Conventional CABG on Cardiopulmonary Bypass

Chest is opened by midline incision and median sternotomy. Simultaneously saphenous vein or radial artery is harvested. 'The pericardium is opened and aorta, left ventricle and target vessels for grafting are inspected. Using special sternal retractor, LIMA is harvested. After heparinisation distal end of LIMA is ligated and divided and flow checked. It is tucked away in a papaverine soaked gauze piece until it is to be anastomosed.

Ascending aorta is cannulated for arterial return. For venous return a two stage right atrio venous cannula is inserted though a purse string on the right atrial appendage. Cardiopulmonary bypass is instituted and patient cooled down to 28°C. Cardioplegia cannula is inserted into ascending aorta below the aortic cannula. A retrograde coronary sinus cannula is inserted through a purse string on the right atrium and the cannula is guided into the coronary sinus. It is then connected to a pressure monitor. Aorta is clamped and cold blood cardioplegia instilled into the aortic root. After heart is arestcd, rest of' the cardioplegia is administered through the coronaly sinus, taking care not to raise the pressure above 30 mm of Hg. Saphenous vein or radial artery ends are prepared for distal anastomosis cutting at an angle of 45" and trimming the edges. Strategically placed stay sutures on the pericardium and wet sponges placed inside help to elevate and rotate the heart to expose target vessels. It is opened with a sharp scalpel blade. The length of the incision should match the size of the conduit.

Surgeons usually use 2.5 to 4 times magnification for surgery. Ideally the anastomosis made between the end of the conduit and the opened coronary artery should have a cobra hood appearance. Anastomosis is done with single 7 '0' double armed prolene suture taking special care at the heel and the toe. Patency of the graft and presence of any leak is checked by injection of heparinised blood through the conduit. If the same conduit is used for multiple grafting, the last one is an end to side anastomosis and the others are side-to-side anastomoses (Sequential grafting). Care should be taken to get the correct length and lie of the conduit in sequential grafting. The last anastomosis done is usually LIMA to LAD and flow is established through the graft. All the distal anastomosis are checked for patency and bleeding. Aortic cross clamp is released after de-airing of the aortic root. Proximal anastomosis of the conduit is done to the ascending aorta with a partial occlusion clamp. The length of each graft is measured with a full beating heart. This has to be accurate. Aortic punch is used to make circular holes in the ascending aorta on its partially occluded portion. Single 6 '0' double armed prolene suture is used. Before and after releasing the clamps, the conduits are de-airing with a 25-gauge needle.

In another technique, the conduits to ascending aorta anastomoses (proxinlal anastomoses) are done before going on bypass. This is the technique is used in cases of off pump coronary artery bypass grafts (OPCAB). The advantage of this technique is that full coronary flow is established to the myocardium as soon as the distal anastomosis is completed.