Abstract 15 Poster Session III, Monday, 5/3 (poster 284)

Purpose/Methods: To determine the clinical features and prognosis of neurally mediated syncope (NMS), we conducted a retrospective chart review of 190 consecutive adolescents referred to a pediatric cardiologist1 over a 7 year period for evaluation and treatment of NMS, a condition poorly understood in this age group. Patients with important cardiac disease were excluded.

Results: Subjects averaged 14.9±2.3 years of age, and a 1.6±2.2 year symptom history at initial evaluation; half were males. More than 5 episodes of syncope or presyncope occurred in 64%, including 19% with syncope daily. Family history of syncope was present in 21% of subjects. Although the vast majority (85%) had gravity-related orthostatic syncope, 39% had more than one mechanism present (threat-induced, vasovagal, stretch, hair grooming, and positional change). Presyncope occurred in all but three patients (98.4%) and included symptoms of lightheadedness (88%), visual changes (71%), a sensation of warmth (39%), nausea (33%), diaphoresis (33%) and altered hearing (25%). During syncopal episodes, brief, witnessed, tonic-clonic activity and urinary incontinence occurred in 6% and 3% of subjects, respectively, 26% of subjects were hurt, with 2% incurring major injuries. Syncope was reported during various activities: sitting (31%), exercise (12%), walking (9%), driving (2%). Associated conditions included chronic fatigue syndrome (2%) and dieting (1%). A low dietary salt intake was present in 70% of subjects overall.

After initial evaluation, subjects who had gravity-related orthostatic or positional change NMS were monitored for 1.2±1.2 years and 70% had at least one follow-up visit after initiation of increased dietary salt and fludrocortisone acetate therapy. These measures resulted in complete resolution in 68% of these subjects, while an additional 16% experienced >80% improvement in syncopal symptoms.

Conclusion: In a referral population of adolescents with NMS, gravity-related orthostatic stress accounts for the vast majority of cases. Episodes occur in positions other than standing upright and may result in serious injury. Low salt intake and volume depletion appear to be important pathophysiologic mechanisms in many adolescents with NMS, possibly reflecting an iatrogenic condition related to national recommendations to reduce dietary sodium intake. Treatment with salt and volume repletion with fludrocortisone generally leads to resolution or marked improvement in NMS symptoms.