title: Hemodynamic stability during biventricular pacing after cardiopulmonary bypass.
abstract: OBJECTIVE
  To assess the stability of cardiac output, mean arterial pressure, and systemic vascular resistance during biventricular pacing (BiVP) optimization.
  
  
  METHODS
  Substudy analysis of data collected as part of a randomized controlled study examining the effects of optimized temporary BiVP after cardiopulmonary bypass (CPB).
  
  
  METHODS
  A single-center study at a university-affiliated tertiary care hospital.
  
  
  METHODS
  Cardiac surgery patients at risk of left ventricular failure after CPB.
  
  
  METHODS
  BiVP was optimized immediately after CPB. Atrioventricular delay (7 unique settings) was optimized first, followed by the left ventricular pacing site (3 unique settings) and then the interventricular delay (9 unique settings). Each setting was tested twice for 10 seconds each time. Vasoactive medication and fluid infusion rates were held constant.
  
  
  RESULTS
  Aortic flow velocity and radial artery pressure were digitized, recorded, and averaged over single respiratory cycles. Least squares and linear regression/Wilcoxon analyses were applied to the first 7 patients studied. Subsequently, curvilinear analysis was applied to 15 patients. Changes in mean arterial pressure and systemic vascular resistance were statistically insignificant or too small to be meaningful by least squares analysis. During interventricular synchrony optimization, cardiac output and mean arterial pressure decreased (mean changes -5.7% and -2.5%, respectively; with standard errors 2.3% and 1.5%, respectively), whereas SVR increased (mean change 3.1% with standard error 3.4%). Only the change in cardiac output was statistically significant (p = 0.043). Curvilinear fits to data for 15 patients demonstrated progressive hemodynamic stability over the total testing period.
  
  
  CONCLUSIONS
  BiVP optimization may be done safely in patients after CPB. With continuous monitoring of mean arterial pressure and cardiac output, the procedure results in no harmful hemodynamic perturbation.
authors.affiliation: Department of Surgery, Columbia University Medical Center, New York, NY 10032-3784, USA. hms2@columbia.edu
authors.forename: Mathew E
authors.initials: ME
authors.lastname: Spotnitz
authors.forename: Daniel Y
authors.initials: DY
authors.lastname: Wang
authors.forename: T Alexander
authors.initials: TA
authors.lastname: Quinn
authors.forename: Marc E
authors.initials: ME
authors.lastname: Richmond
authors.forename: Alexander
authors.initials: A
authors.lastname: Rusanov
authors.forename: Taylor
authors.initials: T
authors.lastname: Johnston
authors.forename: Bin
authors.initials: B
authors.lastname: Cheng
authors.forename: Santos E
authors.initials: SE
authors.lastname: Cabreriza
authors.forename: Henry M
authors.initials: HM
authors.lastname: Spotnitz
mesh_terms: D000368:Aged; D002302:Cardiac Output / Q000502:physiology; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D002315:Cardiopulmonary Bypass / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000503:physiopathology / Q000517:prevention & control