Limited access or minimally invasive coronary artery surgery is being evaluated in numerous North American medical centers. The purposes of this report are to (1) describe the techniques, (2) examine progress in this new field, (3) comment on the potential of these approaches, and (4) put into perspective the expected goals of minimally invasive coronary surgery, given the proven long-term results achieved with traditional techniques (sternotomy and cardiopulmonary bypass).
Minimally invasive coronary artery bypass is performed using one of two approaches: (1) a series of small holes or “ports” in the chest (referred to as PACAB, PortCAB, or port-access coronary artery bypass) or (2) a combination of ports and a small incision directly over the coronary artery to be bypassed (referred to as MIDCAB or minimally invasive coronary artery bypass). As in standard coronary artery bypass graft surgery (CABG), anesthesia is required.
PACAB is currently used only by investigators at a few university centers. In this method, cardiopulmonary bypass is performed using the femoral vessels. The heart is stopped and the bypasses are performed using instruments passed through the ports, with or without a small additional chest incision. As with abdominal laparoscopic surgery, the cardiac surgeon views these operations on video monitors rather than directly.
The MIDCAB procedure combines both direct and indirect techniques. In contrast to PACAB, it is performed with the intention of avoiding cardiopulmonary bypass. Initially developed in countries where economic resources for cardiopulmonary bypass procedures are limited (most notably Argentina, Brazil, and Italy), MIDCAB is performed on a beating heart. In contrast to PACAB, the procedure was designed for bypassing only one or two coronary arteries; since suturing is done under direct vision, the coronary artery to be bypassed must lie directly beneath the incision. The coronary bypass is usually performed using the left internal mammary artery (LIMA), which lies on the inside of the chest wall very near the left anterior descending coronary artery (LAD). The LIMA is dissected from the chest wall using direct vision and/or video guidance, depending on the patient's anatomy and the surgeon's preference. Afterward the LIMA is sutured directly to the LAD. Occasionally the right internal mammary artery is used to bypass the right coronary artery. By mid-1996 at least 200 MIDCAB procedures had been performed in various universities and private hospitals throughout the United States and several hundred more in Europe and South America.
The Council on Cardio-Thoracic and Vascular Surgery of the AHA has been carefully monitoring the use of these two procedures. Despite tremendous enthusiasm on the part of patients, industry, and the press, their widespread adoption cannot be endorsed until suitable data have accumulated and a conscientious critique can be done. The role of minimally invasive coronary bypass in the treatment of patients with single-vessel coronary artery disease will be defined only by such careful comparative studies. Natural history studies of medically treated patients demonstrate a good long-term prognosis, except for the subgroup with severe proximal LAD stenosis. Conversely, observational studies suggest that angioplasty may provide a slightly better long-term survival benefit than bypass surgery for patients with single-vessel disease.1
These facts suggest that the role of minimally invasive coronary bypass in patients with single-vessel coronary disease will, for now, be limited to the few who need interventional therapy but are not suitable candidates for coronary angioplasty due to their anatomy, ie, those who have undergone one or more failed angioplasties, or those who elect surgical revascularization instead. There is no expectation that a smaller incision will greatly alter the rate of cardiac death after bypass. If coronary surgery can be made so noninvasive to be considered equally invasive to coronary angioplasty by the patient, the more definitive nature of surgery would represent a distinct advantage over angioplasty. However, all current minimally invasive bypass techniques are more invasive than angioplasty, and general anesthesia is necessary.
The most likely future application for minimally invasive surgery is in patients with extensive disease now known to have a survival benefit from the standard bypass. Recent randomized trials demonstrating equivalent 5-year survival in patients with two- and three-vessel disease who have undergone revascularization by either angioplasty or bypass surgery suggest that complete revascularization may not be as necessary as previously believed.2 3 4 Those patients with the most severe disease confined to the LAD and right coronary artery might be well served by two internal mammary artery grafts to these vessels. If this operation can be performed safely using minimally invasive techniques, efficacy comparable to standard coronary bypass might be proved in these patients.
MIDCAB is easier on the patient and is probably less expensive than traditional CABG. Nonetheless, compared with traditional CABG, exposure is limited and performance of the anastomosis more difficult. Significant ischemia leading to hemodynamic compromise of the patient may occur. Therefore, the procedure must be performed with the availability of cardiopulmonary bypass. Predictably, urgent conversion to conventional open-chest methods has occasionally been necessary.
We must neither ignore the very real potential for these new procedures nor trivialize innovations. Rather, we must critically evaluate MIDCAB and PACAB in terms of time-honored end points: immediate and long-term graft patencies and absence of cardiac ischemia. An inclusive database or registry will be established, and minimally invasive techniques will be critically evaluated. This project is being undertaken by a joint committee of members of the Society of Thoracic Surgeons and the American Association of Thoracic Surgeons.
The author thanks Timothy J. Gardner, MD; Alden H. Harken, MD; Robert H. Jones, MD; and D. Craig Miller, MD, for their contributions to the development of this advisory.
“Minimally Invasive Heart Surgery” was approved by the American Heart Association Science Advisory and Coordinating Committee in August 1996.
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- Copyright © 1996 by American Heart Association
Jones RH, Kesler K, Phillips HR III, Mark DB, Smith PK, Nelson CL, Newman MF, Reves JG, Anderson RW, Califf RM. Long-term survival benefits of coronary artery bypass grafting and percutaneous transluminal angioplasty in patients with coronary artery disease. J Thorac Cardiovasc Surg. 1996;111:1013-1025.
Hamm CW, Reimers J, Ischinger T, Rupprecht H, Berger J, Bleifeld W. For the German Angioplasty Investigation. German Angioplasty Bypass Surgery Investigation. A randomized study of coronary angioplasty compared with bypass surgery in patients with symptomatic multivessel coronary disease. N Engl J Med. 1994;331:1037-1043.