Velocity of contractile element shortening in constrictive pericarditis and the effect of pulsus paradoxus

Abstract

Force-velocity curves were constructed in nine patients with CP from a high-fidelity LV pressure tracing and its simultaneously recorded first derivative. V max and peak V ce (V pm) were calculated using the 2-element (Hill) or Voigt model; the curves were also constructed and V max measured using the 3-element Maxwell model. The measurements were compared with those in a group of four patients with CMO and with two control subjects. Measurements of the celerity of ventricular contraction-peak LVdp dt , Max dp/dt/IP and V max (2-element model)-were reduced in CP and greatly reduced in CMO. The effect of beat-to-beat variations in preload during pulsus paradoxus on the indices of ventricular celerity was studied. Peak LVdp dt and V pm varied with the change in LVEDP: the change in V max was negligible using the 2-element (Hill) or Voigt model. The 3-element (Maxwell) model failed to discriminate between the three groups of patients and seems to be invalid at high LV end-diastolic pressures.