Postural orthostatic tachycardia syndrome — formative SAQs

SAQ 1 — The adolescent girl with chronic daily orthostatic symptoms (10 marks)

Stem. A 15-year-old girl presents with four months of daily lightheadedness, palpitations, fatigue and difficulty concentrating that come on within minutes of standing and ease when she lies down. She felt well before this and recalls a viral illness at the onset. She has missed several weeks of school. On a supervised 10-minute active stand test her heart rate rises from 76 supine to 124 bpm upright, and her blood pressure stays at 108/68 mmHg throughout. Examination is normal and she has no family history of sudden death. [1]

Task. (a) State the diagnosis and the specific criteria that confirm it. (b) List the cardiac red-flag features that must be excluded before settling on this diagnosis. (c) Outline the stepwise management. [3]

Model answer

(a) Diagnosis and criteria (3 marks). The diagnosis is postural orthostatic tachycardia syndrome (POTS). The criteria are: chronic orthostatic intolerance on most days for ≥3 months; symptoms provoked by standing and eased by lying down; a heart-rate rise of ≥40 bpm in adolescents (≥30 bpm in adults, or an upright rate ≥120 bpm) within 10 minutes of standing or head-up tilt; and no orthostatic hypotension (no systolic fall ≥20 mmHg or diastolic fall ≥10 mmHg). This child meets all four. [1] [2]

(b) Cardiac red flags to exclude (3 marks). POTS does not cause collapse, so before settling on it you exclude: exertional syncope; syncope while supine or swimming; syncope provoked by a loud noise or fright; syncope with no prodrome; palpitations at the moment of collapse; chest pain or dyspnoea; and a family history of sudden death before about 50 years of age or a known inherited arrhythmia. A 12-lead ECG is obtained on every child. [3] [1]

(c) Stepwise management (4 marks). Step 1: educate, validate and reassure (POTS is real and treatable), keep a symptom and standing diary, and put a school plan in place. Step 2: hydration and salt — around 2–3 L of fluid and titrated sodium chloride per day, avoiding excess salt in hypertension or renal disease. Step 3: physical counter-pressure manoeuvres and compression garments. Step 4: structured recumbent or sub-threshold exercise to reverse the deconditioning spiral — the most evidence-based component. Step 5: phenotype-guided pharmacotherapy (midodrine, fludrocortisone, beta-blocker or ivabradine) only if non-drug measures are insufficient. Treat sleep, mood and school return in parallel. [5] [10]

SAQ 2 — The boy who collapses sprinting (10 marks)

Stem. A 14-year-old boy is brought to the emergency department after collapsing while sprinting the 400 metres at school. He had no warning. His father died suddenly at 34 years of age. On arrival he is fully recovered and back to normal. Heart rate is 76, blood pressure is 112/70 with equal four-limb pulses, and cardiovascular examination is normal. [3]

Task. (a) What is the significance of this presentation, and why is a diagnosis of POTS or vasovagal syncope inappropriate here? (b) Outline the immediate and urgent management. [1]

Model answer

(a) Significance (4 marks). This is cardiac syncope until proven otherwise. The combination of exertional collapse, absent prodrome and a family history of sudden death before 50 places hypertrophic cardiomyopathy, long-QT syndrome, catecholaminergic polymorphic ventricular tachycardia and arrhythmogenic cardiomyopathy at the top of the differential. POTS is a chronic orthostatic intolerance with a posture-driven daily symptom pattern and a preserved blood pressure; it does not cause exertional, warning-free collapse. Vasovagal syncope is episodic with a clear prodrome. Both benign autonomic labels are therefore inappropriate and dangerous here. [3] [1]

(b) Immediate and urgent management (6 marks). Restrict competitive sport pending evaluation. Obtain a 12-lead ECG immediately and read it for a long QTc, pre-excitation, Brugada pattern, heart block and the voltage/T-wave changes of cardiomyopathy. Refer urgently to cardiology for echocardiography, ambulatory monitoring and an exercise test as indicated, and arrange family screening and genetic evaluation. Admit or observe if there is any abnormality, ongoing symptoms, an abnormal ECG or a high-risk family history. Do not discharge to routine care. [3] [1]

The contrast with SAQ 1 is the whole point: the standing-test pattern and the chronic daily course define POTS; the exertional, warning-free, family-history-positive collapse defines the cardiac screen that must come first. [3] [2]