title: Presence of ventricular dyssynchrony and haemodynamic impact of right ventricular pacing in adults with repaired Tetralogy of Fallot and right bundle branch block.
abstract: OBJECTIVE
  Late after surgical repair, adults with Tetralogy of Fallot (TOF) commonly present with right ventricular (RV) dysfunction and right bundle branch block (RBBB). We aimed at (i) investigating whether this prolonged RV conduction induced detrimental electromechanical dyssynchrony in both RV and left ventricle (LV) and (ii) determining the acute haemodynamic effects of pacing at different RV sites.
  
  
  RESULTS
  A total of 42 adults with surgically repaired TOF and RBBB were investigated by echocardiography. Intra-RV dyssynchrony (IRVD) and intra-left ventricular dyssynchrony (ILVD) were compared with measurements performed in 30 healthy matched control subjects. An acute haemodynamic study was subsequently performed in a subgroup of 10 patients with New York Heart Association functional class II or class III and echocardiographic signs of RV dysfunction. Cardiac index was measured by a thermodilution technique during spontaneous rhythm (SR) and during atrio-synchronized RV pacing at four different sites (infundibulum, apex, septal, and lateral walls). Fifty-five per cent of the patients with repaired TOF demonstrated abnormal RV and/or LV dyssynchrony. We observed an increased IRVD (37 +/- 12 vs. 18 +/- 8 ms; P= 0.02) and ILVD (34 +/- 12 vs. 20 +/- 10 ms; P= 0.04) in TOF patients when compared with control subjects. We did not observe any significant acute improvement in the cardiac output during atrio-synchronized ventricular pacing vs. SR. Similarly, RV pacing did not induce any significant reduction in the QRS duration.
  
  
  CONCLUSIONS
  Some TOF adults with RBBB exhibit biventricular electromechanical dyssynchrony. However, in symptomatic patients with RV dysfunction, atrio-synchronized RV pacing does not induce significant acute haemodynamic improvement.
authors.affiliation: University Victor Segallen, 33000 Bordeaux, France. bordacharp@hotmail.com
authors.forename: Pierre
authors.initials: P
authors.lastname: Bordachar
authors.forename: Xavier
authors.initials: X
authors.lastname: Iriart
authors.forename: Julie
authors.initials: J
authors.lastname: Chabaneix
authors.forename: Frederic
authors.initials: F
authors.lastname: Sacher
authors.forename: Stephane
authors.initials: S
authors.lastname: Lafitte
authors.forename: Pierre
authors.initials: P
authors.lastname: Jais
authors.forename: Michel
authors.initials: M
authors.lastname: Haissaguerre
authors.forename: Jacques
authors.initials: J
authors.lastname: Clementy
authors.forename: Pierre
authors.initials: P
authors.lastname: Dos Santos
authors.forename: Jean-Benoit
authors.initials: JB
authors.lastname: Thambo
mesh_terms: D000328:Adult; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging* / Q000517:prevention & control*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D013318:Stroke Volume; D013771:Tetralogy of Fallot / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery*; D016896:Treatment Outcome; D014463:Ultrasonography; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging* / Q000517:prevention & control*