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Coronary Surgery without Cardiopulmonary Bypass
Aramendi JI, Castellanos E, Llorente A, Aldamiz-Echevarria G, Otero A, Martínez P.
Hospital de Cruces
Materials and Methods
Introduction: Off-pump coronary bypass surgery (OPCABG), since the pionering work of Benetti and Buffolo has now become a widely used procedure. Although long-term results are not known initial and mid-term results are excellent in most series. In this communication we present our initial results with OPCABG and more recently with minimally invasive direct coronary artery bypass (MIDCAB).
Materials and Methods: Since December 1993 to February 1999, 119 consecutive patients underwent coronary a. Bypass surgery without cardiopulmonary bypass. Of them 95 via a median sternotomy and 24 via a small left anterior thoracotomy. Demographic data are showned in table I. There has been a selection of the patients. Most patients were 1 or 2 vessel disease with favorable anatomy and a specific cohort of proximal left main coronary stenosis. Patient selection varied with time but essentially consisted in indicating off-pump surgery in "good patients" in an attempt to decrease surgical aggression and, on the other hand, patients with contraindications for CPB, like severe COPD, poor LV function or patients in hemodialisis. Type of grafts are depicted in figure 1. Since October 1995 we began practicing minimally invasive surgery for 1 vessel disease through a left anterior small thoracotomy(LAST). Table II. Since 1997 we use routinely specific retractors and heart stabilizers, CTS, Autosuture, to facilitate exposure. Details of surgical technique have been published thoroughly. We do not use preconditioning, and since we use stabilizers we do not attempt to slow heart rate except oral b -blockers preoperatively. Initially, a control cardiac catheterisation was done in the first 2 months postoperatively(39 pt.), but not at present time. To the LAST patients a transthoracic Echo-Doppler study is done in the first intercostal space to assess the patency of the LIMA graft: a good diastolic flow is indicative of a patent and non restrictive graft.
Table I. Demographic data for OPCAB
Table II. Demographic data for MIDCAB.
Figure 1. Type of grafts.
Results: There were 4 hospital deaths (3.3%) for the whole series: 4.3% for the median sternotomy group (1% for elective cases) and 0% for the LAST patients (p=ns). Table III.The mode of death was: intractable respiratory failure in a Class IV COPD patient who could not be weaned from the ventilator. The other 3 patients died of cardiac cause: 2 patients with severe preoperative heart failure continued with low cardiac output despite maximal therapy. The last patient was a LIMA to LAD graft with an initial uneventful recovery who had a cardiac arrest on postoperative day 2. He was resuscitated and emergent cardiac catheterisation was done: he had a severe spasm of the LIMA graft extended to the LAD. Intracoronary nitroglycerin solved the problem and showed a non-restrictive anastomosis. Nevertheless, the patient died of neurological deficit due to the cardiac arrest. Bleeding, postop. MI and medistinitis occurred in 2% of median sternotony patients and no complications was present in LAST patients. Table III .Graft patency was assessed in 54 patients (44%). Angiography was done in 39 pt. and Echo-Doppler in 15 pt. Of 79 grafts tested, there were 3 graft occlusions (2 saphenous vein and 1 LIMA graft) and 2 LIMA graft stenoses. The stenosis was not located at the anastomotic site but consisted in diffuse narrowing of the distal part of the LIMA graft just proximal to the anastomosis which was normal. This finding was attributed to postop. pericarditis which produced spasm of the part of the graft in contact with the pericardium and finally fibrosis. This complication was solved with PTCA in one patient and reoperation in the other one consisting in end to end anastomosis or RIMA to the distal part of the LIMA graft off-pump. 3 other patients required reoperation with saphenous vein graft, 2 of them off-pump. Patency rate was 94%. Blood transfusion was avoided in 77% of LAST patients and 28% of the median sternotomy group. Most LAST patients were dismissed at the 4th or 5th postop. Day
Table III. Results.
Discussion: It is well assumed that OPCABG permits to perform coronary revascularization in selected patients with good operative results and fast recovery. In our series good operative results similar to conventional surgery have been achieved despite the presence of high risk patients with contraindications for CPB. Nevertheless bleeding and mediastinitis are still present with this technique. Probably these complications are attributable to the median sternotomy itself irrespective of the use of CPB. We recently switched to skeletonized dissection of the IMA in an effort to maintain the irrigation of the sternum and diminish bleeding. There were some concerns in the past about the quality of coronary anastomosis in OPCABG. Since the advent of cardiac stabilizers and flowmeters optimal conditions are granted for a perfect anastomosis in most circumstances. Most groups are now extending the indication of OPCABG to 3 vessel disease to favor its widespread use, leaving conventional CABG for the exceptional unsuitable patient.
MIDCAB is a newer technique that has supposed the greatest advance in myocardial revascularization in the last 5 years. It is based on the evidence that the best way to revascularize the LAD is a LIMA graft. The initial objectives of no mortality, few complications and short hospital stay are easily achieved by most groups. It is an evolving concept and the final goal would be a totally endoscopic anastomosis in a cuasi ambulatory procedure. The main limitation of this technique is the shortage of 1 vessel diseased patients who are preferably addressed to medical therapy or PTCA. This prolongs the learning curve and difficults the acquisition of expertise. Therefore, a positive search for surgical candidates is suggested to increase its use.
Conclusions: OPCAB surgery is a safe and low risk operation. Graft patency is equivalent to and complication rate lower than conventional surgery. Nevertheless, median sternotomy still carries a definite risk of bleeding and mediastinitis. LAST operation seems to offer better results as far as mortality, morbidity and blood transfusion requirements are concerned. It also offers a faster recovery.
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