title: Correlations between urinary excretion of catecholamines and electrocardiographic parameters of vagal hyperreactivity in infants with fainting spells. Implication of sympathetic hypotonia?
abstract: BACKGROUND
  Vagal hyperreactivity (VHR) is a frequent etiology of infant fainting spells; but it is sometimes difficult to diagnose. A biochemical test would therefore be useful, especially as the oculocardiac reflex (OCR) test innocuity is not absolute.
  
  
  OBJECTIVE
  To evaluate urinary excretions of norepinephrine, epinephrine and dopamine as markers for vagal hyperreactivity.
  
  
  METHODS
  During check-up of 55 infants from 0.5 to 11 months of age, for discomfort episodes, including OCR and Holter recording, 24h urinary assays of total norepinephrine, epinephrine and dopamine were carried out to evaluate sympathetic activity.
  
  
  RESULTS
  Epinephrine and norepinephrine urinary excretions were negatively correlated with VHR intensity, as measured by the OCR ECG parameters: RRmax, % cardiac deceleration and minimal frequency; dopamine excretion was not. When RRmax(OCR) was greater or equal to 800 ms, epinephrine urinary excretion tended to be less or equal to 9 nmol/mmol creatinine and norepinephrine excretion less or equal to 190 nmol/mmol creatinine.
  
  
  CONCLUSIONS
  A delay in maturation of the sympathetic system and/or adrenomedullary glands with low secretion of norepinephrine and epinephrine inducing a desequilibrium of the sympathetic/parasympathetic balance may contribute to the fainting spells observed with VHR. Epinephrine and norepinephrine urinary excretions may provide informative complementary noninvasive markers for VHR.
authors.affiliation: Équipe deRecherches sur laBiochimie et la Pharmacologie des Vaisseaux et du rein, Laboratoire dePharmacologie, Faculté de Pharmacie, 4, avenue de l'Observatoire, 75006 Paris, France.
authors.forename: Claire-Odile
authors.initials: CO
authors.lastname: Leroy-Bouchereau
authors.forename: Paul
authors.initials: P
authors.lastname: Urios
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Borsos
authors.forename: Samir
authors.initials: S
authors.lastname: Nakib
authors.forename: Sylvie
authors.initials: S
authors.lastname: Escolano
authors.forename: Vincent
authors.initials: V
authors.lastname: Lucet
authors.forename: Michel
authors.initials: M
authors.lastname: Sternberg
mesh_terms: D015415:Biomarkers / Q000652:urine; D002395:Catecholamines / Q000652:urine*; D004298:Dopamine / Q000652:urine; D015716:Electrocardiography, Ambulatory; D004837:Epinephrine / Q000652:urine; D006339:Heart Rate; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009638:Norepinephrine / Q000652:urine; D011237:Predictive Value of Tests; D012024:Reflex, Oculocardiac; D013564:Sympathetic Nervous System / Q000378:metabolism* / Q000503:physiopathology; D013575:Syncope / Q000209:etiology* / Q000503:physiopathology / Q000652:urine; D014630:Vagus Nerve / Q000503:physiopathology*; D020421:Vagus Nerve Diseases / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology / Q000652:urine
chemical_list: D015415:Biomarkers; D002395:Catecholamines; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine