Ventricular Pressure-Volume Relations Demonstrate Positive Inotropic Effect of Increased Arterial Impedance

  • Jan Baan
  • Enno T. van der Velde


The influence of different types of loading intervention on the end-systolic pressure-volume relation (ESPVR) of the left ventricle (LV) in situ was investigated in anesthetized open-chest dogs. LV volume was measured by conductance catheter. Two loading interventions were applied: a pressure intervention (INp) by gradually occluding the descending aorta, and a volume intervention (INv) by rapidly infusing 180 ml blood intathe vena cava. The P-V loops during an intervention always showed a linear ESPVR, the slope of which, Ees, was calculated. Results from 16 dogs show that Ees(INp) was always larger (1.37 ± 0.45 kPa/ml) than Ees(INv) (0.73 ± 0.32 kPa/ml) (P<.001). This difference was enhanced by beta-blockade through metoprolol. The same phenomenon was found for the slope (SdPV) of the relation between dP/dtmax and EDV: SdPV(INp) = 45.17 ± 22.63 kPa/ml per s and SdPV(INv) = 20.55 ± 11.13 kPa/ml per s (P <.001).

Since INv increases stroke volume while INp decreases it, the results can be explained in part by shortening deactivation. However, the similar behavior of SdPV as compared to Ees suggests that INp leads to an increased inotropic state with respect to INv. We speculate that an intrinsic myocardial mechanism related to changes in calcium turnover forms the basis of this phenomenon.


Volume Intervention Pressure Intervention Left Ventricle Volume Conductance Catheter Inotropic State 
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Copyright information

© Springer-Verlag Tokyo 1989

Authors and Affiliations

  • Jan Baan
  • Enno T. van der Velde
    • 1
  1. 1.Laboratory of Clinical Physiology, Department of CardiologyLeiden University HospitalLeidenThe Netherlands

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