Cardiovascular magnetic resonance of a hiatus hernia causing positional cardiac compression

A69-year-old lady with intermittent breathlessness and chest pain underwent cardiovascular magnetic resonance (CMR) in the supine position. A large hiatus herniawas seen compressing the left ventricle, atrium, and mitral annulus. The CMR, including adenosine stress perfusion, was otherwise normal. The patient was immediately repositioned into the prone position and rescanned. In this position, the cardiac compression from the hiatus hernia was reduced, thus demonstrating its positional nature. Positional cardiac compression may in fact be an under-diagnosed phenomenon. Echocardiography in the left lateral decubitus position may not detect compression that occurs only when supine, unless an index of suspicion calls to reposition the patient, which is feasible with echocardiography. CMR may be more likely to detect this rare phenomenon given its supine nature.