Orthostatic Hypotension Due to Suppression of Vasomotor Outflow After Amphetamine Intoxication  Adrianus A.J. Smit, M.D., Wouter Wieling, M.D., Ph.D., Albertus J. Voogel, M.D., Rudolph W. Koster, M.D., Ph.D., Pieter A. van Zwieten, M.D., Ph.D.  Mayo Clinic Proceedings  Volume 71, Issue 11, Pages 1067-1070 (November 1996) DOI: 10.4065/71.11.1067 Copyright © 1996 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 1 Diagrammatic representation of arterial baroreflex pathways that control vasomotor tone and heart rate. I, Carotid sinus and aortic arch stretch receptors. 2, Unmyelinated fibers running in glossopharyngeal and vagus nerve synapsing at nucleus tractus solitarii (NTS). 3, Parasympathetic preganglionic fibers running in vagus nerve emerging from nucleus ambiguus. 4, Intermediate neurons. 5, Inhibitory neuron from caudal ventrolateral medulla (CVLM) to rostral ventrolateral medulla (RVLM). 6, Afferent pathway for release of vasopressin. 7, Sympathetic cardiac and vasomotor fibers passing intermediolateral column (ILC) of spinal cord and sympathetic chain ganglia. In healthy subjects, a blood pressure increment signaled by the stretch receptors elicits a decrease in heart rate and an inhibitory reflex on sympathetic vasomotor tone. A decrease in blood pressure will cause the opposite. In cases of amphetamine intoxication, the following cardiovascular reflex tests should be done. (1) “Overall” baroreflex pathways are studied by assessment of compensatory blood pressure or heart rate responses (or both) on standing, Valsalva maneuver, and phenylephrine infusion. (2) Cardiovagal pathways are studied by assessment of heart rate changes on deep breathing. (3) Efferent sympathetic vasomotor pathways are tested by assessment of blood response during cold stimulus testing, which elicits somatosympathetic vasomotor response in normal subjects (cold pressor test). (4) Afferent baroreflex pathways are selectively tested by assessment of vasopressin release during orthostatic hypotension. Mayo Clinic Proceedings 1996 71, 1067-1070DOI: (10.4065/71.11.1067) Copyright © 1996 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 2 Circulatory derangements in 17-year-old female adolescent after ingestion of amphetamine. Blood pressure and heart rate responses on standing (left) and Valsalva straining of 30 mm Hg in supine position (right), as measured by Finapres device.8 Upper tracings 36 hours and lower tracings 1 month after ingestion of tablets. Note immediate, substantial heart rate increase up to 175 beats/min (bpm) on standing. Mayo Clinic Proceedings 1996 71, 1067-1070DOI: (10.4065/71.11.1067) Copyright © 1996 Mayo Foundation for Medical Education and Research Terms and Conditions