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All treatment can be categorised as either medical (i.e. non-surgical) or surgical.
Medical treatment
Medical treatment is used to alleviate symptoms in patients whose valve problems aren’t yet serious enough to warrant surgery, or for patients for whom surgery isn’t possible for various reasons.
Several important aspects are:
• Reducing the workload of the heart, e.g. with digitalis to improve effective contractions.
• Reducing the amount of fluid the heart has to pump, e.g. with diuretics (water pills) to shed excess fluid and salt.
• Slowing the heart rate, e.g. with beta-blockers.
• Keeping the blood pressure normal, using various medications.
• Anticoagulants. These are very important in patients with rhythm disturbances such as atrial fibrillation (AF). In AF, clots can form in the atrium causing a stroke, heart attack or fatal pulmonary embolism. Anticoagulants such as warfarin prevent these clots from forming.
For some types of narrowed valves, a procedure called balloon valvuloplasty can be tried. In this procedure, a balloon-tipped catheter is introduced into the heart, much like an angiogram. When the balloon is situated within the narrowed valve, the balloon is inflated to stretch the valve open.
Once this is achieved, the balloon is deflated and removed. Only certain types of valve problems can be handled in this way, and the procedure is seldom a permanent cure. If inexpertly done, the valve may be damaged, leaving the patient worse off than before.
Surgical treatment
Tremendous advances have been made in treating heart-valve problems. Previously, valve repair or replacement was only possible under full anaesthesia and cardiac bypass using the heart-lung machine. Today, certain types of valve repair can be done using the same access routes used for angiograms and angioplasty, i.e. via a catheter.
It still remains a major procedure, only undertaken in specific circumstances. The success rate of these procedures is increasing as operators become more skilled and equipment is refined. This type of procedure offers a chance of successful valve surgery to those patients who are considered bad risks for open-heart surgery – e.g. the more frail and elderly patient.
Open heart procedures
Traditional valve surgery is done with the patient on heart-lung bypass, so that the heart can be stopped and cut open for the surgeon to access and work on the valve inside the heart.
Valve repair
Some valves may be repaired. This is usually only done for leaking mitral and tricuspid valves, and rarely for aortic valves. Only certain patients are suitable candidates for valve repair. The repair may involve:
• Inserting a supporting ring to reduce an overstretched valve ring to normal size, thereby eliminating the leak.
• "Tailoring" or trimming the cusps to allow better closure or less prolapse into the atrium.
• Specially placed sutures can help to “re-suspend” cusps.
Valve repair is technically difficult and often not successful. As valve replacement has become safer and gives a longer-lasting result, most surgeons nowadays would opt for valve replacement instead of repair.
Valve replacement
In most cases, though, valve replacement is much more effective, and can be done faster than can a delicate repair. As many patients are elderly and often have other co-existing diseases, it may be a better choice to limit the time spent under anaesthetic and on bypass.
There are different types of valves that can be used. Mechanical valves are made of a virtually indestructible substance called pyrolytic carbon. Provided they’re correctly inserted, these valves can last the patient’s lifetime. Because they’re a foreign substance in the body, and thus promote clot formation, the patient needs to use warfarin anticoagulant permanently. This may be a problem in young females who still want to have children, as warfarin in pregnancy can cause foetal defects.
Bioprosthetic valves are harvested from cow or pig tissue, and are treated to become inert (non-irritant). For this reason, they don’t tend to cause clot formation and the patient may be spared using warfarin. The disadvantage is that these valves have a limited lifespan, and may calcify after 10-15 years, and thus need to be replaced. If the patient has permanent AF, then s/he will need to use warfarin anyway, but may still receive a bioprosthesis for other reasons.
Young women needing valve surgery (but who still want to have children) may choose to have a biological valve inserted so that they can avoid using warfarin. By the time the valve becomes calcified and needs replacing, their family is complete. They can then have another valve replacement, but this time with a permanent prosthetic valve, and are free to use the warfarin without the risk of possible foetal abnormalities. Even though this entails two operations, many women needing valve replacement choose this route so that they can safely bear children.
What is the outcome?
Valve surgery usually has an excellent outcome, especially if done by an experienced surgeon. Technical problems can (rarely) be encountered during the insertion of the valve, and this may result in:
• A residual leak
• Rhythm disturbances, if the conduction tissue is damaged
• Persistent stenosis, if too small a valve is chosen
With time, the body tries to re-line the valve with the same cells lining the inside of the heart. If this becomes excessive, the overgrowth of tissue can act as an obstruction to the valve (sub-valvar pannus overgrowth) and the overgrown valve may then need to be replaced.
Most valve replacements allow the patient to resume a near-normal life, with moderate exercise etc. Attention to the need for anti-coagulantion is vital, as is antibiotic prophylaxis. Other co-existing problems must also be managed.
Once a patient has had a valve replacement, s/he must be made aware of the need for antibiotic prophylaxis. This consists of a special type and dosage to be used before any surgical procedure, no matter how minor.
Of crucial importance is that visits to the dentist must be covered: the bacteria most often implicated in infective endocarditis come from the mouth, and fillings, extractions and even cleaning by the hygienist have been shown to dislodge these bacteria from the gum margins. They enter the bloodstream and settle on the artificial valve, where they flourish, forming cauliflower-like growths. Bits of this infected growth can break off and be carried in the blood stream to “seed out” as abscesses anywhere in the body. Brain abscesses caused in this way are often fatal. At the same time, the heart tissue around the valve (into which the valve is stitched) can also become infected and totally destroyed, causing a ring abscess. This loosens the whole valve apparatus, and can also be fatal. Surgery to rescue valves damaged by infective endocarditis carries an extremely high mortality risk, especially if attempted when the infection is still active.
The same process can occur with any abnormal valve (e.g. a congenitally abnormal valve, or a natural valve damaged by disease such as rheumatic fever). An unprotected visit to the dentist or a minor operation can thus have catastrophic results when the patient’s own natural valve is suddenly destroyed. Patients with known valve abnormalities should seek advice from their cardiologist about prophylactic antibiotics before undergoing procedures of any kind.
Reviewed by Dr Anna Hall, B Soc Sci (SW), MB ChB, CDE., March 2014
