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Valve sparing aortic root replacement
Provided by "Pediatric Heart Surgery — a reference for professionals"
Anatomy and pathophysiology
Valve sparing aortic root replacement is performed to correct aneurysms of the aortic root when the valve is otherwise anatomically intact. Varying degrees of valve insufficiency may occur with progressive dilation of the root. When valve abnormalities disqualify it as a viably functional valve moving forward, other aortic root replacement techniques such as the Bentall operation are performed. The Bentall procedure involves replacement of the aortic root, the aortic valve, and the ascending aorta with a composite graft designed for that purpose.
Aortic root dilation can be caused by progressive deterioration over time in the elderly or by connective tissue disorders such as Marfan syndrome. Marfan syndrome is one of a group of related connective tissue disorders that predisposes the patient to multiple systemic manifestations, including weakened arterial walls. Patients with these disorders are followed closely and monitored for aneurysms. As aneurysm size grows over time, measurements are made using serial echocardiography. Specific indications for timing of surgery, such as aortic root dimensions, rate of change, and variance from predicted normal, are analyzed. Referral for surgery is done when the data indicates the timing is optimal based on predictive evaluation and evidence-based data. When surgery is delayed, progressive valve deterioration and insufficiency can occur. Catastrophic rupture of the aneurysmal aortic root has a frequently fatal outcome and must be avoided.
Valve sparing aortic root replacement requires median sternotomy, cardiopulmonary bypass, and aortic cross-clamping. The aorta is opened distal to the aortic commissures, and the anatomy is evaluated. The sinuses of Valsalva are resected and coronary arteries removed from their respective sinuses with a generous cuff of aortic wall known as “buttons.”
The commissures are carefully separated from the aneurysmal aortic wall. Next, a specially designed synthetic graft is selected to fit the new aortic root dimension. The graft is sewn into position, replacing aneurysmal wall with durable synthetic material. The three valve commissures are suspended at the appropriate position along the wall of the tube graft. Suture lines are created to ensure complete seat- ing of the valve in optimal position. The coronary buttons are re-implanted, and the aorta is reconnected beyond the aneurysmal tissue.
The valve sparing aortic root replacement operation is an extensive procedure requiring multiple long suture lines and many carefully orchestrated steps to ensure optimal valve geometry. Aortic cross-clamp time is moderate to long due to these factors. Despite this, postoperative hemodynamics are usually excellent given satisfactory postoperative valve performance. Invasive monitors used include arterial and central venous catheters. An LA line is used when needed for hemodynamic management. LA pressure acts as a surrogate for left ventricular end diastolic pressure, an excellent indicator of left ventricular performance. Non-invasive monitors include NIRS (near-infrared spectroscopy) probes to assess adequacy of regional and global perfusion and traditional pulse oximetry. Vasoactive agents might include epinephrine and/or milrinone. Numerous other agents are available and are tailored to the specific needs of the patient, targeting adequate oxygen delivery to the tissues of the body and optimization of cardiac output. Postoperative bleeding is usual, and hemostasis is controlled with additional sutures and blood products as needed. Rhythm is monitored closely, and temporary pacing wires are placed.
Hospital stay required following valve sparing aortic root replacement averages 5 to 7 days.