1. Introduction
Human hydatid disease (HD) is a parasitic infection disease, occurs mainly as a result of infection with the larvae ofEchinococcus granulosus . Dogs are main primary hosts and sheep are intermediate hosts, thus, HD can be more common seen in persons living in areas where animal husbandry is practiced. The most commonly involved site of hydatid cysts (HC) is the liver, while cardiac echinococcosis is an uncommon disease1. A considerable proportion of the HD patients can stay asymptomatic, until the space-occupying effect in the involved organ brings out symptoms2. However, not similar with other organ involved, patients with cardiac HC usually appear symptomatic, though the exact proportion remains unknown3,4. Chest pain, dyspnea, syncope and palpitations are common symptoms in patients with cardiac HC, while patients can also show infection-associated symptoms such as cough and fever1,5. Among all cases of cardiac HC, the interventricular septum (IVS) is the site rarely involved1,2,5. Here, we reported a case of old woman who suffered a cardiac HC located in the IVS.