When specific symptoms are present, they are usually related to aneurysmal expansion and compression of surrounding structures or to malperfusion related to aortic dissection. The onset of symptoms is usually considered an indication of impending rupture or significant malperfusion and should prompt urgent evaluation and repair. Patients may have dysphagia from esophageal compression, respiratory symptoms due to airway compression, or edema of the upper body from superior vena caval compression. Other problems that can arise from aneurysms involving the aortic arch and the adjacent segments include thromboembolic events such as stroke, and aortic valve regurgitation from associated root enlargement. Chest wall compression can cause chronic dull or aching retrosternal or mid-scapular pain. New severe pain usually indicates aneurysm rupture or acute dissection. Arch aneurysms can rupture into the pleural cavity (usually on the left), mediastinum, esophagus, or tracheobronchial tree. Common scenarios in which aortic dissection occurs include uncontrolled hypertension, connective tissue disorders (such as Marfan syndrome), and bicuspid aortic valve; aortic dissection may cause cerebral malperfusion and result in symptoms such as syncope and neurologic deficits.

The arch is particularly challenging to repair because—unlike other aortic sections—its replacement usually necessitates interrupting both cerebral and distal aortic perfusion, leaving the brain, spinal cord, and other organs vulnerable. Most aortic arch repairs necessitate a period of systemic circulatory arrest combined with varying degrees of hypothermia to protect the brain and other vital organs. Prolonged hypothermic circulatory arrest (HCA) is associated with increased mortality, neurologic morbidity, and other complications. Cerebral perfusion (CP) techniques were developed to reduce these risks. Antegrade (ACP) and retrograde (RCP) techniques have been explored, and although definitive data are lacking, ACP appears to substantially reduce operative risk. In contemporary practice, nearly all aortic centers have shifted toward routinely using ACP to provide enhanced cerebral protection; although such protection may be provided in a unilateral fashion, provided the circle of Willis is complete, many centers, ours included, prefer to provide bilateral protection. That being said, HCA alone remains an acceptable approach when arch repair of limited duration (i.e., <30 minutes) is anticipated, and HCA with RCP continues to be favored by some centers because it can remove embolic debris and air, as well as potentially aiding cannulation approaches in cases of acute aortic dissection.

We perform aortic arch repair through a standard median sternotomy. Throughout the process of obtaining exposure, meticulous hemostasis is maintained to reduce problems with bleeding after the aortic repair. We currently favor using the innominate artery as the inflow site for cardiopulmonary bypass. When the innominate artery is not suitable for this purpose (due to aneurysm, dissection, or severe atherosclerotic disease involving the vessel), we use the right axillary artery for cannulation. In addition, when an aneurysm encroaches upon the sternum, cannulation on the axillary artery is preferred prior to sternal entry to avoid cutting directly into the aneurysm. In such cases, we access the axillary artery through an incision in the right deltopectoral groove. We separate the pectoralis major muscle fibers, divide the pectoralis minor muscle, and carefully mobilize the adjacent vein and cords of the brachial plexus.

When using the innominate artery as the inflow site, we administer intravenous heparin and apply a partially occluding clamp to the distal aspect of the vessel. After creating a longitudinal arteriotomy, we suture an 8-mm gelatin-sealed, woven polyester graft to the vessel (Fig. 12.2). Polypropylene suture is used for all anastomoses during repair unless otherwise noted. After the graft is carefully flushed and deaired, it is attached to the inflow line from the cardiopulmonary bypass circuit.

Other cannulas placed in preparation for cardiopulmonary bypass generally include a two-stage venous cannula placed via the right atrium, a left ventricular sump placed via the right superior pulmonary vein, and a coronary sinus retrograde cardioplegia cannula. After cardiopulmonary bypass is initiated, systemic cooling is begun to establish moderate hypothermia; our target temperature generally ranges between 23°C and 25°C nasopharyngeal temperature. If the patient has significant aortic valve regurgitation, it is often possible to cross-clamp the ascending aorta to prevent ventricular distension and enable delivery of cardioplegia while maintaining systemic flow and cooling through the innominate artery graft.

During the cooling phase, we begin the process of reconstructing the brachiocephalic vessels. We often find that it is easier to approach the LSCA after the arch aneurysm has
been decompressed than during the initial cooling period; under these circumstances, we typically address the LCCA first and reserve the LSCA for later. After the mid-portion of the LCCA is clamped and its base is ligated, the artery is divided and sutured end-to-end to the middle branch of a prefabricated trifurcated graft (Fig. 12.3). The graft has been stretched and trimmed to an appropriate length to avoid kinking. This anastomosis is performed while full flow from the cardiopulmonary bypass circuit is maintained.

After the LCCA anastomosis is completed and the desired degree of hypothermia has been reached, systemic HCA is established. The proximal aspect of the innominate artery is occluded with a snare, and flow from the pump is reduced to approximately 10 mL/kg/min. The ascending aorta and transverse aortic arch are then opened. A balloon-tipped cannula is connected to a Y-limb from the inflow tubing and placed in the proximal aspect of the trifurcated graft to provide perfusion to the LCCA (Fig. 12.4). After the LSCA is transected, the first branch of the trifurcated graft is trimmed to
appropriate length and sutured end-to-end to the vessel. This branch of the graft is deaired and its clamp is removed, thereby enabling antegrade perfusion to the LSCA. When the left vertebral artery is anomalous and arises directly off the transverse aortic arch, we reimplant it by either transposing it end-to-side to the LCCA or directly onto the graft.