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Regional Patterns of Pulsatility Index and Wall Shear Stress Across Cerebral Circulation of Adolescents with High Insulin Resistance
Author(s) -
Carter Katrina J.,
Kellawan J. Mikhail,
Peltonen Garrett L.,
Ward Aaron T.,
Carrel Aaron L.,
Wieben Oliver,
Bendlin Barbara B.,
Schrage William G.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.836.10
Subject(s) - cardiology , medicine , cerebral blood flow , cerebral arteries , middle cerebral artery , internal carotid artery , posterior cerebral artery , cerebral circulation , anterior cerebral artery , ischemia
Background Insulin resistance (IR) is associated with altered arterial stiffness, blood flow, and shear stress patterns in the peripheral circulation of middle‐aged and older diabetic and non‐diabetic hypertensive populations. Both altered blood flow and shear stress patterns may contribute to the elevated risk of cerebrovascular disease in IR populations. The aim of this study was to determine if adolescents (12–18yrs) with high IR (indexed as High Homeostatic Model Assessment of IR, HOMA‐IR) display early signs of cerebrovascular dysfunction. We hypothesized that young adolescents with a high HOMA‐IR would exhibit increased stiffness and decreased shear patterns in cerebral conduit arteries. Methods 2 healthy controls (17±3) and 3 IR subjects (14±1) underwent a single 4D Flow MRI scan (scan time ~ 5min, no contrast given) to quantify cerebral blood flow (CBF), pulsatility index (PI) and wall shear stress (WSS) in extracranial and intracranial conduit arteries. 11 arteries were analyzed: middle cerebral (MCA) x2, anterior cerebral (ACA) x2, posterior cerebral (PCA) x2, vertebral (VA) x2, internal carotid (ICA) x2, and basilar. PI was calculated for each artery as [(CBF max − CBF min )/CBF mean ]. WSS was measured by segmenting the vascular tree from PC angiograms and calculating the velocity gradient at the vessel wall using 4D flow MRI data over ~3 voxel. Due to voxel limitations, the PCA value is exploratory. Total CBF was calculated as the sum of both ICA and both VA. Significance was determined using a two‐tail Welch's t‐test. Results Individuals with IR displayed higher HOMA‐IR (IR 5.3±0.2, Ctrl, 3.3±0.3, p=0.02), BMI (kg•m 2 ; IR 28±2, Ctrl 19±4, p=0.03) and fasting insulin (μU/mL; IR 25±4, Ctrl 13±0, p=0.04), but fasting glucose was not different (mg/dL; IR 79±4, Ctrl 93±5, p=0.07). PI was not different between groups among the 11 conduit arteries. However, there was a trend for higher PI in the IR group in the left PCA and right VA. Resting WSS did not differ between Ctrl and IR among the 11 conduit arteries. Similarly, total resting CBF was not different between Ctrl and IR (mL/min; IR 811±115, Ctrl 735±79, p=0.64). Conclusion PI or WSS were similar in 11 conduit arteries of cerebral circulation in adolescent controls compared to IR. These data indicate IR does not cause measurable arterial stiffening or altered total cerebral blood flow patterns. Therefore, the pathogenic arterial characteristics observed in middle‐aged adults with IR may be linked to the duration and/or severity of IR in association with other known vascular pathological processes linked to aging. Support or Funding Information This research was made possible by the National Science Foundation Grant #HRD‐1500138 (UW‐Madison WiscAMP‐BD program) and UW Graduate School Pilot Funding.