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Valve Sparing in Type A Aortic Dissection
A 45-year-old male hypertension presented with severe chest and back pain. Computed tomography (CT) scan revealed a type A aortic dissection extending into the abdominal aorta. Intraoperative transesophageal echocardiogram demonstrated severe central aortic insufficiency with a dissection flap in the ascending aorta. The patient had distal palpable pulses and no signs of malperfusion.
General anesthesia was induced and the patient received invasive hemodynamic monitoring with a right heart catheter and bilateral arterial lines. This is important particularly in cases that the axillary artery is cannulated for arterial inflow since the right radial pressure is falsely elevated when the patient is on cardiopulmonary bypass (CBP). An activated clotting time > 480 seconds indicates adequate anticoagulation before initiating CBP. Aminocaproic acid was used. Near infrared spectroscopy (Somanetics Corp., Troy, MI) was also used to confirm symmetric cerebral perfusion during the operation. The patient’s head was packed in ice once cooling began.
An infraclavicular incision was performed to expose the right axillary artery. The right axillary artery was cannulated using an 8 mm side graft. Next, cannulation of the right atrium and the coronary sinus were performed. The patient was placed on cardiopulmonary bypass and was cooled to 24°C (minimum cooling time is 30 minutes). During cooling, the innominate vein as well as the innominate and left carotid artery were mobilized. The aorta was then cross-clamped 2 cm proximal to the innominate artery and electromechanical arrest was achieved with cardioplegia given in a retrograde fashion. A transverse aortotomy was performed 2 cm above the sinotubular junction. There was an intimal tear 1 cm above the sinotubular junction. The dissection extended proximally in the aortic root. The aortic root was mobilized by dividing its attachments to the pulmonary artery and dome of the left atrium. Three 4-0 pledgeted polypropylene sutures were placed at the tip of the 3 commissures and secured, effectively resuspending the aortic valve. The integrity of the aortic valve was easily assessed by pulling the commissural sutures tight, securing them in the operative field, and applying suction on the aortic valve.
Given the extensive involvement of the aortic root and the age of the patient, a decision was made to perform a valve sparing surgery. Then the right and left main coronary buttons were mobilized from inside the root. The noncoronary sinus was excised. The aortic valve had normal cusp morphology. A circumferential series of 2-0 Ethibond pledgeted annular sutures were placed underneath the annulus of the aortic valve in a clockwise fashion, beginning at the nadir of the noncoronary sinus. These sutures were placed in a horizontal plane formed by the base of the interleaflet triangles between the noncoronary and left coronary sinuses, with exceptions at the left coronary/right coronary and right coronary/noncoronary commissures. The precise height of each commissure was measured, transposed onto the graft, and the graft was trimmed in these areas. The subvalvular sutures were passed through a 32 Valasalva graft aortic graft. The graft was positioned and fastened with an automated suture fastener device over a 23 Hagar dilator. The commissures were secured at the appropriate height within the graft with 4-0 pledgeted polypropylene suture. Subsequently, the circumference of the aortic valve apparatus was secured to the graft with running 4-0 polypropylene sutures. The competency of the aortic valve was reassessed. The left coronary button was reimplanted into the graft with Teflon-reinforced continuous full-thickness 5-0 polypropylene sutures. Since the right coronary button was dissected circumferentially, a 6 mm graft was anastomosed to the right coronary opening with 5-0 polypropylene suture using the Cabrol technique to prevent undue tension and bleeding. This graft was subsequently anastomosed to an opening in the main graft.
Deep hypothermic circulatory arrest was initiated at 24°C. The aortic arch was inspected. There was a secondary tear between the left carotid and the innominate artery. The aorta was then transected between the innominate and left common carotid arteries. The innominate artery was transected at its base. A 12 mm graft was anastomosed to the innominate artery with 5-0 Prolene in a continuous fashion. The graft was de-aired and clamped, and flow was re-established into the right common carotid artery via the right axillary graft. A Pruitt catheter was placed in the left carotid artery to deliver supplemental antegrade cerebral perfusion. Antegrade cerebral flow was established at 8-10 cc/kg per minute with a perfusion pressure between 50-70 mm Hg, a temperature of 24°C, and a hematocrit of 25%. Alpha stat was used for pH monitoring. Cerebral perfusion was monitored with cerebral oximetry.
A 32 mm Valsalva graft was anastomosed to the aorta just proximal to the takeoff of the left common carotid artery using 4-0 Prolene continuous suture with Teflon-felt reinforcement. The 12 mm graft was then anastomosed to the 32 mm graft in end-to-side fashion. The graft was de-aired, clamped, and flow was re-established to the rest of the body. Rewarming was begun.
The two grafts were then anastomosed to each other using 4-0 Prolene in continuous fashion, and the clamp was removed. After the patient was rewarmed, and de-airing of the heart was achieved under transesophageal echocardiographic (TEE) guidance, the patient was weaned off cardiopulmonary bypass. TEE demonstrated that the aortic valve was competent, and the left and right ventricular functions were normal. The chest was closed in standard fashion. The patient was discharged home on postoperative day 12.
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