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Ann Thorac Surg 1998;66:1008-1011
© 1998 The Society of Thoracic Surgeons
a Department of Cardiovascular Surgery, Institute of Cardiology and Cardiovascular Surgery, Favaloro Foundation, Buenos Aires, Argentina
Address reprint requests to Dr Weinschelbaum, Department of Cardiovascular Surgery, Institute of Cardiology and Cardiovascular Surgery, Favaloro Foundation, Belgrano 1746, 1093 Buenos Aires, Argentina
e-mail: (weins001{at}ffinme.edu.ar)
Presented at "Facts and Myths of Minimally Invasive Cardiac Surgery: Current Trends in Thoracic Surgery IV", New Orleans, LA, Jan 24, 1998.
Abstract
Background. In recent years, minimally invasive direct coronary artery bypass grafting has emerged as a valid tool for revascularization in a select group of patients with severe lesions of the left anterior descending coronary artery. Here we report the clinical results using two devices designed by us to facilitate the harvesting of the left internal mammary artery up to its origin and to occlude and stabilize the left anterior descending coronary artery while placing the anastomosis.
Methods. From January 1996 to January 1998, 122 patients underwent minimally invasive direct coronary artery bypass grafting in the Department of Cardiac Surgery, Favaloro Foundation. One hundred twelve patients received a single left internal mammary artery–left anterior descending coronary artery bypass graft, and in 10 patients, an additional bypass graft was performed.
Results. Most patients were discharged on day 2 or 3 after the procedure. Three patients (2.5%) had a perioperative myocardial infarction. The overall hospital mortality rate was 3.3% (4 patients).
Conclusions. The combination of team experience, more careful dissection of the left internal mammary artery up to its origin, and use of the stabilizer-occluder and interrupted suture technique for the anastomosis has markedly improved our results.
In the last 3 years, minimally invasive direct coronary artery bypass grafting (MIDCABG) has been introduced into cardiac surgery. Benetti and colleagues [1] were the first to describe thoracoscopic harvesting of the left internal mammary artery (LIMA) and performed the anastomosis with the left anterior descending coronary artery (LAD) through a small anterior left thoracotomy. Subramanian and Stelzer [2] and Standbridge and associates [3] used the same surgical approach but harvested the LIMA under direct observation. A LIMA–LAD anastomosis through a standard left thoracotomy without a pump was reported by Kolessov [4] in 1967. Since then, many approaches and technical variations have been described and this makes it desirable to obtain a standard for the procedure. We present here our results with MIDCABG with special emphasis on technical modifications aimed at dissecting the LIMA and stabilizing and occluding the LAD during the anastomosis by means of devices we have developed.
Material and methods
From January 1996 to January 1998, 122 patients underwent MIDCABG in the Department of Cardiac Surgery, Favaloro Foundation. The most common indications for the procedure were as follows: total occlusion of an LAD not suitable for percutaneous transluminal coronary angioplasty (PTCA); severe obstruction of an LAD unsuitable for PTCA; restenosis of an LAD after repeat PTCA or stenting; presence of multiple risk factors precluding conventional CABG with cardiopulmonary bypass (eg, chronic renal failure, chronic obstructive pulmonary disease, stroke); reoperation for a single bypass graft to the LAD; combined strategy in two- or three-vessel disease with MIDCABG to the LAD and PTCA to the other vessels; and LIMA–LAD grafting in patients who underwent valve procedures (two simultaneous minithoracotomies with cardiopulmonary bypass). The following conditions were considered relative contraindications to MIDCABG: acute myocardial ischemia at the time of the procedure; a small LAD (luminal diameter less than 1.5 mm); and cardiac arrhythmias (atrial fibrillation). An intramyocardial or calcified LAD represented an absolute contraindication.
Preoperative patient data are summarized in Table 1.
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One hundred twenty-two patients received a LIMA–LAD bypass graft. In 10 patients, an additional composite Y graft (inferior epigastric in 8, radial artery in 2) was connected to a diagonal branch. In one patient, the LIMA–LAD procedure was combined with mitral valve replacement, and concomitant aortic valve replacement and mitral valve repair was performed in another 2 patients (through two simultaneous minithoracotomies with pump).
Study protocol
The protocol included Doppler study in the operating room (all patients), transthoracic Doppler study in the intensive care unit (early in the study), angiography on the first postoperative day (all patients), Dobutamine hydrochloride stress echocardiography 30 days after operation (early in the study), and clinical follow-up. Initially, a transthoracic Doppler study was performed postoperatively in the intensive care unit. However, we found this technique was somewhat limited because the harvesting of the LIMA was done up to its origin in the subclavian artery, and the graft descended deep behind the sternum. This anatomic situation narrowed the echo window substantially, and so we gave up this step. The postoperative angiographic study was performed in all patients regardless of the Doppler results. All patients were followed in the outpatient clinic.
Results
Patients were admitted to the intensive care unit immediately after the procedure. The mean postoperative mechanical ventilation time was 4.8 ± 4 hours. Most patients were discharged on postoperative day 2 or 3. Three patients (2.5%) sustained a perioperative myocardial infarction. Seventeen patients (13.9%) had development of low cardiac output syndrome, but none required inotropic support longer than 24 hours or an intraaortic balloon pump. Acute atrial fibrillation occurred in 12 patients (9.8%). No patient experienced a superficial wound infection or mediastinitis.
The overall hospital mortality rate was 3.3% (4 patients). The causes of death were cardiogenic shock (a patient with severe left ventricular systolic dysfunction preoperatively), cerebrovascular accident (a patient with a history of repeated strokes), acute myocardial infarction (a patient operated on during an evolving anterior subendocardial myocardial infarction), and unsuccessful CABG (angiogram showed graft occlusion).
Angiographic studies showed total occlusion of the graft in 4 patients (3.3%), who subsequently underwent elective conventional CABG. A stenosis at the site of anastomosis was demonstrable in 5 patients (4.1%) and was successfully treated with PTCA. Two patients (1.6%) in whom snare lesions developed on the LAD distal to the anastomosis were also treated with PTCA. These complications occurred mainly early in the series. As we gained experience and corrected technical drawbacks, the incidence of events decreased dramatically. Twelve patients (9.8%) underwent elective PTCA to other coronary arteries (combined therapy or hybrid revascularization).
Follow-up was complete for all patients. The mean follow-up was 10 months (range, 1 to 23 months). Three patients (2.5%) died during long-term follow-up. One had a dilated cardiomyopathy and had been previously evaluated for heart transplantation; 1 died after elective conventional CABG (third reoperation because of repeated failures); and 1 died of noncardiac causes. Two patients (1.7%) underwent conventional CABG and another required PTCA to the LAD. At the end of follow-up, 4 of the long-term survivors (3.5%) were in New York Heart Association class II, and the 111 others (96.5%) were asymptomatic.
Comment
Minimally invasive direct coronary artery bypass grafting without CPB is considered a promising technique. The early or late failures observed during the initial period of our experience could be ascribed to technical flaws. The no-pump LAD revascularization approach is challenging, requires more technical skills, and is associated with a higher risk of suboptimal results.
From the beginning, we identified several pitfalls and modified the procedure so as to make it easier, safer, and more reproducible and to provide better outcomes. It may be useful, at least during the learning period, to use a standard sternotomy, which allows a much wider surgical field.
We recognized that the harvesting of the LIMA should go up to its origin in the subclavian artery differently as it was described originally [9]. We agree with Calafiore and associates [9] that the side branches of the LIMA, can be left intact during a partial dissection without causing a steal syndrome as long as the anastomosis to the LAD is accurate. We also believe that the LIMA must be completely dissected to achieve the same anatomic condition as under standard CABG, ie, it is long enough to reach the LAD with a wide curve and without tension. A short pedicle bending over the edge of the endothoracic fascia can produce an acute angle in the graft. This, combined with lung excursion, can cause early closure of the graft in some instances. On the other hand, the complete dissection of the LIMA up to its origin that we advocate results in a compromised Doppler window.
We emphasize the risk of the development of snare lesions as a sequela of using the sutures encompassing the LAD to try to stabilize and occlude the artery; this complication occurred in 2 of our patients. To avoid this problem, we designed an adaptable device that stabilizes and occludes the LAD during the anastomosis, thus eliminating the risk of vascular damage or excessive pressure over the left ventricle. All of our patients underwent angiographic evaluation of the graft on the first postoperative day. This protocol assures adequate monitoring of the revascularization.
With the standardization of our surgical technique (including the modifications mentioned), MIDCABG has become a more reproducible, more frequently used, and more continual successful procedure without the complications we observed at the beginning of our experience (eg, early occlusion of the graft, PTCA complementary to the anastomosis, snare lesion of distal LAD). The combination of team experience, more careful dissection of the LIMA up to its origin, use of the stabilizer-occluder for the LAD, and interrupted suture technique has markedly improved our results and expanded the horizons of this promising technique.
References
This article has been cited by other articles:
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  R. Marano, M. L. Storto, B. Merlino, N. Maddestra, G. Di Giammarco, and L. Bonomo A Pictorial Review of Coronary Artery Bypass Grafts at Multidetector Row CT Chest, April 1, 2005; 127(4): 1371 - 1377. [Abstract] [Full Text] [PDF]
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 E. E. Weinschelbaum, A. Machain, H. A. Raffaelli, V. M. Caramutti, M. R. Favaloro, E. A. Dulbecco, and R. Danielo Off-pump coronary operation at the Favaloro Foundation: results in 264 patients Ann. Thorac. Surg., September 1, 2000; 70(3): 1030 - 1033. [Abstract] [Full Text] [PDF]
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 R. D. L. Stanbridge and L. K. Hadjinikolaou Technical adjuncts in beating heart surgery Comparison of MIDCAB to off-pump sternotomy: a meta-analysis Eur. J. Cardiothorac. Surg., November 1, 1999; 16(suppl_2): S24 - S33. [Abstract] [Full Text] [PDF]
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P. P. McKeown Minimally invasive cardiac surgery. Ann. Thorac. Surg., February 1, 1999; 67(2): 600 - 601. [Full Text] [PDF]
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