The heart has 4 valves-the aortic, mitral, pulmonic and tricuspid. Their job is to open at the correct time in the cardiac cycle and make sure the blood flows through the heart in the right direction. Valves are usually operated on for stenosis (where they fail to open fully and let the blood flow through) or insufficiency (also known as regurgitation-where they fail to close properly and allow blood to go backwards). Patients with stenosed valve are not operated on until the stenosis is causing symptoms. Patients with insufficient valves may be advised to undergo surgery even before the development of symptoms if an echocardiogram shows that the leakage appears to be weakening the heart muscle. In this case, it may be too late if you wait for symptoms to develop. Medications are often of no or limited value in these situations.
The traditional method of valve surgery involves stopping the heart from beating. The patient is put on cardiopulmonary bypass. The blood that normally returns to the heart is sent through tubes to an oxygenator ( a heart-lung machine) which then pumps the oxygenated blood back through tubes into the aorta. This makes sure the body gets enough blood flow and oxygen while the heart is not beating. The heart itself is bathed in a"cardioplegic solution" to lower its metabolism so it can tolerate not receiving blood during the procedure. Once the operation is finished, the heart is given an electrical shock and it starts beating again. These operations generally last anywhere from 2 to 5 hours.
After the surgery, the patient is brought to the ICU. There, they wake up and the breathing tube is removed from their mouth. Various other IVs and drainage tubes are removed over the next 48 hours. Patients are often eating on their own within 24 hours and on their feet within 48 hours. They may go home as early as the fourth postoperative day although longer stays are not uncommon.
It is normal to feel weak and short of breath after a valve surgery. These symptoms resolve over time. By the time of hospital discharge, the patient is able to walk on their own. They will gradually return to full strength over the next 6 to 8 weeks. Enrollment in a cardiac rehabilitation program is quite effective at restoring patient's strength. Pain from the healing incisions is usually not severe and easily controlled with medications. Patients usually have to wait about 6 weeks before they are allowed to drive and return to work.
Diseased valves can either be repaired or replaced. Valve replacement can be done with either metal (mechanical) valves or with preserved biological valves made from pig or cow tissue. The main advantage of the metal valve is longevity. Biological valves not infrequently wear out after about 10 years, thus necessitating another surgery. The disadvantage of metal valve is the they require powerful blood thinning with a medication called coumadin for the remainder of the patient's life. This has to be monitored with frequent blood tests. Furthermore, coumadin can have serious side effects on the fetus. Other blood thinners, given by injection, are substituted in pregnant women.
There are 2 other techniques available to replace the aortic valve. One is called an aortic homograft. This is an aortic valve harvested from a human donor that has been preserved. This does not require coumadin and probably has a longer lifespan than pig or cow valves. Another technique that shares the same advantages is the Ross procedure. Here, the patient's own pulmonic valve is transplanted to the aortic position and a pulmonic homograft obtained from a human donor is the placed in the pulmonic position.
Diseased mitral valves can often be repaired rather than replaced. When repair is possible, this is generally the preferred treatment. Stenosed mitral valves can sometimes be opened with a balloon catheter without resorting to open heart surgery. Tricuspid valves may also be amenable to repair. Diseases of the pulmonic valve are quite rare. Stenosed pulmonic valves can also be dilated with a balloon catheter.
Related topic: Minimally Invasive Open Heart Surgery
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