Correlations between urinary excretion of catecholamines and electrocardiographic parameters of vagal hyperreactivity in infants with fainting spells. Implication of sympathetic hypotonia?

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. AIMS: 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. CONCLUSION: 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.

Salt supplement increases plasma volume and orthostatic tolerance in patients with unexplained syncope.

OBJECTIVE: To determine whether in patients presenting with posturally related syncope administration of salt increases plasma volume and improves orthostatic tolerance. Patients with poor tolerance of orthostatic stress tend to have lower than average plasma and blood volumes. DESIGN: A double blind placebo controlled study in 20 patients and an open study in 11 of the effects of giving 120 mmol/day of sodium chloride. PATIENTS: 31 patients presenting with episodes of syncope who had no apparent cardiac or neurological disease. Plasma volume was determined by Evans blue dye dilution, orthostatic tolerance by time to presyncope in a test of combined head-up tilt and lower body suction, and baroreceptor sensitivity by the effect of neck suction on pulse interval. RESULTS: 8 weeks after treatment, 15 (70%) of the 21 patients given salt and three (30%) of the placebo group showed increases in plasma and blood volumes and in orthostatic tolerance, and decreases in baroreceptor sensitivity. Improvement was related to initial salt excretion in that patients who responded to salt had a daily excretion below 170 mmol. The patients in the placebo group who improved also showed increases in salt excretion. CONCLUSIONS: In patients with unexplained syncope who had a relatively low salt intake administration of salt increased plasma volume and orthostatic tolerance, and in the absence of contraindications, salt is suggested as a first line of treatment.

[Catecholamines in migraine and other paroxysmal conditions in children]. / Katekholaminy pri migreni i drugikh paroksizmal'nykh sostoianii u detei.

A study was made of the diurnal excretion of adrenaline and noradrenaline in children aged 7 to 14 years suffering from migraine (n = 33), epilepsy (n = 21), and from syncopes (n = 13). For that purpose use was made of fluorometry. The patients with epilepsia and syncopes manifested a fall of adrenaline excretion; noradrenaline excretion correlated with the control data. The children suffering from migraine demonstrated a statistically significant reduction of adrenaline excretion and a rise of noradrenaline excretion, leading to dramatic changes in the amines ratio. Therefore, in patients suffering from vegetovascular dystonia with paroxysmal crises, measurements of adrenaline and noradrenaline excretion may serve an additional criterion for making correct diagnosis.