Critical aortic stenosis

Provided by "Pediatric Heart Surgery — a reference for professionals"

Patient families can visit our aortic stenosis page for more information and answers to common questions.

Pathophysiology

Critical aortic stenosis is a severe form of congenital aortic stenosis that presents in the neonatal period. Cardiovascular symptoms become acute as the patent ductus arteriosus closes, forcing the left ventricle to supply the entire systemic circulation. The severity of symptoms depends on the degree of obstruction. The aortic valve may be bicuspid or unicuspid. Abnormalities of the left ventricle can occur and include dilatation, depressed function, and endocardial fibroelastosis. Cardiovascular collapse may occur in patients with severe obstruction. Early surgical intervention is required.

Surgical technique

The goal of therapy in patients with critical aortic stenosis is to relieve obstruction of the flow of blood through the aortic valve without causing aortic valve insufficiency. Percutaneous balloon valvotomy can be effective in relieving valve obstruction in these patients. The surgical approach to this lesion is via median sternotomy with cardiopulmonary bypass. The aortic valve is visualized and incised at the commissure(s). Unicuspid or bicuspid valves are commonly encountered. Precise commissurotomy may be difficult due to the abnormal nature of aortic valve development in these patients. Care is taken to avoid aortic insufficiency, as this is poorly tolerated.

Postoperative considerations

The postoperative course following relief of critical aortic stenosis depends on the degree of left ventricular dysfunction present preoperatively and the relative success of the procedure. 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. With recovery of left ventricular function following repair, prognosis is good. Aortic valve replacement may be required later in life. Length of hospital stay is variable, but 1 to 3 weeks is average.