HeartWare HVAD Flow Estimator Accuracy for Left and Right Ventricular Support

Area of Science:

• Cardiovascular Engineering
• Biomedical Instrumentation
• Medical Device Technology

Background:

• Left ventricular assist device (LVAD) and biventricular assist device (BiVAD) systems are critical for managing advanced heart failure.
• Accurate flow estimation is essential for optimizing device performance and patient management.
• The HeartWare HVAD system's integrated flow estimator requires validation across different support modes.

Purpose of the Study:

• To assess the accuracy of the HeartWare HVAD flow estimator.
• To compare the estimator's performance in LVAD, BiVAD-reduced speed (BiVAD-RS), and BiVAD-banded outflow (BiVAD-B) configurations.
• To evaluate the impact of varying physiological parameters on flow estimation accuracy.

Main Methods:

• Utilized a mock circulatory loop to simulate cardiovascular conditions.
• Systematically altered systemic and pulmonary vascular resistance, heart rate, central venous pressure, and simulated hematocrit.
• Measured and compared estimated flow from the HVAD device against actual flow rates.

Main Results:

• Mean flow estimation errors were comparable across LVAD (0.1 ± 0.3 L/min), BiVAD-RS (-0.1 ± 0.2 L/min), and BiVAD-B (0 ± 0.2 L/min) modes.
• Flow waveform pulsatility showed high correlation in LVAD (r²=0.98) but lower correlation in BiVAD-RS (r²=0.85) and BiVAD-B (r²=0.60).
• Error spread for pulsatility was consistent across configurations (0.7 ± 0.1 to 0.3 L/min).

Conclusions:

• The HVAD flow estimator demonstrates consistent mean flow accuracy regardless of LVAD or BiVAD support mode.
• Instantaneous flow waveform analysis necessitates careful interpretation, particularly in BiVAD configurations.
• Clinical application of the HVAD flow estimator in BiVAD support should consider potential waveform inaccuracies.