title: Continuous on-line measurement of absolute left ventricular volume by transcardiac conductance: angiographic validation in sheep.
abstract: OBJECTIVE
  Validation of the transcardiac conductance method for continuous, on-line measurement of absolute left ventricular volume by comparison with biplane angiography.
  
  
  METHODS
  Controlled, prospective animal study.
  
  
  METHODS
  Catheterization laboratory of the Leiden University Medical Center.
  
  
  METHODS
  Six anesthetized sheep.
  
  
  METHODS
  Subjects were studied at baseline, during infusion of dobutamine, and during volume loading and beta blockade. In a pilot experiment, a coronary artery was occluded by a balloon, and the behavior of the transcardiac conductance signals during ischemia was tested.
  
  
  RESULTS
  Calibration factors alpha and V(p) were determined by thermodilution and hypertonic saline dilution, respectively. Calibrated transcardiac conductance volume was compared with angiographic volume in four different hemodynamic conditions, and transcardiac conductance measurements were registered during a period of ischemia. Results showed a good linear correlation between transcardiac conductance and angiographic volume (r =.77, p <.01) with an intercept of 12.5 +/- 5.6 mL (interanimal variability, 17.8 mL) and a slope of 1.49 +/- 0.15 (interanimal variability, 0.34). Mean alpha and V(p) were 0.12 +/- 0.01 (interanimal variability, 0.07) and 104 +/- 3 mL (interanimal variability, 38 mL), respectively. V(p) did not vary significantly between conditions, and alpha varied only during propranolol (p =.04). Transcardiac conductance enabled immediate visualization of acute left ventricular volume changes during coronary occlusion in a pilot experiment.
  
  
  CONCLUSIONS
  Transcardiac conductance is a method to register an on-line, continuous, left ventricular volume signal, which correlates well with angiography. However, calibration factors need to be determined in individual subjects. The method appears promising to monitor absolute volume in the intensive care unit.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, The Netherlands.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Staal
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Gerhard
authors.initials: G
authors.lastname: Koning
authors.forename: Jouke
authors.initials: J
authors.lastname: Dijkstra
authors.forename: J Wouter
authors.initials: JW
authors.lastname: Jukema
authors.forename: Jan
authors.initials: J
authors.lastname: Baan
mesh_terms: D000792:Angiography; D000818:Animals; D006439:Hemodynamics; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D012756:Sheep; D014694:Ventricular Outflow Obstruction; D020257:Ventricular Remodeling