Mitral valve replacement

Mitral valve replacement is a cardiac surgical procedure in which a patient’s diseased mitral valve is replaced by either a mechanical or bioprosthetic valve. Mitral valve replacement is performed when the valve becomes too tight (mitral valve stenosis) for blood to flow into the left ventricle, or too loose (mitral valve regurgitation) in which case blood can leak back into the left atrium and thereby back into the lung.^[1][2] Mitral valve disease can occur from infection, calcification,^[3][4] inherited collagen disease, or other causes.^[5] Since a mitral valve replacement is an open heart surgical procedure, it requires placing the patient on cardiopulmonary bypass.^[1]

Options

Many mitral valves can be repaired instead of replaced, especially for minimally damaged valves.^[1] Advantages to valve repair instead of replacement include lower surgical mortality (1-2% for repair versus 6-8% for replacement), lower risk of stroke, lower rate of endocardial infection, and improved long-term survival. Patients who receive a valve repair stay on the same survival curve as the normal population. After mitral valve repair, blood thinners are not required; however, lifelong maintenance on blood thinners is required after mechanical mitral valve replacement.^[6] Mitral valve surgery can now also be performed robotically although the procedure may take longer.^[7]

Non-Surgical Options

Most patients can endure surgery without complications; however, there are some whose heart functions are too weak to withstand surgery. Non-surgical approaches to treat heart valve disease without surgery are divided into three categories: Clinical Practice treatment (this is used in every day clinical practice), Investigational treatment (current clinical studies that are underway), Early Development treatment (early stages of investigation).^[8]

Types of Valves

There are two primary types of artificial mitral valves: mechanical valves and bioprosthetic tissue (biological) valves.^[6] The mechanical valves are made from metal and pyrolytic carbon, and can last a lifetime.^[1] Patients with mechanical valves must take blood-thinning medications to prevent clotting. Bioprosthetic valves are made from animal tissues.^[1] Use of these biological valves allows patients to avoid blood thinners. However, the bioprosthetic valves may only last 10 to 15 years.^[6] The choice of which valve type to use depends upon the patient's age, medical condition, preferences with medication, and lifestyle.^[1]

Details of the procedure

Patients having mitral valve surgery receive general anesthesia.^[2] Incision can be made somewhat horizontally under the left breast, or vertically through the sternum. After the heart is exposed, canulae are placed to rerout blood to a heart-lung machine for cardiopulmonary bypass.^[2] An incision is made in the left atrium to expose the mitral valve. The valve is then replaced with either a biological or mechanical valve. The left artium is then closed, and the patient weaned from cardiopulmonary bypass. After surgery patients are typically taken to an intensive care unit (ICU).^[2]

Risks

With mitral valve replacement surgery, there are risks such as bleeding, infection or reaction to anesthesia.^[2] Risks depend on a patient’s age, general condition, specific medical conditions, and heart function.^[1]

Postoperative Complications/ Risks

A common postoperative complication with mitral valve surgery in a study involving 99 patients who had surgery for mitral regurgitation from January 1990 to June 1996 is atrial fibrillation. This occurred in 32% of patients. A common pulmonary complication is congestion necessitating prolonged use of oxygen. Other patients required prolonged ventilation of longer than 24 hours for conditions like pulmonary edema, ARDS, and pulmonary thromboemboli ^[9] Nine patients had renal failure with six of them dying within 30 days after their operation. Five patients had permanent strokes, and nine patients were readmitted to the hospital within 30 days of their discharge.^[9]

Effectiveness

In a clinical study done of 99 patients who had mitral valve surgery for regurgitation from January 1990 to June 1996, long-term and short-term outcomes were evaluated. These evaluations included; mortality rate, clinical complications, readmissions, valve deterioration, reoperation, and health perception. Overall mortality was 4%, which included 3 operative deaths and 4 late deaths. Overall 5-year survival rate was 92%.^[9]

Condition after mitral valve replacement

After the surgery the patient is taken to a post-operative intensive care unit for monitoring. A respirator may be required for the first few hours or days after surgery. After a day, the patient should be able to sit up in bed. After two days, the patient may be taken out of the intensive care unit. Patients are usually discharged after about seven to ten days.^[2] If the mitral valve replacement is successful, patients can expect to return to their regular condition or even better. Patients who have biological valve are prescribed blood thinners (Anticoagulation) with warfarin for 6 weeks to 3 months postoperative, while patients with mechanical valves are prescribed blood thinners for the rest of their lives. These blood thinners are taken to prevent blood clots that can move to other parts of your body and cause serious medical problems, such as a heart attack. Blood thinners will not dissolve a blood clot but they prevent other clots from forming or prevent clots from becoming larger.^[10] Once the patient’s wounds are healed they should have few, if any, restrictions from daily activities.^[1] Patients are advised to walk or undertake other physical activities gradually to regain strength. Patients who have physically demanding jobs will have to wait a little longer than those who don’t. Patients are also restricted from driving a car for six weeks after the surgery.^[2] Once a person has a mitral valve procedure, they are required to have prophylactic antibiotics as a preventative measure against infection whenever they have dental work done.^[1] Some scarring occurs after surgery. For median sternotomy (access through the sternum, or breastbone), the patient will have a vertical scar on the anterior chest above the sternum. If the heart is accessed from under the left breast there will be a smaller scar in this location.^[2]

See also

• Mitral regurgitation
• Mitral stenosis
• Artificial heart valve
• Cardiac surgery
• Heart-lung machine

References

External links

• Mitral Valve Replacement vs. Repair
• BCM: The Michael E DeBakey Department of Surgery. Mitral Valve Repair/ Replacement. n.d. 29 Apr. 2007
• "FDA approves second clinical trial for robotic heart surgery." Health Sciences News. 9 Nov. 2000. ECU Division of Health Sciences. 2 May 2007
• "Heart Disease: Warfarin and Other Blood Thinners." WebMD. The Cleveland Clinic. 10 May 2007
• Heart and Vascular Institute. Heart Valve Disease - Percutaneous Interventions: Non-surgical approaches. 2007. 7 May 2007
• "Mitral Valve Replacement." University of Maryland Medical Center: 1-2. 26 Apr. 2007
• Motulsky, Harvey. Intuitive Biostatistics. Oxford University Press Inc, 1995. 2 May 2007