Blood Flow Regulation During Exercise in Peripheral Arterial Disease
Open Access
- Author:
- Miller, Amanda Joy
- Graduate Program:
- Neuroscience
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 03, 2017
- Committee Members:
- Lawrence Isaac Sinoway, Dissertation Advisor/Co-Advisor
Amy Christine Arnold, Committee Chair/Co-Chair
Kirsteen Nairn Browning, Committee Member
Charles H Lang, Committee Member
Urs Andreas Leuenberger, Outside Member - Keywords:
- peripheral arterial disease
blood pressure
exercise physiology
coronary blood flow
Near-infrared spectroscopy - Abstract:
- Peripheral arterial disease (PAD) affects 8-10 million Americans and greatly increases risk of cardiovascular mortality. PAD is a form of atherosclerosis that affects medium to large arteries in the legs and causes pain with walking. Previous studies reveal that blood pressure (BP) responses to exercise are augmented in PAD patients. However, how blood flow in the heart and legs are regulated during exercise in PAD is unknown. The studies comprising this dissertation investigated BP and blood flow responses to exercise in PAD and how leg vascular interventions affect those responses. In the first study, 12 PAD patients and 15 healthy subjects performed dynamic plantar flexion exercise and isometric handgrip exercise while BP and coronary blood velocity (CBV) were measured. BP and skeletal muscle oxygen saturation (SmO2) in the legs were measured during treadmill walking in 8 PAD patients and 8 healthy subjects (study 2). For the third study, BP and CBV responses to plantar flexion exercise were measured before and 1 month following a leg vascular intervention in 17 PAD patients. Coronary blood velocity responses to plantar flexion exercise (PAD: Δ 2.4 ± 1.2, healthy: Δ 6.0 ± 1.6 cm/s, P = 0.039) and to isometric handgrip exercise (PAD: Δ 8.3 ± 4.2, healthy: Δ 16.9 ± 3.6, P = 0.033) were attenuated in PAD patients. The fall in SMO2 in response to treadmill walking was greater in PAD (healthy: 15 ± 12 vs. PAD: 49 ± 5 %, P < 0.001). Leg revascularization decreased the mean BP response (pre-intervention: 15 ± 4 vs. post-intervention: 7 ± 3 mmHg, P = 0.013) and increased the CBV response (pre-intervention: -1 ± 2 vs. post-intervention: 4 ± 1 vs. cm/s, P = 0.038) to plantar flexion exercise in PAD. Collectively, data from these studies suggest that exercise hyperemia is impaired in PAD patients compared to healthy subjects. Furthermore, the origin of the impaired coronary hyperemia and exaggerated exercise BP in PAD may be related to leg ischemia.