Mid-to-long-term patency comparison of the right internal thoracic artery grafts on the left anterior descending and on the right coronary arteries

BACKGROUND: The excellent results obtained from internal thoracic artery for myocardial revascularization have led surgeons to simultaneous use of other arterial conduits, particularly the right internal thoracic artery. However, some controversy still exists regarding the optimal target coronary artery for this graft; different strategies have been proposed for bilateral internal thoracic artery grafting. PATIENTS AND METHODS: 59 patients with right internal thoracic artery grafts were monitored using coronary arteriography in order to compare the patency of this graft on the left anterior descending and the right coronary arteries. The right internal thoracic artery was grafted to left anterior descending artery in 39 patients (group 1) and to right coronary artery in 20 patients (group 2). RESULTS: The mean period of follow-up was 64.07 months (range: 37 to 185 months). Overall, 8 of the 59 grafts (13.6%) were occluded at the arteriography. In group 1, 1 of 39 (2.6%) grafts and in group 2, 7 of 20 (35%) grafts are found to be occluded. These results are considered statistically significant (p < 0.001). COMMENT: The results show that the patency of the right internal thoracic artery is significantly better on the left anterior descending artery than on the right coronary artery in the mid-to-long term, and patency does not differ from the left internal thoracic artery on the left anterior descending artery.     

Early postoperative occlusion of a left internal mammary artery bypass graft with subsequent restoration of patency.

Total occlusion of a left internal mammary artery (LIMA) bypass graft is a rare complication, and reversal of a documented occlusion has not been reported. This is a case of an early postoperative occlusion of a LIMA graft that was found to be patent 4 months later. A patient with three vessel disease (including a moderate lesion in the proximal left anterior descending artery and a severe lesion in its mid-portion) underwent coronary artery bypass grafting with a LIMA to the mid-left anterior descending artery (LAD) and saphenous vein grafts to the right coronary and left circumflex arteries. Coronary angiography 3 months after surgery revealed a totally occluded internal mammary artery and saphenous vein grafts. The patient then underwent a successful angioplasty of the more distal lesion in the LAD. She subsequently returned with recurrent angina. Repeat coronary angiography revealed rapid progression of the disease in the proximal LAD with the more distal angioplasty site being widely patent. Selective arteriography of the internal mammary artery at that time revealed a patent vessel. Thus, the internal mammary graft is a physiologically active conduit that is dependent on flow dynamics. Competitive flow through the nonobstructive native LAD in combination with impedance of flow through the internal mammary artery due to a severe lesion in the LAD distal to the anastomosis led to a functionally occluded LIMA. When the obstruction in the proximal LAD progressed and the distal obstruction was successfully angioplastied, the flow dynamics in the internal mammary improved, allowing for its dilatation and restoration of patency.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early postoperative occlusion of a left internal mammary artery bypass graft with subsequent restoration of patency

Total occlusion of a left internal mammary artery (LIMA) bypass graft is a rare complication, and reversal of a documented occlusion has not been reported. This is a case of an early postoperative occlusion of a LIMA graft that was found to be patent 4 months later. A patient with three vessel disease (including a moderate lesion in the proximal left anterior descending artery and a severe lesion in its mid-portion) underwent coronary artery bypass grafting with a LIMA to the mid-left anterior descending artery (LAD) and saphenous vein grafts to the right coronary and left circumflex arteries. Coronary angiography 3 months after surgery revealed a totally occluded internal mammary artery and saphenous vein grafts. The patient then underwent a successful angioplasty of the more distal lesion in the LAD. She subsequently returned with recurrent angina. Repeat coronary angiography revealed rapid progression of the disease in the proximal LAD with the more distal angioplasty site being widely patent. Selective arteriography of the internal mammary artery at that time revealed a patent vessel. Thus, the internal mammary graft is a physiologically active conduit that is dependent on flow dynamics. Competitive flow through the nonobstructive native LAD in combination with impedance of flow through the internal mammary artery due to a severe lesion in the LAD distal to the anastomosis led to a functionally occluded LIMA. When the obstruction in the proximal LAD progressed and the distal obstruction was successfully angioplastied, the flow dynamics in the internal mammary improved, allowing for its dilatation and restoration of patency. Therefore, an angiographically occluded internal mammary graft may be only functionally occluded and reversible even when the occlusion is demonstrated several days apart.     

Coronary flow reserve provided by sequential internal mammary artery grafts

Although internal mammary artery bypass grafts have a high patency rate, the adequacy of blood flow through such conduits, particularly if used sequentially, has been questioned. To evaluate this issue, coronary flow reserve was studied in 20 patients after coronary bypass surgery. Nine patients had sequential internal mammary grafts to the diagonal and left anterior descending coronary arteries; five had a single internal mammary graft to the left anterior descending artery and six had sequential saphenous vein grafts. Fifteen additional single vein grafts were also placed in these patients. Coronary flow reserve was measured after contrast-induced hyperemia by a digital subtraction angiographic technique an average of 25 days after surgery. There was no difference in coronary flow reserve between the proximal and distal anastomotic regions in either the sequential internal mammary graft group (2.14 +/- 0.50 versus 2.29 +/- 0.68, n = 8, p = NS) or the sequential vein group (1.77 +/- 0.49 versus 2.08 +/- 0.78, n = 6, p = NS). In addition, the flow reserve provided to either vascular bed of the sequential internal mammary graft was not different from that provided by a single internal mammary graft (1.64 +/- 0.39, n = 5), a single vein graft (1.95 +/- 0.95, n = 15) or nonstenotic native coronary arteries (2.04 +/- 0.87, n = 34). No cases of intracoronary steal were observed. Although some patients had unequal flow reserves between the proximal and distal anastomotic zones, these occurred in the setting of residual coronary stenoses distal to the site of graft insertion or prior myocardial infarction in the grafted distribution.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term patency of bilateral internal thoracic artery Y composite coronary artery bypass grafts—determinants and impact on survival

BackgroundBilateral internal thoracic artery Y-composite grafting with sequential anastomoses is a well-established strategy for multi-arterial coronary artery bypass grafting. This study investigated the factors affecting long-term patency of bilateral internal thoracic artery Y-composite grafts and their influence on survival.MethodsPatients who underwent coronary artery bypass grafting using bilateral internal thoracic artery Y-composite grafts due to triple-vessel disease were included. In total, 415 cases (2003–2020) with at least 1 postoperative coronary computed tomography or angiography examination were enrolled. Through a retrospective review of medical records and computed tomography, risk factors for graft events (string sign or occlusion) were analysed, and the influence of string sign or occlusion in the initial postoperative computed tomography on long-term survival was evaluated.ResultsPatients’ mean age was 66±9 years and 324 were male (78%). The mean number of anastomoses from bilateral internal thoracic artery grafts was 4.0±0.9. The mean follow-up duration was 8.0±4.0 years (interquartile range: 4.8–11.5 years). Beating-heart surgery negatively affected the patency of grafts to the left circumflex and right coronary artery territories (P=0.015 and P=0.030, respectively), but in the left anterior descending territory, the graft patency did not differ (P=0.053). Non-severe (<90%) native-vessel stenosis was a risk factor for poor patency in the left anterior descending, left circumflex, and right coronary artery territories (P<0.001 for all). Twenty-four of the 104 nonvisible or narrowed grafts (23%) on early imaging later became widely patent. Occlusion of the grafts or the string sign within postoperative 1 year did not have a negative impact on long-term survival (P=0.421).ConclusionsThe patency rate was suboptimal in case of non-severe target-vessel stenosis (<90%). The beating-heart technique may negatively influence the patency of anastomoses to the left circumflex and right coronary artery territories. Compromised graft patency observed on initial computed tomography did not lead to worse survival.     

Pedicled right internal mammary artery for reoperative off-pump revascularization of left anterior descending coronary artery

In situ right internal mammary artery is the graft of choice in reoperative off-pump coronary artery bypass grafting, as well as in primary on-pump coronary artery bypass grafting, unless the vessel has been used previously. However, there are not enough data about postoperative angiographic findings of the in situ right internal mammary artery in reoperative coronary artery bypass grafting with the off-pump technique. From September 1993 through January 2004, we reviewed the postoperative course and the graft patency of 12 selected patients who underwent off-pump coronary artery bypass grafting reoperation only for revascularization of the left anterior descending artery, by means of a pedicled right internal mammary artery graft. All patients were evaluated clinically and by postoperative coronary angiography. There were no early or late deaths during the mean follow-up period of 33.08 +/- 30.05 months (range, 1-77 months). The mean interval from the 1st operation to the 2nd operation was 74.1 +/- 57.01 months (range, 4.5-171 months). Postoperative coronary angiograms of all patients showed a 100% patency rate for both in situ grafts and composite grafts. We suggest that use of the in situ right internal mammary artery in off-pump coronary artery bypass grafting is a safe and reliable option for revascularizing the left anterior descending artery, especially in reoperation.     

Left internal mammary graft stenosis and restenosis following angioplasty and stenting

Coronary bypass grafts using the internal mammary artery usually have an excellent record of success and long term patency. We report a 42 year old man who initially presented with a history of atypical left sided chest pain, who had coronary artery bypass surgery for a severe stenosis in his proximal left anterior descending coronary artery (LAD) and moderate stenosis of his proximal circumflex artery, with his LIMA being grafted to his mid-LAD and a saphenous venous graft to the proximal LAD. He subsequently developed multiple stenoses in the LIMA graft which required coronary augioplasty and stenting, on more than one occasion, in view of very rapid restenosis within the LIMA graft.


Keywords: graft patency; left internal mammary artery grafts; restenosis; stenosis     

Progression from stenosis to occlusion in the proximal native coronary artery after coronary artery bypass grafting

Coronary artery bypass grafting (CABG) is an established treatment for multivessel coronary artery disease. However, problematic situations are occasionally encountered after CABG, such as disease progression in the native coronary artery with graft occlusion, which causes difficulty in revascularization. The purpose of this study was to evaluate changes in the native coronary artery after CABG. Between 2009 and 2012 in our institution, 351 patients underwent CABG, and 768 bypass grafts were anastomosed to non-occluded coronary arteries. Of these, 489 bypass grafts had available early postoperative angiographic results (≤6 months) suitable for assessment in this study. We defined malignant graft failure after CABG to be bypass graft occlusion and de novo complete occlusion of the target native coronary artery proximal to the graft anastomosis site. In the early angiographic results, 17 grafts were occluded (17/489; 3.5 %). Two of the grafts displayed malignant graft failure (a saphenous vein graft to the right coronary artery and a saphenous vein graft to the diagonal branch) (2 of 17 occluded grafts, and 2 of 489 studied grafts). Of the patent bypass grafts, 24 involved progression to occlusion in the proximal native coronary artery (19 saphenous vein grafts, 4 left internal thoracic artery grafts, and 1 right internal thoracic artery graft). Malignant graft failure was uncommon during short-term follow-up after CABG. At the same time, disease progression in the proximal native coronary artery from stenosis to occlusion following patent bypass grafting was relatively common, especially for vein grafts.     

Mid to long-term results of circumflex coronary artery revascularization with left internal thoracic artery grafts

The current trend in coronary artery surgery is to revascularize the left coronary artery branches with bilateral internal thoracic arteries (ITA). For this procedure, the right ITA is usually grafted to the left anterior descending coronary artery while the circumflex coronary artery is revascularized by the left ITA. The mid to long-term results of the left ITA on the circumflex system were examined in this study. Forty of 48 patients operated on between 1996 and 1998 who had undergone revascularization of the left coronary artery with both ITAs and who fulfilled the study criteria underwent control coronary arteriography to determine the mid to long-term patency of LITA grafts on the circumflex artery. The median time for follow-up was 53 months (range, 49 to 70 months). Of the 40 angiographically controlled patients, 35 had patent left ITA to circumflex artery anastomosis (87.5%). One graft stenosis and four graft occlusions were observed. In the same group, right ITA to left anterior descending coronary artery anastomoses were patent in 38 patients (95%). Left ITA grafts seem to be the conduit of choice for revascularization of the circumflex coronary artery. In combination with the in situ right ITA to left anterior descending coronary artery anastomosis, in situ left ITA grafting to the circumflex system can be done with acceptably low mortality and excellent long-term patency rates. Its utilization is particularly advised in young patients where the importance of left coronary artery revascularization by bilateral ITA grafts is increased.     

Off-pump bypass surgery: the early experience, 1969-1985

This is a review of 733 patients who underwent off-pump bypass surgery of the right coronary artery and left anterior descending coronary artery between 1969 and 1985. Two hundred sixty-four patients underwent single bypass of the left anterior descending coronary artery, and 79 patients underwent single bypass of the right coronary artery. Both the left anterior descending and right coronary arteries were bypassed in 390 patients. In contrast to the present-day use of mechanical devices to stabilize the target vessel, a 4-suture surgical technique was used for this purpose. This technique, which we illustrate, proved less cumbersome and made the graft anastomosis easy to perform. Our early experience (1969 through 1972) in operating on 199 patients resulted in an operative mortality rate of 4.5% (9/199). From 1973 through 1985, improved patient selection and use of the left internal thoracic artery as the conduit of choice for bypass of the left anterior descending coronary artery reduced the operative mortality rate for 534 patients to 1.3% (7/534). Routine postoperative angiograms were not performed; therefore, the graft patency rate is not available. However, an ongoing 34-year follow-up study of the 264 patients who underwent a single left anterior descending bypass showed the saphenous vein graft to be open in 64.3% (18/28) patients and the left internal thoracic graft in 92.2% (59/64) of patients studied. Seventy-four of the 264 patients in this study were still alive in 2003.     

Assessment of coronary bypass graft patency by electron-beam computed tomography

Twenty-one patients undergoing coronary artery bypass grafting were prospectively evaluated by conventional selective coronary angiography and electron-beam computed tomography. Eighty bypass grafts (60 saphenous vein and 20 left or right internal mammary artery) were evaluated for patency. The sensitivity and specificity of electron-beam computed tomography were 72% and 100%, respectively; positive and negative predictive values were 100% and 92.5%, respectively. Sensitivity and specificity according to coronary region were: left anterior descending artery, 33% and 100%; diagonal artery, 67% and 100%; circumflex artery, 75% and 100%; right coronary artery, 100% and 100%. Electron-beam computed tomography is relatively accurate and a promising tool for noninvasive evaluation of graft patency after coronary artery bypass graft surgery.     

Systolic compression of bypass grafts

Myocardial bridging, systolic compression of an intramyocardial segment of an epicardial coronary artery, is well known to involve native coronary arteries. Systolic compression of bypass grafts has been rarely described. We present two cases of dynamic systolic compression of bypass grafts to native coronary arteries: one of a vein graft to the right coronary artery, and another of a left internal mammary artery to the left anterior descending artery.     

Sensitivity and specificity of assessing coronary bypass graft patency with ultrafast computed tomography: results of a multicenter study

Because a significant number of all patients seen by cardiologists have had coronary bypass surgery, a relatively noninvasive method of assessing coronary bypass graft patency would be very helpful. Ultrafast computed tomography, by virtue of its rapid data acquisition time and reasonable spatial resolution, may be useful in this regard. To determine the sensitivity, specificity and predictive accuracy of this imaging modality as compared with cardiac catheterization, a multicenter study was undertaken. There were two parts to the study. Part I involved the evaluation of 179 grafts in 74 patients studied in the five participating centers between March 1985 and August 1986. Twenty-nine percent of these graft studies were found to be technically inadequate and were excluded before patency determinations began. The remaining group of 127 bypass grafts in 62 patients had studies adequate for interpretation. Fifty-one grafts were to the left anterior descending coronary artery or a diagonal branch, 37 to branches of the left circumflex artery and 28 to the right coronary artery or a posterior descending vessel; in addition, there were 11 internal mammary artery bypass grafts primarily into the left anterior descending or diagonal artery distribution. The sensitivity of detecting angiographically open grafts was 93.4%, the specificity of detecting angiographically closed grafts 88.9% and the predictive accuracy was 92.1%. A subsequent study (Part 2) was performed 9 months later to assess the ability to carry out technically adequate examinations. Of the 138 consecutive graft examinations (50 patients) included in this part of the study, 94.2% of the examinations were found to be technically adequate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Results of internal mammary artery-coronary artery bypass surgery and the characteristics of internal mammary artery grafts

Coronary artery bypass grafting utilizing the internal mammary artery (IMA) was performed in 108 patients with an operative mortality (less than 1 month) of 0% and a hospital mortality of 1.9%. The IMA was used most often in the left anterior descending artery system in combination with saphenous vein grafts (SVG) to the right and left circumflex artery systems. Although the IMA flow was smaller than the SVG flow when measured intraoperatively by an electromagnetic flow meter, postoperative clinical, electrocardiographic, isotopic, angiographic and coronary sinus flow-metric studies all demonstrated that the IMA can respond well to myocardial blood flow demand both at rest and during exercise, resulting in excellent clinical improvements with no detectable signs of flow deficiency. In addition, no signs of ischemia were detected in any of the 15 patients with stenosis in the left main trunk treated with an IMA graft. The IMA graft appears to have a great adaptive capacity to meet increased myocardial demand. Postoperative angiography performed at an average of 3 months after surgery in 60 unselected patients demonstrated an IMA patency rate of 98% in comparison with 88% patency in SVGs to the left anterior descending artery (p less than 0.05). Not only the patency rate, but also the graft wall characteristics were much better in IMA grafts than in SVGs. Some SVGs showed marked wall irregularity as early as 3 months after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of the rheologic parameters in left internal thoracic artery grafts with those in saphenous vein grafts.

BACKGROUND: Left internal thoracic artery (LITA) grafts have superior patency to saphenous vein grafts (SVG). Because shear stress augments the release of nitric oxide throughout the LITA endothelium, shear stress and shear rate in coronary artery bypass grafts (CABG) may play an important role in the higher patency, so the aim of the present study was to evaluate and compare the rheologic parameters in CABG using LITA and SVG. METHODS AND RESULTS: Rheologic examinations were done in 197 patients using a vacuum-suction glass tube viscometer after CABG surgery was completed. Shear stress and shear rate were calculated from the geometry of the graft, blood flow in the graft and blood viscosity. Of 197 patients, 177 underwent LITA grafting to the left anterior descending artery (LAD) and 160 had SVG anastomosis to coronary arteries. Mean wall shear stress in the LITA grafts to the LAD (13.8+/-1.0 dyne/cm2) was nearly 4-6-fold larger than that in the SVG grafts. Mean shear rate (559.1+/-57.0 s(-1)) of LITA-LAD grafts was approximately 2-3-fold higher than that of SVG. CONCLUSION: These results suggest that high wall shear stress and shear rate play an important role in the higher patency rate of LITA grafts.     

Comparison of coronary hemodynamics in patients with internal mammary artery and saphenous vein coronary artery bypass grafts: a noninvasive approach using combined two-dimensional and Doppler echocardiography

Blood flow in bypass grafts and recipient left anterior descending coronary arteries was evaluated with combined two-dimensional and Doppler echocardiography in 15 patients with an internal mammary artery graft and in 24 patients with a saphenous vein graft. Comparative studies of coronary hemodynamics were also performed regarding these two different grafting techniques. The graft vessel was detected in 11 (79%) of 14 patients with an internal mammary artery graft and in 20 (87%) of 23 with a saphenous vein graft. The recipient left anterior descending coronary artery was detected in 10 (67%) of the former group and 17 (71%) of the latter. The blood flow patterns obtained were generally biphasic, consisting of systolic and diastolic phases with higher velocity during diastole. The maximal diastolic flow velocity in internal mammary artery grafts was much higher than that in saphenous vein grafts. In patients with an internal mammary artery graft, the flow pattern characteristics within the recipient coronary artery were quite similar to those within the arterial graft, and flow velocities within the recipient coronary artery and the arterial graft were quantitatively almost identical. This outcome may contribute to the long-term patency seen in internal mammary artery grafts. On the other hand, the flow velocity in saphenous vein grafts was fairly low throughout the cardiac cycle. Flow velocity in the recipient coronary artery in patients with a saphenous vein graft was accelerated only in early diastole. As a result, the recipient coronary artery flow pattern and velocity differed substantially from those in the saphenous vein graft.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sequential internal mammary artery bypass for multiple coronary stenoses

Long-term studies (10 years) show a 50 per cent patency rate of saphenous vein autograft and 95 per cent patency rate of internal mammary artery coronary bypass grafts. In some situations (after saphenous vein stripping, varicose and fibrotic veins) it is not possible to use venous grafts and the internal mammary artery has to be used. However, the internal mammary artery is usually only used for revascularisation of the left anterior descending artery. Sequential internal mammary artery bypass is a technique which can be used for revascularizing the left anterior descending artery. Seven men aged 44 to 68 years (average 55 years) were operated between November 1983 and February 1985. These patients had clinically stable (4 cases) or instable (3 cases) angina. Two patients had previously undergone bilateral saphenous vein stripping and one patient a terminal anastomosis on the left anterior descending and a latero-lateral anastomosis on the diagonal artery. Three patients had an associated venous bypass graft and one patient also underwent aortic valve replacement. There were no cases of postoperative myocardial infarction. Five control angiographies were carried out during the first postoperative month. In 4 patients the internal mammary graft ant the latero-lateral and termino-lateral anastomoses were patent. In the other case, the latero-lateral anastomosis and the diagonal artery was occluded but the internal mammary graft and the termino-lateral anastomosis on the left anterior descending artery were patent. The average follow-up period is now 18 months: there have been no recurrences of chest pain or any ECG changes. These results show that internal mammary artery bypass grafting is a delicate procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Five-year follow-up after long plaque-bridging coronary arteriotomy for diffuse coronary artery disease

Long arteriotomy bridging a stenotic plaque or segment may improve runoff in diffuse coronary artery disease. However, patency might be impaired due to vascular wall pathology. OBJECTIVE: To determine the patency rates of plaque-bridging arteriotomy compared to conventional coronary artery bypass grafting. METHODS: Between May 1995 and December 1998, 104 patients with a mean age of 65 +/- 7 years received a long arteriotomy extending over a heavily plaqued area in an effort to treat their diffuse coronary artery disease. The length of the arteriotomy ranged from 14 mm to 40 mm. We retrospectively analyzed the intra-individual bypass graft patency rates by multidetector-computed tomography or coronary angiography. RESULTS: The mean follow-up was 5 years. There were 5 (4.8 %) early and 10 (9.6 %) late deaths, three non-cardiovascular. Graft patency for internal thoracic artery (ITA) to left anterior descending artery (LAD) (plaque-bridging) was 94.8 %, for saphenous vein graft (SVG) to circumflex artery (CX) (plaque-bridging) 67 %, and SVG to right coronary artery (RCA) (plaque-bridging) 79.5 %. Graft patency for ITA to LAD (conventional) was 94.9 %, for SVG to CX (conventional) 72.4 %, and SVG to RCA (conventional) 75 %. Freedom from angina was 82.8 % (n = 58/70), freedom from myocardial infarction was 95.7 % (n = 67/70), freedom from reintervention was 91.4 % (n = 64/70) and freedom from reoperation was 100 % (n = 70/70). CONCLUSION: Diffuse coronary artery disease can be treated by extending the arteriotomy over the plaques, with graft patency rates comparable to bypass grafts onto less diseased segments.     

Use of stents to treat kinks causing obstruction in a left internal mammary artery graft

Left internal mammary arteries (LIMA) are used routinely as grafts to the left anterior descending coronary artery (LAD) in selected patients undergoing coronary artery bypass graft (CABG) surgery because of better long-term patency rates. Pathology other than fibrointimal hyperplasia, accelerated atherosclerosis, or thrombus can sometimes cause obstructive lesions in such grafts. This report illustrates a kink in a LIMA graft to the LAD causing an obstructive lesion shortly after surgery and describes the subsequent management of this lesion with intracoronary stents. Cathet. Cardiovasc. Intervent. 46:223–226, 1999. © 1999 Wiley-Liss, Inc.     

Follow-up angiography of 100 revascularizations of the anterior interventricular artery by the left internal mammary artery

One hundred and fifty patients who underwent revascularisation of the left anterior descending artery (LAD) by the left internal mammary artery (LIMA) between 1981 and 1983 were recalled for control coronary angiography one year after surgery. One hundred patients gave consent. The patency rate in these 100 patients was 90 per cent. The presumed causes of the 10 thromboses observed were: for LAD (5 cases), technical problems (3 cases), competitive flow (2 cases). Ten per cent of the patent LIMA grafts were abnormal: moderate stenosis of the anastomosis (5 cases), small LIMA (3 cases), stenosis of the middle segment of the LIMA (1 case). In addition, we observed 7 cases of competitive flows: 3 cases with a LAD which was not sufficiently stenotic, 4 cases with a large saphenous diagonal bypass graft. If a diagonal artery bypass is necessary, it is better to revascularize by either a latero-lateral anastomosis with the LIMA or by using the right IMA. Ninety per cent of the patent grafts were quite satisfactory ar 1 year: regular, supple, and perfectly congruent with the bypassed artery which was injected massively. As a number of North American teams have shown, this good patency rate seems to be maintained at long term, which is not the case with saphenous vein bypass grafts.