P85 Acute Systemic Inflammation Reduces both Carotid and Aortic Wave Reflection in Young Healthy Adults

Abstract

Acute inflammation increases the risk of cardiac and cerebrovascular events, potentially associated with altered hemodynamic load. Wave reflection at the aorta and carotid artery can contribute to central hemodynamic load and provide insight into downstream changes in vascular tone. Acute inflammation may reduce wave reflection via downstream vasodilation, however, this is not firmly established and has only been investigated at the aorta. Purpose: Explore the effect of acute inflammation on aortic and carotid hemodynamics and wave reflection. Methods: Twenty-three young adults (26 ± 4 yrs, 22.7 ± 3.2 kg/m2) underwent vascular measures at baseline and 24 h following typhoid vaccine-induced inflammation. Aortic (estimated from radial) and carotid pressure waveforms were obtained via tonometry. Augmentation index and wave separation analyses (WSA) were used to assess wave reflection. Aortic stiffness was estimated from single-point pulse wave velocity (PWV). Carotid beta-stiffness and arterial diameters were assessed via ultrasound. Results: Acute inflammation reduced aortic and carotid wave reflection at 24 h (See Table 1 AIx, Reflection index, p 0.05). Brachial and carotid artery diameter increased from 3.79 ± 0.76 to 3.86 ± 0.76 mm (p = 0.055) and 6.44 ± 0.72 to 6.55 ± 0.69 mm (p = 0.04), respectively. Table 1 Aortic Carotid n Baseline 24-h p-value Baseline 24-h p-value SBP, mmHg 23 104 ± 10 104 ± 8 0.88 107 ± 11 107 ± 10 0.98 DBP, mmHg 23 72 ± 8 71 ± 7 0.23 71 ± 8 70 ± 7 0.26 MAP, mmHg 23 86 ± 9 85 ± 7 0.31 86 ± 9 85 ± 7 0.29 Pulse pressure, mmHg 23 32 ± 6 33 ± 8 0.21 36 ± 7 37 ± 8 0.39 AIx, % 23 3 ± 10 −1 ± 10 0.04 −4 ± 15 −9 ± 16 0.04 AIx@75, % 23 −6 ± 12 −9 ± 12 0.048 −13 ± 15 −18 ± 15 0.09 Augmented pressure, mmHg 23 1 ± 3 0 ± 3 0.05 −2 ± 6 −4 ± 7 0.08 Pf, mmHg 22 30 ± 7 31 ± 7 0.40 34 ± 8 36 ± 12 0.07 Pb, mmHg 22 14 ± 3 13 ± 4 0.24 16 ± 3 15 ± 4 0.09 Reflection index, au 22 47 ± 8 44 ± 9 0.04 48 ± 11 43 ± 13 0.01 Time to reflection, ms 22 158 ± 16 161 ± 20 0.20 180 ± 25 185 ± 26 0.53 All data mean ± standard deviation. SBP, systolic blood pressure; DBP, diastolic blood pressure; MAP, mean arterial pressure; AIx, augmentation index; Pf, forward wave magnitude; Pb, reflected wave magnitude. Conclusion: Acute inflammation reduces aortic and carotid wave reflection in young adults, potentially due to downstream vasodilation. Although reduced wave reflection can decrease cardiac workload, reduced wave reflection in the carotid may render the brain vulnerable to pulsatile blood flow. These findings may implicate changes in wave reflections are a contributing mechanism behind acute inflammation-induced cerebrovascular risk.