2.Operative Technique:
A re-implantation technique (David V) was performed in all patients. All patients underwent emergency surgery with CPB initiated with arterial cannulation via the right axillary artery and venous cannulation of the right atrium, then general cooling was started. The ascending aorta was cross clamped and myocardial protection was ensured through antegrade cold crystalloid cardioplegia followed by intermittent administration of selective coronary cardioplegia throughout the clamping time. Resection of the aortic root leaving 3 to 4 mm of aortic remnants above the aortic valve annulus was done systematically. Six sub-annular U stiches were placed and anchored to a Valsalva Dacron tube (28-30mm diameter). The aortic valve commissures were attached within the Valsalva Dacron tube.
At a rectal temperature of 28 °C, and with cerebral monitoring by NIRS, hypothermic peripheral circulatory arrest was started. Cerebral perfusion was ensured by blood injection (7.5 to 10 ml/kg/min) into the right subclavian artery and by clamping the origin of the Brachiocephalic artery and the Left Common Carotid artery. Exploration of the aortic arch demonstrated no supplementary entry tears in any patient. Transection of the aorta was performed 1 cm proximal to the origin of the Innominate trunk. A 55-55 mm uncovered AMDS was systematically used and deployed over a guidewire in the true lumen of the descending aorta. Anastomosis between the aorta and the AMDS collar was performed with a addition of a Dacron tube and reinforced by an external Teflon felt. General cardiopulmonary bypass was then re-initiated for rewarming after the aortic arch was purged and the Dacron tube clamped .
During rewarming time, re-implantation of the aortic remanents into the valsalva Dacron tube with running 4.0 Polypropylene sutures then re-implantation of the coronary ostia were performed. In one patient, the dissection reached the coronary right ostium needing repair. End to end anastomosis between the two Dacron tubes was done using before declamping and CPB was weaned in a standard manner withour inotropic support in any patient.