Surgical Aortic Valve Replacement (SAVR) is an established open-heart operation performed to treat a diseased aortic valve. This procedure involves replacing the compromised natural valve with an artificial one, restoring proper blood flow and function to the heart. SAVR has been the standard of care for decades and remains a highly effective treatment for patients with severe aortic valve disease.
Conditions That Require SAVR
The need for SAVR arises when the aortic valve, which controls blood flow from the heart’s main pumping chamber into the body’s largest artery, fails to open or close correctly. This malfunction is primarily caused by two conditions: Aortic Stenosis and Aortic Regurgitation. Aortic Stenosis involves the narrowing and stiffening of the valve leaflets, often due to age-related calcium buildup, which obstructs the forward flow of blood. The heart’s left ventricle must then work harder, causing the muscle wall to thicken and leading to symptoms like shortness of breath, chest pain, or fainting.
Aortic Regurgitation, also known as insufficiency, occurs when the valve does not close tightly, allowing blood to leak backward into the left ventricle. This backflow increases the volume of blood the ventricle must handle with each beat, eventually leading to chamber enlargement and heart failure symptoms such as fatigue and swelling. When these conditions become severe and symptomatic, valve replacement is necessary to prevent irreversible damage to the heart muscle.
How the Procedure is Performed
The SAVR procedure is a major operation requiring a highly coordinated surgical team and the use of specialized equipment. The process begins with the administration of general anesthesia, ensuring the patient is completely unconscious and pain-free. The surgeon performs a median sternotomy, which is a vertical incision made down the center of the chest, followed by dividing the breastbone to expose the heart.
The next step involves connecting the patient to a heart-lung bypass machine, which temporarily takes over the function of both the heart and lungs. This cardiopulmonary bypass is necessary because it allows the surgeon to safely stop the heart, creating a motionless, bloodless surgical field. The diseased aortic valve is then precisely excised from its ring-like base, known as the annulus, removing all the calcified or damaged tissue.
After the native valve is removed, the new prosthetic valve is meticulously sutured into the aortic annulus, ensuring a secure and leak-free fit. Once the new valve is secured, the heart is carefully restarted, and the patient is weaned off the heart-lung machine. The surgical team then closes the breastbone using permanent wires and closes the chest incision.
Choosing the Replacement Valve
A significant decision in the SAVR procedure involves selecting the type of replacement valve, a choice made collaboratively between the patient and the heart team. The two primary options are mechanical valves, which are made of highly durable materials like pyrolytic carbon, and bioprosthetic valves, which are created from animal tissue, usually from a cow or pig. Mechanical valves are exceptionally long-lasting and are unlikely to wear out, making them highly suitable for younger patients with a long life expectancy.
However, the moving parts of a mechanical valve increase the risk of blood clot formation, which requires the patient to take lifelong blood-thinning medication, called anticoagulants, to prevent stroke. This medication carries its own risk of bleeding complications. Bioprosthetic valves, conversely, are designed to closely mimic the function of a natural valve and typically do not require long-term blood thinners, significantly reducing the risk of bleeding.
The trade-off for the bioprosthetic valve is its limited durability, as the tissue will eventually degenerate and wear out, often necessitating a reoperation after 10 to 15 years. Patient age is a major factor in the decision, with guidelines often favoring mechanical valves for those under 60 years old and bioprosthetic valves for those over 65, balancing the need for durability against the risks of lifelong anticoagulation.
SAVR Compared to TAVR
Surgical Aortic Valve Replacement is often compared with Transcatheter Aortic Valve Replacement (TAVR), a newer, minimally invasive option for patients needing a valve replacement. TAVR is a catheter-based procedure where the new valve is delivered to the heart through a small incision, usually in the groin, without the need for a large chest incision or the heart-lung machine. This difference in approach results in a significantly shorter hospital stay and a much faster recovery time for TAVR patients.
The choice between SAVR and TAVR is determined by a patient’s overall health, age, anatomy, and the presence of other heart conditions. SAVR is generally the preferred option for younger patients, typically those under 65, who are considered low-risk for open-heart surgery and have a long expected lifespan. The durability of the traditional surgical valve is a primary reason for this preference, as the long-term data for TAVR valves in young people is still being gathered.
SAVR is also necessary for patients who require other heart repairs at the same time, such as a coronary artery bypass graft or the repair of other heart valves. Conversely, TAVR is frequently recommended for older patients, often over 75 or 80, or those who have other serious health issues that make the major operation of SAVR too risky. The heart team, comprised of cardiac surgeons and cardiologists, uses these factors to make an individualized treatment recommendation.