The operation is performed with patients under general anesthesia ventilated with a double lumen endotracheal tube, thus permitting the left lung to be collapsed during the aortic surgery. A right radial catheter and a femoral arterial catheter are inserted to monitor upper and lower blood pressure. A triple-lumen central venous catheter and a pulmonary artery catheter are also inserted. An epidural catheter can also be positioned to ensure the monitoring of intraliquoral pressure, the possible drainage of cerebrospinal fluid, and the infusion of anesthetics drugs.
The patient is positioned as for a left thoracotomy procedure although the left hip is rolled back to expose the left groin sufficiently to allow access to the femoral vessels.
The aortic isthmus is approached via a posterolateral thoracotomy through the fourth or fifth intercostal space. After opening the pleural space and removing any clots that may be present, the aorta must be controlled above and below the adventitial hematoma. The damaged aortic wall is manipulated only after vascular clamping. The proximal clamp can be positioned below or above the left subclavian artery depending on its involvement within the rupture; various techniques can ensure perfusion of the distal aorta and are discussed below.
Once the hematoma is opened, the margins of the rupture can be identified. If the aortic tear is limited enough, a primary wall repair with stitches reinforced with Teflon pledges should be considered. If the lesion is wider, the hematoma is removed, and the two transected margins of the aorta are sutured with an end-to-end anastomosis. These procedures are not feasible in the majority of patients because of the tendency of the two aortic intimal margins to retract and to move away from each other, especially if the rupture is circumferential, in which case the interposition of a preclotted dacron graft is advisable. The choice of surgical technique is based on the type of lesion and the time of execution: primary sutures (also with pledges) and end-to-end anastomoses are suitable in patients with linear lesions without extensive dissection and in young patients with an easily mobilized aorta. A tube prosthesis is recommended in lacerated or multiple lesions with a wide intimal dissection and in elderly patients with atherosclerotic lesions.
Patients tend to be hypertensive immediately after surgery, probably due to an imbalance of the baroreceptors of the aortic arch. Therefore, during the postoperative course, intensive monitoring of arterial pressure values is mandatory.
Rupture involving the anterior portion of the aortic arch is usually characterized by a partial or complete avulsion of the brachio-cephalic trunk. In these cases, the surgical approach is via a median sternotomy, and the operation is performed with the patient on cardiopulmonary bypass and deep hypothermia with complete circulatory arrest. The extracorporeal circulation can be a right atrium-femoral artery or a femoral vein-femoral artery to be implanted before sternotomy. The operation involves completely detaching the brachio-cephalic trunk, repairing the aortic arch with a dacron patch or replacing it with a dacron
tube prosthesis and reimplanting the brachio-cephalic trunk on the ascending aorta with the interposition of a prosthesis.
In the case of rupture of the ascending aorta (Figure 15.8), the involved segment needs to be replaced during heart cardioplegic arrest and extracor-poreal circulation with right atrium-femoral artery or femoral vein-femoral artery. Small lesions that can be treated with a direct suture and lateral clamping without the need for extracorporeal circulation are very rare.
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