title: Biophysical parameters during radiofrequency catheter ablation of scar-mediated ventricular tachycardia: epicardial and endocardial applications via manual and magnetic navigation.
abstract: BACKGROUND
  There is a paucity of data on biophysical parameters during radiofrequency ablation of scar-mediated ventricular tachycardia (VT).
  
  
  RESULTS
  Data were collected from consecutive patients undergoing VT ablation with open-irrigation. Complete data were available for 372 lesions in 21 patients. The frequency of biophysical parameter changes were: >10Ω reduction (80%), bipolar EGM reduction (69%), while loss of capture was uncommon (32%). Unipolar injury current was seen in 72% of radiofrequency applications. Both EGM reduction and impedance drop were seen in 57% and a change in all 3 parameters was seen in only 20% of lesions. Late potentials were eliminated in 33%, reduced/modified in 56%, and remained after ablation in 11%. Epicardial lesions exhibited an impedance drop (90% vs. 76%, P = 0.002) and loss of capture (46% vs. 27%, P < 0.001) more frequently than endocardial lesions. Lesions delivered manually exhibited a >10Ω impedance drop (83% vs. 71%, P = 0.02) and an EGM reduction (71% vs. 40%, P < 0.001) more frequently than lesions applied using magnetic navigation, although loss of capture, elimination of LPs, and a change in all 3 parameters were similarly observed.
  
  
  CONCLUSIONS
  VT ablation is inefficient as the majority of radiofrequency lesions do not achieve more than one targeted biophysical parameter. Only one-third of RF applications targeted at LPs result in complete elimination. Epicardial ablation within scar may be more effective than endocardial lesions, and lesions applied manually may be more effective than lesions applied using magnetic navigation. New technologies directed at identifying and optimizing ablation effectiveness in scar are clinically warranted.
authors.affiliation: UCLA Cardiac Arrhythmia Center, UCLA Health System, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Tara
authors.initials: T
authors.lastname: Bourke
authors.forename: Eric
authors.initials: E
authors.lastname: Buch
authors.forename: Nilesh
authors.initials: N
authors.lastname: Mathuria
authors.forename: Yoav
authors.initials: Y
authors.lastname: Michowitz
authors.forename: Ricky
authors.initials: R
authors.lastname: Yu
authors.forename: Ravi
authors.initials: R
authors.lastname: Mandapati
authors.forename: Kalyanam
authors.initials: K
authors.lastname: Shivkumar
authors.forename: Roderick
authors.initials: R
authors.lastname: Tung
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017115:Catheter Ablation / Q000379:methods*; D002921:Cicatrix / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D004562:Electrocardiography / Q000379:methods; D004699:Endocardium / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008280:Magnetics / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D010496:Pericardium / Q000503:physiopathology*; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery
keywords: ablation; biophysical; endocardial; epicardial; radiofrequency; scar; ventricular tachycardia