Christopher P Cheng1, Charles A Taylor2, Ronald L Dalman3. 1. Department of Surgery, Stanford University, Stanford, CA. Electronic address: cpc@stanford.edu. 2. Department of Bioengineering, Stanford University, Stanford, CA. 3. Department of Surgery, Stanford University, Stanford, CA.
Abstract
BACKGROUND: Lower-extremity exercise has been shown to eliminate adverse hemodynamics conditions, such as low and oscillating blood flow and wall shear stress, in the abdominal aortas of healthy young and older adults. METHODS: We use cine phase-contrast magnetic resonance imaging and a custom MRI-compatible exercise cycle to quantify hemodynamic changes because of pedaling exercise in patients diagnosed with intermittent claudication. RESULTS: With only an average heart increase of 35 ± 18% and exercise workload of 36 ± 16 watts, the patients experienced approximately 3- and 6-fold increases in blood flow, and 4- and 16-fold increases in wall shear stress at the supraceliac and infrarenal aortic locations, respectively. Also, all oscillations in flow and shear stress at rest were eliminated with exercise. CONCLUSIONS: Claudication patients experience 3- to 4-fold lower oscillations in flow and shear stress at rest as compared with healthy age-matched controls, likely because of reduced distal arterial compliance as a result of distal atherosclerosis. The magnitude of flow and shear oscillatory indices may be good indicators of distal arterial compliance and health, and may provide predictive power for the efficacy of focal interventions.
BACKGROUND: Lower-extremity exercise has been shown to eliminate adverse hemodynamics conditions, such as low and oscillating blood flow and wall shear stress, in the abdominal aortas of healthy young and older adults. METHODS: We use cine phase-contrast magnetic resonance imaging and a custom MRI-compatible exercise cycle to quantify hemodynamic changes because of pedaling exercise in patients diagnosed with intermittent claudication. RESULTS: With only an average heart increase of 35 ± 18% and exercise workload of 36 ± 16 watts, the patients experienced approximately 3- and 6-fold increases in blood flow, and 4- and 16-fold increases in wall shear stress at the supraceliac and infrarenal aortic locations, respectively. Also, all oscillations in flow and shear stress at rest were eliminated with exercise. CONCLUSIONS:Claudicationpatients experience 3- to 4-fold lower oscillations in flow and shear stress at rest as compared with healthy age-matched controls, likely because of reduced distal arterial compliance as a result of distal atherosclerosis. The magnitude of flow and shear oscillatory indices may be good indicators of distal arterial compliance and health, and may provide predictive power for the efficacy of focal interventions.
Authors: Michael J Pentecost; Michael H Criqui; Gerald Dorros; Jerry Goldstone; K Wayne Johnston; Eric C Martin; Ernest J Ring; James B Spies Journal: J Vasc Interv Radiol Date: 2003-09 Impact factor: 3.464