title: Biventricular pacing improves left ventricular function by 2-D strain in right ventricular failure.
abstract: BACKGROUND
  We used speckle-tracking echocardiography to test the hypothesis that regional left ventricular (LV) strain would improve during optimized biventricular pacing (BiVP) in acute right ventricular (RV) pressure overload (PO).
  
  
  METHODS
  Complete heart block and RVPO were induced in five open-chest fully anesthetized pigs. BiVP was optimized by adjusting atrioventricular and interventricular delays to maximize cardiac output derived from an aortic flow probe. LV short axis views were obtained during atrio-RV pacing (RVP), atrio-LV pacing (LVP), and BiVP. Intraventricular synchrony was assessed by comparing speckle-tracking echocardiography-derived time to peak (TTP) strain in the anterior septal (AS) and posterior wall segments. Segmental function was assessed using radial strain.
  
  
  RESULTS
  Cardiac output was higher with optimized (RV first) BiVP than with LVP (0.96 ± 0.26 L/min versus 0.89 ± 0.27 L/min; P = 0.05). AS TTP strain (502 ± 19 ms) during LVP was prolonged versus BiVP (392 ± 58 ms) and versus RVP (390 ± 53 ms) (P = 0.0018). AS TTP strain during LVP was prolonged versus posterior (502 ± 19 ms versus 396 ± 72 ms, P = 0.0011). No significant difference in TTP strain in these segments was seen with BiVP or RVP. Posterior strain (20% ± 5%) increased 66% versus AS strain (12% ± 6%) during BiVP (P = 0.0029). A similar increase occurred during RVP (posterior 20% ± 3% versus AS 12% ± 7%, P = 0.0002). Posterior strain did not increase during LVP.
  
  
  CONCLUSIONS
  BiVP and RVP restore intraventricular LV synchrony and increase regional function versus LVP during RVPO. RV pre-excitation unloads the RV and reduces the duration of AS contraction, facilitating synchrony of all LV segments and increasing free wall LV contraction.
authors: Weill Cornell Medical College, New York, New York, USA.
authors: Casey
authors: C
authors: Wong
authors: Santos E
authors: SE
authors: Cabreriza
authors: Maria
authors: M
authors: Nugent
authors: Daniel Y
authors: DY
authors: Wang
authors: Rabin
authors: R
authors: Gerrah
authors: Alexander
authors: A
authors: Rusanov
authors: Vinay
authors: V
authors: Yalamanchi
authors: Alice
authors: A
authors: Wang
authors: Bin
authors: B
authors: Cheng
authors: Henry M
authors: HM
authors: Spotnitz
mesh_terms: D000818:Animals; D002302:Cardiac Output; D058406:Cardiac Resynchronization Therapy; D008297:Male; D009200:Myocardial Contraction; D013552:Swine; D018497:Ventricular Dysfunction, Right / Q000503:physiopathology / Q000628:therapy*; D016277:Ventricular Function, Left