Preload-adjusted right ventricular maximal power: Concept and validation

Soren Schenk, Zoran B. Popović, Yoshie Ochiai, Fernando Casas, Patrick M. McCarthy, Randall C. Starling, Michael W. Kopcak, Raymond Dessoffy, Jose L. Navia, Neil L. Greenberg, James D. Thomas, Kiyotaka Fukamachi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Right ventricular (RV) maximal power (PWRmx) is dependent on preload. The objective of this study was to test our hypothesis that the PWRmx versus end-diastolic volume (EDV) relationship, analogous to the load-independent stroke work (SW) versus EDV relationship (preload-recruitable SW, PRSW), is linear, with the PWR x-axis intercept (V OPWR) corresponding to the PRSW intercept (VOSW). If our hypothesis is correct, the preload sensitivity of PWRmx could be eliminated by adjusting for EDV and VOPWR. Ten dogs were instrumented with a pulmonary flow probe, micromanometers, and RV conductance catheter. Data were obtained during bicaval occlusions under various conditions and fitted to PWRmx = a·(EDV - VOPWR)β, where a is the slope of the relationship. The PWRmx versus EDV relationship did not deviate from linearity (β = 1.09, P = not significant vs. 1), and VOPWR correlated with VOSW (r = 0.93, P <0.0001). VOPRW was related to steady-state EDV and left ventricular end-diastolic pressure, allowing for estimation of VOPWR (V OEst) and single-beat PWRmx preload adjustment. Dividing PWRmx by the difference of EDV and VOPWR (PAMP VOPWR) eliminated preload dependency down to 50% of the baseline EDV. PWRmx adjustment using VOEst (PAMPVOEst) showed similar preload independency. Enhancing contractility increased PAMP VOPWR and PAMPVOEst from 176 ± 52 to 394 ± 205 W/ml × 104 and 145 ± 51 to 404 ± 261 W/ml × 104, respectively, accompanied by an increase of PRSW from 13.0 ± 4.5 to 29.7 ± 16.4 mmHg (all P <0.01). PAMP VOPWR and PAMPVOEst correlated with PRSW (r = 0.85; r = 0.77; both P <0.001). Numerical modeling confirmed the accuracy of our experimental data. Thus preload adjustment of PWRmx should consider a linear PWRmx versus EDV relationship with distinct VOPWR. PAMPVOPWR is a preload-independent estimate of RV contractility that may eventually be determined noninvasively.

Original languageEnglish (US)
Pages (from-to)H1632-H1640
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume287
Issue number4 56-4
DOIs
StatePublished - Oct 2004

Keywords

  • Contractility
  • Hemodynamics
  • Right ventricle

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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