Internal Mammary Artery Harvest

Patients are monitored in the usual way for cardiac surgery. A central venous line and a radial artery cannula are placed on the same side as the harvested internal mammary artery. There is a mandate for single-lung ventilation with a double-lumen tube, a Univent tube, or bronchial blocker, the position of which is confirmed by bronchoscopy. The patient is positioned supine, with the thorax rotated 20 degrees by placing a roll under the left scapula. External defibrillation and pacing pads are applied to the left posterior chest and anterolateral right chest. Raising the left arm provides more exposure and thins the skin overlying the left anterolateral chest. The opposite can be done to the right chest when harvesting only the right internal mammary artery. Carbon dioxide insufflation is needed to provide exposure and counter-traction. Carbon dioxide insufflation (5 to 10 mm Hg) into the left hemithorax pushes the mediastinal fat pad medially and enlarges the space between the sternum and heart to a small extent to provide a better view. When harvesting both internal mammary arteries, insufflation of the left hemithorax is sufficient to expose the right internal mammary artery because of the leftward position of the heart^[49] and the improved angle of sight. Insufflation is begun in increments of 2 to 4 mm Hg. The insufflation flow rate is adjusted automatically to achieve a preset intrathoracic pressure limit. Caution should be exercised when insufflating the thorax in patients who have poor left ventricular function or are hypovolemic (central venous pressure <5 mm Hg). Patients should have their volume status augmented before proceeding to full insufflation. Carbon dioxide insufflation and one-lung ventilation increases central venous pressure and pulmonary artery pressure by a small amount.^[50] Bilateral pneumothoraces are deliberately produced when doing bilateral internal mammary artery harvest. Most patients studied tolerate small bilateral pneumothoraces well for periods less than 1 hour.^[51] Table 66-3 lists patient criteria to be avoided when attempting a robotically assisted approach to surgery.

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