Morbidity in patients with systolic heart failure is significantly increased by functional mitral valve regurgitation. In addition to pharmaceutical treatment or surgical reconstruction of the impaired valve, minimally invasive procedures have continuously advanced into the focus of interest. The Carillon Mitral Contour System (Cardiac Dimensions) is a new catheter-based method to converge dehiscent mitral valve leaflets with implantation of a nitinol clip into the coronary sinus, leading to a closer approach of the valve leaflets with subsequent decrease in mitral regurgitation. The device is implanted via a central venous catheter, using a special delivery system under fluoroscopy. The immediate success of minimizing mitral valve regurgitation is verified by online transesophageal echocardiography (TEE), device-related impairment of perfusion of contiguous coronary vessels is ruled out by coronary angiography performed simultaneously during deployment of the device. As soon as reduction of the mitral valve regurgitation is demonstrated in TEE, the Carillon System is disconnected from the delivery system, before, however, the Carillon device can be withdrawn into the delivery system as necessary. Following the successful implantation of the Carillon Mitral Contour System, a left ventricular lead for cardiac resynchronization therapy can still be successfully placed alongside through the coronary sinus.