**Re-Engineering in OPCAB Surgery**

Murali P. Vettath, Et Ismail, Av Kannan and Athmaja Murali *Kozhikode Kerala India* 

### **1. Introduction**

180 Special Topics in Cardiac Surgery

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coronary artery bypass graft surgery:Off-pump CABG significantly reduces

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Aortic Cross Clamping – Myocardial Revascularisation: Single Center Expirience.

Coronary artery bypass surgery is a procedure that started off with the first implantation of the internal mammary artery to the cardiac muscle in 1946 by Vineberg [Vineberg AM, 1954]. Later, the coronary anastomosis distal to the occlusion using the saphenous vein graft (SVG) or the internal mammary artery (IMA) was experimentally conceived by Murray [Murray et al, 1954]. Bailey et al [Bailey et al, 1957] were the first group to approach the problem of coronary occlusion in 1957. Though the pioneers of OPCAB were Goetz and colleagues [Goetz et al, 1961] and Kolessov [Kolessov VL, 1967] who performed the procedure in isolated cases. The first clinical series of consecutive patients was by Trapp and Bisarya [Trapp WG, Bisarya R,1975] and Ankeney [Ankeney JL,1975].

Then, with the development of direct coronary surgery, under the leadership of Favaloro [Favaloro RG,1968] and Green and coworkers [Green GE, Stertzer SH 1968], with procedures being performed in an arrested heart with the use of extracorporeal circulation, off-pump coronary surgery was abandoned. Thus the surgeons all over the world started performing CABG on the heart lung machine , and that became the standard of care for patients with coronary artery disease.

 In 1981 Enio Buffolo [Buffolo E ,et.al,1985]from Brazil and Benneti [Benetti FJ,1985] from Argentina had started experimenting on this technique of Direct Myocardial revascularization. Both of them published their series around 1985 which rekindled the idea of OPCAB in the western world. It was probably the idea of minimally invasive direct coronary artery bypass graft (MIDCABG), introduced in the mid-1990s by Benneti [Benetti FJ ,1985,1995], that called attention to the possibility and advantages of not using CPB. Calafiore's [Calafiore AM,et al,1996,1998] publications re- enforced the advantages of the LAST(left anterior small thoracotomy) operation. The LIMA stitch was acclaimed as an extraordinary step in the development of off-pump coronary surgery, which allowed grafting of posterior branches of the coronary arteries. The introduction of stabilizers in the mid 1990s further facilitated the procedure[Borst C,1996]. Eric Jansen, was one of those surgeon in the mid nineties who was probably the man who had made the word -Octopusso very popular in the rest of the world. The article published in 1991 by Benetti [Benetti F.J et al,1991] in Chest, gave confidence to the Cardiac surgeons around the world to perform OPCAB in all anterior vessels. But even then the circumflex territory became a danger zone for most surgeons to perform a safe coronary anastomoses. Though LIMA stitch was used quite often, it was the availability of the Positioners that that made the process of Verticalisation of the heart more comfortable.

Re-Engineering in OPCAB Surgery 183

 Tumor necrosis factor (TNF-) peaked 24–48 h after CPB at a significantly higher value compared to OPCAB patients who had no increase. Tumor necrosis factor receptors 1

 Different markers tested in each study (interleukin 6 and plasma elastase) were significantly elevated with CPB. OPCAB patients showed a blunted response. The other variables of CPB such as haemodilution, non-pulsatile flow, and aortic crossclamping, which may act in concert with SIRS to increase postoperative morbidity, are

Thus avoiding the heart lung machine would be a logical solution in performing coronary

Adequate myocardial preservation is crucial in CABG operations. Preoperative resuscitation of ischemic myocardium enables recruitment of hibernating myocardium and forms an important component of any myocardial protection strategy. The intraoperative strategy varies (within physiological boundaries) as much from patient to patient as it is from surgeon to surgeon, to the extent that a good clinical outcome becomes the ultimate determinant of the optimal strategy. Even with the same surgeon, the strategy is adapted to the patient and clinical scenario that a prescriptive regimen is not standard. The objective of intraoperative myocardial preservation is to enable efficient myocardial energy management by reducing cardiac metabolic demands on the one hand, while improving

In on-pump CABG, cardioplegia or cross-clamp fibrillation are conventional methods of intraoperative myocardial protection. Cardioplegia favorably affects myocardial energy metabolism but results in the alteration of both the intra- and extracellular milieu and, together with CPB can precipitate changes in cardiac performance postoperatively [Mehlhorn U.,1995]. Cross-clamp fibrillation can increase the endocardial viability ratio and lead to similar changes in cardiac function. In both strategies of myocardial protection, a period of global myocardial ischemia is followed by reperfusion with oxygen-rich blood predisposing to reperfusion injury which manifests as myocardial stunning and

Since deliberate induction of global ischemia is unnecessary in OPCAB, it is logical to suppose that iatrogenic biochemical injury to the myocardium would not occur. More so, the blunted inflammatory response with avoidance of CPB is characterised by low production of IL-8 which is involved in myocardial injury . In fact, Atkins et al. first suggested that OPCAB preserved cardiac function in 1984 [Atkins C.W .et al,1984]. In different prospective randomized studies, Ascione [Ascione R.et al,1999], Penttilä [Penttilä H.J.,et al,2001], Van Dijk [Van Dijk D..et al,2001], Czerny [Czerny M.,et al 2001], Bennetts [Bennetts J.S.et al,2002], and Masuda [Masuda M.et al,2002], and their collaborators reported minimal change in the biochemical markers of myocardial injury (troponin T and/or creatinine kinase-MB isoenzyme), and in some cases, better myocardial function after OPCAB compared to on-pump CABG. Changes in myocardial metabolism indicative of oxidative stress due to local ischemia when the target coronary artery is occluded to enable visualization for distal anastomoses have been reported in OPCAB [Matata B.M. et al 2002]. Compared to on-pump CABG, OPCAB is associated with better myocardial energy preservation, less oxidative stress and minimal myocardial damage [Penttilä H.J et al.2001].

myocardial oxygen supply and utilization on the other [Buckberg G.D et.al,1996].

and 2 were elevated to three times their preoperative level only with CPB.

eliminated by the avoidance of CPB.

**3. Myocardial preservation** 

arrhythmias in the early postoperative period.

artery bypass surgery

By the end of the 90's, most of the surgeons in India and in the far east had been performing OPCAB in 90% of their Coronary artery patients, but by early 2000, there was a sharp decline in the numbers, as most of the surgeons did not find the comfort zone in OPCAB surgery, and that their patency rates were being questioned. In the 1990s the visibility of coronary anastomosis was again a doubtful proposition, and also converting, and going on to the pump became a recipe for disaster. Then came the comparative trials of OPCAB and ONCAB , which obviously brought in results which showed that both the techniques produce nearly the same results, and that the patency was a question of concern[Kim KB,et al,2001&.Puskas JD.et al,2001] The Rooby trial showed that, at 1 year of follow-up, patients in the off-pump group had worse composite outcomes and poorer graft patency than did patients in the on-pump group[A. Laurie Shroyer,et al,NEJM,2009]. The surgeons had then come to a conclusion that OPCAB is good in experienced hands and the results in that group of people have been outstanding.

The appeal of avoiding cardiopulmonary bypass with its direct and indirect physiological insult, the prospect of improved clinical outcomes, and the favorable economic impact gives OPCAB the potential of preference that may mark the dawn of a new era in our search for the optimal surgical strategy for the treatment of coronary artery disease.

OPCAB has been performed in many different ways. It's like different ways of skinning a cat. Ultimately, the gold standard of a perfect patent coronary anastomosis remains the corner stone of a good surgeon and a good operation. It is to be emphasized here that Coronary artery bypass surgery has a come a long way from performing them off pump, then on pump and now going back to off pump. But the most important point, one has to bear in mind is that , the surgeon has to do what he is most comfortable with and by which he would be able to give the best result.

The topic of Re-engineering in OPCAB came up , because, there was an engineering that was done during the early phase of OPCAB by the great pioneers of this procedure. But what happened along the way was that these procedures were not reproducible by lesser mortals like us and hence we had to re-engineer this procedure to suit us.
