2. Case presentation
A 48-year-old female from Tibet, China was admitted to our hospital presented with a 4-month history of intermittent pain of chest and back. Each time the pain attacked would last about 1 hour and usually twice a day, it often followed with mild fever and headache. For personal history, the patient raised sheep and cattle for a living. With the exception of a slightly slow heart rate of 47 bpm, her vital signs revealed normal. Cardiac murmur was not found within each cardiac cycle, the electrocardiogram also revealed no significant abnormity. For routine laboratory tests, all results remained in the normal limits, except an elevated percentage of eosinophils.
Among further cardiac examination, the main anomaly found by transthoracic echocardiography (TTE) was a slightly weak-echo mass located at the myocardium of the right ventricular apex (Figure 1,panel A ). Besides the mass, TTE also revealed a patent foramen ovale, mild tricuspid regurgitationand a small pericardial effusion. Computed tomography angiography (CTA) of the chest was performed, which revealed a soft tissue nodule without enhancement within the IVS near the right ventricular apex, the boundaries between the mass and surrounding myocardium were indistinct (Figure 1, panel B ). To clarify the diagnosis, enhanced MRI of the heart was carried out and revealed a cystic, heterogeneous-intensity IVS mass (3.0cm× 2.8cm) which was isointensity in T1-weighted images, slight hyperintensity in T2-weighted images, and no significant enhancement in contrast-enhanced images (Figure 1, panel C ). Imaging characteristics of CTA and MRI suggested parasitic infection, thus, further antibody assay of parasite was performed with a positive result of Echinococcus granulosus antibody.
After detailed communication, the patient consented to surgical treatment and signed the operation agreement. The patient underwent routine median sternotomy, while cardiopulmonary bypass was established between the superior vena cava, the inferior vena cava and the aorta. After puncturing and drawing the cyst content, 3% hypertonic saline was injected into the cyst, and then, the excision of the cyst was done. The 3% hypertonic saline was also poured into the pericardial cavity to prevent local dissemination. Postoperative histopathological examination confirmed the diagnosis of cardiac HC (Figure 1, panel D ). The patient was discharged from the hospital without complications on the 5th postoperative day and albendazole would be used for at least 6 months to prevent recurrence.