Large Cardiac Hydatid Cyst in the Interventricular Septum

Abstract

Cystic hydatid disease results from infection with the larval or adult form of the Echinococcus granulosus tapeworm. Cardiac involvement is seen in 0.5% to 2% of patients with hydatid disease, and involvement of the interventricular septum is even rarer. Herein, we report our surgical treatment of a large cardiac hydatid cyst in the interventricular septum.

A 39-year-old woman presented with dyspnea. Transthoracic echocardiography revealed a large cyst in the apical part of the interventricular septum. Thoracic computed tomography showed a cystic lesion in that site, and magnetic resonance imaging confirmed the presence of a 50 × 55-mm mass.

The patient was placed on cardiopulmonary bypass. Hypertonic saline solution-soaked sponges were distributed within the pericardial cavity to prevent local invasion of the parasite intraoperatively. Through an incision parallel to the left anterior descending coronary artery, and without opening adjacent cardiac chambers, we aspirated the entire contents of the cyst, removed its germinative membrane, and washed the cavity with 20% hypertonic saline solution. The patient recovered uneventfully. She had begun taking albendazole 5 days preoperatively, and this therapy was continued for 12 weeks postoperatively.

In cases of an interventricular cardiac hydatid cyst, the combination of surgical resection, washout of the remaining cavity with hypertonic saline solution, and albendazole therapy typically yields excellent results.

Hydatid disease (cystic echinococcosis), which arises from the Echinococcus granulosus tapeworm, is endemic in some livestock-raising countries.¹ Cardiac involvement is seen in only 0.5% to 2% of patients with hydatid disease,^1–3 and the interventricular septum is involved in just 4% of cardiac cases.⁴ Cardiac hydatid cysts can rupture and cause cardiac tamponade, fatal arrhythmias, or systemic infection. Herein, we report the case of a woman who had a large hydatid cyst in the interventricular septum.

Case Report

In July 2009, a 39-year-old woman with dyspnea was admitted to our hospital. Physical examination revealed nothing unusual, and the results of routine laboratory tests were normal. An electrocardiogram showed negative T waves in the inferior leads (II, III, and aVF) and in leads V₄ through V₆. A chest radiograph showed a normal cardiothoracic ratio. Transthoracic echocardiography revealed a large cyst in the apical part of the interventricular septum. Computed tomography (CT) and magnetic resonance imaging (MRI) were performed to further characterize the lesion. Thoracic CT showed a cystic lesion in the apical part of the interventricular septum (Fig. 1), and MRI confirmed the presence of a 50 × 55-mm mass (Fig. 2). An enzyme-linked immunosorbent assay (ELISA) was positive for echinococcus antibodies.

Fig. 1 Computed tomograms taken at the A) T8 and B) T9 levels show the hydatid cyst (arrows).

Fig. 2 Magnetic resonance images of the hydatid cyst (arrows) in A) sagittal and B) axial views.

We decided to excise the hydatid cyst. The patient underwent median sternotomy and was placed on cardiopulmonary bypass with aortic arterial and bicaval venous cannulation. The aorta was cross-clamped. Isothermic, potassium-enriched blood cardioplegic solution was used. The left atrium was vented through the right upper pulmonary vein. Sponges soaked with hypertonic saline solution were distributed throughout the pericardial cavity to prevent local invasion by the parasite.

The incision to excise the cyst was parallel to and on the right side of the left anterior descending coronary artery, to avoid damaging that vessel (Fig. 3). We reached the cyst directly through the interventricular septum without opening any adjacent cardiac chambers. We aspirated the entire contents of the cyst, removed its germinative membrane, and washed the cavity with 20% hypertonic saline solution (Figs. 4 and 5). Capitonnage was performed, and the incision was closed with the use of Teflon felt (Fig. 6). The postoperative period was uneventful. The patient had begun taking albendazole (400 mg twice daily) 5 days before surgery and continued with this therapy postoperatively for 12 weeks. At the routine follow-up examination 2 years postoperatively, the patient was in New York Heart Association functional class I, with no trace of cysts on echocardiography.

Fig. 3 Diagram depicts the incision (broken line) parallel to the left anterior descending coronary artery on the right side.

Fig. 4 Intraoperative photographs show A) an external view and B) the cavity of the hydatid cyst.

Fig. 5 Photograph shows the germinative membrane of the cyst that was removed from the interventricular septum.

Fig. 6 Diagrams depict capitonnage and closure of the incision with the use of Teflon felt.

Discussion

Hydatid disease is endemic in Turkey and other livestock-raising countries.⁵ The most common sites of hydatid cysts are the liver (in 50%–70% of cases), lungs (5%–30%), muscles (5%), bones (3%), kidneys (2%), spleen (1%), and brain (1%).^4,6 Cardiac hydatid cysts are rare.^1–3 The coronary circulation is the main pathway by which the parasitic larvae reach the heart.⁷ Because of a rich coronary blood supply, the left ventricle is the site of cardiac hydatid cysts in 55% to 60% of cases. Less frequently involved are the right ventricle (10%–15% of cases), pericardium (7%), pulmonary artery (6%–7%), left atrium (6%–8%), right atrium (3%–4%), and interventricular septum (4%).3,4,7,8

Although cough is typically the chief clinical symptom of hydatid disease, cardiac hydatid cysts are usually asymptomatic, especially in their early stages, and only 10% of patients have clinical symptoms.^1,7,9 Chest pain is most common; however, palpitations and cough—and dyspnea, as in our patient—are also seen.¹

Chest radiographs usually show a normal cardiothoracic ratio, as in our patient.¹⁰ Electrocardiographic findings vary according to the sites of the cysts.³ Echocardiography is simple and useful in the diagnosis of cardiac hydatid cysts.³ Computed tomography and MRI provide further information, such as the extent and anatomic relationships of the cysts.^3,4 Serologic tests can be false-negative in 10% to 20% of patients with hepatic hydatid cysts, 40% with pulmonary cysts, and 50% with cardiac cysts; this is most likely linked with an insufficient immune response.^2,3,11 However, the ELISA is one of the most specific serologic tests that can be used, and a positive result for echinococcus antibodies confirms the diagnosis.³

Surgical excision is the preferred treatment.^8,12–14 Inoperable patients require long-term therapy with albendazole.^14,15 We recommend excising the cyst with the patient on cardiopulmonary bypass. Either aortic cross-clamping or aortic and pulmonic cross-clamping and a direct interventricular septal approach can be used to prevent dissemination of the parasite.^12,15 Venting the left atrium through the right upper pulmonary vein is generally safe in patients who have an interventricular hydatid cyst. The contents of the cyst must be entirely aspirated and the germinative membrane removed.^8,13

Although many protoscolicidal agents have been introduced, none is ideally effective and safe for intraoperative use. A 20% hypertonic saline solution is one of the few effective, relatively nontoxic protoscolicidal agents.¹⁴ This solution destroys protoscolices by creating a significant osmotic gradient.¹⁴ We have also used this solution to wash out the remaining cavity.^7,8,14 It is prudent to place solution-soaked sponges in the pericardial cavity during the operation to prevent local dissemination.¹²

Capitonnage can also be performed (Fig. 6).¹⁶ Albendazole therapy (400 mg twice daily) is typically prescribed for at least 4 days preoperatively and for 4 to 12 weeks postoperatively.^8,10,14

Conclusion

Although cardiac hydatid cysts can be fatal, they are rare and often asymptomatic in their early stages. Therefore, clinical suspicion is important for a correct diagnosis. Echocardiography, CT, and MRI are useful in the diagnosis and location of cardiac hydatid cysts. Combined surgical resection of an interventricular cardiac hydatid cyst, washout of the remaining cavity with hypertonic saline solution, and concurrent albendazole therapy typically yield excellent results.