Off-Pump Coronary Artery Bypass Grafting

OPCAB is a team effort. The anesthesia team should be engaged prior to surgery for better support of the patient's hemodynamics during induction and conduit harvesting and at the time of grafting.

The operating room should be kept warm during these operations, similar to the practice in pediatric operating rooms. If this is not done, the patient's temperature can drop to a dangerous level, where spontaneous, malignant ventricular arrhythmias, such as ventricular fibrillation and ventricular tachycardia, could occur.

The availability of pacing wires, atrial and ventricular, can help maintain normal hemodynamics in patients with heart block or extreme bradycardia.

Both the surgical and anesthesia teams should carefully monitor hemodynamic changes during heart positioning. If inadequate hemodynamics are observed, the best course of action is to return the heart into the pericardium for optimal functioning. The surgeon should then consult with the anesthesia team while the heart is allowed to recover. Once hemodynamics stabilizes, an attempt may be made to carefully reattempt the required positioning.

Off-pump CABG has been made possible by the development of many specialized tools. Two of the most important tools are vacuum-based devices that are used to position the heart or stabilize the segment of coronary artery to be anastomosed. For the purposes of this text, the former will be referred to as positioning devices, and the latter will be referred to as stabilization devices. In addition to adequately placed pericardial sutures, these allow for optimal exposure of the target vessels.

Enhanced visualization devices, such as the Blower/Mister (Clear View Misted Blower; Medtronic, Minneapolis), have also been adopted, and they allow a safe construction of the anastomosis. We routinely use a Blower/Mister to optimize visualization. It delivers a jet of CO ₂ under pressure in the middle of a jet of a pH-balanced saline solution, resulting in atomization of the liquid. The resulting stream of mist and CO ₂ , when directed over the arteriotomy, clears the blood from the anastomosis without resulting in air embolism because the CO ₂ is rapidly resorbed. The device does not prevent blood loss but improves visualization during the anastomosis.

Table tilt maneuvers can aid with visualization and allow adequate filling of the heart. If table tilting is not sufficient to correct preload, fluid infusion should be initiated by anesthesia. The Trendelenburg position and rotating the operating table toward the surgeon may also optimize lateral wall visualization. Changes to the operating table should be performed slowly and incrementally to allow the heart to adapt to different loading conditions.

Most OPCAB procedures are performed through the standard median sternotomy.

An extensive inverted-T pericardial incision is usually required. The opening should reach the cardiac apex on the left side and reach the pericardial reflection on the right side ( Fig. 4.1 ). This allows heart positioning without any compressions or deformity.

When harvesting the internal thoracic arteries, we strongly recommend complete skeletonization. This approach decreases the rate of pleural effusions postoperatively and decreases the incidence of ischemic injury to the chest wall and subsequent mediastinitis. This is particularly important during BITA harvesting.

The lie of the conducts is critical to avoid kinking and compression by the lungs. An incision is made on the pericardium to accommodate the internal thoracic artery (ITA). This pericardial incision starts at the edge and is located at the level of the base of the left appendage for the LITA and at the level of the transverse sinus for the right internal thoracic artery (RITA). It is posteriorly directed toward the phrenic nerve. At 1 cm anterior to the phrenic nerve, the incision extends 2 cm superiorly and inferiorly, creating a T-inverted incision. This trench accommodates the in situ ITAs where they enter the pericardium.

The radial artery can be harvested endoscopically or using an open approach, and either pedicled or skeletonized, depending on the surgeon's preferences. The gastroepiploic artery should be harvested in a skeletonized manner for better patency. Veins can be harvested endoscopically or using an open approach. Veins harvested through an endoscopic approach have shown lower patency rates than those harvested in an open manner.

There are several possibilities for graft configuration, and the approach should be tailored to the number and location of targets to be grafted:

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  In situ grafts do not require aortic anastomosis, but they offer fewer distal anastomoses, and their length is constrained.

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  Free grafts are less constrained by length but require aortic manipulation for the inflow creation.

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  Composite grafts pair an in situ graft, usually a LITA, with another conduit branching in a Y or T fashion. Composite grafts offer greater length and flexibility for grafting. In all cases, the graft configuration should be planned to take into consideration the availability of conduits and degree of stenosis in the target vessel.

For a full arterial revascularization in a patient with multivessel coronary artery disease, the plan should almost always include composite grafts due to the limited length of arterial conduits.