title: Mahaim automatic accelerated rhythm: a marker of successful radiofrequency ablation.
abstract: BACKGROUND
  Mahaim pathways are characterized by the presence of an accessory pathway potential-the 'M' potential, at the tricuspid annulus. M potential is a very useful guide during radiofrequency ablation of Mahaim pathway. During ablation, an accelerated rhythm with ORS morphology, identical to fully pre-excited QRS complex is observed, and has been labeled as Mahaim automatic rhythm. We analyzed this rhythm during radiofrequency ablation of these pathways.
  
  
  RESULTS
  Eighteen patients with Mahaim accessory pathways were taken up for electrophysiology study and radiofrequency ablation. Tricuspid annulus was mapped for 'M' potentials and targeted for ablation. Duration of ablation and number of ablation attempts were guided by Mahaim automatic rhythm during ablation. Mahaim tachycardia was inducible in all. 'M' potentials were recorded in 15/18 patients. Radiofrequency energy was delivered at the site where Mahaim accelerated rhythm was noticed and was continued till abolition of the rhythm. This resulted in long-term success. In 3 patients, M potentials were not recordable, and in them other methods including 3-dimensional electroanatomical mapping was also not successful.
  
  
  CONCLUSIONS
  'M' potential-guided radiofrequency ablation is a useful technique. Presence of Mahaim automatic rhythm and its abolition during ablation is associated with long-term success of the procedure.
authors.affiliation: Department of Cardiology, Batra Hospital and Medical Research Centre, New Delhi.
authors.forename: Balbir
authors.initials: B
authors.lastname: Singh
authors.forename: Ripen Kumar
authors.initials: RK
authors.lastname: Gupta
authors.forename: Anil
authors.initials: A
authors.lastname: Dhall
authors.forename: Tapan
authors.initials: T
authors.lastname: Ghose
authors.forename: Rahul
authors.initials: R
authors.lastname: Trehan
authors.forename: Upendra
authors.initials: U
authors.lastname: Kaul
mesh_terms: D016170:Accelerated Idioventricular Rhythm / Q000175:diagnosis* / Q000503:physiopathology*; D000293:Adolescent; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000503:physiopathology; D017115:Catheter Ablation / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results