Editorial

Bilateral internal thoracic artery grafting in reoperations

Background. Skeletonization of the internal thoracic artery (ITA) produces greater length for coronary bypass grafting. We studied the effect of skeletonization on the morphology, histology, and tissue viability of the ITA wall.

Methods. Six mongrel dogs underwent unilateral ITA dissection; the contralateral ITA was the control. Study periods were 3 weeks (n = 3) and 12 weeks (n = 3). At sacrifice, the entire anterior chest wall was removed and dynamically fixed with formalin. Extensive histologic comparisons were performed on three tissue blocks taken from each ITA, 2, 8, and 24 cm from their origin.

Results. Flows at the end of the study were comparable to measurements taken during operation, immediately after skeletonization. Grossly, the ITA wall was not injured by skeletonization and there was no adventitial hematoma or bleeding from the sealed branch ends. Microscopic observations showed intact, normal wall structures. Histologic data showed no major significant difference between controls and skeletonized ITAs.

Conclusions. Careful skeletonizing dissection is not detrimental to the integrity of ITAs, which justifies their use for myocardial revascularization.

Reoperation for coronary artery disease has become a routine procedure; however, a second reoperation is exceptional. In this report we describe our experience with 16 patients undergoing a second reoperation for coronary atherosclerosis. The absence of operative mortality is certainly related to the patient selection. The number of patients is still too small to draw major conclusions. Striking, however, is that the first reoperation was usually done for angina because of progression of atherosclerosis in the native coronary system and the second reoperation was done because of graft failure. This experience supports the idea that the replacement of old, even patent, venous grafts and the choice of the best available conduits are of great importance at the first reoperation and may prevent a second reoperation. (J THORAC CARDIOVASC SURG 1994;107:684-9)

This study was undertaken to more clearly define the operative risks and appropriate strategies for the selection of patients who might be candidates for bilateral internal mammary artery grafting. A review of the 674 patients who underwent this procedure was performed over a 10-year period from January 1982 through 1991. These patients represented 5% of the 12,824 patients who underwent bypass grafting during this period. The mean patient age was 54 ± 9.4 years, and 92% of the patient were male. Diabetes was present in 17.5%, with 24% of this group insulin dependent. The ejection fraction was less than 0.50 in 26.7% and 14% had had previous bypass procedures. Hospital mortality was 1.9% (n = 13). Hospital morbidity included wound infection in 3.6%, reoperation for bleeding in 2.1%, and stroke in 1.6%. Postoperative intraaortic balloon pump support was necessary in 2.8%. Univariate and multivariate analysis revealed that advanced age, an emergent operative status, and the number of diseased vessels (especially left main obstruction) were predictors of hospital death. Except for wound infection (9.3% versus 2.5%) and length of hospital stay (10.8 ± 11.8 days versus 8.8 ± 7.6 days), the complications in diabetics were similar to those in patients without diabetes, respectively. At 5 years, freedom from death, death or infarctions, and death, myocardial infarction, or coronary reoperation was 90%, 70%, and 62%, respectively. The only significant multivariate correlates of long-term survival were diabetes and reoperative surgery.

Graft patency after coronary artery bypass grafting depends largely on the choice of conduit. Because an increasing number of patients have insufficient or poor-quality autologous material, there is a need for a suitable synthetic graft that is readily available and easy to handle and that has good long-term patency. Early results suggest that the bovine internal mammary artery graft may meet these criteria. We have used a total of 26 such grafts in 18 patients. Postoperative angiography has been performed in 19 grafts in 14 patients, 3 to 23 months after operation; of these grafts, 3 are currently patent (15.8%, compared with 85.7% and 75.0% patency for native internal mammary artery and saphenous vein grafts in the same patients). We report the results of clotting studies and an analysis of lipid status. These patients do not, however, appear to represent any atypical group, either in terms of coagulopathy, native coronary artery size, or the type of vessel disease. Nevertheless, our poor results contrast markedly with the early enthusiasm reported from other centers.

In recent years, use of the internal mammary artery (IMA) as first graft of choice has been expanded with bilateral and sequential grafts in primary myocardial revascularization. The use of bilateral IMA grafts in reoperation has seldom been reported. The experience and early results with bilateral IMA grafting in 47 patients undergoing coronary reoperation are described. Hospital mortality was 6.3%. Four patients had postoperative signs of low cardiac output, and 4 had a perioperative myocardial infarction. At follow-up (18 ± 18 months), 2 cardiac-related, late deaths were noted. Thirteen patients (29%) improved 1 New York Heart Association class, and 28 (63%) improved >1 class. In 1 of 44 surviving patients, operation did not result in a decrease in angina. On the basis of the early results, the bilateral use of the IMA in coronary reoperation appears justified.