Palpitations in a well 27-year-old woman.

A 27-year-old healthy woman with a history of childhood asthma (currently well controlled) and no other known comorbidities presents with a history of acute-onset palpitations. She reports associated light-headedness and sweating, with no history of chest pain and no other associated symptoms. There is no history of recent use of inhaled beta-agonist, or recent stimulant or drug use. The patient also does not report any family history of known cardiovascular disease. She is haemodynamically stable, and other than being markedly tachycardic examines well.\n\nUrgent ECG with standard calibration done at the time is depicted in figure 1.\n\n\n\nFigure 1 \nUrgent standardised 12-lead ECG taken at the time of palpitations. RBBB, …