title: Two-dimensional echocardiographic features of the inferior right atrial isthmus: the role of vestibular thickness in catheter ablation of atrial flutter.
abstract: OBJECTIVE
  The aim of this study was to examine the feasibility of transthoracic two-dimensional (2D)-echocardiography in defining the cavo-tricuspid isthmus (CTI) anatomy and its value concerning the ease of catheter ablation of isthmic atrial flutter (AF).
  
  
  METHODS
  CTI analysis was accomplished in 39 cases: 16 necropsy specimens and 23 patients. Sixteen were patients with isthmus-dependent AF and seven controls with other supraventricular re-entrant tachycardias. Two-dimensional transthoracic echocardiography and a right atrium angiogram were performed before radiofrequency catheter ablation (RFCA).
  
  
  RESULTS
  The measurements of the CTI with angiography were compared with those taken with echocardiography and correlation was excellent (r= 0.91; P < 0.0001). In normal patients, the dimension of the vestibular thickness was successfully compared and validated with the histological examination of the necropsy specimens: histology median 6.8 mm, range 4.4-10.5 vs. echo median 6.2 mm, range 5.4-8.7; P: NS. Vestibular thickness was greater in complex than in simple RFCA (13.6 ± 1.9 mm vs. 10.0 ± 2.3 mm; P = 0.01). When vestibular thickness ≥11.5 mm, the ablation prone to be complex (sensitivity 83.3%, specificity 80%, positive predictive value 71.4%, and negative predictive value 88.9%).
  
  
  CONCLUSIONS
  Two-dimensional transthoracic echocardiography clearly depicts the inferior isthmus and, displaying the thickness of the tricuspid vestibule, it was related with complexity of the ablation procedure in isthmus-dependent AF.
authors.affiliation: Cardiology Department, Instituto Cardiovascular, Hospital Clínico San Carlos, c/ Prof. Martín Lagos s/n. 28040 Madrid, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Marcos-Alberca
authors.forename: Damián
authors.initials: D
authors.lastname: Sánchez-Quintana
authors.forename: José A
authors.initials: JA
authors.lastname: Cabrera
authors.forename: Jerónimo
authors.initials: J
authors.lastname: Farré
authors.forename: José M
authors.initials: JM
authors.lastname: Rubio
authors.forename: Jose A
authors.initials: JA
authors.lastname: de Agustín
authors.forename: Carlos
authors.initials: C
authors.lastname: Almería
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Pérez-Isla
authors.forename: Carlos
authors.initials: C
authors.lastname: Macaya
mesh_terms: D000368:Aged; D001282:Atrial Flutter / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D002102:Cadaver; D017115:Catheter Ablation / Q000379:methods*; D017023:Coronary Angiography; D004452:Echocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013617:Tachycardia, Supraventricular / Q000000981:diagnostic imaging; D016896:Treatment Outcome; D014261:Tricuspid Valve / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*
keywords: Atrial flutter; Catheter ablation; Echocardiography