Aortic Stenosis/The Ross Procedure

What is aortic stenosis?

In a normal heart the aortic valve lies between the left ventricle and the aorta (the large artery that carries the red or oxygenated blood away from the heart to the body). The aortic valve opens to allow blood to pass from the left ventricle into the aorta, and when it closes it prevents blood from backing up. The narrowing of the aortic outflow tract and/or the inability of the aortic valve to open properly and fully is termed “aortic stenosis”. One reason for aortic stenosis may be that the aortic valve leaflets (doors) may be thick and/or may not open all the way like they should. Another cause for a stenotic aortic valve may be that the circumference of the valve (annulus) may be small, causing the valve opening to be small. Aortic narrowing can occur directly above (supravalvar) or below (subvalvar) the aortic valve.

What happens when aortic stenosis occurs?

When the aortic valve leaflets thicken or the aortic valve annulus is small, the volume of blood that can be ejected from the left ventricle into the aorta can be greatly reduced. When this happens the heart’s ability to supply the body with blood decreases proportionately. When the blood cannot be expelled from the heart the blood may ultimately back up into the lungs. Initially the left ventricle will try to compensate by thickening (increasing the muscle mass of the ventricle) to help force the blood from the heart to the body. This may help for a while, but over time the increased work load on the heart can cause the ventricle to dilate (enlarge in diameter) and gradually lose its ability to generate enough force to squeeze against the stenotic valve. Aortic stenosis may be mild, moderate, or severe.

What can occur if aortic stenosis is left untreated?

A mild narrowing of the aortic valve opening usually does not cause any serious problems for the patient. Clinical follow-up for this condition may be the only treatment recommended. Moderate or severe aortic stenosis can cause undue strain to the left ventricle as it struggles to push the blood through the smaller opening into the aorta. Eventually the left ventricle would increase its muscle mass (hypertrophy) to compensate and help push the blood out of the heart to the body. The left ventricle continues to do this until it gets tired and begins to dilate. A fatigued ventricle fails to pump the appropriate amount of blood to the body (heart failure). When the left ventricle fails, the blood that would normally go to the body will begin to back up into the lungs, causing the patient to become short of breath (Left heart failure). If this back-up continues the right side of the heart will eventually become overloaded and fail as well.

When should aortic stenosis be treated?

With aortic stenosis, the need and timing of the therapy depends on the seriousness of the stenosis. An infant with severe aortic stenosis may require an urgent operation. Mild aortic stenosis when diagnosed can usually be treated by follow-ups with the cardiologist. If the aortic stenosis worsens or is initially diagnosed as moderate or severe, left and right ventricular failure can be the outcome. Patients with the severe or moderate forms of aortic stenosis can also have turbulent blood flow through the aortic valve. This turbulent flow can predispose the patients to infection in the valve known as endocarditis. Prophylaxis with oral antibiotics prior to dental or other interventions is therefore recommended. Prompt and early diagnosis and intervention are essential.

How is aortic stenosis treated?

As stated earlier mild aortic stenosis can usually be observed by a cardiologist. If it progresses to moderate or severe stenosis intervention is indicated. The following procedures are usual treatment options for stenosis of the aortic valve:

1. Balloon dilatation
2. Aortic valvotomy
3. Valve replacement (artificial valve)
4. Konno procedure (aorticoventriculoplasty).
5. Ross procedure
6. Aortic homograft root replacement.

Balloon Dilatation

If the stenosis is moderate balloon dilation of the valve may be indicated. Balloon dilitation is usually performed through cardiac catheterization. A catheter with a small deflated balloon is introduced into the femoral artery in the leg and threaded up into the aorta across the aortic valve. Once the tip of the catheter is across the aortic valve the balloon is inflated until the stretched valve pops (opens up) to an adequate size. The balloon breaks any adhesions that are present between the aortic valve cusps.

Balloon dilatation of the aortic valve is the procedure of choice for infants with critical aortic stenosis.

Is balloon dilation a safe procedure?

Balloon dilatation of the aortic valve can result in better flow from the left ventricle to the body, but it can also result in damage to the aortic valve, preventing it from closing properly and stopping the blood from leaking back into the left ventricle.

What happens if balloon dilation does not open the valve sufficiently, or the valve is to severely stenotic that a balloon dilatation is not an option?

Surgical Valvotomy

The infant with severe aortic stenosis may require an emergent aortic valvotomy. Although an expeditious operation is required for these children care must be taken to have the infant arrive to the operating room in good physical condition. A medication called Prostaglandin E1 may be used to help keep the ductus arteriosus open to supply the body with an appropriate amount of blood flow.

Aortic valvotomies can usually be performed as a primary procedure in children with aortic stenosis. A surgical valvotomy is usually done while the patient is on the heart lung machine. During this procedure the valve leaflets are divided adequately to open the hole. Great care is taken to avoid disrupting the leaflets enough to cause aortic insufficiency. Usually aortic insufficiency, and not mild residual stenosis, is more likely to lead to early valve replacement.

Why would the cardiologists and physicians recommend proceeding with replacement of the aortic valve?

Aortic Valve Replacement

There are usually two reasons why physicians will recommend proceeding with a valve replacement procedure. First, once the patient begins to show symptoms of left heart failure, aortic stenosis can quickly become fatal. Signs and symptoms include shortness of breath, chest pain, and /or fainting spells. These problems are usually accepted as strong indications for valve replacement. Secondly, if findings during a cardiac catheterization suggest that the left ventricle is beginning to decompensate or get tired out, valve replacement may also be recommended.

What are the options for valve replacement surgery?

The ROSS Procedure

A first option that can be presented for consideration in the case of valve replacement for the treatment of aortic stenosis is known as the “Ross procedure”. The Ross procedure is considered when the patient has a well-formed and functioning pulmonic valve. This procedure utilizes a pulmonary autograph and requires taking the patient’s own pulmonary artery and valve and placing it in the aortic position, replacing the damaged aortic valve.

The surgeon then inserts a donor valved cryopreserved homograft into the patient’s pulmonary outflow tract. In this manner the Ross procedure places a valved conduit in the aortic position that is of similar tissue make-up of the patient’s native aortic valve and one that is almost always a perfect size match. Upon completion of this procedure the burden of a less structurally viable valve is now placed on the right side of the heart, which can usually tolerate a moderate amount of insufficiency and/or stenosis.

Since it has the advantage of requiring no anticoagulants ( blood thinners), there is little to no change in life style or restrictions after surgery .In addition to this it has the potential for growth since the transplanted valve is considered live tissue, thus hopefully minimizing the need for reintervention in the aortic valve. This procedure has become increasingly popular for children requiring valve replacement.

Prosthetic Valve Replacement

A second option for the treatment of aortic stenosis is replacing the stenotic or diseased valve with an artificial valve. Aortic valve replacement requires open-heart surgery. During the operation a small area in the heart is opened and the diseased valve is removed and a new valve is sewn in. There are three basic types of valves used to replace the diseased heart valve:

Porcine valve- made of tissue from a pig. The advantage of the porcine valve is that it is not prone to clot formation; thus, patients usually do not have to be on blood thinners. The disadvantage is that after a few years some of these valves degenerate, and must be replaced.
Mechanical Valve- Valve fashioned from synthetic materials and metal. The advantage of mechanical valves is that they are usually quite durable, and can last a lifetime. The disadvantages are, the need for anticoagulation with the necessary lifestyle adjustments, and the need for reintervention as the child grows in order to replace it with a larger valve to accommodate for the larger body surface. Another disadvantage of mechanical valves is the small potential for a clot to form on the valve. These blood clots, because they are located in the left side of the heart, can actually break away from the valve and travel through the aorta into the brain causing a stroke. To prevent this complication patients who receive a mechanical valve are also treated with Coumadin, a blood thinner that decreases the chances of clot formation. Because Coumadin is a blood thinner it increases the possibilities of bleeding after trauma, and therefore its usage is not without risk to the patient.

Homograft valve

Valved homografts are taken from human donors who approximate the size and weight of the patient. These valves are not at significant risk for clot formation; thus no blood thinners are required after the operation. It is thought from the data that has thus far been obtained that these valves have excellent hemodynamic performance, and closely resemble a native valve. The disadvantages are the lack of growth from the implant (therefore requiring reintervention with the change in body size), and calcification.

Aortoventriculoplasty ( Konno-Rastan procedure).

Subaortic obstruction

In cases of children whose aortic roots are too small to accept a replacement valve, or when the obstruction is underneath the aortic valve or both (complex subaortic obstruction) the surgeon may utilize a procedure known as the Konno procedure. This procedure enlarges the area of the aorta that the valve must fit in. The surgeon may also choose to enlarge the root area so that an oversized valve may be placed in a younger patient in order to provide for future growth. The Konno procedure is performed by making a vertical incision starting in the aorta and carried down into the right ventricular outflow tract. The resulting defect is repaired with a large patch of synthetic material. This effectively enlarges the area for securing the new valve.

The Konno-Rastan aortoventriculoplasty can be performed with autologous tissue in the form of a Ross-Konno, or with cryopreserved homograft tissue in the form of an extended root replacement.

What are some of the complications that can arise from aortic valve replacement?

Artificial valves- One of the major complications with valve replacement surgery is in particular the future need for additional surgeries to insert a larger prosthesis as the child grows. Additionally, the need for and problems related to the anticoagulation for mechanical valves.

Ross procedure- Although the Ross procedure is probably the best choice for infants and children with valvular or subvalvular aortic obstruction, it is not a perfect solution for the problem. Firstly, the right sided cadaver valve utilized to replace the native pulmonic valve lacks growth potential and needs to be changed several times before reaching adult size. In addition the autograph or the native pulmonic valve now transplanted into the aortic position is susceptible to the same risks of wear and tear as the other, normal valves and can develop aortic insufficiency after implantation.

Contact Information:

John Mark Morales MD, FACS, FAAP
Chief of Cardiothoracic, Director of Perfusion Services
Certified by the American Board of Surgery, American Board of Thoracic Surgery

Mark Bielefeld, MD
Driscoll Children's Hospital Chief of Staff
Certified by the American Board of Surgery, American Board of Thoracic Surgery

Thoracic surgeons are available for questions and consultations: (361) 854-0201. For appointments, assistance, and physician references in Corpus Christi call:
(361) 854-0201 or (800) DCH-LOVE
Fax : 361-855-7572
E-MAILS : Mark Morales, MD
Mark Bielefeld, MD

For further information on any surgical procedures you can contact Carol Kaplan, RN, Surgical Nurse Liaison at (361) 694-5150. Consultation and surgery for inpatients is provided in concert with neonatology and pediatric cardiology departments. Complete evaluation and management for infants, children, adolescents and adults with congenital or acquired cardiac, vascular or thoracic anomalies.

Cardiothoracic Associates
3533 S. Alameda, Suite 202
Corpus Christi, Texas 78411
Office: (361) 854-0201 or (361) 694-5150
Fax: (361) 855-7572
Hours: 9am to 6pm
Fri 9am to 5pm