21. Pediatric Syncope, POTS, and Autonomic Disorders

Syncope in pediatric patients is predominantly benign and neurally mediated (vasovagal), but requires exhaustive exclusion of life-threatening cardiogenic substrates (channelopathies, structural defects, outflow obstruction).

1. Differentiating Benign vs Cardiogenic Syncope

Clinical Parameter	Benign Neurally Mediated (Vasovagal) Syncope	Life-Threatening Cardiogenic Syncope
Precipitating Triggers	Prolonged standing, warm crowded rooms, sight of blood, venipuncture, emotional distress.	Syncope during active physical exercise / exertion, emotional surge (alarms), swimming.
Prodromal Symptoms	Lightheadedness, warmth, diaphoresis, tunnel vision, nausea, pallor ($>10-15\text{ s}$).	Zero prodrome (sudden "drop attack") or sudden sensation of rapid palpitations.
Family History	History of vasovagal episodes in parents.	Unexplained sudden cardiac death $<35-40$ yr, drowning, recurrent motor vehicle accidents.
12-Lead Electrocardiogram	Completely normal.	Prolonged $QTc$, short $QTc$, delta wave (WPW), Brugada pattern, RVH, deep septal $Q$ waves.

2. Postural Orthostatic Tachycardia Syndrome (POTS)

Pediatric Diagnostic Criteria:
1. Sustained heart rate increase $\ge 40\text{ bpm}$ (or HR $>130\text{ bpm}$) within $10\text{ minutes}$ of standing / head-up tilt table test in adolescents ($12-19$ years).
2. Absence of orthostatic hypotension (systolic BP drop $<20\text{ mmHg}$).
3. Chronic orthostatic symptoms (dizziness, fatigue, brain fog, palpitations) persisting for $\ge 3$ months.

3. Evidence-Based Clinical Management Protocols

Vasovagal Syncope: Patient education on prodromal recognition, physical counterpressure maneuvers (leg crossing, hand grip), hydration ($2-2.5\text{ L/day}$), increased dietary sodium.
POTS Management: Fluid expansion, aerobic reconditioning (recumbent cycling, swimming), compression garments, pharmacotherapy with Fludrocortisone ($0.1\text{ mg/day}$), Midodrine ($2.5-5\text{ mg}$ tid), or Ivabradine.