title: In vivo quantification of blood flow and wall shear stress in the human abdominal aorta during lower limb exercise.
abstract: Magnetic resonance (MR) imaging techniques and a custom MR-compatible exercise bicycle were used to measure, in vivo, the effects of exercise on hemodynamic conditions in the abdominal aorta of eleven young, healthy subjects. Heart rate increased from 73 +/- 6.2 beats/min at rest to 110 +/- 8.8 beats/min during exercise (p<0.0001). The total blood flow through the abdominal aorta increased from 2.9 +/- 0.6 L/min at rest to 7.2 +/- 1.4 L/min during exercise (p <0.0005) while blood flow to the digestive and renal circulations decreased from 2.1 +/- 0.5 L/min at rest to 1.6 +/- 0.7 L/min during exercise (p<0.01). Infrarenal blood flow increased from 0.9 +/- 0.4 L/min at rest to 5.6 +/- 1.1 L/min during exercise (p<0.0005). Wall shear stress increased in the supraceliac aorta from 3.5 +/- 0.8 dyn/cm2 at rest to 6.2 +/- 0.5 dyn/cm2 during exercise (p<0.0005) and increased in the infrarenal aorta from 1.3 +/- 0.8 dyn/cm2 at rest to 5.2 +/- 1.3 dyn/cm2 during exercise (p<0.0005).
authors.affiliation: Department of Surgery, Stanford University, CA, USA. taylorca@stanford.edu
authors.forename: Charles A
authors.initials: CA
authors.lastname: Taylor
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Cheng
authors.forename: Leandro A
authors.initials: LA
authors.lastname: Espinosa
authors.forename: Beverly T
authors.initials: BT
authors.lastname: Tang
authors.forename: David
authors.initials: D
authors.lastname: Parker
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Herfkens
mesh_terms: D000328:Adult; D001012:Aorta, Abdominal / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000295:instrumentation / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008955:Models, Cardiovascular; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033081:Shear Strength; D013314:Stress, Mechanical