An unusual cause of hypoxia: getting to the heart of the matter

: A 63 year old female presented to hospital with progressive exertional dyspnoea over a 6 month period. In the year preceding her admission, she reported an intercurrent history of abdominal pain, diarrhoea and weight loss. She was found to be hypoxic, the cause for which was initially unclear. A ventilation-perfusion scan identified a right-to-left shunt. Transoesophageal echocardiography (TOE) demonstrated a significant right-to-left intracardiac shunt through a patent foramen ovale (PFO); additionally severe tricuspid regurgitation was noted through a highly abnormal tricuspid valve. The findings were consistent with carcinoid heart disease with a haemodynamically significant shunt, resulting in profound systemic hypoxia. 24 hour urinary 5-Hydroxyindoleacetic acid (5-HIAA) and imaging were consistent with a terminal ileal primary carcinoid cancer with hepatic metastasis. Liver biopsy confirmed a tissue diagnosis. The patient was commenced on medical therapy for carcinoid syndrome. She subsequently passed away while undergoing anaesthetic induction for valvular surgery to treat her carcinoid heart disease and PFO.