Hemodynamic effects of direct biventricular compression studied in isovolumic and ejecting isolated canine hearts

Background-Biventricular direct cardiac compression (DCC) can potentially s upport the failing heart without the complications associated with a blood/ device interface. The effect of uniform DCC on left and right ventricular p erformance was evaluated in 7 isolated canine heart preparations. Methods and Results-A computer-controlled afterload system either constrain ed the isolated heart to contract isovolumically or simulated hemodynamic p roperties of physiological ejection. Biventricular DCC was provided by a ch amber surrounding the heart that allowed adjustment of the compression pres sure, onset time, and duration. Through a series of ventricular preloads, t he effect of DCC on the end-systolic pressure-volume relationship (ESPVR) w as evaluated under isovolumic and ejecting conditions. Under both condition s, DCC shifted the ESPVR of the left and right ventricles upward by an amou nt approximately equal to the compression pressure. The augmentation of end -systolic pressure for each initial preload tested, however, was less under ejecting conditions, because reductions in end-systolic and end-diastolic volumes occurred with ejection. Nevertheless, the net effect was to increas e stroke volume. Measurement of M(V) over dot o(2) demonstrated that at a g iven ventricular volume, M(V) over dot o(2) did not change with DCC; howeve r, peak ventricular pressure increased substantially, so that the effective pressure-volume area increased. Conclusions-Biventricular DCC can augment end-systolic pressure with no add ed costs of M(V) over dot o(2). Under ejecting conditions, this augmentatio n of ventricular contracting ability manifests as increases in stroke volum e. Thus, DCC represents a feasible alternative form of ventricular assist, and devices that support the heart in this manner should be further explore d.