Energy equivalent pressure and total hemodynamic energy associated with the pressure-flow waveforms of a pediatric pulsatile ventricular assist device
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Updated: Aug 14, 2026
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Published on: June 12, 2021
William J Weiss1, Branka Lukic, Akif Undar
1Departments of Surgery and Bioengineering, The Pennsylvania State University, The Milton S. Hershey Medical Center, Hershey, PA 17033, USA. bweiss@psu.edu
Insights
This study evaluated a pediatric ventricular assist device (VAD), finding that shorter systolic duration significantly increased pulsatility (energy equivalent pressure). Lower flow rates also enhanced pulsatility in the pediatric VAD.
Area of Science:
- Biomedical Engineering
- Pediatric Cardiology
- Hemodynamics
Background:
- Pediatric ventricular assist devices (VADs) are crucial for managing heart failure in children.
- Optimizing VAD performance requires understanding factors influencing pulsatility, a key hemodynamic parameter.
- Energy Equivalent Pressure (EEP) quantifies hemodynamic energy and is a critical metric for pulsatility assessment.
Purpose of the Study:
- To quantify the impact of flow rate and systolic duration on the pulsatility of a pulsatile pediatric VAD.
- To determine how these parameters affect hemodynamic energy transfer and energy loss within the device's outflow cannula.
- To provide data for optimizing the design and clinical use of pediatric VADs.
Main Methods:
- A pulsatile pediatric VAD with a 12 ml stroke volume was tested using a mock circulatory loop.
- Systemic arterial pressure was maintained at approximately 90/60 mm Hg (mean 75 mm Hg).
- Energy Equivalent Pressure (EEP) was measured at proximal and distal cannula ends across four flow rates (0.50-1.25 L/min) and two systolic durations (230 ms, 400 ms).
Main Results:
- Arterial EEP ranged from 5.58% to 8.41% with rapid ejection (230 ms) and 2.33% to 4.20% with slower ejection (400 ms).
- Higher pulsatility (EEP) was observed at lower flow rates, particularly with shorter systolic durations.
- Hemodynamic energy loss in the outlet cannula increased significantly with decreased systolic duration but was less sensitive to mean flow rate.
Conclusions:
- Systolic duration is a critical determinant of pulsatility in this pediatric VAD, with shorter durations yielding higher pulsatility.
- Flow rate also influences pulsatility, with lower rates enhancing the effect, especially under rapid ejection conditions.
- Findings highlight the trade-offs between pulsatility and energy loss, informing VAD management and design for pediatric applications.
Abstract:
A pulsatile pediatric ventricular assist device (VAD) with a dynamic stroke volume of approximately 12 ml was tested to quantify the effect of flowrate and systolic duration on pulsatility as quantified by the energy equivalent pressure (EEP), defined as the hemodynamic energy per unit volume of fluid pumped. The VAD was tested on a mock circulatory loop, adjusted to maintain a systemic arterial pressure of approximately 90/60 mm Hg (systolic/diastolic) and a mean of 75 mm Hg. The EEP was calculated for each beat for 1 minute at both the proximal end of the pump outlet cannula and at the distal end (arterial EEP). Nominal mean flowrates were 0.50, 0.75, 1.00, and 1.25 l/min. Systolic duration was set at either 230 or 400 milliseconds. With a rapid systolic ejection (230 milliseconds), the arterial EEP ranged from 5.58% to 8.41% relative to the mean arterial pressure. The highest EEP occurred at the lowest flowrate. With a slower (400 milliseconds) systolic ejection, the arterial EEP ranged from 2.33% to 4.20%. Hemodynamic energy loss in the outlet cannula was also quantified by the differential EEP and shown to increase markedly as systolic duration was decreased, but was relatively insensitive to mean flowrate.
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