**Introduction/Hypothesis:**
Hydatid cysts caused by the parasite Echinococcus granulosus commonly affect the liver and lungs. Isolated cardiac involvement is rare and typically involves the left ventricular free wall. Because of their close resemblance to cardiac tumors, congenital cysts, and aneurysms, cardiac hydatid cysts pose a diagnostic dilemma on imaging. We present a unique case of cardiac hydatid cyst and describe diagnostic and management strategies.

**Methods**
A 36-year-old male with no known history of cardiovascular disease presented with chest discomfort. He experienced new-onset chest pressure with palpitations which awoke him from sleep. The patient described his lifestyle as active without limitations. He recently went on a hunting expedition in the North and South Carolinas and was exposed to turkeys and wild pigs. He denied any lethargy, fevers, rashes, diaphoresis, unintentional weight loss, gastrointestinal symptoms, or respiratory complaints. The patient denied having any relevant family history of cardiovascular diseases or consumption of any prescription medications.

**Results**
A 12-lead electrocardiogram (ECG) showed normal sinus rhythm without any abnormal ST segment changes or conduction defects. Troponin levels were negative. Initial transthoracic echocardiograph (TTE) showed a 1.3 by 1.4 cm wide, round, well-circumscribed cystic mass embedded in the mid-interventricular septum (Figure 1A). The left ventricular ejection fraction was estimated to be 71% with normal chamber dimensions, normal valvar function, and an absence of regional wall motion abnormalities. Subsequent cardiac magnetic resonance (CMR) imaging confirmed normal left and right ventricular function and a well-defined cystic mass measuring 2.5 cm by 2.0 cm without signs of early or late gadolinium enhancement (Figure 1B-C).
With his exposures and hunting history, there was suspicion for a parasitic cystic lesion. Echinococcus serologic studies were negative, but patient was still presumed to have a hydatid cyst in the interventricular septum due to characteristic imaging findings in the setting of exposures. Due to the small size of the cyst and serial imaging showing stable size without growth and no change in symptoms, patient was monitored clinically with serial TTEs, and symptoms were treated with anti-antianginal therapies. Surgical options continue to be discussed.

**Conclusion**
Isolated cardiac hydatid cysts represent a rare pathology and pose a diagnostic dilemma due to their imaging resemblance to cardiac tumors, congenital cysts, and aneurysms. Furthermore, they have a propensity to enlarge which can lead to increased myocardial pressure and consequent ventricular dysfunction. Complications of these cysts include heart failure, tamponade, rhythm disturbances, and displacement of coronary vessels. Diagnosis requires multimodality imaging with chest radiograph, TTE, and CMR. Treatment of hydatid cysts requires serial imaging, surgical intervention, and pharmacotherapy with albendazole.



**Introduction/Hypothesis:**
Hydatid cysts caused by the parasite _Echinococcus granulosus_ commonly affect the liver and lungs. Isolated cardiac involvement is rare and typically involves the left ventricular free wall. Because of their close resemblance to cardiac tumors, congenital cysts, and aneurysms, cardiac hydatid cysts pose a diagnostic dilemma on imaging. We present a unique case of cardiac hydatid cyst and describe diagnostic and management strategies.

**Methods**
A 36-year-old male with no known history of cardiovascular disease presented with chest discomfort. He experienced new-onset chest pressure with palpitations which awoke him from sleep. The patient described his lifestyle as active without limitations. He recently went on a hunting expedition in the North and South Carolinas and was exposed to turkeys and wild pigs. He denied any lethargy, fevers, rashes, diaphoresis, unintentional weight loss, gastrointestinal symptoms, or respiratory complaints. The patient denied having any relevant family history of cardiovascular diseases or consumption of any prescription medications.

**Results**
A 12-lead electrocardiogram (ECG) showed normal sinus rhythm without any abnormal ST segment changes or conduction defects. Troponin levels were negative. Initial transthoracic echocardiograph (TTE) showed a 1.3 by 1.4 cm wide, round, well-circumscribed cystic mass embedded in the mid-interventricular septum (Figure 1A). The left ventricular ejection fraction was estimated to be 71% with normal chamber dimensions, normal valvar function, and an absence of regional wall motion abnormalities. Subsequent cardiac magnetic resonance (CMR) imaging confirmed normal left and right ventricular function and a well-defined cystic mass measuring 2.5 cm by 2.0 cm without signs of early or late gadolinium enhancement (Figure 1B-C).
With his exposures and hunting history, there was suspicion for a parasitic cystic lesion. Echinococcus serologic studies were negative, but patient was still presumed to have a hydatid cyst in the interventricular septum due to characteristic imaging findings in the setting of exposures. Due to the small size of the cyst and serial imaging showing stable size without growth and no change in symptoms, patient was monitored clinically with serial TTEs, and symptoms were treated with anti-antianginal therapies. Surgical options continue to be discussed.

**Conclusion**
Isolated cardiac hydatid cysts represent a rare pathology and pose a diagnostic dilemma due to their imaging resemblance to cardiac tumors, congenital cysts, and aneurysms. Furthermore, they have a propensity to enlarge which can lead to increased myocardial pressure and consequent ventricular dysfunction. Complications of these cysts include heart failure, tamponade, rhythm disturbances, and displacement of coronary vessels. Diagnosis requires multimodality imaging with chest radiograph, TTE, and CMR. Treatment of hydatid cysts requires serial imaging, surgical intervention, and pharmacotherapy with albendazole.



A rare case of isolated cardiac hydatid cyst