the left anterior descending (LAD) coronary artery and concomitant myocardial revascularization with the internal mammary artery (IMA) were performed in five men aged 52-62 years. There was no perioperative myocardial infarction and no hospital mortality. Early postoperative angiography was performed in four cases and showed patent IMA grafts. The infrequent association of LAD endarterectomy and IMA grafting in the literature is commented on. The authors recommended myocardial revascularization with the IMA in all cases of LAD atherosclerosis, even though the condition is severe and diffuse, requiring endarterectomy.     

Comparative anatomic studies of various arterial conduits for myocardial revascularization

Comparison was made between the morphologic condition of the left anterior descending artery and four arterial conduits: the internal mammary, right gastroepiploic, inferior epigastric, and radial arteries, harvested from 17 patients (aged 15 to 85 years, mean 64 years) who had died of nonvascular diseases. Proximal, mid, and distal segments were examined microscopically. The internal mammary artery was elastic, but the others were muscular. In all four conduits, atherosclerosis was absent to mild, the internal elastic lamina showed only minimal defects, and the vasa vasorum were confined to the adventitia. In all cases the left anterior descending artery showed mild to severe atherosclerosis and substantial defects in the internal elastic lamina with penetration of the vasa vasorum into the media and intima. Comparison of the mean distance (+/- standard deviation) from the lumen to the outermost portion of the media for the left anterior descending artery (320 +/- 63 microns) with the four conduits gave comparable values for the internal mammary artery (350 +/- 92 microns); p = not significant) and the right gastroepiploic artery (291 +/- 109 microns; p = not significant), versus 529 +/- 52 microns; p less than 0.002) for the radial artery and 249 microns (+/- 87 microns) (p less than 0.04) for the inferior epigastric artery (Kruskal-Wallis and Mann-Whitney U tests). The relatively scanty presence of smooth muscle cells in the thin-walled media of the internal mammary artery combined with a well-formed internal elastic lamina, even at advanced age, may be an important cause for its low susceptibility to atherosclerosis and a major determinant in its superior long-term patency as a coronary artery bypass graft. This finding emphasizes the justification of continued use of the ideally matching internal mammary artery, either as in situ or free graft, in coronary artery bypass grafting. In contrast to the thick-walled radial artery, which may be relatively prone to ischemia, an acceptable long-term patency of the inferior epigastric artery and right gastroepiploic artery, if harvested as pedicled grafts, is anticipated.