title: Feasibility study of percutaneous transvalvular endomyocardial cryoablation for the treatment of hypertrophic obstructive cardiomyopathy.
abstract: BACKGROUND
  Left ventricular outflow tract (LVOT) obstruction in the setting of hypertrophic cardiomyopathy (HCM) confers negative adverse outcomes. Current nonpharmacologic treatment options include surgical myectomy and percutaneous transcoronary ablation of septal hypertrophy (TASH). While TASH negates a more invasive procedure, concern remains with particular regard to the arrhythmogenic potential of the resultant myocardial scar. Percutaneous transvalvular endomyocardial septal cryoablation (PTESC) may circumvent some of these potential limitations and offer a novel treatment strategy.
  
  
  OBJECTIVE
  The purpose of this study was to report our early experience and outcomes with percutaneous endomyocardial cryoablation of the interventricular septum in obstructive HCM.
  
  
  RESULTS
  Between March 2005 and May 2006, 3 patients (2 male, 1 female) with symptomatic obstructive HCM underwent PTESC. Basal LVOT gradients measured during left heart catheterization were 70, 126 and 100 mmHg for Patients 1, 2 and 3, respectively. Using 7 Fr and 9 Fr 8 mm tip CryoCath Freezor catheters (CryoCath Technologies, Inc., Montreal, Quebec, Canada), cryothermal energy was applied to the interventricular septum under fluoroscopic guidance. A total of 20 to 32 applications of cryothermal energy were delivered, with the mean nadir temperature sustained during cryoablation being -88 degrees Celcius. Two of the 3 patients had an immediate reduction in the LVOT gradient. However, at 6 months, only 1 patient had a significant sustained reduction in LVOT gradient. No adverse events relating to the procedure were experienced.
  
  
  CONCLUSIONS
  PTESC is feasible, but did not result in a significant, sustained reduction in LVOT gradient in 2 of the 3 patients in this small series of obstructive HCM patients. The technique warrants further study to improve the consistency and duration of reduction in outflow gradient.
authors.affiliation: Department of Cardiac Arrhythmia, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: David
authors.initials: D
authors.lastname: Keane
authors.forename: Brian
authors.initials: B
authors.lastname: Hynes
authors.forename: Gerard
authors.initials: G
authors.lastname: King
authors.forename: Paul
authors.initials: P
authors.lastname: Shiels
authors.forename: Angie
authors.initials: A
authors.lastname: Brown
mesh_terms: D000328:Adult; D006328:Cardiac Catheterization; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology / Q000601:surgery*; D003452:Cryosurgery / Q000379:methods*; D017147:Defibrillators, Implantable; D005240:Feasibility Studies; D005260:Female; D006346:Heart Septum / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D016277:Ventricular Function, Left