• Richard B Thompson, Ewout J van den Bos, David J Esposito, Clarence H Owen, and Donald D Glower.
• Departments of Thoracic Surgery, Box 3851, Duke University Medical Center, Durham, NC 27710, USA.
• Eur. J. Heart Fail. 2003 Dec 1;5(6):741-9.

BackgroundTo date, no data exist on the linearity and, therefore, the usefulness of the preload recruitable stroke work (PRSW) and end-systolic pressure-volume (ESPVR) relationships during acute afterload changes in heart failure.AimsOur aim was, therefore, to characterize both relationships in a model of ventricular pacing induced heart failure at baseline and during acute changes in afterload.MethodsDynamic left ventricular volume and transmural pressure were measured in 10 conscious dogs using sonomicrometry and micromanometry under control conditions and during heart failure produced by 3 weeks of rapid right ventricular pacing. Afterload was varied from baseline with intravenous infusions of nitroprusside and phenylephrine. Left ventricular function was assessed using the PRSW and ESPVR relationships.ResultsCardiac output demonstrated a linear inverse relationship with afterload in both normal and failing hearts (r2>0.5, P<0.001) with failure producing a parallel, downward shift of the afterload (x) vs. cardiac output (y) relationship (P<0.01). Yet, afterload variation did not affect PRSW or ESPVR relationships in either normal or failing hearts (r2<0.12, P>0.05).ConclusionThus, the PRSW and ESPVR relationships are insensitive to acute afterload changes in both failing and normal hearts, and the failing left ventricle is no more afterload-sensitive than the normal heart.

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