Quantification of reflected wave magnitude and transit time using a multi-Rayleigh flow waveform model: A simplified approach to arterial wave separation analysis

Quantification of wave reflection necessitates the simultaneous measurement of pressure and flow waveforms from the same arterial site, enabling wave separation analysis (WSA). A simplified approach to WSA, which involves modelling the flow waveform, offers a methodological advantage over the conventional method. Nevertheless, the current methods of pressure-only WSA is constrained to the aortic site. In this study, we propose a method to model the carotid artery flow rate waveform using multi-Rayleigh functions (Q(m-RAY)(t)) for WSA (WSA(m-RAY)). The carotid artery is associated with central and cerebral haemodynamics and has an anatomical advantage for easier accessibility of non-invasive measurements, unlike the aorta. The accuracy of the Q(m-RAY)(t) was assessed against the actual carotid flow rate waveform (Q(REF)(t)), and the performance of the WSA(m-RAY) was evaluated against the Q(REF)(t) based WSA (WSA(REF)) on 4374 virtual (healthy) subjects. The Q(m-RAY)(t) has captured the time instants of characteristic peaks in the flow profile of the common carotid artery with an RMSE < 8.26 ms (<1 % of average heart rate). A strong and statistically significant correlation (r = 0.99, p < 0.001) was observed for both Delta P-F and Delta P-B when compared between WSA(REF) and WSA(m-RAY). The reflection quantification indices obtained from WSA(REF,) and WSA(m-RAY) yielded strong and statistically significant correlation (r > 0.78, p < 0.001). The WSA(m-RAY) demonstrated the capability to ease the carotid WSA by modelling the flow rate waveform and thereby expanding the possibilities for vascular screenings and diagnostics that rely on single pulse waveform measurements.