Mitral annular reduction with subablative therapeutic ultrasound: pre-clinical evaluation of the ReCor device.
To evaluate the potential for mitral annular (MA) size reduction using a novel device utilising therapeutic ultrasound (TU).



The ReCor device (ReCor Medical, Inc., Ronkonkoma, NY, USA, Investigational device, not for use in human application) was studied in a closed chest canine animal model (35 dogs). Under fluoroscopy, a 12 Fr TU balloon catheter was advanced into the left atrium (transseptal approach). The TU balloon was inflated with contrast-saline, positioned at the MA and energy delivered circumferentially, to heat the tissue locally. Five TU applications were delivered (at least 60W for at least 40 sec). Relative to baseline, mitral valve annular diameter reduction (measured by transthoracic echocardiography) was 8.4% immediately post procedure(p<0.001), 8.6% at one week (p<0.001), 8.8% at two weeks (p<0.001), 9.3% at three weeks (p<0.001), 10.8% at four weeks (p<0.001), 8.6% at three months (p<0.001) and 5.7% at six months (p<0.001). Histology showed an increase in elastin associated with tissue thickening at the annular level. Transmission electron microscopy demonstrated a decrease in diameter of individual collagen fibres in treated regions compared to controls.



Therapeutic ultrasound (TU) energy application to the mitral annulus is feasible percutaneously. A reduction in annular dimensions occurs immediately and appears to be durable without peri-annular damage.
Jilaihawi
Hasan
H
Interventional Cardiology, Montréal Heart Institute, Montreal, Canada.
Virmani
Renu
R
Nakagawa
Hiroshi
H
Ducharme
Anique
A
Shi
Yan-Fen
YF
Carter-Monroe
Naima
N
Ladich
Elena
E
Iyer
Mano
M
Ikeda
Atsushi
A
Asgar
Anita
A
Bonan
Raoul
R
D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D004285:Dogs; D015150:Echocardiography, Doppler; D004549:Elastin / Q000378:metabolism; D004867:Equipment Design; D005240:Feasibility Studies; D024022:Fibrillar Collagens / Q000648:ultrastructure; D008422:Materials Testing; D046529:Microscopy, Electron, Transmission; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000378:metabolism / Q000601:surgery* / Q000648:ultrastructure; D023421:Models, Animal; D015641:Radiography, Interventional; D013997:Time Factors; D014464:Ultrasonic Therapy / Q000295:instrumentation*
D024022:Fibrillar Collagens; D004549:Elastin