Mitral valve regurgitation

Heart valves enable single-direction blood flow between the chambers of the heart as well as in and out of the heart. The mitral valve, on the left side of the heart, allows blood to flow from the upper chamber (left atrium) to the lower chamber (left ventricle). Mitral valve regurgitation involves leakage of blood back through the mitral valve each time the left ventricle contracts.

It is caused by insufficient leaflet coaptation. If regurgitation is severe, the left atrium tends to become enlarged due to the extra effort induced by higher blood volumes leaking back from the ventricle. This can be a high-prevalence life-threatening disease that gradually leads to heart failure.

Mitral valve repair and replacement

Where regurgitation is severe, surgery is necessary to repair or replace the mitral valve.

If it is feasible, mitral valve repair is the gold standard surgical option because it preserves the native valve and ensures better long-term results. The most common repair technique is the annuloplasty procedure involving the implantation of a device surrounding the mitral valve to reduce annular dilatation and draw the leaflets together to restore coaptation.

However, regurgitation can recur in 40% of patients within two years (Goldstein). In certain complex cases, residual regurgitation may occur immediately after surgery and, except in certain high-risk patients, further valve exploration must be

considered to carry out renewed valve repair using a smaller annuloplasty ring. However, available mitral implants are not always optimal because they cannot be adjusted after implantation.

In certain situations, mitral valve repair is impossible (severe infection, severe calcification of the mitral leaflets and annulus, massive degenerative disease, severe tethering of the leaflets) and mitral valve replacement is necessary.

Mitral valve replacement usually takes between three to five hours under general anesthesia. During the procedure, the diseased mitral valve is removed and replaced with either a mechanical heart valve or a bioprosthetic (tissue) heart valve.

However, some patients cannot undergo surgery due to a comorbidity which places them at extreme risk. Consequently, alternatives to current surgical options could potentially benefit many patients. Transcatheter mitral valve replacement is the perfect new therapeutic option for high-risk patients with mitral regurgitation.