Development of a new experimental model for total exclusion of the right heart without the aid of cardiopulmonary bypass

Changes in venous return parameters associated with univentricular Fontan circulations

“…Second, our experimental biventricular and Fontan circulations were functioning under two different cardiac function curves. These results are in agreement with previously reported studies allowing the comparison of baseline biventricular hemodynamics versus Fontan hemodynamics (20,24,27,36). This could be related to: 1) a right-to-left ventricular interaction loss, which constitutes an inherent drawback to any experimental univentricular model, implying that this observation cannot necessarily be applied to the clinical practice because it has been considered that the additional load of the PVR can be easily accommodated by the normal left ventricle (8); and 2) an heterometric autoregulation due to TVR increase (24) or more accurately to total impedance increase of the Fontan circulatory system (37), which might explain the difficulties of SBF adaptation of univentricular circulations.…”

“…Components of the model. To compare hemodynamics between biventricular and Fontan circulations, important conditions have been fulfilled: 1) protocols were similar in both groups; 2) postoperative SBF was set to its baseline value to avoid simultaneous changes in preload, afterload, and SBF (24); 3) anesthesia caused a desirable decrease in baroreflex sensitivity (12,18,35); 4) use of extracorporeal circulation and transient ventricular fibrillation time did not affect hemodynamics in the biventricular group, indicating that univentricular Fontan hemodynamics were per se related to the circulatory arrangement; and 5) steady-state hemodynamic changes in P la and PVR between baseline and experimental Fontan circulations were similar to those reported previously for either a decreased (20,27,36) or preserved resulting SBF (24).…”

“…The present study demonstrates that in Fontan circulations, PVR were similar to RVR and induced the characteristic downward rotation of the Q vr curve due to the proportional decrease in G vr (13). Moreover, PVR values are increased in Fontan circulations (3,20,24,27,36), reducing G vr as much. This can be related to: 1) a lack of dilatation and recruitment of the pulmonary vessels, 2) an asymmetric pulmonary perfusion, and 3) the loss of pulsatility of the pulmonary blood flow (3).…”

“…The heart was defibrillated after usual deairing procedures. Fontan circulations were realized according to previously described models (24,27). Briefly, two polytetrafluoroethylene 16-mm-diameter conduits (FEP ringed Gore-Tex Vascular Graft, Gore and Associates, Elkton, MD), reinforced with polyethylene cannulas, were introduced in the inferior and superior venae cavae, and connected to a Y-shaped conduit of our design, which was introduced into the distal main pulmonary trunk.…”

Experimental Study of Nonpulsatile Flow Perfusion and Structural Remodeling of Pulmonary Microcirculation Vessels

“…When the shear stress of blood flow on vascular endothelial cells increases, the synthesis and secretion of active vascular contraction factors increases, vascular smooth muscle cell proliferation and pulmonary vessel remodeling are induced, and angiospasm with thickening and fibrosis of vessel walls occurs [12][13][14][15][16]. However, few studies have previously investigated the remodeling and subsequent development of the structure of the vascular bed with long-term nonpulsatile flow perfusion [17,18]. We hypothesized that the significant decrease in the shearing force of the pulmonary blood flow in a Fontan circulation may result in changes of vascular endothelial cell functions and the remodeling of pulmonary vessels, and may be associated with long-term complications.…”