Individuals with Post-COVID Conditions Exhibit Delayed Vasodilatory Response following Brachial Artery Occlusion in the Absence of Endothelial Dysfunction and Arterial Stiffness
Authors: Somers Emma , Fietsam Alexandra , Thenuwara Samalya , Stroud Amy , Rudroff Thorsten , Pierce Gary 
Published: May 2024

Background: Post-COVID Conditions (PCC) is a disorder in which individuals who contract the SARS-CoV-2 virus experience prolonged symptoms such as fatigue beyond 4 weeks after initial infection. Preliminary data suggest that individuals who are acutely infected display increased arterial stiffness and endothelial dysfunction, as well as autonomic dysfunction. However, it is not well understood if individuals with PCC continue to experience these dysfunctions beyond acute infection. Therefore, this study aimed to investigate whether vascular and autonomic function are impaired in individuals with PCC compared to individuals without PCC. Methods: Individuals previously infected with the SARS-CoV-2 virus at least 4 weeks prior to participation in the study had vascular and autonomic function assessed at baseline. Individuals experiencing PCC symptoms were classified as symptomatic (SYM, n=12) and individuals without PCC symptoms were classified as asymptomatic (ASYM, n=9). Participants were matched for age (30-55 years) and date since SARS-CoV-2 infection (ranging from 1-12 months). Arterial stiffness (carotid-femoral pulse wave velocity, cfPWV via tonometry), common carotid artery b-stiffness (via ultrasonography and tonometry), and endothelial function (brachial artery flow-mediated dilation, baFMD via ultrasonography) were assessed. Time-to-peak vasodilation (TTP) was assessed from baFMD as the time after cuff release until peak brachial artery dilation. Autonomic function was assessed with spontaneous cardiovagal baroreflex sensitivity (BRS) via sequence technique. Results: At baseline, there were no differences between groups in cfPWV (SYM: 6.2 ± 0.7 m/s, ASYM: 6.3 ± 1.1 m/s; p=0.90), baFMD (SYM: 7.3 ± 6.1%, ASYM: 7.7 ± 5.6%; p=0.87), brachial artery baseline diameter (SYM: 3.4 ± 0.6 mm, ASYM: 3.2 ± 0.4 mm; p=0.37) and common carotid b-stiffness index (SYM: 9.2 ± 2.1U, ASYM: 8.2 ± 2.5U; p=0.360). Despite no differences in baFMD% between groups, the SYM group had a significantly higher baseline baFMD TTP compared with the ASYM group (SYM: 61.6 ± 23.1 s, ASYM: 36.8 ± 14.3 s; p=0.010). There were no significant differences in cardiovagal BRS (SYM: 10.9 ± 6.8 ms/mmHg, ASYM: 11.8 ± 2.6 ms/mmHg; p=0.80). Conclusions: While arterial stiffness, endothelial function and baroreflex function did not differ between groups, individuals with PCC did present with delayed peak brachial artery vasodilation in response to shear stress. These data suggest any possible effects on vascular and autonomic function from acute SARS-CoV2 infection appear to be resolved beyond 4 weeks in those who experience prolonged symptoms. However, the delayed vasodilatory response may indicate some level endothelial dysfunction that persists in individuals with PCC. Funded by: Russell B. Day and Florence D. Day Chair in Liberal Arts and Sciences fund. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.