title: Effect of multisite pacing on ventricular coordination.
abstract: OBJECTIVE
  To determine the effect of multisite pacing on left ventricular function.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  18 patients with heart failure with a dilated poorly functioning left ventricle (LV) and left bundle branch block.
  
  
  METHODS
  Pacing for 5 minutes in random order at the right ventricle (RV) apex, RV outflow tract, mid posterolateral LV, RV apex and LV simultaneously, and RV outflow tract and LV simultaneously. The best achieved measurements with RV, LV, and biventricular pacing were compared.
  
  
  METHODS
  LV dimension, filling characteristics, and long axis indices were measured on echocardiography simultaneously with LV pressure. Cycle efficiency (%)--that is, the ratio of the area of the acquired pressure dimension loop to that of the ideal loop for that segment--quantified coordination.
  
  
  RESULTS
  The pacing site that gave the best achieved cycle efficiency differed between patients (biventricular in five, LV in two, RV in seven, and no site in four). In patients with baseline incoordination (cycle efficiency < or = 72%, n = 12) cycle efficiency improved significantly with RV pacing (cycle efficiency 76%, p = 0.01) but not with LV (65%) or biventricular (67%) pacing. LV based pacing induced premature short axis contraction in a subset of patients (n = 4), which was associated with a prolonged time from the Q wave on the ECG to the onset of inward movement of the long axis (from apex to mitral ring): biventricular 145 ms, LV 105 ms, RV 85 ms (biventricular v RV, p < 0.05). Excluding patients with baseline incoordination in whom premature activation occurred, pacing at all sites led to a similar increase in cycle efficiency (RV 78%, LV 72%, biventricular 73%).
  
  
  CONCLUSIONS
  Ventricular coordination can be improved with pacing in patients with baseline incoordination. Short and long axis fibres may be asynchronised in a subset of patients with LV or biventricular pacing, which may worsen coordination. The clinical significance of these findings remains to be defined.
authors.affiliation: Department of Cardiological Sciences, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK. cvarma@sghms.ac.uk
authors.forename: C
authors.initials: C
authors.lastname: Varma
authors.forename: P
authors.initials: P
authors.lastname: O'Callaghan
authors.forename: N G
authors.initials: NG
authors.lastname: Mahon
authors.forename: K
authors.initials: K
authors.lastname: Hnatkova
authors.forename: W
authors.initials: W
authors.lastname: McKenna
authors.forename: A J
authors.initials: AJ
authors.lastname: Camm
authors.forename: E
authors.initials: E
authors.lastname: Rowland
authors.forename: S J D
authors.initials: SJ
authors.lastname: Brecker
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000503:physiopathology / Q000628:therapy*; D002303:Cardiac Output, Low / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004452:Echocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D011446:Prospective Studies; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy*; D018879:Ventricular Premature Complexes / Q000503:physiopathology