Overzealous elevation of the hemisternum by retractors may result in rib fractures or even costochondral disruption. This is more apt to occur in patients with pectus deformities or morbid obesity and in elderly patients with osteoporosis.

Although it is possible to dissect the internal thoracic artery without entering the pleural cavity, we prefer to routinely open the left pleura widely to provide excellent exposure and greatly facilitate harvesting of the internal thoracic artery.

Opening the pleura allows the left internal thoracic artery pedicle to fall away from midline. This decreases the risk of injury at reoperation.

Alternatively, the left internal thoracic artery can be harvested through a lower ministernotomy, dividing the left half of the sternum (see Chapter 1). A Favaloro retractor allows the left hemisternum to be elevated to provide adequate exposure for mobilizing the internal thoracic artery. This approach allows off-pump bypass grafting of the left internal thoracic artery to the LAD coronary artery (see subsequent text).

The internal thoracic artery is usually harvested as a pedicle with extensive use of electrocautery for chest wall hemostasis but not pedicle hemostasis. The parietal pleura on the internal intercostal musculofascial layer of the chest wall is incised approximately 7 to 10 mm medial to the internal thoracic artery along its entire course (Fig. 9-1). The blade of the electrocautery is then used to depress and dissect the pedicle from the chest wall. The lowest current is used to coagulate the internal thoracic artery and vein branches, well away from the parent trunks. The side branches on the artery are then occluded with fine metal clips. The pedicle is dissected from the level of the rectus sheath to the level of the subclavian vein where the artery passes beneath this vessel. Care is taken to identify and divide two intercostal branches, one passing anterior to the subclavian vein and a high first intercostal branch coursing laterally above the subclavian vein.

When the patient’s condition is unstable, it may be preferable to harvest the internal thoracic artery while the patient is on cardiopulmonary bypass.

Because the internal thoracic artery is a delicate structure, any undue stretching, clamping, or misplaced metal clips results in permanent vascular injury and therefore unsatisfactory short- and long-term results. Excessive traction during mobilization should be avoided as it can lead to dissection of the vessel wall.

When an electrocautery is used to divide the internal thoracic artery branches after application of metal clips, the heat and the electric current may conduct through the metal clip adjacent to the parent trunk and cause a burn injury. Therefore, branches must be
divided with scissors or coagulated well away from the metal clip adjacent to the internal thoracic artery.

The internal thoracic artery pedicle must be dissected free from the chest wall along its entire course, from near its origin in the first intercostal space to well past its bifurcation into the rectus sheath to provide maximal length.

The first intercostal branch of the internal thoracic artery must be identified and divided to avoid any possible steal phenomenon from the internal thoracic flow.

Before commencing cardiopulmonary bypass, papaverine is sprayed gently over the pedicle and the adequacy of flow is determined. If there is no flow, a 1-mm vascular probe (Parsonnet) is cautiously introduced into the lumen of the vessel for a varying distance. This should be done with extreme care to avoid intimal injury. Usually very good flow is noted. Unless traumatized during harvesting, the internal thoracic artery usually provides adequate flow and should not be discarded.

In elderly patients, it may be preferable to skeletonize the internal thoracic artery rather than harvesting it as a pedicle. This may decrease the incidence of avascular necrosis and infection affecting the sternum.

The pedicle is laid on the heart to judge the appropriate length. The end of the pedicle is then grasped and occluded with forceps, allowing the internal thoracic artery to distend with blood. The artery is then cleaned free of the surrounding tissues, using sharp dissection. The artery is transected obliquely with the heel on the fascial side of the pedicle and prepared as a large hood orifice.

The internal thoracic artery can be lengthened considerably with multiple pedicle fasciotomies. Maximal length can be obtained by skeletonizing the vessel along its course. Division of the internal thoracic veins should be avoided when performing the fasciotomies. If the pedicle remains too short, the artery may be divided proximally and used as a free graft.

Excessive stretch and tension on the internal thoracic artery result in narrowing of the lumen and graft failure. This is seen as a string sign on a selective angiogram of the artery.

Before the distal end of the internal thoracic artery is divided, its correct length must be ascertained. The internal thoracic pedicle should lie very comfortably on the heart when it is full and the lungs are fully inflated; otherwise, the artery will be stretched and could become detached at the anastomotic site.

Similarly, it should not be redundant because too long a pedicle may curl or kink into the substernal area, increasing the risk of injury at reoperation.

The caliber of the internal thoracic artery is smaller and resistance to flow is higher the longer the pedicle is. A tortuous internal thoracic artery course makes later catheter intervention nearly impossible.

The internal thoracic artery, when fully mobilized and divided, is occluded with an atraumatic bulldog clamp after the patient has been fully heparinized to prevent any clotting within the lumen of the vessel.

The pericardium is divided with electrocautery where the internal thoracic artery pedicle crosses it down to 1 cm above the left phrenic nerve. This allows the pedicle to assume a more lateral position and lie against the medial surface of the lung instead of coursing over the apex of the lung. This is especially important when the left internal thoracic artery is grafted to an obtuse marginal branch of the circumflex coronary artery.

An in situ right internal thoracic artery can easily reach the diagonal, ramus intermedius or a proximal obtuse marginal branch of the circumflex coronary artery. The pedicle should cross the distal ascending aorta near the innominate vein. Thymic tissue and fat can be used to cover the pedicle. If the right internal thoracic artery is grafted to the LAD coronary artery, its course will be across the more proximal aspect of the ascending aorta, which puts it at high risk of injury during reoperative procedures.

The arm is abducted to 90 degrees and under sterile conditions prepared and draped on an armboard. An incision is made in the midportion of the forearm over the belly of the brachioradialis muscle. The opening is then extended for a variable distance proximally toward the groove between the brachioradialis and biceps tendon (Fig. 9-2). Distally the incision is extended toward the wrist crease. With experience, the opening in the forearm can be fairly limited in length and still allow adequate exposure to harvest the radial artery.

The dissection of the radial artery begins distally by dividing the fascia and then proceeding proximally between the belly of the brachioradialis and flexor carpiradialis muscles. A vessel loop is then passed around the radial artery to facilitate exposure. The artery is dissected along with the two venae comitantes, double clipping and sharply dividing all the branches. When the radial artery is completely mobilized, the radial recurrent artery is identified proximally and the superficial palmar artery is seen distally. These two large branches define the limits of the dissection and should be preserved (Fig. 9-2). The radial artery is divided distally and proximally and placed in a solution of heparinized blood and papaverine. The arm incision is closed in two layers with continuous absorbable suture. The deep layer includes the subcutaneous tissue distally.

The distal limit of the skin incision should be 3 cm above the wrist joint to decrease postoperative discomfort.

In the operating room, the arm is abducted to 90 degrees. Under sterile conditions, the arm is prepared and draped on an armboard. A sterile blood pressure cuff is placed around the upper arm and connected to a sphygnomanometer. In addition, a small roll is placed under the wrist to hyperextend the hand. A 1-in. longitudinal incision is made over the radial artery distally, such that it will be covered with the sleeve of a shirt (Fig. 9-3A). Under direct vision, the radial artery is dissected for a short distance proximally and distally. The blood pressure cuff is inflated to 20 mm above the patient’s systolic blood pressure. The endoscope is inserted through the incision while the tunnel is being insufflated. The tissue plane under the radial artery is dissected first, followed by circumferential mobilization. The branches are freed gently for a sufficient length so that cautery can be applied without injury to the radial artery wall. The dissector is then replaced with scissors equipped with cautery to divide all side branches (Fig. 9-3B). A counter incision at the elbow is made, and the proximal end of the radial artery is divided and controlled. Alternatively, an endoloop can be advanced through the tunnel and proximal control can be obtained. The latter technique avoids the counter incision. After removal of the radial artery from the tunnel, metal clips are applied to the branches (Fig. 9-3C). The distal radial artery is ligated and divided. Under endoscopic visualization, the blood pressure cuff is deflated and optimal hemostasis is ensured. The wrist incision is closed in two layers and a sterile pressure dressing is applied. The radial artery is irrigated with heparinized saline. Papaverine may be sprayed on the pedicle to prevent spasm.

A 2-cm transverse incision is made just above the medial aspect of the knee (Fig. 9-4A). The greater saphenous vein is identified and encircled with a vessel loop. An endoscope is then introduced using carbon dioxide insufflation to dissect a plane superficial to the vein. Circumferential dissection of the vein is completed by the dissector. The side branches are dissected for a minimum of 5 mm, so
that with cauterization, the vein wall is not damaged (Fig. 9-4B). After removal of the dissector, a specialized cautery device/scissors is introduced to divide the side branches (Fig. 9-4C). Once the proximal extent of the dissection is reached, a counterincision is made to facilitate division of the vein and oversewing of the stump. The vein is then gently withdrawn through the knee incision.

If two vein graft segments are required, the thigh vein is harvested as described. For additional conduit, the lower leg vein can be harvested by directing the endoscope inferiorly through the same knee incision.

The two incisions are then closed in two layers, and an elastic bandage is snugly wrapped around the leg and kept in place for 24 hours.

An incision is made in the groin, one fingerbreadth medial to the femoral artery pulse. The subcutaneous tissue is dissected to expose the greater saphenous vein as it curves to pierce the cribriform fascia of the femoral sheath and join the femoral vein. The skin incision is then extended downward along the course of the vein. The incision can alternatively be started at the ankle, anterior to the medial malleolus, and extended upward. Many surgeons consider this approach convenient and elect to use it routinely.

The vein is harvested using the “no touch” technique. This entails handling of the vein only by its adventitia with an atraumatic vascular forceps. The vein is then gently removed from its bed by careful dissection and division of its branches.

The leg wound is closed in layers with absorbable sutures. In the groin region or where the wound is deep, an extra layer of closure may be necessary. The skin is closed with fine absorbable suture material in a subcuticular manner.

Cold blood cardioplegia is infused into the aortic root to achieve cardioplegic arrest of the heart initially and repeated every 10 to 15 minutes during the cross-clamp time. Additional cardioplegic solution is infused directly into the vein graft after the distal anastomosis is completed. Core cooling to 34°C and topical cold or iced saline supplement myocardial protection. Critical proximal disease of major coronary arteries may interfere with the uniform distribution of cardioplegia and prevent complete cardioplegic arrest of the myocardium. Retrograde cardioplegic perfusion through a coronary sinus catheter is a useful adjunct for optimal myocardial protection during coronary revascularization (see Chapter 3).

In patients with acute coronary occlusion and impending infarction, the culprit vessel is grafted first to allow cardioplegic solution to be delivered through the vein graft to the involved myocardial territory.

Retrograde administration of cardioplegia may be particularly useful when arterial conduits are used because cardioplegia cannot be delivered through the graft.

Patients undergoing redo coronary artery bypass procedures with patent but diseased vein grafts are at risk of embolization of graft debris into the distal coronary artery bed. In these cases, retrograde cardioplegia is indicated.