title: Radiofrequency ablation of the interventricular septum to treat outflow tract gradients in hypertrophic obstructive cardiomyopathy: a novel use of CARTOSound® technology to guide ablation.
abstract: OBJECTIVE
  Septal reduction is needed for hypertrophic obstructive cardiomyopathy (HOCM) patients with severe left ventricular outflow tract (LVOT) gradients and symptoms despite medication. Myectomy cannot be performed in all. Alcohol septal ablation cannot be performed in 5-15% due to technical difficulties. A method of delivering percutaneous tissue damage to the septum that is not reliant on coronary anatomy is desirable. To directly ablate the interventricular septum at the mitral valve (MV) systolic anterior motion (SAM)-septal contact point using radiofrequency (RF) energy guided by CARTOSound.
  
  
  RESULTS
  Five patients underwent RF ablation (RFA); we describe follow-up at 6 months in four patients. Intracardiac echocardiography (ICE) images are merged with CARTO to create a shell of the cardiac chambers. The SAM-septal contact area is marked from ICE images and mapped on to the CARTO shell; this becomes the target for RF delivery. Conduction tissue is mapped and avoided where possible. Twenty-eight to 42 min of RF energy was delivered to the target area using retrograde aortic access and SmartTouch catheters. Resting LVOT gradient improved from 64.2 (±50.6) to 12.3 (±2.5) mmHg. Valsalva/exercise-induced gradient reduced from 93.5 (±30.9) to 23.3 (±8.3) mmHg. Three patients improved New York Heart Association status from III to II, one patient improved from class III to I. Exercise time on bicycle ergometer increased from 612 to 730 s. Cardiac magnetic resonance shows late gadolinium enhancement up to 8 mm depth at LV target myocardium. One patient died following a significant retroperitoneal haemorrhage.
  
  
  CONCLUSIONS
  Radiofrequency ablation using CARTOSound(®) guidance is accurate and effective in treating LVOT gradients in HOCM in this preliminary group of patients.
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK rob.cooper@lhch.nhs.uk.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Cooper
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Adeel
authors.initials: A
authors.lastname: Shahzad
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Hasleton
authors.affiliation: Birmingham Children's Hospital, Birmingham, UK.
authors.forename: Joseph
authors.initials: J
authors.lastname: Digiovanni
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hall
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Derick M
authors.initials: DM
authors.lastname: Todd
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Modi
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Rodney H
authors.initials: RH
authors.lastname: Stables
mesh_terms: D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods*; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome; D014694:Ventricular Outflow Obstruction / Q000175:diagnosis / Q000209:etiology / Q000601:surgery*; D054088:Ventricular Septum / Q000000981:diagnostic imaging / Q000601:surgery
keywords: Ablation; CARTOSound®; Hypertrophic obstructive cardiomyopathy; Intracardiac echocardiography