title: Novel, single-beat approach for determining both end-systolic pressure-dimension relationship and preload recruitable stroke work.
abstract: The end-systolic pressure-dimension relationship (ESPDR) and the preload recruitable stroke work (PRSW) relationship are load-insensitive measures of contractility, but their clinical application has been limited by the need to record multiple beats over a wide volume range. In this study, we therefore sought to validate a new method to concomitantly determine the ESPDR and the PRSW relationship from a single beat.
  
  
  
  Pressure-dimension loops were recorded in 14 conscious dogs under various haemodynamic and pathological conditions. Multiple-beat PRSW relationship was determined for its slope (Mw) and for a dimension-axis intercept (Dw). The ESPDR represented by the formula [Formula: see text], was estimated from a steady-state, single-beat late-systolic pressure-dimension relationship. The single-beat Mw was determined as an end-systolic pressure when the end-systolic dimension was equal to Dw.
  
  
  
  A strong correlation was observed between multiple-beat and single-beat ESPDRs (zero-stress dimension; r=0.98, p<0.0001). The single-beat estimation of Mw calculated using the wall thickness was strongly correlated with the actual Mw (r=0.93, p<0.0001) and was sensitive enough to detect the change in contractility by dobutamine infusion (p<0.001) and by tachycardia-induced heart failure (p<0.001). Similar results were obtained for Mw estimated without information on wall thickness.
  
  
  
  Mw can be interpreted as an end-systolic pressure when the end-systolic dimension is equal to Dw. By using the non-linear ESPDR, accurate single-beat estimation of the ESPDR and Mw is possible even without information on wall thickness. These results should enhance the applicability of pressure-volume framework to clinical medicine.
authors.affiliation: Department of Pediatrics , University of Tokyo , Tokyo , Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Inuzuka
authors.affiliation: Department of Cardiology , Johns Hopkins Medical Institution , Baltimore, Maryland , USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Kass
authors.affiliation: Department of Pediatric Cardiology , Saitama Medical Center, Saitama Medical University , Kawagoe , Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Senzaki
keywords: CARDIAC FUNCTION; CONTRACTILITY; HEART FAILURE