title: Echocardiographic AV-interval optimization in patients with reduced left ventricular function.
abstract: BACKGROUND
  Ritter's method is a tool used to optimize AV delay in DDD pacemaker patients with normal left ventricular function only. The goal of our study was to evaluate Ritter's method in AV delay-interval optimization in patients with reduced left ventricular function.
  
  
  METHODS
  Patients with implanted DDD pacemakers and AVB III degrees were assigned to one of two groups according to ejection fraction (EF): Group 1 (EF > 35%) and Group 2 (EF < 35%). AV delay optimization was performed by means of radionuclide ventriculography (RNV) and application of Ritter's method.
  
  
  RESULTS
  For each of the patients examined, we succeeded in defining an optimal AV interval by means of both RNV and Ritter's method. The optimal AV delay determined by RNV correlated well with the delay found by Ritter's method, especially among those patients with reduced EF. The intra-class correlation coefficient was 0.8965 in Group 1 and 0.9228 in Group 2. The optimal AV interval in Group 1 was 190 +/- 28.5 ms, and 180 +/- 35 ms in Group 2.
  
  
  CONCLUSIONS
  Ritter's method is also effective for optimization of AV intervals among patients with reduced left ventricular function (EF < 35%). The results obtained by RNV correlate well with those from Ritter's method. Individual programming of the AV interval is fundamentally essential in all cases.
authors.affiliation: I Medizinische Klinik mit Schwerpunkt Kardiologie, Angiologie und Pulmologie, Charité, Campus Mitte, Berlin, Germany. christoph.melzer@charite.de
authors.forename: C
authors.initials: C
authors.lastname: Melzer
authors.forename: A C
authors.initials: AC
authors.lastname: Borges
authors.forename: F
authors.initials: F
authors.lastname: Knebel
authors.forename: W S
authors.initials: WS
authors.lastname: Richter
authors.forename: W
authors.initials: W
authors.lastname: Combs
authors.forename: G
authors.initials: G
authors.lastname: Baumann
authors.forename: H
authors.initials: H
authors.lastname: Theres
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D011877:Radionuclide Imaging; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000150:complications / Q000000981:diagnostic imaging* / Q000628:therapy*; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology / Q000517:prevention & control*