The effect of sudden failure of a rotary blood pump on left ventricular performance in normal and failing hearts

We investigated the hemodynamic effect of regurgitation (or back-flow) due to sudden failure of a rotary blood pump (diagonal pump). Seven healthy she ep (Group C) and 7 with chronic heart failure (Group F) were studied. Chron ic heart failure was obtained by intracoronary injection of microspheres se veral weeks earlier. Left ventricular function and ventricular efficacy wer e assessed by the pressure-volume relationship. The back-flow through the s topped pump was significantly lower in Group F (2.3 +/- 0.34 L/min) than in Group C (2.8 +/- 0.33 L/min). Mean aortic blood pressure dropped significa ntly from 68.3 +/- 9.65 to 61.9 +/- 9.75 mm Hg in Group C and from 62.5 +/- 9.12 to 51.5 +/- 9.08 in Group F but remained stable during the 15 min per iod of pump stop. Parameters of left ventricular contractility (preload rec ruitable stroke work) dropped significantly in both groups, remained stable during the pump stop, and returned to baseline values 30 min after the end of back-flow. The ventricular efficacy (in terms of energy transfer) was t olerant against this acute volume overload even in the failing hearts. Sudd en pump failure of a rotary blood pump leads to an acute depression of the hemodynamic state and myocardial contractility. However, this depression re mained stable over 15 min, did not lead to further deterioration of the ani mals, and was completely reversible.