19 Bradhurst Avenue
New York Medical College
Hawthorne, NY 10532
CDC-NIH Committee on Chronic Fatigue in Adolescents
NIH/NIAID Special Emphasis Panel
DOD Gulf War Syndrome
Ad Hoc Reviewer CVS-A
Associate Chairman IRB
Our investigational clinical interests involve the regulation of heart rate and blood pressure in children and adolescents. Circulatory physiology remains ill-determined in children with a variety of problems with neurovascular dysfunction. We have established a Center for Hypotension-Related Disease aimed at young people from childhood through young adult with neurally mediated syncope, chronic orthostatic intolerance, chronic fatigue syndrome, orthostatic intolerance of other etiologies such as occur in the postural tachycardia syndrome (POTS). Research focus is on circulatory and vascular problems and their autonomic consequences including altered peripheral arterial and venous properties and changes in blood volume and its redistribution. Molecular mechanisms including cytokine and nitric oxide assessment are explored. Treatment protocols are tested. Methods include plethysmographic measurements of peripheral and central blood flow, capacitance and peripheral permeability measurements, skin blood flow measurements using laser-Doppler flowmetry, baroreflex assessment, standard circulatory autonomic function tests, assessment of the efficacy of the skeletal muscle pump, and tests of heart rate and blood pressure variability. Orthostatic stress is used as a provocative stimulus.
Other research interests include computational circulatory physiology investigating vascular and cardiac properties in animal model systems as well as during diagnostic procedures such as cardiac catheterization and flow-volume monitoring and redistribution in critically ill infants and children. Correlative work studying the relation of cardiovascular properties to nitric oxide physiology is in progress. Recent work has also included connections of peripheral flow and muscle pump activity with osteoporosis, and contractual work with the Department of Defense related to muscular dystrophy.
Post Graduate Studies: Medicine - Physiology/Biophysics
Post Doctoral Studies: Pediatric Cardiology - Cornell/NY Hospital
Residency: New York University Medical Center
Fellowship: Cornell University - New York Hospital
Graduate Degree: M.D., Ph.D.
Graduate Degree Institution: University of Chicago
Undergraduate Degree: A.B. Physics
Undergraduate Institution: Cornell University
Stewart JM, Erb M, Sorbera C. Heart rate variability and the outcome of head-up tilt in syncopal children. Peds Res 1996;5:702-709.
Julian Stewart, Amy Weldon, Nina Arlievsky, Karl Li, Jose Munoz Neurally Mediated Hypotension and Autonomic Dysfunction Measured by Heart Rate variability During Head-up tilt Testing in Children with the Chronic Fatigue Syndrome. Clin Autonom Res 1998;8:221-230.
Julian M. Stewart, Michael H Gewitz, Amy Weldon, Nina Arlievsky, Karl Li, Jose Munoz. The Nature of Neurally Mediated Hypotension in Adolescents with the Chronic Fatigue Syndrome.Pediatrics 1999;103:116-121.
Stewart JM, Weldon A, Munoz JL. Pattern of orthostatic intolerance: the orthostatic tachycardia . Jl of Pediatrics 1999; 135: 218-225.
Stewart JM. Vascular Perturbations in the Chronic Orthostatic Intolerance of the Postural Orthostatic Tachycardia Syndrome. Jl Applied Physiology, 2000;89:1505-1512.
Stewart JM. Autonomic Nervous System Dysfunction in Adolescents with Orthostatic Tachycardia Syndrome and the Chronic Fatigue Syndrome is Characterized by Attenuated Vagal Baroreflex and Potentiated Sympathetic Vasomotion Peds Res 2000;48:218-226.
Stewart, JM, Weldon AA. Reflex vascular defects in the orthostatic tachycardia syndrome of adolescents J. Appl. Physiol. 2001 90: 2025-2031.
Stewart JM, Lavin J, Weldon AA. Orthostasis Fails to Produce Active Limb Venoconstriction in Adolescents. J Appl Physiol 91: 1723–1729, 2001.
Stewart JM. Transient orthostatic hypotension is common in adolescents. J Pediatr 2002;140:418-424.
Stewart JM Pooling in chronic Orthostatic Intolerance: Arterial Vasoconstrictive but not Venous Compliance Defects. Circulation 2002;105:2274-2281.
Stewart JM Medical Progress Orthostatic Intolerance In Pediatrics. J Pediatr 2002; 140:404-411.
Stewart JM, Kyle, K, Weldon A. Acute Effects of Phenylephrine and Esmolol Infusions on Autonomic Function in Chronic Orthostatic Intolerance. Circulation 106(23):2946-2954, 2002.
Stewart JM. Microvascular Filtration is Increased in Postural Tachycardia Syndrome Circulation 107:1-7; 2003.
Stewart JM, Medow M, Montgomery LD. Local Vascular Responses Affecting Blood Flow in Postural Tachycardia American Journal of Physiology, Heart and Circulatory Physiology Am J Physiol Heart Circ Physiol 285: H2749–H2756, 2003.
Stewart, JM, Medow MS, Montgomery LD, McLeod K. Decreased Skeletal Muscle Pump Activity in Postural Tachycardia with Low Peripheral Blood Flow. Am J Physiol Heart Circ Physiol 286:H1216–H1222,2004.
Stewart, JM A Physiological Classification of the Postural Tachycardia Syndrome Based on Peripheral Blood Flow. In Articles in Press. Am J Physiol Heart Circ Physiol, 2004.