title: "Double" potentials define linear lesion conduction block using a novel mapping/linear lesion ablation catheter.
abstract: BACKGROUND
  A novel mapping/ablation catheter using a coaxially ablation electrode (E) that is moveable between distal and proximal ring electrodes along its shaft was used to create a linear lesion over the cavotricuspid isthmus (CTI) and bidirectional block in 32 patients (21 men; age 38-79 years) undergoing ablation for counterclockwise atrial flutter.
  
  
  RESULTS
  Two bipolar electrograms (E1 and E2) were recorded: between E and the distal ring electrode and between E and the proximal ring electrode. Interpole distance varied for both as the E traversed the slide shaft. Given the catheter's concept, these bipoles are orientated exactly along the line of lesion creation. Prior to ablation, unitary bipolar electrograms were recorded along the catheter slide shaft position. As the CTI lesion was created (E moved along the catheter slide shaft in 2-mm steps with radiofrequency energy delivered to achieve 65 degrees C for 60 sec at each), double potentials (DP) were observed. Interpotential distance became maximal with completion of the linear lesion and bidirectional block. DPs were noted in all these procedures. With pacing from the low septal right atrium at bidirectional block creation, interpotential timing was 140.9 +/- 15 msec and from the low right atrial free wall was 145.13 +/- 18 msec. In sinus rhythm, DP interpotential timing was less (35.13 +/- 9 msec) as activation fronts arrived from both septal and anterior atrial aspects.
  
  
  CONCLUSIONS
  Bipolar recordings from the coaxially moveable electrode catheter provide unique electrogram data. DPs recorded during and after linear lesion creation can define conduction block across that lesion without the need for additional mapping catheters or complex mapping technology.
authors.affiliation: Wessex Cardiac Centre, Southampton University Hospitals, Southampton, United Kingdom. jmm@cardiology.co.uk
authors.forename: John M
authors.initials: JM
authors.lastname: Morgan
authors.forename: Guy
authors.initials: G
authors.lastname: Haywood
authors.forename: Alexander
authors.initials: A
authors.lastname: Schirdewan
authors.forename: Pedro
authors.initials: P
authors.lastname: Brugada
authors.forename: Peter
authors.initials: P
authors.lastname: Geelen
authors.forename: Udo
authors.initials: U
authors.lastname: Meyerfeldt
authors.forename: Paul
authors.initials: P
authors.lastname: Roberts
authors.forename: Chuck
authors.initials: C
authors.lastname: Gibson
mesh_terms: D000328:Adult; D000368:Aged; D001282:Atrial Flutter / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation / Q000295:instrumentation* / Q000379:methods; D004562:Electrocardiography; D004566:Electrodes; D005260:Female; D006327:Heart Block / Q000209:etiology; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged