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A 47 year old woman was kicked in the sternum by a horse and fell to the ground with brief loss of consciousness. She presented nine hours later with chest pain. Initial assessment revealed tenderness over the sternum and in the epigastrium, but the cardiological examination, 12 lead ECG, and plasma creatine kinase (112 IU/l) were normal. A transthoracic echocardiogram (TTE) revealed a small (1 cm) pericardial effusion without diastolic right ventricular collapse. Overnight the chest pain worsened and the patient developed signs of tamponade. TTE now showed a larger pericardial effusion, located predominantly posteriorly, with right ventricular diastolic collapse. Computed tomography confirmed the pericardial effusion (left panel) and also showed small pleural effusions with dilatation of the inferior vena cava and hepatic veins (right panel). The pericardial effusion was drained surgically to reveal straw coloured fluid without blood staining. Thereafter, all signs of tamponade resolved.
Pericardial effusion caused by blunt trauma is usually haemorrhagic rather than serous. Presumably, the force of the kick caused myocardial and pulmonary contusion that led to an inflammatory response with serous effusion into the pericardial and pleural spaces. Whether inferior vena cava compression at the time of the horse kick was responsible for the brief loss of consciousness is not clear. Other potential mechanisms include asystole or complete heart block if the kick coincided with the T wave or the QRS complex, respectively.