HVAD Flow Waveform Morphologies: Theoretical Foundation and Implications for Clinical Practice
Continuous-flow ventricular assist device (cfVAD) performance and patient hemodynamic conditions are intimately interrelated and dynamic, changing frequently with alterations in physiologic conditions, particularly pre- and afterloading conditions. The Heartware cfVAD (HVAD) provides a unique feature among currently approved VADs of providing an estimated instantaneous flow waveform, the characteristics of which can provide significant insights into patient and device properties. Despite being readily available, HVAD waveforms are poorly understood, underutilized, and insufficiently leveraged, even by clinicians who regularly manage HVAD patients. The purpose of this review is to provide the theoretical foundation for understanding the determinants of HVAD waveform characteristics and to provide practical examples illustrating how to interpret and integrate changes of HVAD waveforms into clinical practice. Heartware cfVAD waveforms should be considered a complimentary tool for the optimization of medical therapies and device speed in HVAD patients.