Clinical Vascular Research Lab
Location: Room 164G Forker
The Clinical Vascular Research Lab investigates the interaction of aging and exercise on cardiovascular and cerebrovascular function in health and disease across the human lifespan. Our mission is to use exercise as medicine to improve vascular aging, and prevent and treat chronic disease. To accomplish this mission, we use non-invasive measures of vascular function in humans to understand how behaviors and lifestyle (e.g. exercise) alter vascular health and prevent chronic disease or slow/reverse disease progression. Our research spans smaller, controlled experimental studies, randomized controlled trials, and cross-sectional/longitudinal study designs.
Current Research Topics
Understanding vascular mechanisms behind the protective effects of exercise on the brain: It is widely established that exercise benefits the brain and protects against later-life Alzheimer’s disease and dementia, but the mechanisms behind this protection remain elusive. Our goal is to identify the role of large artery stiffness and pulsatile (i.e. discontinuous) brain blood flow in the protective effects of exercise in the brain in middle-aged adults.
Examining sex differences in vascular mechanisms of brain health: Alzheimer’s disease is forecast to impact nearly 5 million more women than men by 2040. The mechanism behind these sex differences in brain health and Alzheimer’s disease risk is unknown but may be related to vascular health in middle age, a critical window during which vascular health is highly related to later-life brain health. Our goal is to examine sex differences in vascular mechanisms governing brain blood flow (artery stiffness, endothelial function) in men and women during middle age to identify vascular targets that can be utilized for preventive efforts (pharmaceutical, behavioral/lifestyle interventions) to reduce sex differences in Alzheimer’s disease that disproportionately burden women with advancing age.
Selected recent work from our group include:
- Lefferts WK, Lefferts EC, Hibner BA, Smith KJ, Fernhall B. Impact of acute changes in blood pressure and arterial stiffness on cerebral pulsatile hemodynamics in young and middle-aged adults. Experimental Physiology; in press. PMID: 33938052.
- Lefferts WK, Smith KJ. Let’s talk about sex, let’s talk about pulsatility, let’s talk about all the good things and the bad things of MCAv. Journal of Applied Physiology; in press. PMID: 33856255.
- Lefferts WK, DeBlois JP, Augustine JA, Keller AP, Heffernan KS. Age, sex, and the vascular contributors to cerebral pulsatility and pulsatile damping. Journal of Applied Physiology 2020; 129: 1092-1101. PMID: 32940561.
- Lima NS, Krishna H, Gerber BS, Heffernan KS, Gump BB, Lefferts WK. Greater physical activity is associated with lower pulsatile load but not carotid stiffness in children. Journal of Human Hypertension 2020. PMID: 33712711.
- Lefferts WK, Augustine JA, Spartano NL, Hughes WE, Babcock MC, Heenan B, Heffernan KS. Effects of whey protein supplementation on aortic stiffness, cerebral reactivity and cognitive function in community-dwelling older adults: findings from the ANCHORS-A-WHEY clinical trial. Nutrients 2020; 12(4):1054. PMID: 32290271.
- Lefferts WK, DeBlois JP, Soriano JE, Mann L, Rampuri Z, Herrington B, Thrall S, Bird J, Harman TS, Day TA, Heffernan KS, Brutsaert TD. Preservation of neurovascular coupling to cognitive activity in anterior cerebrovasculature during incremental ascent to high altitude. High Altitude Medicine & Biology 2020; 21(1):20-27. PMID: 31750741.
The CVRL houses non-invasive vascular equipment designed to allow assessment of heart function, and large artery structure/function (stiffness, blood flow, remodeling/geometry) throughout the body from the aorta to the cerebral vessels. We additionally measure cognitive function as a downstream measure of brain health in order to assess relations between vascular mechanisms of brain health and cognitive function. Our noninvasive equipment (see Figure) allow us to assess:
Brain blood flow: measurement of blood flow patterns in the major intracranial cerebral arteries using Transcranial Doppler and Color Doppler ultrasound
Artery stiffness and central hemodynamics: measurement of (1) artery stiffness via gold-standard pulse wave velocity at multiple artery segments (carotid-femoral, carotid-brachial, carotid-radial) and (2) blood pressure and wave reflection at each pulse site (carotid, femoral, brachial, radial) via tonometry. By integrating pressure waves assessed via tonometry with blood velocity waveforms obtained through vascular Doppler ultrasound, we are able to calculate advanced properties of the artery and gain insght into some of the physical forces driving blood flow and wave transmission within the arteries.
Large artery hemodynamics and heart function: measurement of (1) large/conduit artery (brachial, carotid, femoral) blood flow volume and patterns via Doppler ultrasound, wave-intensity analysis, and echo-tracking, and (2) heart function and structure via cardiac ultrasound combined with left-ventricular m-mode, Doppler, tissue-Doppler and speckle-tracking.
Cognitive function: measurement of executive function and memory domains via computerized cognitive battery designed by our collaborators in Psychology. With the help of our external collaborations we are able to conduct mathematical modeling of the behavioral data to understand mechanistic changes in the underlying decision-making process.
Specific equipment used in these techniques include:
Multigon Transcranial Doppler with 2 probes and headset
Hitachi-Aloka Arietta 70 ultrasound with vascular and cardiac probes
Cardiovascular Engineering, NIHem USB 2.0 with 2 high-fidelity tonometers
Omron Automated oscillometric blood pressure cuff
MediPines AGM100, end-tidal CO2 and pulmonary function measurement system
Please see Dr. Lefferts’ lab webpage for more information
We are currently recruiting graduate students (master and PhD). If you are interested, please email Dr. Lefferts.
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534 Wallace Rd
Ames, IA 50011-4008