Surgical Ostioplasty for Isolated Ostial Stenosis of the Left Main Stem Coronary Artery

Abstract

We report the cases of 4 patients in whom surgical ostioplasty was performed for isolated severe ostial stenosis of the left main stem coronary artery. No perioperative death or myocardial infarction occurred. One patient required reoperation for symptomatic recurrent ostial stenosis after 6 months. The others remained angina free after a mean follow-up of 23 months. The literature associated with this procedure is briefly reviewed.

The conventional treatment for ostial stenosis of the left main stem (LMS) coronary artery is coronary artery bypass grafting. However, one of several drawbacks with this approach is the requirement for multiple vascular anastomoses that consume bypass conduits. This can be avoided by correcting the ostial stenosis with an augmentation patch. We report our experience with surgical ostioplasty as an alternative option to treat this group of patients.

Patients and Methods

From the beginning of February 1997 through September 1999, 4 patients—2 men and 2 women, between the ages of 43 and 57 years—underwent surgical ostioplasty for isolated LMS coronary artery stenosis at our institution. Three patients were experiencing stable angina and one had sustained a recent myocardial infarction. Preoperative angiography showed substantial stenoses (50% to 70%) in the LMS coronary arteries. There was no associated stenosis observed in the coronary circulation. Moderate calcification in the LMS was seen in 1 patient, and ascending aortic atherosclerosis was observed in another. The left ventricular ejection fraction was normal in each instance. Surgery was performed under general anesthesia. After median sternotomy and the institution of cardiopulmonary bypass, the patients were cooled to 32 °C. Cryocardioplegia was induced by intermittent antegrade infusion into the aortic root after cross-clamping of the ascending aorta. After cardioplegic arrest, the aorta was opened by means of an oblique incision that was continued rightward to the top of the left coronary ostium. The ostial lesion was divided and the incision was extended down approximately 15 mm into the LMS coronary artery. A tailored patch of autologous pericardium fixed in 10% glutaraldehyde was sutured in place as a gusset with continuous 6-0 Prolene (Fig. 1). Bovine pericardium was used in 1 patient who had experienced previous pericarditis. The aortotomy was closed with continuous 4-0 Prolene suture in the usual fashion.

Fig. 1 A patch of pericardium is sutured in place as a gusset with continuous 6-0 Prolene.

Results

The postoperative progress was uneventful in all patients; there was no hospital death or myocardial infarction. The average intensive care unit stay was 10.8 hours, and all patients were discharged from the hospital within 7 days. Outpatient follow-up ranged from 8 to 40 months (mean, 23 ± 13.2 months). One patient had recurrent angina, and a repeat coronary angiogram 6 months after operation revealed significant restenosis of the LMS ostium. This patient subsequently underwent successful and uneventful coronary artery bypass grafting. At the most recent follow-up, in early June 2001 (not accounted for in our statistics), the 3 remaining patients were free of angina, with good quality of life and exercise tolerance.

Discussion

Isolated ostial stenosis of the LMS coronary artery is rare, accounting for 1% of all coronary artery disease. ¹ The cause is unclear, but may be arteriosclerosis, inflammatory processes affecting the surrounding aortic wall, or both. ² In at least 2 of our patients, aortic atherosclerosis and calcification was observed around the LMS coronary ostium.

Traditionally, LMS coronary artery stenosis is treated by coronary artery bypass grafting. However, drawbacks include multiple vascular anastomoses (which consume bypass conduits and can lead to complications), permanent occlusion of the LMS coronary artery, ¹ and less physiologic retrograde myocardial perfusion. ³ On the other hand, treatment with surgical ostioplasty avoids these problems, and good clinical outcomes have been reported. ^1–8

Different techniques for exposing the LMS coronary artery have been reported; these include anterior, posterior, transaortic, and transpulmonary approaches. 1,2,7,8 In the anterior approach, ¹ the incision starts at the front of the ascending aorta and extends left-ward toward the LMS coronary ostium. The incision across the ostial LMS stenosis is made anteriorly. The posterior approach, described by Hitchcock and colleagues, ³ uses a spiral aortotomy. The aorta is opened from left to right, and the incision extends across the top of the commissure between the noncoronary cusp and the left coronary cusp. The posterior wall of the left main coronary artery is incised across the stenosis. To facilitate exposure, the aortic root is rolled to the left by traction sutures. Liska and co-authors ² recently reported a transaortic approach in which the ascending aorta is completely transected above the coronary commissures. The aortic root is mobilized in an anterior direction and the LMS coronary artery exposed. In both the anterior and transaortic approaches, the pulmonary trunk is retracted to the left by either traction sutures or tape, to improve the exposure. In the transpulmonary approach, described by Villemot's group, ⁸ visualization of the LMS coronary artery is achieved by transection of the left main pulmonary artery.

The best approach remains a matter of controversy. The anterior approach provides better exposure than does the posterior approach, but the acute angle formed by the junction between the LMS coronary artery and the aortic wall increases both the diffi-culty of inserting the patch and the possibility of re-stenosis at that point. This acute angle associated with the anterior approach can be lessened, however, by making an oblique incision on the aorta across the LMS artery. ¹ We used the posterior approach in all our patients, because it was simple and provided adequate access for the insertion of a large augmentation patch without compromising the result.

The augmentation patch on the LMS ostium can be of autologous pericardium, bovine pericardium, internal mammary artery, or saphenous vein. ^1–8 Theoretically, the use of an arterial patch can increase long-term patency, but this is not proven. We used autologous or bovine pericardium for the sake of simplicity. A major recognized complication of this procedure is restenosis, 1,2,6–7 which occurred in 1 of our patients. In this patient, the coronary ostium was found to be calcified during the 1st operation. The cause of early failure is unknown, but it could be that the pericardial patch's lack of fibrinolytic activity accelerated degeneration and promoted thrombo-sis. ² We therefore recommend that this technique be avoided if the LMS coronary artery has severe calcification. We also recommend that patients be placed on anticoagulative prophylaxis for 3 months postoperatively to prevent early ostial thrombosis.

In conclusion, surgical ostioplasty may be a useful option for selected patients with isolated ostial LMS coronary artery stenosis. We found the combination of a posterior approach and a pericardial augmentation patch to be both simple and effective. However, caution must be exercised to avoid early ostial re-stenosis, particularly in patients with calcification of the aortic wall and ostium.