Abstract 21036: Subablative Therapeutic Ultrasound Reduces Mitral and Tricuspid Annular Dimension: Preclinical Evaluation of the ReCor Device
Background: We hypothesized that Therapeutic Ultrasound(TU) from the ReCor device could result in a reduction in mitral annular(MA) and tricuspid annular(TA) dimension with potential application in mitral and tricuspid regurgitation(MR/TR) associated with annular dilatation.
Methods: The ReCor device was studied in a closed chest procedure in an anesthetized canine model. Under fluoroscopy, a 12 Fr TU balloon catheter(ReCor, Inc) was advanced into the left atrium(transseptal approach for MA reduction) or the right atrium(for TA reduction). The non-obstructive TU balloon was inflated with contrast-saline and positioned at the MA or TA. A modification has been made to the TA catheter: a mirror balloon is attached to one side of the main balloon and is inflated with CO2, insulating the AV node and other surrounding structures. TU energy(9MHz) was delivered circumferentially, to heat tissue locally. The position was monitored through specific fluoroscopic and/or intra-cardiac US recordings. Five TU applications were delivered to each animal(up to 130W for up to 120 sec). Transthoracic echocardiogram measured the annular diameter(short and long axes) in the apical 4-c and 2-c views at various timepoints before and after the mitral procedures and peri-procedurally for the tricuspid procedures.
Results: Thirty eight dogs were studied. Complications observed included 1 device-related death following ventricular fibrillation at the end of the second TU application. In addition there were 2 other non device-related deaths: 1 anaesthesia-related and 1 following a retroperitoneal hemaetoma necessitating early sacrifice. There was no significant damage to the mitral leaflets or the coronary arteries. Relative to baseline, mitral valve annular diameter reduction was 8.4% immediately post procedure(n=32,p<0.001), 8.6% at 1 week(n=20,p< 0.001), 8.8% at 2 weeks(n=20,p< 0.001), 9.3% at 3 weeks(n=20, p<0.001), 10.8% at 4 weeks(n=22,p<0.001), 8.6% at 3 months(n=12,p<0.001) and 5.7% at 6 months(n=9,p<0.001). TU was applied to the tricuspid annulus in 3 dogs and resulted in a 26.9% immediate annular reduction(p=0.03).
Conclusions: Therapeutic Ultrasound(TU) energy application to both mitral and tricuspid annuli results in reduction in annular dimensions.
- © 2010 by American Heart Association, Inc.