Asian Cardiovasc Thorac Ann 1998;6:54-56
© 1998 Asia Publishing EXchange Pte Ltd
Total Resection of Interatrial Septal Echinococcosis
Ali Asghar Bolourian, MD
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Cardiac Surgery Division Ghaem University Medical Center Mashad, Iran
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For reprint information contact: Ali Asghar Bolourian, MD 5 Dadgar Avenue Ahmad Abad Boulevard Mashad 91766, Iran Tel:98 51 80 0001 Fax:98 51 80 9612
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ABSTRACT
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Echocardiography indicated a myxoma in the right atrium of a 19-year-old male who suffered an episode of syncope. At surgery, a mass containing hydatid cysts was found in the interatrial septum. The patient underwent en bloc resection of the cysts and patch closure of the defect in the interatrial septum. Transient atrioventricular dissociation was observed for 12 hours postoperatively. Subsequent radiography revealed very two small cysts in the lungs, which were treated with albendazol. The patient made a good recovery with no recurrence during the short-term follow-up.
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INTRODUCTION
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In spite of the prevalence of echinococcosis in many Mediterranean countries, the involvement of the heart by echinococcus granolosus is uncommon. It appears in only 0.4% to 2% of patients with echinococcosis due to invasion of the myocardium through the coronary circulation.1 An extremely rare case of cardiac echinococcosis presenting as a huge right atrial myxoma is described here, including the echocardiographic characteristics and the surgical technique for removal of the cysts.
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CASE REPORT
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A 19-year-old male soldier with no previous history of hydatid cystic disease was admitted to an army hospital because of an episode of syncope during strenuous military exercise. Radiography and laboratory examinations were negative but echocardiography showed a right atrial mass attached to the interatrial septum (Figure 1
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Figure 1. Echocardiogram (four chamber view) showing right atrial mass of hydatid cysts extending towards the left atrial cavity.
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After a median sternotomy, the aorta and superior vena cava were cannulated but the inferior vena cava had to be cannulated lower than normal due to the protrusion of a hard irregular mass from the right atrium into the pericardial cavity. Cardiopulmonary bypass was established, the aorta was cross-clamped, and cold crystalloid cardioplegia was employed. The right atrium was opened obliquely revealing a dense mass consisting of approximately 30 small cysts surrounded by a fibrous layer and attached to the interatrial septum from the top of the septum to the tricuspid valve (Figure 2). En bloc resection of the cystic mass was performed without perforation of the fibrous layer that was surrounded by saline sponges. However, some connective tissue at the base of the mass was left. The large defect in the interatrial septum was closed with a Dacron patch. The patient was easily weaned from cardiopulmonary bypass and the postoperative period was uneventful except for transient atrioventricular dissociation that converted spontaneously to sinus rhythm after 12 hours.
Subsequent chest radiograph revealed two small cysts of less than 1 cm in diameter in each lung. These were confirmed by standard thoracic computed tomography scanning, while an abdominal scan showed that the liver and other abdominal organs were free of hydatid cysts. The patient was discharged on the 5th postoperative day and received four 30-day cycles of albendazol 10 mg•kg–1 per day with a rest period of 2 weeks between cycles. At the 12-month follow-up his echocardiogram and electrocardiogram were normal and he was feeling well (Figure 3).
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Figure 3. Echocardiogram at 3 months after surgery showing an intact interatrial septum.
LA = left atrium, LV = left ventricle, RA = right atrium, RV = right ventricle.
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DISCUSSION
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Cardiac echinococcal hydatid cystic disease is caused by the small tapeworm, taenia echinococcus or echinococcus granolosus. Parasites in the alimentary tract of dogs shed ova that contaminate the food of sheep. Hydatid cysts develop in the viscera including the lung of sheep. When infected sheep are slaughtered and the entrails are eaten by dogs, the life cycle of the organism is completed. Humans interrupt this sequence when hands or food become contaminated with canine fecal material containing the ova of the worm. The ingested parasitic larvae burrow through the gastric mucosa and are carried to the liver in the portal venous circulation where most of the larvae are filtered out. Some form hydatid cysts of the liver, others lodge in the lungs or other organs where they form one or more hydatid cysts. Most cysts are unilocular and consist of an external laminated cuticula and an inner germinal layer.2 The heart is rarely affected and the cysts are usually located in the free wall of the left ventricle (50% to 77% of cases). Pericardial involvement occurs in 50% of cases but the localization of hydatid cysts in the interatrial septum is extremely rare.1,3,4
The cardiovascular manifestations of cardiac echinococcosis include palpitation, syncope (as a result of conduction abnormalities, arrhythmias, or valvular or outflow tract obstructions), angina, pulmonary or systemic emboli, or sudden death in 20% of cases.1,5 However, most patients with cardiac hydatid cysts are free of symptoms. The episode of syncope in the patient reported here was caused by tricuspid valve obstruction during strenuous exercise. Electrocardiography in such cases might show varying degrees of atrioventricular or intraventricular block, premature ventricular contractions, nonspecific repolarization changes, or electrically inactive zones.1 Chest radiograph might reveal the diagnosis from the presence of pulmonary cysts or the finding of a round mass with calcification on the cardiac silhouette. Echocardiography may reveal the number, location, and size of the cysts.6 Two-dimensional echocardiography is of greater diagnostic value than computed tomography or nuclear magnetic resonance imaging, which are more useful for extracardiac echinococcosis.7 Cardiac catheterization has helped to define the relationship of the cysts to the coronary arteries.1
The preoperative diagnosis of right atrial myxoma in this patient was based on the echocardiograms. Postoperative re-evaluation of the echocardiograms revealed the invasion of a cystic mass beyond the atrial septum towards the left atrial and right ventricular cavities, which could have distinguished between a myxoma and hydatid cysts (Figure 1
). It is recommended that echinococcal infection should be included in the differential diagnosis of solid mass lesions of the heart.8 Serologic diagnosis can be obtained by several methods such as a radioallergosorbent test, an indirect hemagglutination reaction, a basophil degranulation test, and a latex agglutination test. Indirect hemagglutination has a sensitivity of 82% and a specificity of 91%; these rates are similar to those of the radioallergosorbent test. Serologic tests were not performed in this patient because of the inappropriate diagnosis before surgery.
It is currently accepted that treatment of cardiac hydatid disease must be surgical in all cases because of the incidence of sudden death (20%), rupture into the cardiac chamber (39%), or rupture into the pericardium (10%).1,3 A median sternotomy and the use of cardiopulmonary bypass is the safest surgical procedure. The risk of perioperative embolism justifies aortic cross-clamping and the use of cardioplegia. In cases such as this one of interatrial septal localization, total resection of the cysts by dissection of the external laminated cuticula (pericystectomy) may be the best treatment. For other localizations of these cysts the routine procedure is sterilization with hypertonic saline or glucose solution and aspiration. Patch closure of the defect in the cardiac wall is recommended to prevent myocardial rupture or aneurysm formation. Only patients with recurrent or inoperable disease should be considered candidates for chemotheraphy with albendazole. The recommended standard therapeutic regimen is four cycles of 30 days with a rest period of 2 weeks between cycles to avoid toxicosis (18% of patients have adverse effects).7 The lungs and liver must also be examined for hydatid cysts.
Although the diagnosis of intramural hydatid cystic disease of the heart is difficult by the available diagnostic tools, echocardiography may be the best modality for differentiating between hydatid cysts and other diseases such as myxoma. Resection of the cysts in this case of interatrial septal echinococcosis gave good results without recurrence in the short-term.
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Acknowledgments
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The author would like to thank Dr. Radpoor, Dr. Isazadeh, and Dr. Hassanzadeh who provided valuable echocardiograms before and after surgery.
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REFERENCES
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O'Connor F, Tellez G, Mantero C, et al. Hidatidosis cardiaca: a proposito de 10 cases intervenidos quirurgicamente. Rev Esp Cardiol
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Khaiari A, Fabre JM, Azali R, et al. Unusual locations of hydatid cysts. Ann Gastroenterol Hepatol Paris
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Desnos M, Brochet E, Cristofini P, et al. Polivisceral echinococcosis with cardiac involvement imaged by twodimensional echocardiography, computed tomography and nuclear magnetic resonance imaging. Am J Cardiol
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Davis A, Dison H, Pawaloski Z. Multicentric clinical trials of benzinidazole carbamates in human cystic echinococcosis (Phase 2). Bull WHO
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Klodas E, Roger VL, Miller FAJR, et al. Cardiac echinococcosis: case report of unusual echocardiographic appearance. Mayo Clin Proc
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ABSTRACT
INTRODUCTION
