The Role of the Pericardium in Cardiac Performance of the Trout (Salmo gairdneri)

Cardiac performance was compared in an in situ perfused heart from rainbow trout with the pericardium intact and then cut. Cutting the pericardium reduced the control cardiac output by 44% and significantly shifted the ventricular function curve to the right. Maximum cardiac output and power output were also reduced by 8% and 18%, respectively, with the pericardium cut. Intrapericardial pressure was subambient and was reduced during ventricular contraction. These data suggest that vis a fronte filling of the heart is very important under resting conditions in trout and that vis a tergo filling of the heart becomes progressively more important as maximum cardiac output is reached.