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Tex Heart Inst J. 2009; 36(2): 174–176.
PMCID: PMC2676597

Direct Approach to Hydatid Cyst of the Interventricular Septum

Abstract

A 37-year-old woman who had undergone an operation for hydatid cyst of the liver 10 years earlier decided to have a check-up for echinococcosis, because she had not been seen by a clinician for 4 years. The case is of particular interest not only because it enabled a rare preliminary diagnosis of cardiac echinococcosis by simple electrocardiographic analysis, but also because our technique of excision appears to be one never before reported in connection with interventricular hydatid cysts. In such an instance, we recommend a direct approach (if possible) through the interventricular septum without entering the cardiac chambers, in order to avoid dissemination; and we recommend enucleation of the germinative membrane without capitonnage, to avoid impairment of the atrioventricular conduction pathway or of myocardial contraction. In our patient, electrocardiographic findings improved postoperatively at the 1-year follow-up examination.

Key words: Cardiac surgical procedures/methods, echinococcosis/diagnosis/surgery, electrocardiography, heart septum/parasitology/surgery

Echinococcal infestation is endemic in sheep- and cattle-raising areas of the world, notably in the Mediterranean countries, the Middle East, South America, Australia, and New Zealand.1,2 Cardiac echinococcosis is uncommon, accounting for 0.5% to 3% of all hydatid infestations in human beings.3 Hydatid cysts of the heart are located most often in the left ventricle; involvement of the interventricular septum (IVS) is rare and can cause symptoms arising from compression of the atrioventricular conduction pathway and obstruction of the right or left ventricular outflow tract.4

Case Report

A 37-year-old woman who had undergone an operation for hydatid cyst of the liver 10 years earlier decided to have a check-up for echinococcosis, because she had not been seen by a clinician for 4 years. Therefore, in December 2006, the patient was admitted to the internal medicine unit of our hospital, although she was asymptomatic. On physical examination, there were no findings indicative of disease. Electrocardiographic (ECG) analysis disclosed poor R-wave progression, low voltage at anterior leads V1 through V4, and an incomplete right bundle branch block (RBBB). Hence, she was sent to the cardiology unit.

Two-dimensional echocardiography (Fig. 1) showed a 2.75 × 1.75-cm cystic formation that arose from the IVS and bulged into the right ventricle; the left ventricular ejection fraction was 0.60. Serologic tests for echinococcus were negative. Abdominal and cranial computed tomographic (CT) scans ruled out those locations of the disease. Thoracic CT revealed a cystic formation of 3 × 2.5-cm dimensions in the same location as shown by echocardiography. The patient was referred to surgery immediately and received 15 mg·kg−1 albendazole for 2 weeks in order to decrease, preoperatively, the number of living parasites.

figure 23FF1
Fig. 1 Two-dimensional echocardiography shows a 2.75 × 1.75-cm hydatid cyst arising from the interventricular septum.

On-pump, beating-heart excision of the cyst was performed through the IVS via an incision adjacent to the left anterior descending artery, without entering any cardiac chambers; after the cyst was punctured and its fluid contents were aspirated, polyvinylprolidone iodine solution was instilled and enucleation was performed without capitonnage (Fig. 2). The epicardium was then sutured.

figure 23FF2
Fig. 2 Surgical excision of the germinative membrane of the hydatid cyst through a direct approach to the interventricular septum.

Histopathologic analysis of the surgical specimen confirmed that it was a hydatid cyst. At the patient's 1-year follow-up appointment, ECG analysis demonstrated that the R-wave progression had been restored, the voltage was normal, and the RBBB had disappeared. Echocardiographic results were normal and showed an ejection fraction of 0.65.

Discussion

In the middle of the last century, ECG had great importance not only in the diagnosis of ischemic myocardial events but in the diagnosis of intracardiac conditions such as hydatid cysts.5 The introduction of imaging techniques such as echocardiography, CT scanning, and magnetic resonance imaging has reduced the value of ECG in the diagnosis of space-occupying lesions of the heart.4 In this instance, however, poor R-wave progression on ECG, together with the patient's history of echinococcosis, led to a tentative diagnosis, which was confirmed with the aid of echocardiography and CT scanning.

Removal of the cyst improves myocardial compliance and myocardial perfusion, which corrects cardiac deformation and strengthens myocardial contraction.6 It has been reported that electrical activity, as well as contractile function, can be restored by excision of interventricular septal cysts.7 In our patient, there were no preoperative echocardiographic signs of obstruction, and the preoperative ECG findings of poor R-wave progression, incomplete RBBB, and low voltage at the anterior leads (V1–V4) disappeared by the end of the 1st postoperative year. We thereby infer that surgical removal of the cyst improved electrical activity.

In deciding upon an operative technique, the location of the cyst is of great importance.6 Most cysts in the ventricular myocardium can be resected off-pump, but isolated septal cysts are best resected under cardiopulmonary bypass (while the heart is arrested), because they are difficult to approach.6 Although in the case reported here we excised germinative membrane through the IVS without entering the cardiac chambers, we performed the surgery with the patient under cardiopulmonary bypass (without cross-clamping), because cystic rupture could otherwise have led to potentially lethal sequelae, such as embolic phenomena or anaphylactic shock.3,8,9 In most prior reports, hydatid cysts of the IVS have been excised through the right ventricle. We in fact did not encounter any article that reported the removal of a hydatid cyst of the IVS in a manner similar to ours: excision via the IVS, with no entry of cardiac chambers.

In 2000, there was a report10 of complete atrioventricular block necessitating VDD pacemaker implantation, secondary to enucleation and capitonnage of a hydatid cyst of the IVS. Performing capitonnage (closure of the cystic cavity with sutures) on the IVS might in that case have caused the conduction defect. In our judgment, the more the IVS is manipulated, the greater is the risk of a conduction or contraction defect. In order to avoid aggressive surgery, we excised the hydatid cyst, including the germinative membrane (which is a part of the hydatid cyst) but not the cyst capsule—because the capsule is formed from host tissue and is not a part of the cyst. Moreover, we chose not to perform capitonnage, because we wanted to keep intact the atrioventricular conduction pathway and the IVS (which has an important role in contractile function). The surgery did not adversely affect the contractile function or conduction pathway of the heart: indeed postoperative echocardiography revealed an unchanged ejection fraction of 0.65, and postoperative ECG findings actually improved.

In conclusion, the case reported here is of particular interest not only because it enabled a rare preliminary diagnosis of cardiac echinococcosis by simple ECG analysis, but also because our technique of excision appears to be one never before reported in connection with this entity. In cases of interventricular hydatid cysts, we recommend a direct approach (if possible) through the IVS without entering the cardiac chambers, in order to avoid dissemination; and we recommend excision of the germinative membrane without capitonnage, to avoid impairment of the atrioventricular conduction pathway or of myocardial contraction.

Footnotes

Address for reprints: Omer Zuhtu Yondem, MD, Department of Anesthesiology, Akay Hastanesi, Buklum Sokak, No. 4, Kavaklidere, Ankara 06660, Turkey. E-mail: moc.oohay@mednoyzremo

References

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8. Aydogdu T, Sahin N, Ulusan V, Gurpinar F, Turkay C, Bayezid O. Right atrial hydatid cyst associated with multiple organ involvement: case report. J Thorac Cardiovasc Surg 2001;121(5):1009–11. [PubMed]
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