Heart valve regurgitation, or leakage from the outflow to the inflow side of a heart valve, occurs when a heart valve fails to close properly. Regurgitation often occurs in the mitral valve, located between the left atrium and left ventricle, or in the tricuspid valve, located between the right atrium and right ventricle. Regurgitation through the mitral valve is typically caused by changes in the geometric configurations of the left ventricle, papillary muscles and mitral valve annulus. Similarly, regurgitation through the tricuspid valve is typically caused by changes in the geometric configurations of the right ventricle, papillary muscles and tricuspid valve annulus. These geometric alterations result in incomplete leaflet coaptation during ventricular systole, thereby producing regurgitation.
A variety of heart valve repair procedures have been proposed over the years for treating heart valve regurgitation. With the use of current surgical techniques, it has been found that between 40% and 60% of regurgitant heart valves can be repaired, depending on the surgeon's experience and the anatomic conditions present. The advantages of heart valve repair over heart valve replacement are well documented. These advantages include better preservation of cardiac function and reduced risk of anticoagulant-related hemorrhage, thromboembolism and endocarditis. Although surgical techniques are typically effective for treating heart valve regurgitation, due to age or health considerations, many patients cannot withstand the trauma associated with an open-heart surgical procedure.
In recent years, a variety of new minimally invasive procedures for repairing heart valves have been introduced. These minimally invasive procedures do not require opening the chest or the use of cardiopulmonary by-pass. At least one of these procedures involves introducing an implant into the coronary sinus for remodeling the mitral annulus. The coronary sinus is a blood vessel commencing at the coronary sinus ostium in the right atrium and passing through the atrioventricular groove in close proximity to the posterior, lateral and medial aspects of the mitral annulus. Because the coronary sinus is positioned adjacent to the mitral valve annulus, an implant deployed within the coronary sinus may be used to apply a compressive force along a posterior portion of the mitral annulus for improving leaflet coaption.
Although implants configured for use in the coronary sinus have shown promising results, it has been found that this treatment may not be effective for all patients. For example, in certain cases, the coronary sinus may be too weakened or fragile to support the implant. In other cases, due to variations in heart anatomy, the location of the coronary sinus may not be well-situated for treating the mitral valve. For example, the coronary sinus may be above or below the mitral valve annulus, thereby diminishing the effectiveness of the implant. In other cases, it has been found that deployment of the implant in the coronary sinus may impinge on the circumflex artery. Due to the limitations associated with existing treatment procedures, a need exists for still further approaches for treating heart valve regurgitation in a minimally invasive manner.