title: Simultaneous measurement of right and left ventricular volume by the conductance catheter technique in the newborn lamb.
abstract: BACKGROUND
  Measurement of absolute ventricular volume with the conductance catheter technique has been documented extensively for the left ventricle (LV). More recently, the same technique has been applied in studies of right ventricular (RV) performance. In the present study we performed simultaneous measurements of LV and RV volumes. Conversion of measured conductances to absolute volumes requires the assessment of slope factor alpha (α) and parallel conductance correction volume (Vc) for both the RV and LV. We investigated the magnitude and variability of these calibration factors during a typical study period of four hours.
  
  
  METHODS
  In five anaesthetised, ventilated newborn lambs, conductance catheters were introduced into the LV and RV and a thermodilution catheter was positioned in the pulmonary artery. Alphas and Vc's were determined by thermodilution and hypertonic saline dilution, respectively, at one hourly intervals. At the same time points, biventricular haemodynamic parameters were obtained. Results were analysed by multiple linear regression analysis.
  
  
  RESULTS
  During the course of the experiments all haemodynamic parameters were stable. There were no significant changes in Vcor α for either ventricle. RV-Vcwas systematically higher than LV-Vc: both as absolute values and as percentage of the uncalibrated conductance signal (79% for RV, and 49% for LV, respectively). This probably reflects the geometrical differences of the two ventricles. Right ventricular ejection fraction (RV-EF) was higher than left ventricular ejection fraction (LV-EF), and neither changed significantly during four hours.
  
  
  CONCLUSIONS
  These results show that calibration factors α and Vcfor the RV, as well as EF, show values that are consistent with the observed haemodynamic stability and in line with the LV factors. These results indicate that the conductance catheter method can be used satisfactorily for biventricular function assessment.
authors.forename: R H Lopes
authors.initials: RH
authors.lastname: Cardozo
authors.forename: M
authors.initials: M
authors.lastname: de Vroomen
authors.forename: F
authors.initials: F
authors.lastname: van Bel
authors.forename: J
authors.initials: J
authors.lastname: Baan
authors.forename: P
authors.initials: P
authors.lastname: Steendijk
keywords: pressure-volume loops; right ventricle; ventricular function