Novel Centroid Method for Robust Evaluation of Return Time of Reflected Waves in the Systemic Arterial Network

Abstract

Arterial ageing is thought to cause a diastolic-to-systolic shift in the return time (RT) of backward waves to central arteries. However, current methods of estimating RT-inflection point, zero crossing, and foot methods-depend on a single waveform feature and produce systolic RT throughout life. We propose a novel centroid method that accounts for the entire backward pressure waveform and develop a ground truth RT (GTRT), which can be used in computational models to test the accuracy of RT estimation methods. Linear wave tracking was implemented in a one-dimensional systemic arterial tree model and GTRT was calculated as the amplitude-weighted mean RT of backward waves at the ascending aorta. Using a virtual cohort of 1200 patients, the centroid RT was closest to GTRT compared to the zero crossing, inflection point, and foot methods; mean differences (limits of agreement) were -8 (-47,30), vs -42 (-136,52), -78 (-305,149), and -197 (-379,-15) ms, respectively. The sensitivity of the methods to changes in RT was also assessed in ten sheep. A balloon catheter in the descending thoracic aorta was used to generate a backward-running pulse that arrived at the ascending aorta at different times during diastole or systole, allowing the "bulk" RT of the backward-running wave ensemble to be manipulated. Only the centroid method was sensitive to both diastolic and systolic changes in RT. We conclude that the accuracy and robustness of the centroid method make it most suitable for evaluating the diastolic-tosystolic shift in RT of backward waves with ageing.

Modulation of Pulsatile Left Ventricular Afterload by Renal Denervation in Heart Failure With Preserved Ejection Fraction

“…As such, absolute values might differ significantly when different techniques are used. 18 We also observed an increased magnitude of the backward wave in HFpEF, which might be attributed to a greater sum impedance mismatch in the light of a greater sympathetically mediated arterial stiffness, especially at intermediate sized muscular arteries with high adrenergic innervation. 20 Importantly, the observed abnormalities in arterial function exhibited partial normalization following RDN.…”

“…16 Key parameters of arterial function were extracted and compared from baseline to follow-up: total arterial compliance (TAC); characteristic impedance of the proximal aorta (Zc); timing of wave reflections, defined as backward transit time normalized to ejection time (BTT) according to the foot-method; the magnitude of wave reflections, defined as reflection coefficient (RC)=(PP of backward divided by PP of forward wave)•100; and PWV (Figure 1). 9,[17][18][19]…”

Development and characterization of canine‐specific computational models to predict pulsatile arterial hemodynamics and ventricular‐arterial coupling

“…Analytic approaches have been extensively used in human clinical research studies to analyze arterial pressure waveforms to gain further mechanistic information regarding central hemodynamics (Chirinos & Segers, 2010 ; Denardo et al, 2010 ; Hashimoto et al, 2008 ; Kondiboyina et al, 2023 ; Paglia et al, 2014 ; Townsend et al, 2015 ; Weber et al, 2012 ; Weber & Chirinos, 2018 ), providing insights about pulsatile load, ventricular function, and ventricular‐arterial interactions (Adji et al, 2011 ; Chirinos, 2013 ; Chirinos & Segers, 2010 ; Denardo et al, 2010 ; Hametner et al, 2017 ; Wilkinson et al, 2002 ). Common analytical methods include pulse wave analysis (PWA), wave separation analysis (WSA), and wave power analysis (WPA), an extension of wave intensity analysis (WIA) to volume flow (rather than flow velocity) measurements.…”