Percutaneous Heart Valve Therapy – Options, Risks and Benefits
animal experience has showed the feasibility of this procedure.55 Early FIM experiences published by Webb and colleagues56
Figure 7: Edwards Monarc Device
reported
procedural success in nine of 15 patients who underwent the procedure, and among these nine patients, acute reduction in MR was maintained at 30-day follow-up.
Bridge
Transcatheter Coronary Sinus Techniques
The stronghold of surgical therapy for MR has been ring reduction annuloplasty, either as a stand-alone treatment for MR or in conjunction with mitral leaflet repair.57
Recently, the observation of
the relationship of the coronary sinus to the mitral annulus has allowed the development of transcatheter annuloplasty approaches.58
A variety of devices delivered via a transjugular
approach can be placed into the coronary sinus. In this case, tension placed on the coronary sinus provokes a decrease in the mitral annular circumference and approximation of the leaflets. Of note, branches of the circumflex coronary artery frequently cross under the coronary sinus, and coronary compression by transcatheter device deployment has resulted in myocardial infarction in some patients in the early FIM experiences.
MONARC
The first permanent implants of a coronary sinus annuloplasty device were reported using the Edwards MONARC device (Edwards Lifesciences Inc.).59
The device, placed via the right internal
jugular vein, uses two self-expanding anchors connected with a foreshortening bridge (see Figure 7). The distal and proximal stent anchor in the great cardiac vein and in the proximal coronary sinus, respectively. The bridge element is initially kept in a stretched position by bioabsorbable material. The mitral annular circumference decreases as the bridge shortens over a period of three to six weeks with dissolution of the absorbable material. Among the first five reported patients, the bridge fractured in three without any clinical complications, but with a loss of efficacy.60
This has led to a redesign
of the device. In the Clinical Evaluation Of the Edwards Lifesciences Percutaneous MItral Annuloplasty System for the treatment of Mitral Regurgitation (EVOLUTION I) study,61
of the 72 patients enrolled,
device placement was achieved in 82%. Freedom from death, myocardial infarction (MI) and cardiac tamponade at 30 days was 91%. At 90 days, freedom from death, MI, cardiac tamponade, coronary sinus thrombosis, device migration, device embolisation and pulmonary embolus was 86%, and at 24 months 72% of patients were event-free as defined by the protocol. Of note, angiography performed at three months showed coronary artery compression in 15 of 50 patients (30%). Coronary compression resulting in MI occurred in three patients. The EVOLUTION II trial will assess more functional and clinical outcomes.
CARILLON™
The Carillon™ device (Cardiac Dimensions®, Kirkland, Washington) is a device placed in the coronary sinus via a jugular venous approach.58,61
It consists of a nitinol wire shaping ribbon between
proximal and distal figure-of-eight-shaped anchors that are placed one in the distal coronary sinus and one near the coronary sinus ostium (see Figure 8). The distal anchor is deployed from the guide catheter and the catheter is pulled upward, resulting in tension on the coronary sinus with resultant shortening of the circumference of the coronary sinus. Initial experience in over 50 patients demonstrates the ability to reduce MR by one or two grades. A recent report by Shofer and colleagues62
showed that percutaneous
EUROPEAN CARDIOLOGY
71
Figure 9: The Percutaneous Transvenous Mitral Annuloplasty Device
Figure 8: Carillon Device
Proximal anchor
Distal anchor
Distal stent
Proximal stent
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