Valve Repair and Replacement Alternatives
Diseased heart valves can be treated in several ways. These include:
1) treatment with medication; 2) surgical repair; 3) surgical replacement.
If the surgeon chooses to replace a natural heart valve, the first step is to remove the diseased natural valve (excise the valve and calcific deposits) and then implant a prosthetic heart valve in its place. Prosthetic valves used to replace the heart's diseased natural valves come in different sizes to fit the patient and are made from a variety of materials.
Valve Repair
When possible, it is often preferable to surgically repair the patient's valve rather than to replace it with a prosthetic device. Valve repair usually involves the surgeon modifying the tissue or underlying structures of the mitral or tricuspid valves.
There are two broad categories of heart valves that are classified according to the type of material:
Valve repair can be performed with or without implantation of an annuloplasty ring/band, a device that provides support so that the patient's natural leaflets close completely and function normally.
Tissue Valves
There are a wide variety of tissue valves. They are defined below:
- autograft-valve that has been moved from one position to another position within the same individual (i .e., transfer of the pulmonary valve to the aortic position)
- autologous tissue - constructed from patient's own tissue A heterograft is a biological valve made with animal tissue. For example, pericardial valves traditionally contain leaflets made from bovine (cow) pericardium (the sac surrounding the heart) and are sewn onto a flexible or semi-flexible frame. Another type of tissue valve is a porcine valve. A porcine valve is made from the pig 's aortic heart valve and is either sewn onto a flexible or semiflexible frame to make a "stented" valve, or the natural aortic root is left intact to function as the frame to make a "stentless" valve. See Figure 9.
Mechanical Valves
There are three basic types of mechanical valves. A bileaflet valve has two semicircular discs (referred to as leaflets) that are mounted on hinges within a housing and open and close simultaneously. A tilting disc valve has a housing with a single circular disc that tilts open and closed . The disc is typically supported by "struts." The ball and cage design has a spherical ball that moves within a cage.
Advantages of Tissue Valves
Disadvantages of Tissue Valves
• Potential risk of needing another operation to replace the valve
Advantages of Mechanical Valves
• Potentially last longer
Disadvantages of Mechanical Valves
Criteria and Selection of Heart Valves
The choice between mechanical and tissue valves is typically dependent upon an individual assessment of the benefits and risks of each valve and the lifestyle, age and medical condition of each patient.
The choice of implanting a tissue or mechanical valve is often based on patient age. However, there is no clear agreement on the exact age cutoff where a tissue valve may be preferable to a mechanical valve.
The preoperative condition of the patient is extremely important in determining which type of valve is to be used. Older or sicker patients who have other diseases may be good candidates for tissue valves. Their other problems may include coronary artery disease or kidney problems that often require other surgeries, during which anticlotting medication, which is required for mechanical valves, cannot be taken.
There are many variables that the surgeon/cardiologist must evaluate when determinging which valve option is best for the patient.
The normal recovery period from heart surgery occurs during the first four to six weeks after the surgery. Typically during this time, patients begin to restore muscle tone and return to normal levels of activity. The following information may be helpful for patients who have had their natural heart valves replaced or repaired with an artificial heart valve or annuloplasty device. This information has been provided to help you understand the heart surgery, the prosthesis, and life with the new heart valve prosthesis or about related medical care. Regular check-ups by a heart specialist are essential and you are encouraged to call or see your doctor whenever you have questions or concerns about your health, especially if you experience any unusual symptoms or changes in your overall health.
Diet and Exercise
Two important parts of recovery and continuing health are a good diet and a regular exercise program. If your doctor has recommended a special diet, it is important that it be followed; however, if a special diet has not been recommended, the information listed below can provide guidance to balanced eating which may speed healing and lessen fatigue. In addition, the practice of weight control is important in reducing the work of the heart even after recovery.
Balanced eating is necessary because no one food provides all the nutrients 'needed by the body; therefore, each day a variety of fruits, vegetables, whole grains, breads, meats and dairy products should be eaten. Foods that are high in saturated fats, sugar, salt, and sodium should be limited. In general, a low fat, low cholesterol, high fiber diet is best. Use of supplemental calcium should not be taken without approval from your doctor. To improve overall cardiovascular fitness, it is recommended that you combine a balanced diet with your doctor's recommendations about exercise and weight control. Following a regular exercise program is an important part of maintaining a healthy lifestyle. Under your doctor's guidance, you should gradually build up your exercise and activity level. Before you begin a new sports activity, check with your doctor.
Anticoagulants
It is important to carefully follow your doctor's directions for taking medications, especially if an anticoagulant drug has been prescribed. This type of drug decreases the blood's natural ability to clot or coagulate and is sometimes called a blood thinner. Those who take anticoagulant drugs need a prothrombin time test (commonly called a protime test) every two to four weeks. A pro-time test measures the level of certain clotting factors that indicate the blood's ability to clot. This test result helps the doctor determine the amount of anticoagulant needed. The pro-time test should be done at the same lab every time because results may vary from one lab to another. It may take a while to establish the right dosage for each person, but consistency and working with your doctor are important. Home testing may be available, so check with your physician about this option.