PRECISE QUANTIFICATION OF PRESSURE-FLOW WAVEFORMS OF A PULSATILE VAD DURING CHRONIC SUPPORT

Abstract

Purpose: Unreliable quantification of flow pulsatility has hampered many efforts to assess the importance of pulsatile perfusion. Generation of pulsatile flow depends on an energy gradient. The objective of this study was to quantify pressure-flow waveforms in terms of Energy Equivalent Pressure (EEP) and total hemodynamic energy levels in an adult mock loop using a Pulsatile VAD. Methods: A 70cc Pierce-Donachy pneumatic pulsatile VAD was used with a Penn State adult mock loop. The pump flow rate was constant at 5 Vmin with pump rates of 65, 70,and 80 bpm, and aortic pressures of 80, 90, and 100mmHg, respectively. The EEP [mmHg = (∫fpdt)/(∫fdt)] and total energy [(ergdcu cm) = (1,332 ∫fpdt)/(∫fdt)] were calculated at each experimental stage. The difference between the EEP and the aortic pressure is the extra energy generated by this device. This difference is approximately 10% in a normal human heart. Results: The following table represents the results with a pump rate of 70bpm and a pump flow rate of 5 Vmin.Table RESULTSimilar results were obtained when the pump rate was changed to 65 bpm or 80 bpm. Conclusions: This particular Pulsatile VAD system produces physiologic hemodynamic energy levels at each experimental stage.