Bashar Markabawi, M.D.

FELLOW IN CARDIOLOGY
UNIVERSITY OF CONNECTICUT HEALTH CENTER

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Case Presentation

A.M.G., a 25-year-old white male who worked as a shepherd in the rural area of Syria, presented in 10/94 to Al-Mouassat University Hospital because of unresponsiveness. The patient was brought by family after being found unresponsive with jerky movements, frothing at the mouth, and incontinent. The family reported that the patient was healthy until just before his presentation to the Emergency Room. He was not known to have any neurological disease or to have had any recent trauma. He was on no medication prior to presentation and had no known allergies. His family history was unremarkable. He was single and did not smoke or drink. His physical examination showed a young man, who was somnolent and mildly confused in a postictal state. His pulse was 100/min and his BP was 120/70. The jugular venous pressure was normal. The lung examination was unremarkable. The examination of the heart, except for tachycardia, was unremarkable. The first and second heart sounds were normal and no murmurs were audible. Both abdominal and extremity examinations were unremarkable. The neurological examination showed a confused young man with no focal signs. Laboratory data were obtained and demonstrated normal values for sodium, potassium, BUN, creatinine as well as glucose. The white count was 7,500 with the differential of 60% neutrophils, 22% lymphocytes and 17% eosinophils.

Figure 1: MRI of the brain demonstrating a cystic lesion in the left parietal region.

The patient was sent to the MRI suite to rule out a mass lesion of the brain and the study revealed a cystic lesion in the left parietal area (figure 1). Because of the patient's occupation and exposure, the suspicion of a hydatid cyst was high and an indirect hemagglutination test was obtained, which was positive.

Figure 2: Intraoperative view of the hydatid cyst.

Figure 3: Hydatid cyst after surgical removal.

The MRI findings were discussed with the patient. Surgical removal (the only curative strategy) was recommended and was carried out uneventfully (see figures 2 and 3). During recovery, frequent ventricular ectopic beats were seen on the monitor and cardiology consultation was obtained. The patient was seen and found to have multiple PVC's with occasional bigeminy, but was asymptomatic and awake at the time and reported no chest pain or shortness of breath. An ECG was obtained which demonstrated deep symmetrical T-wave inversions in the anterior leads. A two-dimensional echocardiographic study was obtained to assess for possible ventricular ischemia. This study revealed normal left ventricular systolic function without regional wall motion abnormalities. However, there was a possible cystic mass in the posterior wall of the left ventricle (see figures 4 and 5). Serial cardiac enzymes were negative for evidence of acute infarction.

Figure 4: Parasternal long axis 2-D echocardiographic view with
a cystic lesion in the left ventricular posterior wall (arrow).

Figure 5: Apical four-chamber 2-D echocardiographic view with
a cystic lesion in the left ventricular posterolateral wall (arrow).

There was a drop in blood pressure to 75/40 and fluid resuscitation was started. A repeat ECG was obtained showing the same T-wave abnormalities. The patient was taken to the catheterization laboratory to rule out coronary artery occlusion. The coronary angiogram was normal, but the left ventriculogram revealed a possible cyst (figure 6). The left ventricular end diastolic pressure was normal and there were no significant wall motion abnormalties. The patient improved with fluid resuscitation.

Figure 6: Left venticulogram during cardiac catheterization.
The radiolucency within the left ventricle (arrow) localizes the hydatid cyst.

These study findings were discussed with the patient as well as the need to have the hydatid cyst removed, but the patient refused to undergo cardiac surgery. He was started on mebendazole 1200 mg per day for three months and this was followed by 600 mg per day for another four months. Patient was seen in follow-up and was doing well with no recurrent ectopy. He ultimately agreed to undergo cardiac surgery and the cystic mass was removed and was confirmed by pathology to be a hydatid cyst or echinococcus granulosus of the heart. It was described as a "cystic mass with hyalinized multi-layered wall, with inflammatory reaction in the adjacent tissues. The mass also contains daughter cysts".

Discussion

Hydatidosis is an infestation of the human tissue by the larvae of the echinococcus granulosus. The ova of the tape worm are transmitted to humans by contact with infested dogs or cats, or by ingesting contaminated plants or water. It is generally believed that the hexacanth embryo, released from the ovum, first reaches the portal circulation via the intestinal mucosa.

The liver (followed by the lungs) is the organ most frequently infested by the larvae. Cardiac hydatid cyst comprises only less than 2% of all the hydatidosis cases. Serological testing is helpful in establishing the diagnosis. It may include complement fixation and/or indirect hemagglutination test. The Casoni test is not very reliable with frequent false-positive and false-negative results. Echocardiography is a reliable technique for diagnosing intracardiac masses, but in some cases the echo lucent and multi-septate nature of echinococcal lesions may be absent. Thus, in the appropriate clinical settings, echinococcal infections should be included in the differential diagnosis of tumor-like lesions of the heart.

Figure 7: Hydatid cyst (straight arrow) in the interventricular septum (curved arrow).

Figure 8: Parasternal short axis view at the level of the aortic valve (Ao).
The cyst (curved arrow) is shown prolapsing through the tricuspid valve (TV).

The cyst of the echinococcal infection can occur anywhere in the heart. The most common site is the left ventricle due to embolization through the left anterior descending artery. Most lesions are seen in the interventricular septum (figure 7) or in the left ventricular free wall. Other possible sites include the left or right atrium where the cyst may prolapse through the tricuspid and mitral valves in a fashion similar to a myxoma (figure 8). In some cases, the differentiation between a myxoma and hydatid cyst is made only after surgical removal. The pericardial space is another possible, although not common, site. However, patients with a pericardial cyst may develop constrictive pericarditis over time. We have seen patients with a large cyst compressing the right atrium that limits the flow to the right ventricle (figure 9).

Figure 9: Off axis apical view demonstrating a large hydatid cyst
(curved arrow) compressing the right atrium (straight arrow).

The curative management of echinococcus granulosus is surgical removal. However, medical management can be very helpful and supportive if started before surgery. Medical treatment may be initiated with albendazol by using five cycles of thirty days (10 mg/kg/day with rest periods of two weeks between the cycles) or by using mebendazole as described above in the case discussion. Surgical removal usually includes sterilization of the cyst before enucleation by injection or instillation of 2% formulin, 0.5% silver nitrate solution, 30% hypertonic saline solution, 1% iodine solution or 5% cetimide solution. This precautionary measure is performed to prevent dissemination of the infection in case of rupture of the cyst. Most patients do well on the anti-parasitic medicine as well as with surgical treatment. Fortunately, mortality is relatively low. Routine echocardiographic screening may be useful in endemic regions when infestation is likely. Patients who have hydatidosis of the lungs or other organs also should undergo a routine 2D echo to rule out asymptomatic echinococcus of the heart.

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