The mitral valve is located between the left atrium and left ventricle. It controls blood flow, allowing blood to enter the left ventricle in diastole (filling phase) and preventing backflow of blood into the atrium during systole (contraction phase). The mitral valve has two leaflets (anterior and posterior leaflet), which are fibrous tissue flaps that are anchored through chordae tendineae to the papillary muscles. The zone where the two leaflets meet during systole is called coaptation. A dysfunction of the leaflets or their support structures can lead to mitral regurgitation.
Mitral regurgitation (MR) is a condition in which blood leaks back into the left atrium due to impaired leaflet closure. As a result of this condition, the heart fails to efficiently pump blood and hence is forced to work harder to supply the organs with oxygen. Clinical outcomes of this compensatory mechanisms include fatigue, shortness of breath, light-headedness, and ultimately, heart failure.
MR is categorized into degenerative (primary) and functional (secondary) regurgitation:
- Primary MR is caused by mitral valve prolapse (two valve flaps do not close evenly) due to ruptured chordae.
- Secondary MR is commonly caused by left ventricular remodelling and or left atrial dilatation resulting in incomplete leaflet coaptation.
Moderate to severe MR is frequent, its prevalence lies in a range of 2-3% in Western societies, with an annual incidence of 250.000 (in the US).
The prevalence of MR increases with age, 10% of the population aged >75 years suffer from mitral valve insufficiency. Additionally, young (especially female) patients are frequently affected by mitral valve prolapse.
While surgical intervention is the gold-standard in treating mitral regurgitation, up to 50% of the affected patient population remain untreated owing to increased risk of advanced age and relevant comorbidities, or impaired left ventricular function.
A percutaneous (transcatheter) repair system provides a corrective for patients that are either too old or too weak for surgical intervention, or for patients that refuse open heart surgery due to lacking of severe symptoms or cosmetic reasons.