The internal mammary artery in myocardial revascularization

Internal mammary artery by-pass graft is a very usefull alternative to venous by-pass graft for myocardial revascularization. From February 1982 up to August 1984, 111 patients with coronarosclerosis have been operated on with left internal mammary artery. Right internal mammary artery has been also used in 2 cases. Left internal mammary artery has been used as a sequential graft 13 times. Vein grafts have been associated in more than 2/3 of the patients who had surgery with internal mammary artery and the mean of anastomoses per patient was 2.9. Five patients had a perioperative myocardial infarction and one an infarction shortly after the operation. Ten patients had immediate reoperation: 5 for postoperative bleeding, 2 for arterial graft anastomosis occlusion, 2 for sudden ST elevation and 1 for acute myocardial infarction. Only one patient died for acute myocardial infarction post-operatively, following coronary artery spasm. Eighty-six patients have been followed-up 3 to 31 months after surgery. Advantages and limits of this surgical technique are discussed.     

Chylothorax following myocardial revascularization with the internal mammary artery

Chylothorax is a rare but serious complication of coronary artery bypass grafting. We describe a case of double myocardial revascularization with the internal mammary artery developing the complication ten weeks after cardiac surgery. The reasons for late symptomatology of lymphatic injury are analyzed. Conservative treatment with low-fat diet, total parenteral nutrition and pleural drainage was attempted unsuccessfully; chyle leakage of around 500 ml/day and onset of nutritional deficiency made it advisable to seal the thoracic duct surgically.     

Choice of internal mammary artery or saphenous vein graft for myocardial revascularization

The saphenous vein has been the traditional conduit for elective myocardial revascularization. Although readily available and adaptable to many configurations around the heart, it is prone to intimal hyperplasia and vein graft atherosclerosis, which diminish long-term patency and relief of symptoms. The internal mammary artery graft represents a marked improvement over the saphenous vein graft in many respects. Data are presented comparing saphenous vein graft patency with that of the internal mammary artery, bilateral internal mammary artery, free internal mammary artery, and sequential internal mammary artery grafts.     

Postoperative nursing management in patients undergoing myocardial revascularization with the internal mammary artery bypass

The IMA is being utilized with increasing frequency as the graft of choice for myocardial revascularization. Certain postoperative management requirements differ in patients with the internal mammary bypass, which are often challenging. Because it is important that the nursing staff have a thorough understanding of the peculiarities of postoperative care in patients with IMA grafts, this article was prepared to review the anatomic, pathologic, physiologic, and clinical aspects of the IMA in myocardial revascularization. A retrospective comparative chart review of patients with IMA grafts and SVGs was also performed to better define the specific postoperative nursing problems of hemorrhaging, pulmonary support, and pain control that are encountered in these patients.     

Myocardial revascularization with arterial conduits: comparison of bilateral internal mammary artery and single internal mammary artery

The use of bilateral internal mammary artery (BIMA) grafting for myocardial revascularization has been demonstrated to provide long-term benefits compared to revascularization using single left internal mammary artery (SIMA) and venous conduits. However, it is still controversial whether the use of BIMA is associated with a higher hospital mortality and morbidity. The present study retrospectively evaluated the possible advantages related to the use of BIMA at 3-year follow-up and whether the presence of operative risk factors in patients with BIMA could limit the application of the procedure in myocardial revascularization. We compared two groups of 100 patients matched for preoperative clinical characteristics, who underwent myocardial revascularization on the left coronary system with BIMA (93 males and 7 females, mean age 59 +/- 4 years) or with SIMA and venous conduits (86 males and 14 females, mean age 63 +/- 6 years). Hospital mortality rate was 2% in both groups, the use of BIMA being not a significant risk factor for hospital mortality and morbidity. The mean follow-up was 36 +/- 6 months for the BIMA group and 40 +/- 10 months for the SIMA group. At 3 years, there was no significant differences in the actuarial freedom from cardiac death (96 +/- 2% for BIMA vs 94 +/- 2% for SIMA patients), myocardial infarction (98 +/- 2 vs 97 +/- 2%), angina (93 +/- 2 vs 91 +/- 2%), symptomatic heart failure (92 +/- 3 vs 92 +/- 2%), coronary angioplasty/reoperation (96 +/- 2 vs 97 +/- 2% ), and total cardiac events (80 +/- 4 vs 76 +/- 4%). BIMA grafting was not an independent predictor of late cardiac events. In 66 patients who underwent a late angiographic or echo-Doppler study, the patency rate was 100% for the left mammary artery, 94% for the right mammary artery and 69% for venous conduits. In conclusion, myocardial revascularization with BIMA in situ is associated with low hospital mortality and morbidity, good clinical outcome and excellent patency rate at 3 years, with apparently no significant differences when compared to the use of SIMA and venous conduits. The low hospital mortality and morbidity and the satisfactory medium-term results in our opinion justify a more extensive use of BIMA in myocardial revascularization.     

Intraoperative Doppler spectrum analysis of blood flow in the internal mammary artery used for myocardial revascularization.

Intraoperative Doppler-derived measurements of blood flow velocity were used to characterize the hemodynamics in 6 internal mammary artery grafts before and after anastomosis to the left anterior descending artery. Pulsed Doppler spectrum analysis demonstrated a change from a systolic to a predominantly diastolic flow pattern. The presented technique is a valuable aid to differentiate intraoperatively between normal and low flow states in the internal mammary artery. In addition, this study serve as a pilot study to investigate the clinical applicability of Doppler spectrum analysis in the functional assessment of the internal mammary artery in the pre- and postoperative stages of myocardial revascularization.     

Delayed pleuropulmonary complications following coronary artery revascularization with the internal mammary artery

We have seen four cases of delayed postoperative pleuro-pulmonary complications associated with use of the internal mammary artery (IMA) conduit. In each case the left IMA was used as a bypass conduit to the left anterior descending (LAD) coronary artery. In two of the instances the complications were life-threatening to the patients. Each patient was left with symptomatic residual roentgenographic changes. The IMA is becoming the graft of choice for coronary artery revascularization. The potential for delayed pleuropulmonary complications associated with use of this graft is not well recognized.     

Percutaneous revascularization of the internal mammary artery graft: short- and long-term outcomes

OBJECTIVES: We evaluated the short- and long-term clinical outcomes after percutaneous revascularization of the internal mammary artery (IMA) graft. BACKGROUND: Previous reports in a relatively small number of patients have indicated the safety of balloon angioplasty for the treatment of stenoses in the IMA graft. However, the use of alternative interventional techniques and their long-term results have not yet been evaluated. METHODS: We analyzed the in-hospital and one-year clinical outcomes of 174 consecutive patients who underwent percutaneous revascularization of 202 lesions located in the IMA graft, by either balloon angioplasty or stenting. RESULTS: Anastomotic lesions were evident in 128 cases (63%), and they were more commonly treated with balloon angioplasty (116/128, 91%), whereas lesions located at the ostium (n = 16, 8%) were more frequently treated with stents (11/16, 69%). Procedural success was 97% with excellent in-hospital outcome: 0.6% mortality rate, no Q-wave myocardial infarction (MI) and 0.6% rate of urgent bypass surgery. Cumulative one-year rates were: mortality 4.4%, MI 2.9% and target lesion revascularization (TLR) 7.4%. CONCLUSIONS: Revascularization of the IMA graft can be performed safely, with high procedural success and a low rate of in-hospital complications. Long-term follow-up showed very low TLR rate.     

Skeletonized bilateral internal mammary arteries for total arterial myocardial revascularization

BACKGROUND: Bilateral internal mammary artery (IMA) grafting is associated with an improved long-term survival, low rates of recurrence of angina and late myocardial infarction. However, because of the inadequate length of the conduit, use of bilateral internal thoracic artery grafting occasionally is not suitable for complete revascularization. To overcome this limitation, extra length can be obtained by skeletonization of both IMAs. We decided to prospectively assess the safety of this technique. METHODS: One hundred patients with a mean age of 52.5 +/- 13.1 years underwent complete revascularization with skeletonized bilateral internal mammary arteries on cardiopulmonary bypass (CPB). The right internal mammary artery (RIMA) was used as a free graft connected to the in situ left IMA (LIMA) in 88 patients. A free LIMA was attached to in situ RIMA in 12 patients. The average number of grafts was 3.2 per patient (range: 2-4 grafts per patient). Mean left ventricular ejection fraction was 60% (range: 25-80%). RESULTS: No patient required reexploration for bleeding, and no patient died within 30 days after operation. On the basis of electrocardiographic changes, three patients sustained a perioperative myocardial infarction. One patient had a sternal wound infection. Mean follow-up was 24 months (range: 6-36 months). The actuarial survival rate was 99 +/- 1% at 3 years. No myocardial infarctions were reported during the follow-up. Three patients had recurrent angina with conduit occlusion diagnosed on coronary angiography. CONCLUSION: Complete myocardial revascularization with skeletonized bilateral internal mammary arteries is a safe and reliable technique with excellent early and mid-term results.     

Chylothorax after myocardial revascularization with the left internal thoracic artery

A 38-year-old male underwent coronary artery bypass grafting (CABG). A saphenous vein graft was attached to the left marginal branch. The left internal thoracic artery was anastomosed to the left anterior descending artery (LAD). The early recovery was uneventful and the patient was discharged on the 5th postoperative day. After three months, he came back to the hospital complaining of weight loss, weakness, and dyspnea on mild exertion. Chest X-rays showed left pleural effusion. On physical examination, a decreased vesicular murmur was detected. After six days, the diagnosis of chylothorax was made after a milky fluid was detected in the plural cavity and total pulmonary expansion did not occur. On the next day, both anterior and posterior pleural drainage were performed by videothoracoscopy, and prolonged parenteral nutrition (PPN) was instituted for ten days. After seven days the patient was put on a low-fat diet for 8 days. The fluid accumulation ceased, the drains were removed and the patient was discharged with normal pulmonary expansion.     

First time myocardial revascularization in patients younger than 70 years. Single versus double internal mammary artery.

BACKGROUND: We evaluated the early and late outcomes of bilateral internal mammary artery (BIMA) grafting, with or without saphenous vein grafts (SVGs), compared to single internal mammary artery and SVGs in patients < 70 years undergoing first myocardial revascularization. METHODS: From September 1986 to December 1999, 1389 patients underwent first myocardial revascularization using the left internal mammary artery (LIMA) to the left anterior descending artery and SVGs (n = 480) or BIMA (one internal mammary artery on the left anterior descending artery) with or without SVGs (n = 909). Propensity score analysis was used to select 952 (476 of each group) patients with the same preoperative and operative characteristics. Thirty-day outcome and 10-year freedom from all-cause death, cardiac death, acute myocardial infarction (AMI), AMI in a grafted area, redo/percutaneous transluminal coronary angioplasty (PTCA), redo/PTCA in a grafted artery, cardiac events and any events, were evaluated. Follow-up ranged from 3.5 to 16.8 years (mean 8.8+/-4.0 years). RESULTS: Thirty-day mortality was 2.9% in the LIMA group and 1.9% in the BIMA group, p = NS; the BIMA group showed a better 10-year freedom from all-cause death (92.4+/-2.1 vs 87.5+/-3.5%, p = 0.0216), cardiac death (97.4+/-0.9 vs 91.9+/-1.4%, p = 0.0042), AMI (98.7+/-0.5 vs 94.2+/-1.2%, p = 0.0034), AMI in a grafted area (98.9+/-0.5 vs 94.7+/-1.3%, p = 0.0017), cardiac events (95.4+/-1.2 vs 86.8+/-1.8%, p = 0.0026) and any events (88.8+/-2.2 vs 80.7+/-2.1%, p = 0.0124). Cox analysis confirmed that LIMA + SVGs was a risk factor independent of lower freedom from all the above-mentioned events. CONCLUSIONS: Double mammary artery in patients < 70 years who had a first time myocardial revascularization gives a better clinical outcome even 10 years after the operation.     

Expanded use of the right and left internal mammary arteries for myocardial revascularization

While the use of the left internal mammary artery (IMA) has become routine in many cardiac surgery units there is some reluctance to utilize the right IMA. The reasons for this are the higher morbidity and mortality observed in the initial experience with bilateral IMA grafting, the limited length of the right IMA, and its potential injury in reoperations when used to revascularize the left anterior descending artery. In this series of 50 patients the right IMA was used as a conduit for myocardial revascularization. One hundred and fifty-nine coronary vessels were grafted (3.2 per patient) 67.3% with IMA and only 32.7% with vein grafts. The right IMA was used for 51 anastomoses and the left for 56, either as simple, sequential or Y type grafts. The refinement of techniques for constructing the IMA grafts used in this series show that the right IMA can reach in most of the cases the anastomotic sites of the right coronary artery beyond the acute margin of the heart, and it is hoped that the lateral positioning of the IMA pedicles will lessen the chance of graft injury at reoperation. On the basis of early clinical results (2% mortality and 4% sternal complications), the application of the right IMA seems justified electively for the revascularization of both left and right coronary artery systems or as a free graft in conjunction with the left IMA.     

Triple arterial coronary revascularization using the radial artery and bilateral internal mammary arteries versus the gastroepiploic artery and bilateral internal mammary arteries.

Arterial grafts are frequently used in modern coronary artery bypass grafting (CABG) and the benefit of the 2 internal mammary arteries (IMA) has already been established. However, the choice of the third arterial conduit, in addition to the IMA, is controversial. We have retrospectively analized perioperative and the follow-up results of patients who underwent CABG with triple arterial bypass using either the radial artery (RA) or the gastroepiploic artery (GEA) in conjunction with the bilateral IMA (BIMA). Between December 1995 and June 2001, 1,516 consecutive isolated CABG operations were performed at Shin-Tokyo Hospital. Among them the RA and BIMA were used in 96 patients (78 males, 18 females; mean age, 63.2+/-6.7 years, group R), and the GEA and BIMA in 123 patients (101 males, 22 females; mean age, 61.0+/-11.6 years, group G). Their perioperative and follow-up data were studied. The preoperative risk factors were similar between the 2 groups, except that there were significantly fewer patients with renal dysfunction in group R. The surgical results did not differ between the 2 groups; however, the GEA was more commonly used for revascularization of the right coronary artery, while the RA was used for the diagonal, circumflex or right coronary arteries. Surgical mortality and morbidity rates were not significantly different. During the follow-up period of 2.3+/-1.6 years, the event-free rates as well as the survival rates were not significantly different. CABG with either the RA or the GEA in conjunction with the BIMA can be performed safely. The surgical results as well as the follow-up results were acceptable and no significant differences between the 2 groups were observed.     

Significance of digital subtraction angiography for estimation of early results of myocardial revascularization after internal mammary artery grafting

Between 1st January and 31st December 1987 126 consecutive patients underwent full myocardial revascularization using at least one internal mammary artery bypass grafting in Department of Cardiovascular Surgery of University of Freiburg. In 78 patients (75 males, 3 females) DSA was performed within 8 days after surgery to evaluate dynamics of IMA-graft. The age ranged from 38 to 67 years (mean 53.4 years). DSA study was performed through the brachial artery, contrast medium was injected with flow of 10 ml/sec. in counter current. It was only one series of angiograms necessary to visualise flow from subclavian artery, through IMA to coronary artery. Among 78 investigated patients in 61 (78%) the distal anastomosis appeared to be widely patent and flow through the IMA and anastomosed coronary artery was sufficient. Patency of one of the branches of IMA or stenosis of IMA graft contributed to inadequate flow in 12 patients (15.6%). In 5 (6.4%) operated patients the IMA graft was not patent. Counter current intraarterial DSA requires much smaller amount of contrast medium than classical angiography, moreover avoiding of aortic catheterization with all risks involved. The counter current intraatrial DSA is an excellent technics of estimation of the flow to grafted coronary arteries. The method is easy to perform, repetitive and carry very small risk for the patient. Early postoperative evaluation of IMA-graft patency is essential for estimation of effectiveness of myocardial revascularisation and prognosis for the patient.