A transthoracic echocardiography (TTE) was performed to assess the left-ventricular (LV) function. To our surprise, it revealed multiple, well-defined, cystic lesions consistent with hydatid cysts seen as a cluster in the right ventricular (RV) cavity and as compressing the interventricular septum (IVS) (figure 2). These cystic lesions were compromising the LV cavity. However, LV function was normal without any regional wall-motion abnormality.

CT scan of chest and abdomen revealed similar cysts in the right-lung apex and left lobe of liver. Therefore, a polyvisceral involvement in the setting of multiple cardiac cysts suggested cardiac hydatidosis as the most probable diagnosis.

CT coronary angiography revealed no involvement of coronaries.

Later he under went elective surgery, ‘Evaculation of RV Hydatid Cyst and Obliteration of Cavity with Bovine Pericardium’.

Under general anaesthesia, median sternotomy was done. Cardio pulmonary bypass (CPB) was established with aortic and bicaval cannulation. SVC and IVC were snared. Hypertonic saline was instilled to minimise the risk of dissemination in case of an accidental spillage of hydatid fluid. Six hydatid cysts of about 4–6 cm diameter were removed surgically (figure 3). The cysts show an outer hyaline that was white in colour – the ectocyst. Cavity was packed with bovine pericardial patch and edges were over sewn. One mediastinal chest-drainage tube was placed. Chest was closed in layers after securing haemostasis.

Following surgical removal of the cysts, the hydatid cyst fluid was centrifuged and examined under microscope. It revealed brood capsules and protoscolices that constitute the hydatid sand. The protoscolex is round to oval in shape, measuring about 140 × 80 µm in size and shows hooklets. Both invaginated (figure 4A) and evaginated (figure 4B) protoscolices were found.

Regular exercise, chest physiotherapy, a life-long anticoagulation therapy and antibiotic prophylaxis for dental and other invasive procedures was advised

Cardiac hydatidosis accounts for 0.5% to 2% of all hydatid diseases.² The reason for this rare occurrence appears to be the cardiac contractions that provide resistance to the presence of viable cysts.³ It can occur in any part of the heart, left ventricle being the most common site (75%), followed by the RV (15%), inter ventricular septum (5–9%) left atrium (8%), pericardium (8%), pulmonary artery (7%) and right atrium (3–4%).⁴

Clinical manifestations are seen in less than 10% of the cases and, if present, depend on the location, size and integrity of the cyst.¹ Chest pain is the most common symptom.¹ IVS cysts (very rare) may present with arrhythmias, conduction blocks or ventricular outflow tract obstruction. Other manifestations include ACS, valvular dysfunction and so on.^{1 5 6} There are very few case reports of hydatid cyst presenting as an ACS. Most of them are either pericardial cysts compressing coronaries or ruptured cysts.^{7 8} The case reported here is of particular interest because its presentation as an ACS may misdirect diagnosis and its recognition, which is important in planning therapeutic strategies. Treating the patient with inappropriate medication may expose him to life-threatening complications like rupture of the cyst leading to anaphylaxis, embolisation of cyst contents in to pulmonary or systemic circulation, pericardial tamponade, sudden cardiac death and so on.

The chest radiograph can often appear normal, as was the condition in the present case.

Electrocardiographic changes also depend on location, size and integrity of the cyst. These include ischemic changes (ST depressions and T wave inversions) and conduction disturbances (atrioventricular nodal blocks, bundle branch blocks) as observed in the present case. Other changes include arrhythmias and sudden cardiac arrest.^{6 9 10} However, none of the above changes is characteristic of hydatid cyst. Therefore, a cautious interpretation of electrocardiographic changes always with the aid of a bedside echocardiography is necessary, especially in the setting of a stable ACS.

Echocardiography is the diagnostic investigation of choice for all cases of cardiac hydatid cysts.^{1 10} Apart from its non-invasive nature, widespread availability, cost-effectiveness, easy bedside assessment, its potential advantages include accurate differentiation of a solid mass from a cystic lesion; determination of number, location, size and integrity of cysts; and demonstration of thin membranes of daughter cysts and hydatid sand in a multiloculated cystic lesion. It also helps to determine the haemodynamic effects of cysts on the heart.^{10 11} The present case scenario highlights how an early echocardiography unmasked a very rare disease like hydatid cyst, which is a tough clinical diagnosis to make out in a patient presenting with most commonly encountered disease, that is, ACS. Therefore, in the setting of an ACS, an early echocardiography, apart from assessment of LV function, will also help us recognize rare entities like cardiac tumours, aneurysms, cysts (hydatid cysts) and so on.

CT and MRI are the other non-invasive diagnostic modalities but are not superior to echocardiography due to the presence of cardiac-motion artefacts and lack of bedside assessment.¹¹ Nevertheless, CT is helpful in determining polyvisceral involvement, especially when lung parenchyma is involved.

Coronary angiography (conventional/CT) studies should be carried out to evaluate the coronary vessels in all patients with symptoms or when electrocardiographic abnormalities are present as in our case.¹²

Even though serological tests like Casoni's intradermal test and ELISA are available, accuracy of these tests depends on several factors, including type and quality of antigen used. Many false-positive and false-negative results were observed in the past. Therefore, their role is limited to supplement the radiological diagnosis.¹³

Once the diagnosis of cardiac hydatidosis is made, surgery is the definitive mode of treatment to prevent complications. A preoperative albendazole therapy was initiated in our patient to prepare for possible cyst rupture and dissemination of daughter cysts during the surgical procedure. Intraoperative echocardiography gives a definitive diagnosis and can help in planning the surgery by aiding identification of the cannulation site and in making decisions such as whether to use CPB or to perform the surgery on a beating heart or under cross-clamp.¹² In the present case, we performed the surgery under CPB. We can never be careful enough because complications may arise during surgery from rupture of cystone and one must be prepared to handle them.