Large, mobile, transmitral metastastic osteosarcoma presenting as cardiac arrest

UNLABELLED The present case is an unusual one of a 21-year-old female with a primary osteosarcoma and left lung metastasis presenting following a witnessed pulseless electrical activity cardiac arrest. The electrocardiogram was unremarkable. A computed tomography pulmonary angiogram (CTPA) demonstrated a tumour within the left inferior pulmonary veins. Transthoracic echocardiography (TTE) revealed a severely hypokinetic left ventricle and a multi-lobulated, mobile mass arising from one of the left pulmonary veins which prolapsed to varying degrees on a beat-to-beat basis back and forth through the mitral valve into the left ventricle (during ventricular diastole) and retracted back into the left atrium (during ventricular systole). The present case demonstrates the importance of performing TTE in an emergency presentation, its influence on diagnosis and, in the present case, its usefulness in aiding the decision to withdraw life-sustaining treatments. It also highlights the importance of considering urgent intervention for a tumour seen to prolapse through the mitral valve because of the real risk of acute obstruction. LEARNING POINTS The present case emphasises the importance of thorough clinical assessment in triggering TTE assessment in a critical care setting.TTE is a portable, radiation-free imaging modality that can aid rapid diagnosis in a deteriorating patient and guide an informed management plan.Many district general hospitals in the UK lack cardiology support and access to echocardiography 'out-of-hours'. TTE, in the hands of an experienced operator, is an invaluable tool in the emergency assessment and management of critically unwell patients and should be available 24 h a day, 7 days a week.Echosonographers and physicians seeing similar dynamic tumour pathology with variable transmission through the mitral valve should bear in mind acute obstruction as a potential consequence and thus consider urgent intervention.