Accuracy and applicability of non-invasive evaluation of aortic wave intensity using only pressure waveforms in humans

Background. Wave intensity (WI) analysis is a well-established method for quantifying the energy carried in arterial waves, providing valuable clinical information about cardiovascular function. The primary drawback of this method is the need for concurrent measurements of both pressure and flow waveforms. Objective. We have for the first time investigated the accuracy of a novel methodology for estimating wave intensity employing only single pressure waveform measurements; we studied both carotid- and radial-based estimations in a large heterogeneous cohort. Approach. Tonometry was performed alongside Doppler ultrasound to acquire measurements of both carotid and radial pressure waveforms as well as aortic flow waveforms in 2640 healthy and diseased participants (1439 female) in the Framingham Heart Study. Patterns consisting of two forward waves (Wf1, Wf2) and one backward wave (Wb1) along with reflection metrics were compared with those obtained from exact WI analysis. Main Results. Carotid-based estimates correlated well for forward peak amplitudes (Wf1, r = 0.85, p < 0.05; Wf2, r = 0.72, p < 0.05) and peak time (Wf1, r = 0.94, p < 0.05; Wf2, r = 0.98, p < 0.05), and radial-based estimates correlated fairly to poorly for amplitudes (Wf1, r = 0.62, p < 0.05; Wf2, r = 0.42, p < 0.05) and peak time(Wf1, r = 0.04, p = 0.10; Wf2, r = 0.75, p < 0.05). In all cases, estimated Wb1 measures were not correlated. Reflection metrics were well correlated for healthy patients (r = 0.67, p < 0.05), moderately correlated for valvular disease (r = 0.59, p < 0.05) and fairly correlated for CVD (r = 0.46, p < 0.05) and heart failure (r = 0.49, p < 0.05). Significance. These findings indicate that pressure-only WI produces accurate results only when forward contributions are of primary interest and only for carotid pressure waveforms. The pressure-onlyWI estimations of this work provide an important opportunity to further the goal of uncovering clinical insights through wave analysis affordably and non-invasively.