Figure 1.
Representative examples of elastic restoring forces in the RV. Unprocessed PV-loops are shown in left panels. Right panels show the results of pressure decomposition, fitting the passive (green) and active (blue) pressures curves, as well as measured (black), and total fitted (red) pressure tracings ‘for the first beat (pre IVC-occlusion) in the data set’; black dots represent measured end-diastolic pressures and volumes for all beats. V0 is the zero-pressure volume. Values of passive pressure at pulmonary valve closure are shown in the vertical axis. Three patterns of the behaviour of restoring forces on the first beat are illustrated. (A) Negative pressure is measured because contraction is far below V0 from the first run, generating strong restoring forces. (B) Also contraction below V0 generates restoring forces. However, despite restoring forces are increasing the pressure gradient, measured pressure is positive because active pressure is higher. (C) The ventricle does not contract below V0 so restoring forces are not generated. The ventricle is exclusively filled by atrial emptying.