title: Respiratory and cardiovascular indicators of autonomic nervous system dysregulation in familial dysautonomia.
abstract: Familial dysautonomia (FD) is a profound sensory and autonomic nervous system disorder associated with an increased risk for sudden death. While bradycardia resulting from loss of sympathetic tone has been hypothesized to play a role in this mortality, extended in-home monitoring has failed to find evidence of low heart rates in children with FD. In order to better characterize the specific cardio-respiratory pathophysiology and autonomic dysregulation in patients with FD, 25 affected children and matched controls were studied with in-home technology, during day and night. Respiratory and heart rate timing and variability metrics were derived from inductance plethysmography and electrocardiogram signals. Selective shortening of inspiratory time produced an overall increase in respiratory frequency in children with FD, with higher daytime respiratory variability (vs. controls), suggesting alterations in central rhythm generating circuits that may contribute to the heightened risk for sudden death. Overall heart rate was increased and variability reduced in FD cases, with elevated heart rates during 20% of study time. Time and frequency domain measures of autonomic tone indicated lower parasympathetic drive in FD patients (vs. controls). These results suggest withdrawal of vagal, rather than sympathetic tone, as a cause for the sustained increase and dramatic lability in respiration and heart rates that characterize this disorder.
authors.affiliation: Center for Autonomic Medicine in Pediatrics, Children's Memorial Hospital, Chicago, Illinois 60614, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Carroll
authors.forename: Anna S
authors.initials: AS
authors.lastname: Kenny
authors.forename: Pallavi P
authors.initials: PP
authors.lastname: Patwari
authors.forename: Jan-Marino
authors.initials: JM
authors.lastname: Ramirez
authors.forename: Debra E
authors.initials: DE
authors.lastname: Weese-Mayer
mesh_terms: D000293:Adolescent; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D002319:Cardiovascular System / Q000294:innervation / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D004402:Dysautonomia, Familial / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory; D056152:Respiratory Rate / Q000502:physiology; D012137:Respiratory System / Q000294:innervation / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology; D014630:Vagus Nerve / Q000503:physiopathology