Proximal Internal Mammary In Situ Graft and Distal Coronary–Coronary Graft to Revascularize Left Anterior Descending Coronary Artery

Abstract

When a left anterior descending coronary artery passes over the cardiac apex and presents with 2 stenoses, 1 proximal and 1 distal, the available bypass conduit often is too short to enable both the anastomosis below the distal stenosis and the sequential anastomosis on the arterial segment between the 2 stenoses. In this circumstance, we graft the internal mammary artery in situ onto the proximal segment of the left anterior descending coronary artery, then use a short residual segment of the internal mammary to perform a coronary–coronary bypass of the distal stenosis. This technique also spares segments of the internal mammary for other purposes. We present our experience, together with angiographic evidence of long-term patency.

Effler and Favarolo ^1,2 described their pioneering coronary artery bypass procedure as “aorto-coronary artery” bypass, because a segment of the saphenous vein was used as a conduit from the aorta to the right coronary artery (and in some instances to the left circumflex), the diseased portion of which had been excised. For the last 25 years, many heart surgery centers have supplemented aortocoronary bypass grafting with coronary–coronary bypass grafting, not only in patients with such specific characteristics as calcification of the ascending aorta or inadequate length of available graft material, ^3–5 but also in patients without such problems, as a purely technical choice. ⁶ In the treatment of right coronary artery stenosis, the proximal anastomosis is usually performed at the origin of the right coronary artery, while the distal anastomosis is performed either on that same coronary artery or on 1 of its major branches.

In a parallel development, the internal mammary artery (IMA), because of its long-term patency, has become the conduit of choice for performing coronary artery bypass grafting. However, the IMA is frequently too short for aortocoronary bypass of distal lesions; alternatively, a free segment of the vessel may be used as a distal coronary–coronary graft.

Surgical Technique

At our institution, we perform coronary–coronary bypass grafting in specific cases, but especially when we want to revascularize a left anterior descending coronary artery that passes over the cardiac apex and presents with 2 stenoses, 1 proximal and 1 distal (Fig. 1). When we use the right IMA for revascularization, the available conduit is too short to enable both the anastomosis below the distal stenosis and the sequential anastomosis on the arterial segment between the 2 stenoses. Therefore, we graft the IMA in situ onto the proximal segment of the left anterior descending coronary artery. Then we use a short residual segment of the IMA to perform a coronary–coronary bypass of the distal stenosis.

Fig. 1 Preoperative angiogram shows stenoses on the left main coronary artery and on the left anterior descending coronary artery at its point of origin. This vessel runs over the cardiac apex and presents with a severe stenosis in the distal segment (arrow).

From September 1989 to March 1996, we have used this intervention only 6 times because patients seldom present with the right indications for its use. In all 6 patients, we used cardiopulmonary bypass, and for all coronary sutures we used continuous 8-0 Prolene. None of the patients who underwent this procedure suffered intraoperative complications. Only 2 patients underwent follow-up angiography, 1 at 3 years and the other at 8 years. In both patients, angiography showed occlusion or stenosis of a venous bypass graft, which caused recurrent angina, but the IMA graft was patent, both in situ and at the site of the distal coronary–coronary bypass (Fig. 2). On the basis of this experience, we believe that coronary– coronary bypass grafting onto the distal segment of the left anterior descending coronary artery can be a valid alternative to sequential bypass grafting. This procedure has the further advantage of sparing segments of the IMA for other purposes, such as the construction of a new T arterial conduit.

Fig. 2 Postoperative angiogram in same patient, performed 3 years later. Note that both the proximal in situ IMA graft (single arrow) and the distal coronary–coronary IMA graft (double arrow) are patent.