2. Mitral valve disease and Atrial Fibrillation
Q: What is mitral valve repair surgery for mitral regurgitation (MR) and how is it done?
In mitral valve diseases especially mitral regurgitation, there are various causes and patterns. In mitral valve surgery, the valve is reconstructed or replaced by taking the cause of the disease into consideration.
In surgery for MR, valve repair surgery is usually the first choice (VHD Case 1).
In mitral valve repair surgery, the patient's own valve is reconstructed by using various surgical techniques without using artificial valves. Thus, various potential problems of artificial valves can be avoided. We perform not only simple repair of the valve but also complex repair, and most of the patients with MR enjoy the good results of repair surgery. (VHD Case 2 and 3)
After having lots of experiences of valve surgery especially repair one in North America and Australia, I experienced more than 200 cases of mitral valve repair surgery after coming back to Japan. We repair the valve for elderly patients, athletes or young patients, or those who wish to have babies in the future. Thanks to valve repair surgery, the patients can come back to sports activities including martial arts or pregnancy/delivery or occupation with higher chance of injury. (VHD Case 4)
Q: How the mitral valve is repaired in patients with ischemic mitral regurgitation (IMR)?
Among MR, ischemic MR often is reported to be very difficult to repair and prognosis is poor. When the mitral valve has strong "tenting (tethering)", the repair surgery is reported to be difficult. For the type of patients, we repair not only the valve but also the left ventricle (LV) when necessary, and we developed a new surgical method to reconstruct the secondary chordae to fix the tenting and protect the LV. As a result, we succeeded in repairing the valve with IMR in most patients. (VHD Case 5)
In IMR, the disease is not a simple valve disease, but LV disease where LV itself is damaged by myocardial infarction. Thus, when the IMR is resistant to conventional surgery such as mitral annuloplasty, it is important to fix the LV. By fixing the LV, the patient can be free from MR and may have more chance of long-term survival. In fact, data which shows treatment of the valve alone does not prolong patients' life are reported from North America and Europe.
Q: When is mitral valve replaced ?
When the mitral valve is not suitable for repair surgery (i.e., when the valve is calcified or infected badly, or when the surgery should be completed in limited time), the valve is replaced. In other words, the patient's own valve is excised and artificial valve is sewn. Even when the valve has to be replaced, the patient's papillary muscles are preserved and good LV function is secured after the surgery. LV function after the surgery is as good as the one after repair surgery. (VHD Case 6)
In mitral stenosis (the valve becomes narrow), mitral leaflets usually become diseased, solid, and thick. Thus, valve repair surgery cannot give stable results for a long time. As a result, mitral valve is often replaced with preserving papillary muscles and the results of the surgery is very stable and reproducible.
Q: What type of artificial valves are available?
Artificial valve which is employed in the valve replacement surgery has mechanical valve (i.e., metal valve) and tissue valve (i.e., bioprosthesis, tissue valve made of pig or cow's material).
Mechanical valve is made of metal and last long, but it requires the patient to take Warfarin (i.e., blood thinner) for life time. Tissue valve (artificial valve which is made of cow or pig's tissue) last about 10 years in young patients, but last about 20 years in old patients. It does not require the patient to take Warfarin, and therefore the patient has less chance of cerebral bleeding etc. (Note: Warfarin is different from Baffarin)
Which valve is suitable for patients? To make the best possible choice for a patient, we have to consider patient's age, genaral/heart condition, life style, occupation and so forth and after discussion we can choose the best valve in total for the patient. For example, if the patient want to martial arts or hard sports such as rubgy, when the valve is not feasible for repair surgery, tissue valve will be the choice. If the patient is young female and if she wishes to have baby in the future, tissue valve will be the choice. If the patient works mainly in the office, and if he or she wants to play tennis or golf, mechanical valve will be the choice. We try to discuss the plan with the patient and family until satisfaction. Another important point of implanting tissue valve for relatively young patient is how to make the possible future redo safe. As a rule, we reconstruct the tissue around the heart before closing the chest, and therefore the heart will not stick to the organs around, and the possible redo surgery in the future will be safer. We have confirmed the idea correct in our experiences of redo surgery for patients who had had surgery in the past in our unit.
Q: How dangerous is atrial fibrillation (AF) and why? Is there a way to fix it?
Patients with mitral valve disease often have arrhythmias (rhythm disturbances) especially atrial fibrillation (AF). When AF develops, heart has a power down and often thrombi (clots) grow in the heart chamber. If the thrombi moves along blood stream and if it reaches brain, cerebral embolism (stroke) will develop. When AF occurs in On-and-Off fashion, there will be more chance of the embolism.
Mr. Nagashima, the famous Japanese baseball player, Mr. Oshim, the soccer leader, and late Mr. Obuchi, former prime minister in Japan, are reported to suffer from cerebral embolism in the same mechanism. However, AF can be treated together with mitral valve or coronary bypass surgery etc.. AF can be cured by Maze procedure which stops abnormal electrical pathways in the heart. When the valve or coronary arteries is intact (e.g., lone AF), catheter ablation is usually employed, except when large or mobile thrombi is seen in the left arium or ventricle.
We developed "Volume Reduction (Atrial Reduction) Maze procedure (VHD case 7), and it successfully fix the "inoperable" AF in 90% of the patients that were beyond surgical indication.
With the volume reduction Maze procedure, patients beyond the indication for conventional Maze or catheter ablation (such as huge left atrium or AF more than 10-20 years duration) usually defibrillated successfully. EBM shows us that the larger the atrium is, the more difficult to defibrillate it. From the viewpoint, our volume reduction Maze procedure makes sense and reasonable. Moreover, it improves intra-atrial blood flow pattern. If AF is fixed, late survival or QOL will improve as shown in EBM.
Q: To what extent does the heart improve in function by volume reduction Maze procedure?
It improves not only left atrial function (when AF is fixed) but also left ventricular function (see bibliography). It may decrease the problems which are associated with enlarged atrium.
For example, the left figure shows 62 year-old woman who has long-standing mitral stenosis and tricuspid regurgitation, and as a result, huge left atrium, heart failure, and of course AF. Because of the huge left atrium, she was told that surgery is too dangerous and came to us. After (atrial) volume reduction Maze procedure, mitral valve replacement, tricuspid annuloplasty, she improved dramatically and even the AF was cured. Her heart function improved considerably and heart failure has gone. The figure shows echocardiography before and after the surgery. LA means left atrium. Among heart chambers, especially LA has become very much smaller.
