P62 Estimation of Wave Intensity in Humans Using only Pressure Waveforms and Reservoir Analysis

Abstract

Background

Measurement of wave intensity (WI) requires simultaneous or quasi-simultaneous measurement of pressure and flow limiting its use. Previous work in dogs [1] and humans [2] has shown that the excess pressure waveforms calculated using reservoir analysis correspond closely with aortic flow waveforms. This offers a potential method to estimate WI using only pressure waveforms (pWI). We investigated the feasibility of this approach and agreement with established methods.

Methods

262 participants (68.3 (SD = 5.5); 74% male) without aortic stenosis or heart failure were recruited from a UK-based longitudinal study, Southall and Brent Revisited. Central pressure waveforms, aortic flow velocity and carotid WI were measured using tonometry (Sphygmocor, AtCor), echocardiography (iE33, Philips) and ultrasonography (SSD-5500, Aloka) respectively. Reservoir analysis was performed as previously described [2] and excess pressure waveforms were calibrated to flow velocity assuming a peak velocity of 1 m/s. Method agreement was assessed as mean difference (MD), limits of agreement (LOA) and concordance coefficient (CC).

Results

Analysis failed in 9 individuals; results for those with analysable data are shown in Table 1. Aortic pWI was higher than aortic WI but showed good concordance (logW1: MD(LOA) = −0.41(−0.73, −0.09) CC = 0.7; logW2: MD(LOA) = −0.41 (−0.73, −0.09); CC = 0.7). Agreement of pWI with carotid WI showed no bias and concordance was fair to poor (logW1: MD (LOA) = −0.16 (−1.30, 0.99) CC = 0.3; logW2: MD (LOA) = −0.02 (−1.23, 1.2); CC = 0.1).

Conclusion

Estimation of aortic WI from pressure waveforms using reservoir analysis is feasible.

Table1 Results