Heart assist devices and their impact on arterial Doppler: When the waveform appears flat or serrated

The purpose of this article was to review the principal mechanisms of three types of heart assist devices, to explore their haemodynamic impacts on spectral Doppler and to discuss the associated challenges in diagnostic ultrasound.

Heart assist devices are used in patients with advanced heart failure as bridge to transplantation or destination therapy. The arterial Doppler waveform features can be altered after the implantation of the devices. A continuous-flow device converts the arterial waveform into a venous-like waveform with a mean velocity that can be used in stenosis evaluation. When the pulsatile device produces extra pulses between the natural heartbeats, together they produce serrated arterial waveforms. When the pulsatile device serves as the only pumping source, the arterial waveforms are similar to the natural ones. Colour Doppler features are maintained despite all the spectral Doppler changes. These devices can affect both ultrasound scanning and interpretation. Therefore, it is essential to understand the principal mechanisms of these devices and their haemodynamic impacts so that an accurate ultrasound diagnosis can be made.