Key result
Positive tilt test in pediatric neurocardiogenic syncope is linked to higher noradrenaline and cardiac MIBG uptake.
Why the study?
The role of left ventricular sympathetic nervous system function in pediatric patients with neurocardiogenic syncope was not well characterized.
Does left ventricular sympathetic nervous function and plasma noradrenaline differ between tilt-positive and tilt-negative pediatric patients with neurocardiogenic syncope?
Observational (n=30)
Does left ventricular sympathetic nervous function and plasma noradrenaline differ between tilt-positive and tilt-negative pediatric patients with neurocardiogenic syncope?
Pediatric patients with neurocardiogenic syncope and a positive tilt test demonstrate higher cardiac sympathetic activity and noradrenaline storage capacity compared to tilt-negative patients.
Higher MIBG uptake and NA levels in tilt-positive pediatric NCS suggest sympathetic hyperactivity; hypothesis-generating and should not yet change practice.
The purpose of this study was to assess the left ventricular sympathetic nervous system function in the patients with neurocardiogenic syncope (NCS) using I-123 metaiodobenzylguanidine (MIBG) imaging of the heart, and to compare the plasma noradrenaline (NA) and MIBG results of tilt positive and tilt negative patients following a head-up tilt test (HUT). The study included 30 patients. Their physical and laboratory examinations did not show a pathology that may be the cause of their syncope. HUT test was positive in 13 patients and negative in 17 patients. Plasma NA concentrations were higher in the HUT positive than the HUT negative group at the beginning and at the 10th minute of the test. Specific I-123 MIBG uptake assessed as the cardiac to mediastinal activity ratio in the delayed image was significantly higher in HUT positive group. The higher levels of MIBG uptake and plasma NA observed in HUT positive patients may reflect the greater capacity of NA storage in cardiac adrenergic neuronal tissue in patients with NCS. The results of this study support the critical role of autonomic nervous system in the pathophysiology of NCS and the excessive sympathetic nervous stimulation as the trigger of paradox reflex.
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Olguntürk et al. (2003) conducted an observational in Neurocardiogenic syncope (n=30). Head-up tilt test (HUT) positivity vs. Head-up tilt test (HUT) negativity was evaluated on Plasma noradrenaline concentrations and specific I-123 MIBG uptake (cardiac to mediastinal activity ratio). Head-up tilt test positive pediatric patients with neurocardiogenic syncope had significantly higher plasma noradrenaline concentrations and I-123 MIBG uptake compared to tilt negative patients.
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