Noninvasive assessment of the common carotid artery hemodynamics with increasing exercise work rate using wave intensity analysis

Abstract

Noninvasively determined local wave speed (c) and wave intensity (WI) parameters provide insights into arterial stiffness and cardiac-vascular interactions in response to physiological perturbations. However, the effects of incremental exercise and subsequent recovery on c and WI have not been fully established. We examined the changes in c and WI parameters in the common carotid artery (CCA) during exercise and recovery in eight young, healthy male athletes. Ultrasound measurements of CCA diameter and blood flow velocity were acquired at rest, during five stages of incremental exercise (up to 70% maximum work rate), and throughout 1 h of recovery, and noninvasive WI analysis [diameter-velocity (DU) approach] was performed. During exercise, c increased (+136%), showing increased stiffness with work rate. All peak and area of forward compression, backward compression, and forward expansion waves increased during exercise (+452%, +700%, and +900%, respectively). However, WI reflection indexes and CCA resistance did not significantly change from rest to exercise. Furthermore, wave speed and the magnitude of all waves returned to baseline within 5 min of recovery, suggesting that the effects of exercise in the investigated parameters of young, healthy individuals were transient. In conclusion, incremental exercise was associated with an increase in local CCA stiffness and increases in all wave parameters, indicative of enhanced ventricular contractility and improved late-systolic blood flow deceleration.NEW & NOTEWORTHY We examined hemodynamics of the common carotid artery using noninvasive application of wave intensity analysis during exercise and recovery. The hemodynamic adjustments to exercise were associated with increases in local common carotid artery stiffness and all waves’ parameters, with the latter indicating enhanced ventricular contractility and improved late systolic blood flow deceleration.

Reply to Mynard et al.

“…It is worth noting that we have previously demonstrated the reproducibility of the lnDU-loop method (12), and the results agree with those in Ref. 13. At 40% of maximum workload (W max ), the c value of the present study was 9.5 m/s, in close agreement with 9.7 m/s during exercise in Ref.…”

“…14 and Ref. 1 relate to the cohorts involved and methodology used in determining c. Participants of our study (13) comprised of exclusively young male athletes, whereas the cohorts participating in those two studies were recreational active in Ref. 14 and a mix that included both athletes and inactive participants in Ref.…”

Wave propagation and reflection in the aorta and implications of the aortic Windkessel

“…(These results in anesthetized animals should not exclude the possibility that the BCW might arrive during systolic ejection and, thus, contribute to systolic hypertension. Pomella et al [13] have shown recently that wave speed can increase by ~ 50% with exercise.) As not so generally anticipated [14], the FCW was also reflected negatively from an abdominal site approximately 40 cm from the aortic valve; the course of the BDW is depicted by a dashed line.…”

Measurement, Analysis and Interpretation of Pressure/Flow Waves in Blood Vessels

“…Indeed, it has been shown that in the aorta, P res is approximately equal to twice the backward component of pressure (Hametner et al, 2014), while excess pressure (P ex = P − P res ) is approximately equal to flow multiplied by characteristic impedance, which is the pressure that would theoretically exist in the absence of any wave reflection. The debate regarding wave intensity analysis appears to have been resolved, with recent literature reflecting a consensus that measured pressure (or an appropriate distension-based surrogate) should be used for wave intensity, not P ex (Segers et al, 2017;Su et al, 2017;Pomella et al, 2018;Bhuva et al, 2019;Chiesa et al, 2019;Kowalski et al, 2019b;.…”

“…Moreover, rather than being considered exclusive to wave reflection, it is now broadly agreed that the P res in fact arises entirely from wave reflection, with Hughes and Parker (2020) stating that “the reservoir pressure can be understood as the pressure due to the cumulative effect of … reflected and re-reflected waves.” Indeed, it has been shown that in the aorta, P res is approximately equal to twice the backward component of pressure ( Hametner et al, 2014 ), while excess pressure ( P ex = P − P res ) is approximately equal to flow multiplied by characteristic impedance, which is the pressure that would theoretically exist in the absence of any wave reflection. The debate regarding wave intensity analysis appears to have been resolved, with recent literature reflecting a consensus that measured pressure (or an appropriate distension-based surrogate) should be used for wave intensity, not P ex ( Segers et al, 2017 ; Su et al, 2017 ; Pomella et al, 2018 ; Bhuva et al, 2019 ; Chiesa et al, 2019 ; Kowalski et al, 2019b ; Hughes et al, 2020 ).…”