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There are many varieties of valves used as replacements today. No one valve is preferred for every patient. It is important that your surgeon has experience with a variety of different valves so that the best match can be made for your situation.
While some valves come close to the hemodynamic efficiencies of the human valve, nothing is aa perfect in flow or longevity as a normal human valve. The first valve replaced in a human was 1950 by Hufnagel.
Today, the most used mechanical replacement valve is a two leaflet valve. The most used is the St. Jude Medical (SJM) prosthesis. This valve was approved by the FDA in 1977 and worldwide more than one million implants have occurred. The leaflets consists of two discs tilting with the flow of blood and are constructed of pyrolytic carbon. This valve requires anticoagulation therapy (most commonly coumadin) and has a life expectancy of more than 30 years.
The more commonly implanted valve is the tissue valve. Early tissue valves were porcine (pig) or bovine (cow) tissue treated with a glutaraldehyde fixation (1960s). These valves had early calcification and deteriorated in 5-7 years. Preservation techniques have greatly improved. Today, valves are treated with zero pressure glutaraldehyde preparations and have a more normal cellular structure. The longevity of tissue valves is now 18-20 years. Many mechanical and tissue valves are available for patients. The long life expectancy of tissue valves has placed them as the most preferred option. The merits of each valve will be discussed by your heart surgeon.
Homografts or human tissue has been used in the aortic and mitral position. These are frozen valves from hearts not chosen for transplant. The primary indication for this valve is in the aortic position for endocarditis. The longevity of this valve unfortunately, in our experience and others, is not as good as a bioprosthesis treated with current anticalcification techniques.
Valve repair in adults remains a significant therapy for mitral leakage. Presentation of heart function and longevity of repair make it the first choice of mitral valve surgery. Many rings are utilized and the surgeon will discuss preferred options.
Atrial fibrillation is a heart rhythm that consists of an irregular, fast upper chamber heart rate. Fortunately, the lower chamber is able to beat at a slower rate. More than 10 percent of patients older than 60 years have been or currently are in this rhythm.
The three problems with atrial fibrillation include:
- fast heart rate which can cause discomfort;
- loss of coordinated rhythm that lowers the efficiency of the pump
- stasis of blood flow in the upper chamber can cause clots and lead to stroke or travel to other parts of the body.
The traditional treatment for atrial fibrillation is rate control of the heart rhythm and anticoagulation (blood thinners like warfarin). Electrophysiologists can also ablate atrial fibrillation in the cath lab. However, this procedure is a lengthy one and has a success rate in most situations of 30-50%.
James L. Cox pioneered a Maze procedure in 1987, which has evolved into a commonly used surgical procedure today. Other methods of ablation have been introduced into the operating room. These include cryoablation, radiofrequency and high intensity ultrasound.
Our surgical team has taken a very aggressive approach to atrial fibrillation because of the negative side effects of the rhythm. These procedures prolong the operation by 10-30 minutes, but do not increase the morbidity or mortality of the operation. The approaches used are high intensity ultrasound (HIFU) for coronary bypass patients and aortic valve patients.
HIFU ablation success is about 75% of patients are returned to normal sinus rhythm at one year. The modified cut and sew technique (Cox Maze) results in a regular heart sinus rhythm in 90% of patients at one year.