Ventricular and myocardial efficiencies during acute aortic regurgitation in conscious dogs

BACKGROUND: Alterations in cardiac efficiency may signal pathologic stresses and energetic adaptation during aortic regurgitation (AR). METHODS AND RESULTS: LV systolic function, left coronary blood flow, and AVO2 difference were measured in conscious dogs to assess LV and contractile efficiencies at baseline, 1 day (n=10), 1 week (n=10), and 3 weeks (n=8) of AR. LV systolic function was assessed by the preload recruitable stroke work relationship. Total LV Efficiency (TEFF=SWxHeart Rate/MVO2) and contractile efficiency (CEFF=1/the slope of the MVO2 -pressure-volume area relationship) and steady-state potential energy (PVA-SWxHR), mechanical coupling efficiency (MCE=SWxHR/PVA) were calculated. LV systolic function decreased by 17% at 1 day (P