Treatment of mitral insufficiency

The prevalence of mitral valve insufficiency increases with age, and the degenerative processes that begin from age 60 make it more common. The incidence of this condition is increasing in the population and, when moderate or severe, it generates serious problems, with regular hospital admissions for heart failure. Rheumatic causes were the most common in Spain in the past, but they now only represent 20% of the total, as functional and degenerative causes are more common. In the US, only 2% of the 30000 patients diagnosed every year undergo valve replacement surgery. There are a large number of patients with mitral insufficiency who only receive medical treatment. We know that the likelihood of hospitalisation and death is greater in patients with moderate or severe disease.

A mechanical percutaneous method was created in 2005, to reduce or completely resolve mitral valve regurgitation. Based on the Alfieri surgical procedure (figure), the transvenous insertion of a clip in the mitral valve, joining the edges of both leaflets, converts the valve orifice into 2 orifices, improving closure coaptation and thus largely reducing the degree of regurgitation. The MitraClip was initially indicated for functional insufficiency in patients with dilated cardiomyopathy and ventricular dysfunction with ring dilation. These patients cannot be operated and the MitraClip is a mechanical method that improves their tendency to present heart failure. Over time, and with greater experience, its indication spread to degenerative mitral insufficiency, and avoids surgery in such patients. For this indication, there is a series of anatomical conditions that are optimal, limited in some way or inappropriate. A transoesophageal echocardiogram enables a detailed analysis of these fundamental anatomical features. A haemodynamic study is also advisable, to analyse haemodynamic conditions, degree of insufficiency, ventricular function and coronary tree status.

From a technical perspective the procedure involves general anaesthesia and orotracheal intubation. It is percutaneous, and thus guided by a combination of radioscopy, haemodynamic pressure values and transoesophageal ultrasound. After performing 2 venous and one femoral artery punctures, a catheter is passed to the pulmonary artery for constant pulmonary pressure monitors and to record pulmonary capillary pressure values. Another diagnostic arterial catheter is taken to the ascending aorta and then into the ventricular cavity. It monitors systemic pressure, provides and initial evaluation and the partial or final outcome of implantation. The third route, a vein, is used for the procedure proper. It involves ultrasound-guided transseptal puncture, as it must be performed at the ideal site in an antero-posterior position. The cannula that carries the clip is inserted through this point of the interatrial septum (Figure). The folded MitraClip is taken to the mitral valve, attempting to stop the regurgitation in the left atrium. At this point, when over the valve, the clip is opened perpendicular to the leaflets. Without changing the position, the arms are folded slightly to cross the valve, aimed at simultaneously capturing both leaflets. When this happens, the grippers are closed and tension is reduced. This is when status is evaluated. When the haemodynamic, ultrasound and angiographic outcome is appropriate, the clip is released and its efficacy verified. A second (and even a third) clip is occasionally required. The figures provided show details of the device, together with haemodynamic, angiographic and ultrasound outcomes. The patient spends 24 hours in the ICU after the procedure, followed by another 24 hours on a ward. Discharge is usually after three days (links with Abbot video).These percutaneous treatments lead us to expect the implantation of a biological mitral valve soon.