At this point, the patient is placed on the heart–lung machine. Blood is re–directed from the heart into the heart–lung machine. This permits the surgeon to safely operate on the heart without blood pumping through it. The heart is then stopped, and the heart–lung machine continues to pump freshly oxygenated blood to the rest of the body, in effect, taking over the role of the heart and lungs.
The diseased coronary arteries are now identified and opened beyond the level of the blockages (see Figure 4). The open ends of the saphenous veins and LIMA are now sewn to the openings in the coronary arteries using very fine non–absorbable suture material, called "distal" anastamoses (see Figures 5, 6). Surgeons wear special magnifying lenses to see the delicate suture and small vessels.
Because the "inflow" through the LIMA is left intact, as soon as the LIMA anastamosis is completed, blood flow is established to that region of the heart. A vein graft, however, is harvested as a "free graft" and has no "inflow". Therefore, after the "distal" vein graft anastamosis is constructed, the other end of the vein graft is sewn to the aorta (the main artery leaving the heart) to establish "inflow". These are called the "proximal" anastamoses. After this stage, blood flow has now been established beyond all the blocked arteries.
The heart–lung machine is then gradually weaned off, and the patient’s heart and lungs resume their normal functions. The cannulae are removed from in and around the heart, and the sternum and incisions are closed. Drainage catheters are placed around the heart. These are usually removed after 24hrs. Temporary pacing wires to regulate the patient’s heart rate are sewn to the surface of the heart. These are removed before the patient goes home.
Know Your Heart
