Sympathetic nerve abnormality in an adolescent patient with cardioinhibitory vasovagal syncope.

A 15 year-old-Japanese girl was admitted to our ward because of syncope. Electrocardiography (ECG) demonstrated sinus bradycardia with heart rate of 52/min. Holter ECG showed no arrhythmia related to syncope. Coronary enhanced computed tomography and cardiac magnetic resonance imaging showed no abnormal findings. Head-up tilt test revealed syncope with sinus arrest. 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy revealed focally decreased uptake on the anterior wall of the left ventricle but generally maintained uptake of MIBG. Finally, she was diagnosed with cardioinhibitory vasovagal syncope (CIVS). Sympathetic nerve abnormalities seemed to be related to CIVS in this patient. <Learning objective: Vasovagal syncope (VVS) is a common clinical event and is the most common type of syncope. A decrease in sympathetic nervous system activity as indicated by HRV and disturbance in myocardial adrenergic innervation may be one of the pivotal factors in some type 2B (cardioinhibition type) VVS patients without other diseases.>.