Syncope and orthostatic intolerance — branching viva

Stage 1 — The adolescent who faints in assembly

The examiner describes a 14-year-old girl who fainted while singing in a hot, crowded assembly, with pallor, nausea and dimming vision beforehand and a full recovery within a minute of lying flat. [1]

• What is the most likely diagnosis, and what features make it benign? Vasovagal (reflex) syncope: a clear precipitant, a typical prodrome, an upright posture and a rapid complete recovery. [1] [2]
• Despite the benign story, what single investigation is mandatory before discharge, and why? A 12-lead ECG for every child, because the dangerous cardiac causes may be silent on history and examination. [5]
• The examiner asks what the brief jerking during the collapse means. It is cerebral-hypoperfusion myoclonus, not epilepsy — recover the ECG and the history, do not start antiepileptics. [1]

Stage 2 — The boy who collapses sprinting

The examiner moves to a 13-year-old boy who collapsed sprinting the 400 metres with no prodrome. His father died suddenly at 34. [5]

• Which historical features here are cardiac red flags? Exertional syncope, absent prodrome, and a family history of sudden death. [5]
• What is your working diagnosis and your disposition? Cardiac syncope until excluded; urgent cardiology referral, sport restriction, an ECG and an echocardiogram. [11]
• Name the lesions you are excluding and the ECG patterns to seek: hypertrophic cardiomyopathy, long-QT syndrome, CPVT, arrhythmogenic cardiomyopathy and aortic stenosis; measure the QTc, look for deep T-wave inversions and voltage. [11]

Stage 3 — The girl with chronic daily orthostatic symptoms

The examiner describes a 15-year-old girl with months of daily lightheadedness, palpitations and fatigue, worse on standing and eased by lying down, beginning after a viral illness. On standing her blood pressure does not fall but her heart rate rises by 46 beats per minute over 10 minutes. [7]

• What is the diagnosis, and what criteria support it? POTS: a heart-rate rise of at least 30 bpm (over 40 in younger children) sustained over 10 minutes of standing, without a blood-pressure fall. [7] [8]
• Outline the first-line management and explain why reconditioning is central. Hydration, salt, compression and a structured graduated exercise programme; reconditioning breaks the deconditioning-tachycardia cycle, the most evidence-based component. [8] [9]
• What is the prognosis you offer the family? A chronic relapsing but favourable course, with most adolescents improving over months to a few years with adherence to the programme. [9]