Perfusion Model to Quantify Blood Flow in Peripheral Artery Disease Patients

2018 ◽  
Author(s):  
Weihao Xu ◽  
Alessandro Marone ◽  
Christopher Fong ◽  
Jennifer W. Hoi ◽  
Hyun Keol Kim ◽  
...  
Keyword(s):  
Blood Flow ◽  
Peripheral Artery Disease ◽  
Peripheral Artery ◽  
Perfusion Model ◽  
Quantify Blood Flow ◽  
Artery Disease

scholarly journals Eight weeks of nitrate supplementation improves blood flow and reduces the exaggerated pressor response during forearm exercise in peripheral artery disease

2018 ◽  
Vol 315 (1) ◽  
pp. H101-H108 ◽  
Author(s):  
Nicholas T. Kruse ◽  
Kenichi Ueda ◽  
William E. Hughes ◽  
Darren P. Casey
Keyword(s):  
Blood Flow ◽  
Peripheral Artery Disease ◽  
Pressor Response ◽  
Treated Group ◽  
Moderate Intensity ◽  
Peripheral Artery ◽  
Pressor Responses ◽  
Nitrate Supplementation ◽  
Artery Disease ◽  
Forearm Exercise

Peripheral artery disease (PAD) is characterized by a reduced blood flow (BF) and an elevated blood pressure (pressor) response during lower extremity exercise. Although PAD is evident in the upper extremities, no studies have determined BF and pressor responses during upper extremity exercise in PAD. Emerging evidence suggests that inorganic nitrate supplementation may serve as an alternative dietary strategy to boost nitric oxide bioavailability, improving exercising BF and pressor responses during exercise. The present study investigated 1) BF and pressor responses to forearm exercise in patients with PAD ( n = 21) relative to healthy age-matched control subjects ( n = 16) and 2) whether 8 wk of NaNO3 supplementation influenced BF and pressor responses to forearm exercise in patients with PAD. Patients with moderate to severe PAD were randomly assigned to a NaNO3 (1 g/day, n = 13)-treated group or a placebo (microcrystalline cellulose, n = 8)-treated group. Brachial artery forearm BF (FBF; via Doppler) and blood pressure (via finger plethysmography) were measured during mild-intensity (~3.5-kg) and moderate-intensity (~7-kg) handgrip exercise. The absolute change (from baseline) in FBF was reduced (except in the 3.5-kg condition) and BP responses were increased in patients with PAD compared with healthy control subjects in 3.5- and 7-kg conditions (all P < 0.05). Plasma nitrate and nitrite were elevated, exercising (7-kg) ΔFBF was improved (from 141 ± 17 to 172 ± 20 ml/min), and mean arterial pressure response was reduced (from 13 ± 1 to 9 ± 1 mmHg, P < 0.05) in patients with PAD that received NaNO3 supplementation for 8 wk relative to those that received placebo. These results suggest that the BF limitation and exaggerated pressor response to moderate-intensity forearm exercise in patients with PAD are improved with 8 wk of NaNO3 supplementation. NEW & NOTEWORTHY Peripheral artery disease (PAD) results in an exaggerated pressor response and reduced blood flow during lower limb exercise; however, the effect of PAD in the upper limbs has remained unknown. These results suggest that 8 wk of inorganic nitrate supplementation improves the blood flow limitation and exaggerated pressor response to moderate-intensity forearm exercise in PAD.

scholarly journals Systemic and regional hemodynamic response to activation of the exercise pressor reflex in patients with peripheral artery disease

2020 ◽  
Vol 318 (4) ◽  
pp. H916-H924 ◽  
Author(s):  
Danielle Jin-Kwang Kim ◽  
Marcos Kuroki ◽  
Jian Cui ◽  
Zhaohui Gao ◽  
J. Carter Luck ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Peripheral Artery Disease ◽  
Plantar Flexion ◽  
Peripheral Artery ◽  
Exercise Pressor Reflex ◽  
Femoral Blood Flow ◽  
Femoral Blood ◽  
Pressor Reflex ◽  
Artery Disease

Patients with peripheral artery disease (PAD) have an accentuated exercise pressor reflex (EPR) during exercise of the affected limb. The underlying hemodynamic changes responsible for this, and its effect on blood flow to the exercising extremity, are unclear. We tested the hypothesis that the exaggerated EPR in PAD is mediated by an increase in total peripheral resistance (TPR), which augments redistribution of blood flow to the exercising limb. Twelve patients with PAD and 12 age- and sex-matched subjects without PAD performed dynamic plantar flexion (PF) using the most symptomatic leg at progressive workloads of 2–12 kg (increased by 1 kg/min until onset of fatigue). We measured heart rate, beat-by-beat blood pressure, femoral blood flow velocity (FBV), and muscle oxygen saturation ([Formula: see text]) continuously during the exercise. Femoral blood flow (FBF) was calculated from FBV and baseline femoral artery diameter. Stroke volume (SV), cardiac output (CO), and TPR were derived from the blood pressure tracings. Mean arterial blood pressure and TPR were significantly augmented in PAD compared with control during PF. FBF increased during exercise to an equal extent in both groups. However, [Formula: see text] of the exercising limb remained significantly lower in PAD compared with control. We conclude that the exaggerated pressor response in PAD is mediated by an abnormal TPR response, which augments redistribution of blood flow to the exercising extremity, leading to an equal rise in FBF compared with controls. However, this increase in FBF is not sufficient to normalize the SmO2 response during exercise in patients with PAD. NEW & NOTEWORTHY In this study, peripheral artery disease (PAD) patients and healthy control subjects performed graded, dynamic plantar flexion exercise. Data from this study suggest that previously reported exaggerated exercise pressor reflex in patients with PAD is driven by greater vasoconstriction in nonexercising vascular territories which also results in a redistribution of blood flow to the exercising extremity. However, this rise in femoral blood flow does not fully correct the oxygen deficit due to changes in other mechanisms that require further investigation.

Abstract 15456: Enhanced Vasoconstrictor Sensitivity to Exercise Pressor Reflex Engagement in Peripheral Artery Disease

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Zhaohui Gao ◽  
Matthew D Muller ◽  
Cheryl Blaha ◽  
Aimee Cauffman ◽  
Kristen Brandt ◽  
...  
Keyword(s):  
Blood Flow ◽  
Peripheral Artery Disease ◽  
Plantar Flexion ◽  
Maximum Voluntary Contraction ◽  
Ankle Brachial Index ◽  
Peak Exercise ◽  
Peripheral Artery ◽  
Exercise Pressor Reflex ◽  
Pressor Reflex ◽  
Artery Disease

Exercise is associated with a rise in heart rate, blood pressure (BP) and blood flow to active skeletal muscle that is mediated by the exercise pressor reflex and modified by regional release of vasodilator factors. In peripheral artery disease (PAD) the exercise pressor reflex is enhanced and the ability to raise blood flow to the affected limb is impaired. To assess the functional impact of the enhanced exercise pressor reflex on regional blood flow in limbs affected by PAD, we determined beat-by-beat BP and mean blood velocity (MBV, Doppler) in the popliteal artery, and calculated vascular conductance index (VC, MBV/mean BP) in the exercising (ipsilateral) or contralateral resting leg during graded rhythmic plantar flexion exercise in 7 patients with symptomatic PAD (age 67±2 yrs, body-mass-index 27.9±1.1) and in 5 healthy age-matched controls (2 exercise trials with each leg). At peak exercise (2.0 kg, 1 contraction/sec), the pressor effect was greatest in PAD when exercise was performed with the “ischemic” leg (ankle-brachial index 0.58±0.05; mean ΔBP +9.1±2.0 mmHg), lower with the less affected leg (ankle brachial index 0.76±0.07; mean ΔBP +6.9±1.6 mmHg) and lowest in the controls (ankle brachial index 1.11±0.04; mean ΔBP +3.9±1.8 mmHg). In controls, VC increased in the exercising leg ( P <0.05) but did not change in the inactive contralateral leg ( P =NS). Similarly, in PAD, VC increased in the exercising “ischemic” leg ( P <0.05) but did not change in the inactive contralateral leg ( P =NS). In sharp contrast, while VC increased in the less affected exercising leg ( P <0.05), in the contralateral resting “ischemic” leg VC decreased by 24±10% ( P <0.05). Similarly, when static handgrip at 30% maximum voluntary contraction to fatigue served as the exercise stimulus, vasoconstriction was noted in the “ischemic” leg (n=5; P <0.05). Thus, unlike in the exercising leg, in the resting “ischemic” leg activation of the exercise pressor reflex resulted in substantial vasoconstriction. This suggests that despite activation of peripheral vasodilator mechanisms downstream to the arterial obstruction, the vasculature of the “ischemic” leg is exquisitely sensitive to reflex vasoconstriction.

scholarly journals Exaggerated cardiovascular responses to treadmill running in rats with peripheral arterial insufficiency

2018 ◽  
Vol 314 (1) ◽  
pp. H114-H121 ◽  
Author(s):  
J. Matthew Kuczmarski ◽  
Kellee Unrath ◽  
Gail D. Thomas
Keyword(s):  
Blood Flow ◽  
Peripheral Artery Disease ◽  
Femoral Artery ◽  
Muscle Blood Flow ◽  
Cardiovascular Responses ◽  
Treadmill Running ◽  
Female Rats ◽  
Peripheral Artery ◽  
Flow Capacity ◽  
Artery Disease

Patients with atherosclerotic peripheral artery disease have an augmented pressor response to treadmill walking, but the underlying mechanisms remain poorly understood and difficult to isolate because of the confounding presence of numerous cardiovascular risk factors. In the present study, we tested the hypothesis that a chronic deficit in muscle blood flow capacity would be sufficient to trigger an exaggerated pressor response to dynamic exercise. Sprague-Dawley rats (5 male and 5 female) were instrumented with radiotelemetry devices to measure the cardiovascular responses to treadmill running before and after bilateral femoral artery ligation, which has been previously shown to reduce the blood flow capacity of distal hindlimb muscles by >60%. Treadmill running evoked reproducible increases in mean arterial pressure (MAP) and heart rate (HR), which were significantly augmented 3 days after femoral artery ligation in both male rats [ΔMAP: +10 ± 1 (SE) vs. +18 ± 3 mmHg and ΔHR: +94 ± 12 vs. +148 ± 15 beats/min, P < 0.05] and female rats (ΔMAP: +16 ± 3 vs. +30 ± 5 mmHg and ΔHR: +128 ± 20 vs. +178 ± 19 beats/min, P < 0.05). Similar exaggerated MAP and HR responses were observed at repeated intervals between 3 and 65 days postligation. These findings indicate that a chronic deficit in muscle blood flow capacity is an important, persistent cause of the abnormal pressor and cardioaccelerator responses to dynamic exercise in both male and female rats with peripheral arterial insufficiency. NEW & NOTEWORTHY Using radiotelemetry to assess cardiovascular effects of exercise, we showed that femoral artery obstruction in male and female rats is an important, persistent cause of exaggerated pressor and cardioaccelerator responses to treadmill running. This translational model reproduces the abnormal cardiovascular response to exercise seen in patients with peripheral artery disease. Listen to this article’s corresponding podcast at http://ajpheart.podbean.com/e/treadmill-bp-in-simulated-peripheral-artery-disease/ .

scholarly journals Effects of exercise training on calf muscle oxygen extraction and blood flow in patients with peripheral artery disease

2017 ◽  
Vol 123 (6) ◽  
pp. 1599-1609 ◽  
Author(s):  
Wesley B. Baker ◽  
Zhe Li ◽  
Steven S. Schenkel ◽  
Malavika Chandra ◽  
David R. Busch ◽  
...  
Keyword(s):  
Blood Flow ◽  
Exercise Training ◽  
Peripheral Artery Disease ◽  
Near Infrared ◽  
Muscle Blood Flow ◽  
Calf Muscle ◽  
Oxygen Extraction ◽  
Peripheral Artery ◽  
Supervised Exercise ◽  
Artery Disease

We employed near-infrared optical techniques, diffuse correlation spectroscopy (DCS), and frequency-domain near-infrared spectroscopy (FD-NIRS) to test the hypothesis that supervised exercise training increases skeletal muscle microvascular blood flow and oxygen extraction in patients with peripheral artery disease (PAD) who experience claudication. PAD patients ( n = 64) were randomly assigned to exercise and control groups. Patients in the exercise group received 3 mo of supervised exercise training. Calf muscle blood flow and oxygen extraction were optically monitored before, during, and after performance of a graded treadmill protocol at baseline and at 3 mo in both groups. Additionally, measurements of the ankle-brachial index (ABI) and peak walking time (PWT) to maximal claudication were made during each patient visit. Supervised exercise training was found to increase the maximal calf muscle blood flow and oxygen extraction levels during treadmill exercise by 29% (13%, 50%) and 8% (1%, 12%), respectively [ P < 0.001; median (25th percentile, 75th percentile)]. These improvements across the exercise group population were significantly higher than corresponding changes in the control group ( P < 0.004). Exercise training also increased PWT by 49% (18%, 101%) ( P = 0.01). However, within statistical error, the ABI, resting calf muscle blood flow and oxygen extraction, and the recovery half-time for hemoglobin\myoglobin desaturation following cessation of maximal exercise were not altered by exercise training. The concurrent monitoring of both blood flow and oxygen extraction with the hybrid DCS/FD-NIRS instrument revealed enhanced muscle oxidative metabolism during physical activity from exercise training, which could be an underlying mechanism for the observed improvement in PWT. NEW & NOTEWORTHY We report on noninvasive optical measurements of skeletal muscle blood flow and oxygen extraction dynamics before/during/after treadmill exercise in peripheral artery disease patients who experience claudication. The measurements tracked the effects of a 3-mo supervised exercise training protocol and revealed that supervised exercise training improved patient ability to increase microvascular calf muscle blood flow and oxygen extraction during physical activity.

scholarly journals Wall morphology, blood flow and wall shear stress: MR findings in patients with peripheral artery disease

2013 ◽  
Vol 24 (4) ◽  
pp. 850-856 ◽  
Author(s):  
Mauricio S. Galizia ◽  
Alex Barker ◽  
Yihua Liao ◽  
Jeremy Collins ◽  
James Carr ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Peripheral Artery Disease ◽  
Peripheral Artery ◽  
Wall Shear ◽  
Artery Disease
Sign in / Sign up

Export Citation Format

Share Document