Screening for an occult penetrating cardiac injury using transoesophageal echcardiography

Background 30% of patients with a cardiac injury will present with a penetrating chest wound and be haemodynamically stable, the so-called "occult cardiac injury". Current international practice is to screen for occult cardiac injuries using ultrasound (US) of the pericardial sac. If the US confirms the presence of fluid, then the patient undergoes a subxiphoid pericardial window (SPW) under general anaesthetic. In our experience, US Results in a large number of false positives and unnecessary operations. Aim To determine the accuracy of US for screening and whether transoesophageal echocardiography (TOE) may aid in the diagnosis and prevent unnecessary SPW. Methods Prospective study on all haemodynamically stable patients over 28-months with stab wound to the chest in the cardiac zone. Routine work-up comprised a CXR, ECG and an ultrasound. All patients with a positive US underwent a TOE prior to the performance of a SPW. The SPW was considered to be positive if there was blood in the pericardial sac. Results 142 patients underwent a SPW over a period of 28 months with a median age of 29 (range 18-59) years. The sensitivity of US for detecting a haemopericardium was 95% but there were 96 false positives. A total of 51 patients had a TOE prior to the SPW; TOE had a sensitivity of 93%, specificity of 43%, and a positive predictive value of 38% for detecting a haemopericardium. There were 21 false positives and one false negative with TOE. Discussion TOE has a very high sensitivity for identifying a haemopericardium, but as with US, there is a problem with false positives and in this series a single false negative. SPW remains the screening tool of choice in detecting an occult cardiac injury.