Hydatid Cyst of the Interventricular Septum
A 22-year-old woman without medical history presented with a grade 3/6 ejectional systolic murmur. She was asymptomatic. An ECG revealed sinus rhythm and nonspecific repolarization changes in the right precordial leads. The chest radiograph was normal. A transthoracic Doppler two-dimensional echocardiogram showed a spheroidal, 3-cm-diameter cystic mass in the upper interventricular septum protruding mainly into the left ventricular chamber without creating any significant intraventricular gradient (Figs 1⇓ and 2⇓). Transesophageal echocardiography demonstrated a liquid mass with a rounded and well-constrated capsule containing an inner sleigh bell (Fig 3⇓). A CT scan and NMR confirmed a round, cystlike structure in the interventricular septum but finally failed to provide much information on the structure and anatomic relationship of the cyst. A blood test showed an erythrocyte sedimentation rate of 60 mm/h and absence of eosinophilia. Serological tests for Echinococcus granulosus were positive. Right and left cardiac catheterization showed normal pressures without intraventricular obstruction. Right and left ventricular angiography revealed an intraventricular mass defect in the interventricular septum. Coronary arteriography was normal except for a slightly curved and elongated diagonal branch of the left anterior descending coronary artery but without compression. Abdominal ultrasonographic examination, cranial and abdominal CT scans, and radionuclide bone scan imaging were normal. Surgical ablation was performed through the right ventricle; after the cyst was punctured and its contents were drained, hypertonic glucose solution was instilled, and the cyst capsule was entirely removed. Histopathological analysis of the surgical specimen confirmed a hydatid cyst. Postoperative evolution was uneventful, and the patient remains free of symptoms with normal echocardiography after 4 years of follow-up.
Cardiac hydatid disease is very uncommon. When the cysts are intramyocardial, the most common location is the interventricular septum1 ; the diagnostic value of two-dimensional transthoracic and especially transesophageal echocardiography is better than that of CT and NMR imaging. Therefore, these methods should be reserved only for the study of extracardiac involvement of echinococcosis.2 3 4
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke's Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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