The heart contains four valves that ensure blood flows in a single direction. The mitral valve is located on the left side of the heart, situated between the upper chamber (the left atrium) and the main pumping chamber (the left ventricle). This valve has two flaps, or leaflets, that open and close with each heartbeat. Its proper function allows oxygen-rich blood to move from the lungs into the left ventricle, which then pumps the blood out to the rest of the body. Mitral valve replacement (MVR) surgery involves removing a damaged native valve and substituting it with an artificial prosthetic valve when repair is not possible.
Conditions Requiring Replacement
The need for a mitral valve replacement typically arises from two primary types of valve malfunction that compromise the heart’s efficiency. The first is mitral regurgitation, where the valve cannot close completely, causing blood to leak backward into the left atrium instead of moving forward. This backflow forces the heart to re-pump the same blood, which can cause the left ventricle and atrium to enlarge due to the increased workload.
The second issue is mitral stenosis, where the valve leaflets become stiff, thickened, or fused, severely narrowing the valve opening. This narrowing obstructs the smooth flow of blood from the left atrium into the left ventricle. Reduced forward flow causes pressure to build up in the left atrium and the veins leading back from the lungs, potentially leading to fluid accumulation in the lungs and shortness of breath. While infections or congenital issues can cause these problems, stenosis is often a long-term complication of rheumatic fever.
Understanding Replacement Valve Options
When replacement is necessary, patients and surgeons choose between two main categories of prosthetic devices, each involving a distinct trade-off in long-term management.
Mechanical Valves
The first option is a mechanical valve, manufactured from durable synthetic materials. These valves are engineered to last a patient’s lifetime, virtually eliminating the need for a second replacement surgery due to structural wear. However, the non-biological material poses a risk of blood clot formation, making lifelong anticoagulation therapy mandatory. Patients must take blood-thinning medication, such as Warfarin, daily to prevent clots from forming on the valve and causing a stroke. This medication requires careful monitoring through regular blood tests to ensure the patient’s International Normalized Ratio (INR) remains within a specific therapeutic range.
Biological (Tissue) Valves
The second option is a biological or tissue valve, made from animal tissue. The main advantage of this valve type is a significantly lower risk of clotting, meaning most patients do not require long-term, intense anticoagulation therapy. This is beneficial for individuals whose lifestyle or health conditions make long-term blood thinner use risky. The major limitation of the biological valve is its lack of longevity. These valves are subject to structural deterioration over time, typically lasting between 10 to 15 years before replacement may be necessary. For younger patients, this limited durability means a high probability of needing subsequent heart surgery. The decision between the mechanical valve’s durability and the biological valve’s reduced need for blood thinners is guided by the patient’s age and lifestyle.
The Surgical Approach to Replacement
Mitral valve replacement requires the heart to be temporarily stopped so the surgeon can safely work on the internal structures.
Traditional Open-Heart Surgery
The traditional method for accessing the heart is open-heart surgery, which involves a median sternotomy. This procedure requires the surgeon to make a long incision down the center of the chest and divide the sternum (breastbone) to gain full access. Once the heart is exposed, the patient is connected to a cardiopulmonary bypass machine, often called the heart-lung machine. This mechanical circuit takes over the functions of the heart and lungs, circulating and oxygenating the blood while the surgical team works on a non-beating heart. The surgeon removes the damaged mitral valve and sutures the new prosthetic valve into the annulus, the fibrous ring that supports the valve.
Minimally Invasive Approach
A minimally invasive surgical approach may be an option, which avoids a full sternotomy. This technique involves making smaller incisions, typically on the right side of the chest between the ribs. Although the heart-lung machine is still required, the smaller access point often leads to less pain, a reduced need for blood transfusions, and a faster initial recovery time. The choice of approach depends on the patient’s overall health and the specific characteristics of their heart disease.
Life After Mitral Valve Replacement
The recovery period immediately following mitral valve replacement begins in the hospital, where patients generally spend several days in intensive care before moving to a standard recovery floor. The total hospital stay is usually around 5 to 10 days, with a full return to normal activity often taking between four to eight weeks. During this time, patients must follow restrictions on lifting heavy objects and monitor for signs of infection.
Long-term management is heavily influenced by the choice of prosthetic valve, specifically concerning the use of anticoagulant medication. Patients with a mechanical valve must adhere strictly to a lifelong regimen of Warfarin to prevent dangerous blood clots. This requires consistent monitoring of blood clotting levels. For those who received a biological valve, the need for intense blood thinners is usually limited to a short period after the operation, followed by long-term antiplatelet therapy like aspirin. Regardless of the valve type, all patients require lifelong follow-up, which includes regular echocardiograms. These ultrasound tests allow physicians to assess the function and integrity of the new valve and ensure the heart muscle is performing effectively.