Interventional Cardiology
Figure 5: Evalve® Mitraclip Device
Figure 6: MitraClip™ Implantation Procedure
AB
MitraClip®
The MitraClip® System (Menlo Park, California) (see Figure 5) consists of a catheter-based device designed to perform an edge- to-edge reconstruction of the insufficient mitral valve while the heart is beating as an alternative to the conventional surgical approach. The cardiovascular valve repair system (CVRS) includes a clip, a 24Fr steerable guide catheter and a clip delivery system that permits placement of the clip on the mitral valve leaflets. The delivery system is introduced through the femoral vein and placed across the atrial septum using standard transseptal techniques; the transseptal system was then exchanged with the delivery catheter and the distal tip of the guide catheter system is steered into the left atrium in order to obtain a perpendicular orientation to the valve plane. Once the system has been aligned, the two arms of the clip are opened and the clip advanced into the LV (see Figure 6A). Under TOE guidance, the catheter is manoeuvred and the arms are rotated until they are orientatΩed perpendicularly to the line of leaflet coaptation; the open, aligned clip is advanced across the mitral orifice and its arms grasp the leaflets. When a double orifice has been created and confirmed by echocardiography, the clip arms are closed and locked (see Figure 6B). If needed, the clip can be reopened and repositioned. Opening, closing, locking and detaching the clip are all controlled by the delivery catheter handle mechanisms. Once a functional double orifice has been created, the clip is detached and the delivery system and guide catheter withdrawn.
The safety and feasibility of the MitraClip in a porcine model has been reported.51,52
This device approach has been successfully used
in a phase I clinical Endovascular Valve Edge-to-edge Repair Study (EVEREST I) trial in the US, with results at six and 12 months published some years ago.50,53
In the trial, clips were implanted in
A: The clip is advanced into the left ventricle with the arms open; B: The clip arms are closed and locked.
now there have been no clinically viable percutaneous treatment options for patients with MR; this heart valve pathology has traditionally been a surgical disease with excellent short- and long- term results after successful mitral valve surgery.1,2
Mitral valve repair
(MVR) is the preferred surgical option due to higher risk related to valve replacement and improved short- and long-term outcomes compared with patients who receive a mitral valve prosthesis.44,45 Nowadays, several surgical approaches are widely used to correct MR, including annuloplasty, leaflet repair and chordal reconstruction. In the last few years, the basic surgical concepts of annuloplasty and leaflet repair have been adapted for the development of catheter- based percutaneous approaches. These percutaneous approaches imitate aspects of the surgical procedures and are less invasive than the surgical alternatives. Advances in terms of both technique and the development of novel devices have led to a variety of methods to treat MR using a percutaneous course.
Leaflet Repair
Edge-to-edge repair has been used as a surgical technique in open- chest arrested-heart surgery for the treatment of MR since the early 1990s.46–48
With this technique, a portion of the anterior leaflet is sutured
to the corresponding portion of the posterior leaflet, creating a point of permanent coaptation (‘approximation’) of the two leaflets and resulting in a double orifice.46–48
have been developed to accomplish the double orifice repair.8,49,50
70
More recently, several percutaneous methods
88% of patients. No major intra-procedural complications were observed. Mitral stenosis was not a problem.49
Thirty-day major
adverse events included partial clip detachment without embolisation in 7–9% of patients, who underwent elective valve surgery, and post-procedure stroke in one patient, which resolved at one month. Even when a clip was placed and surgery was required, subsequent surgical repair was possible after clip placement.54
More recently, the pivotal randomised controlled
EVEREST II trial has completed enrolment. The trial randomised patients to percutaneous repair versus a standard surgical approach (2:1 allocation), with clinical and echocardiographic safety and efficacy end-points evaluated in 279 patients.
MOBIUS
Edge-to-edge MVR can also be accomplished using the MOBIUS percutaneous suture device (Edwards Lifesciences Inc., Irvine, CA, US). The approach is similar to the MitraClip system. A 16Fr guide catheter is used to deliver a 10 or 12Fr therapy catheter. The therapy catheter uses suction to capture and immobilize a portion of the mitral leaflet and then deliver a suture. The device is rotated and the procedure is repeated on the second leaflet. If incorrectly positioned, the suture can be withdrawn. If correctly positioned, a nitinol fastener is delivered over the suture and the suture is clipped; the end result is the approximation of the two suture points and the creation of a double orifice area. A potential advantage of this approach versus Evalve is that use of a suture rather than a clip device leaves less hardware on the mitral leaflet and theoretically may be less likely to inhibit future repair. Initial
EUROPEAN CARDIOLOGY
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