Effects of carotid pressure waveforms on the results of wave separation, wave intensity and reservoir pressure analysis

Abstract

Objective: Recently great attention has been paid to innovative cardiovascular biomarkers obtained from wave separation (WS), wave intensity (WI) and reservoir-wave (RW) theories. All these approaches share a requirement for pressure information. The aim of this study was to evaluate differences in WS-, WI- and RW-derived parameters obtained achieving pressure waveforms in different ways. Approach: Twenty-two individuals (49 ± 17 years, 59% males) were examined. Common carotid blood flow waveforms were obtained from pulsed-wave Doppler images. Carotid pressure waveforms were achieved in four different ways: (1) with applanation tonometry, used as a reference method; (2) linear scaling from an ultrasound (US)-derived diameter curve; (3) exponential scaling from a US-derived diameter curve; and (4) linear scaling from an accelerometric-derived diameter signal. For each case, the reflection magnitude (RM) and index (RI) were obtained from the WS. The amplitude of the first positive peak (W1), of the second positive peak (W2) and of the negative peak (Wb) were calculated from the WI, while the maximum of the reservoir (maxPr) and the excess (maxPex) pressure were achieved from the RW. Main results: According to the intra-class coefficient values, the agreement between the standard method and all the others was excellent for the RM (linear: 0.82; exponential: 0.83; accelerometric: 0.86), RI (linear: 0.84; exponential: 0.85; accelerometric: 0.87), maxPr (linear: 0.97; exponential: 0.96; accelerometric: 0.97) and maxPex (linear: 0.85; exponential: 0.87; accelerometric: 0.89), while only a fair/good level was reached for W1 (linear: 0.67; exponential: 0.77; accelerometric: 0.52), W2 (linear: 0.52; exponential: 0.69; accelerometric: 0.83) and Wb (linear: 0.60; exponential: 0.44; accelerometric: 0.50). Significance: Measuring carotid pressure waveforms with different approaches does not influence the cardiovascular parameters obtained by WS and RW; those derived by WI are affected by the carotid pressure curve employed.