Significance of left ventricular power waveform on changes in stroke work during pulsatile left ventricular bypass

Abstract

The object of this paper is to introduce the “peakedness” of the left ventricular power waveform as an index of the effectiveness of the pulsatile ventricular bypass (LVBP). The “peakedness” is determined by the position of the peak and the rate of ascent and decline of the instantaneous left ventricular power waveform. In eight open-chested dogs with coronary artery ligation, it has been found that the “peakedness” of the LV power waveform during assistance is important in determining the efficacy of LVBP. When the LV power waveform, the instantaneous product of LV pressure and aortic flow, has a broad width about the peak with an early rise to peak (low value of “peakedness” factor), the chance of improvement in stroke work after bypass is greater than when the waveform is sharply peaked with a delayed rise (high value of “peakedness”). Improvement in stroke work (SW) occurred when the percentage bypass flow was between 45 and 60%. Among the pumping runs with improved SW and CO, there was no consistent relationship between the percentage changes in SW and CO and the percentage bypass flow. The data suggest that “peakedness” may be of importance, because it evaluated the effect of left ventricular bypass on the performance of the native ventricle during postischemic periods.