Aortic arch aneurysm repairs

Cannulation for arch repairs varies among groups. They include the femoral artery, right axillary artery, and ascending aorta. Hypothermic circulatory arrest is required for arch repairs, but the safe period of arrest to avoid neurologic injury is 30-45 minutes at 18°C (64.4°F), but some advocate a shorter period of 25 minutes. Antegrade cerebral perfusion to minimize neurologic injury is thus advocated. Others advocate cooling to 11-14°C (51.8-57.2°F).

Once the patient is cooled to the desired temperature, the circuit is turned off. For retrograde cerebral perfusion, flow is established through the superior vena cava as the arch reconstruction is performed. For antegrade cerebral perfusion, flow is continued through the axillary artery with the innominate artery clamped or individual perfusion catheters are placed into the innominate artery, left carotid artery, and left subclavian arteries. The arch reconstructions are also varied. They basically involve performing the distal anastomosis to the aorta beyond the left subclavian artery as an open distal procedure with or without an elephant trunk. The 3 head vessels may be reanastomosed individually or as an island. They may be reimplanted directly to the graft or anastomosed to a separate graft, which is then attached to arch graft.

Descriptions of different hybrid procedures have been standardized according to the location of the most proximal placement of the endograft in relation to the arch vessels, under the Criado classification: zone 0 extends distally from the ascending aorta to the innominate artery; zone 1 from distal to the innominate artery origin to the left common carotid artery (CCA); zone 2 from distal to the left CCA to the left subclavian artery (LSA); and zone 3 distal to the LSA to the proximal descending thoracic aorta.^[36]

Zone 0 pathology by definition involves all aortic arch vessels and requires revascularization of at least the innominate artery and left CCA and possibly revascularization of the LSA in the case of symptoms of left arm ischemia, functional left internal mammary arterial bypass graft, or dominant left vertebral artery circulation. Revascularization is usually accomplished via a median sternotomy and the use of a bifurcated or trifurcated graft from the ascending aorta to the arch vessels. Following revascularization and during the concomitant operation, a stent-graft is then implanted either in an antegrade or retrograde fashion.

Zone 1 placement, commonly avoids a median sternotomy, via revascularization of the left CCA by a right CCA to left CCA bypass, prior to endograft placement. Depending on the quality of angiographic resources in the operating room, this procedure may be performed in a single or staged procedure to allow use of a dedicated angiographic suite.

A Zone 2 landing requires partial or complete coverage of the LSA. In general, this is well tolerated, however, several reports have detailed higher incidences of neurological complications with LSA coverage and, therefore, a thorough assessment of the carotid, vertebral and circle of Willis circulations should be preoperatively performed.^[37]

Date: 2015-12-11; view: 754