British Journal of Radiology (2007) 80, e278-e282
© 2007 British Institute of Radiology
doi: 10.1259/bjr/78279821
Hydatid cyst of the cardiac interventricular septum: report of two cases
S K Muthu, DMRD
1
A Thiagarajan, DMRD
2
S Govindarajan, DMRD, DNB
2
C M A Coutinho
3
W J Gunawardena
3 and
T S Swaminathan, MD, DMRD, FICR
2
1 Hammersmith Hospital NHS Trust, London, UK, 2 Barnard Institute of Radiology, Madras Medical College, 3 Royal Preston Hospital, Preston, UK
Correspondence: Dr Senthil Kumar Muthu, Hammersmith Hospital NHS trust, 10, Ducane road, East Acton, London W12 0HS, UK. E-mail: msekumar{at}yahoo.com
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Abstract
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Cardiac hydatid cysts are rare and represent less than 2% of all hydatid cases. They can occur as part of a widespread systemic infection or as an isolated event. Cardiac hydatid cysts rarely involve the interventricular septum. Here, we present two cases of cardiac hydatid disease in which one patient had the lesion in the interventricular septum and the other in both the interventricular septum and the apex of the heart. A brief overview of the disease and the role of echocardiography, dynamic enhanced multidetector computed tomography (MDCT) and MRI imaging in establishing the diagnosis are discussed.
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Introduction
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Hydatid disease is a parasitic infestation caused by Echinocccus granulosus and less frequently Echinococcus multilocularis [1]. It is endemic to many parts of the world, including the eastern part of Turkey, parts of South America, Africa and the Mediterranean [1]. In humans, the disease most commonly involves the lung and the liver; cardiac involvement is very rare and occurs in less than 2% of cases [1]. Cardiac hydatid disease can present with non-specific symptoms, and therefore imaging plays a significant role in the diagnosis. We report two cases of cardiac hydatid disease, in which one patient had a lesion in the interventricular septum and the other in both the interventricular septum and cardiac apex.
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Case 1
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A 32-year-old male farmer presented with non-specific precordial chest pain, haemoptysis and exertional dyspnoea of 8 months' duration. The pulmonary component of the second heart sound was loud and his electrocardiogram (ECG) revealed features of right ventricular hypertrophy with right bundle-branch block. A chest radiograph revealed small well-defined non-calcified homogenous rounded opacities in the left lower zone. The cardiac shadow was normal. Echocardiography revealed a large 6.0x4.5 cm well-defined non-calcified cystic lesion with thin internal septations in an intramyocardial location at the junction of the right ventricle and the interventricular septum, producing a honeycomb or cartwheel appearance (Figure 1
), without significant haemodynamic compromise. Multidetector computed tomography (MDCT) (Four slice Lightspeed Plus; General Electric, India) showed a large multiloculated lesion in the interventricular septum, bulging into the right ventricular cavity. The cyst contents were hypodense and there was no cyst or wall calcification (Figure 2). MRI showed a large septated lesion in the interventricular septum (Figure 3). The cyst contents were profoundly hyperintense on T2 weighted sequences, akin to water. The intervening septae had a comparatively lower signal. MRI also showed the left lower zone lung opacities to be unilocular and cystic, with water-like contents. An indirect haemagglutination test for E. granulosus was positive at a titre of 80. The lesion was approached through a right ventriculostomy under cardio-pulmonary bypass. This revealed a cyst with a glistening white appearance (Figure 4), which was injected with hypertonic saline and sterilized. The daughter cysts were then removed and the cyst wall was completely excised.
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Figure 1. Echocardiography shows a large well-defined non-calcified cystic lesion with thin internal septations in an intramyocardial location at the junction of the right ventricle and the interventricular septum, producing a honeycomb or cartwheel appearance.
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Figure 2. Contrast-enhanced axial MDCT section shows large multiloculated lesion with a "cartwheel-like" appearance in the lower interventricular septum bulging into the right ventricular cavity.
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Figure 3. AxialT2 weighted MRI section shows a large septated lesion in the interventricular septum with water-like hyperintense contents and relatively hypointense intervening septae. Small fluid-filled daughter cysts are also noted in the left lower lobe.
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Figure 4. Pre-operative photograph shows a glistening white thick-walled lesion in the exposed right ventricular cavity arising from the lower part of the interventricular septum.
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Case 2
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A 27-year-old woman complained of occasional left-sided chest pain with shortness of breath that had been occurring for 2 years. There was no history of contact with sheep or dogs. An ECG revealed non-specific T wave changes in the inferolateral leads. The chest radiograph did not reveal any abnormality. An echocardiogram showed a large multiseptated cystic lesion in the lower interventricular septum and the cardiac apex, bulging into the left ventricular cavity, without any significant intraventricular pressure gradient. MDCT (Four slice Lightspeed Plus; General Electric, India) showed a large 7.5x6.7 cm multiseptated cystic lesion with hypodense contents (Figure 5a) in the lower intraventricular septum, extending to the cardiac apex. Coronal reformation displayed the extension of the lesion to the cardiac apex (Figure 5b). MRI revealed the cyst contents to be T2 hyperintense (Figure 6), separated by hypointense septae. The indirect haemagglutination test was positive. Pre-operative albendazole was administered at a dose of 10 mg kg–1 for 10 days; the cyst was then approached through a left ventriculostomy and injected with hypertonic saline. However, the cyst was ruptured and was eventually removed piecemeal. Histopathological examination revealed the characteristic multilayered non-nucleated laminated membrane (Figure 7).
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Figure 5. (a) MDCT axial section shows a large multiseptated cystic lesion with hypodense contents in the lower intraventricular septum, extending to the cardiac apex. (b) MDCT coronal reformation shows the multiloculated cyst in the lower part of the interventricular septum extending to the cardiac apex.
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Figure 6. AxialT2 weighted MRI section reveals a multiloculated cyst with hyperintense contents and relatively hypointense septae bulging into, and occupying most of, the left ventricular cavity.
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Figure 7. Photomicrograph(x50; haematoxylin-eosin stain) of the hydatid cyst wall shows a characteristic non-nucleated laminated membrane composed of innumerable laminations.
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Discussion
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Hydatid disease is commonly caused by the parasite E. granulosus. Dogs and other carnivores are the primary host and sheep the intermediate host, whereas humans are the accidental intermediate host who do not complete the life-cycle of the parasite. Humans usually become affected by the ingestion of food or water contaminated by dog faeces containing the eggs [1].
The embryos called oncospheres hatch in the intestine and migrate either through the portal venous system or the lymphatic system. Those entering the portal system become lodged in the capillaries of the liver, where they either die or develop into hydatid cysts [1]. Some pass through this capillary sieve and lodge in other organs, including the lungs and the right side of the heart [1]. The parasite reaches the heart via the pulmonary artery, the coronary artery or via a patent foramen ovale [2].
In the initial stages of infection, the hydatid cyst often appears unilocular and contains a watery transudate. Histologically, the hydatid cyst consists of three layers: the pericyst is the protective outer layer formed principally by host reactive tissue; the middle layer is the laminated membrane permeable to nutrients; and the inner germinal layer gives rise to the scolices [1].
As the cyst grows, daughter cysts or brood capsules are formed from the germinal layer within the mother cyst, giving rise to the typical multiloculated "cyst-within-cyst" or "cartwheel" appearance. The daughter cysts are filled with a watery transudate of serum which contains proteins that are antigenic and capable of provoking anaphylaxis. These daughter cysts are separated from each other by the hydatid matrix. The matrix is composed of hydatid sand-containing membranes of broken daughter vesicles and scolices [1]. A dead cyst becomes calcified.
Cardiac hydatid cysts account for less than 2% of all hydatid diseases [1]. They most commonly affect the left ventricle (55–60%), but also the right ventricle, left atrium (8%), pulmonary artery, pericardium (7–8%) and the interventricular septum (5–9%) [1]. The clinical features of cardiac hydatid disease depend upon the site, size and stage of the cyst and the presence of haemodynamic consequences. When the interventricular septum is involved, disturbances in rhythm and haemodynamics, conduction blocks and features of right or left ventricular outflow tract obstruction can occur. Angina, valvular dysfunction and pulmonary hypertension, depending upon the location of the lesion, have also been reported. Complications such as anaphylaxis and embolisation into pulmonary and systemic sites can occur. Early diagnosis of this condition is crucial to avoid these complications. Occasionally, these cysts have been reported to cause coronary artery compression [3].
The chest radiograph can often appear normal, as occurred in our cases. Depending upon the location, size and stage of the cyst, abnormalities of the cardiac contour and calcifications may be noted.
The multiloculated cystic nature of the lesion and presence of daughter cysts are well demonstrated on echocardiography. The haemodynamic consequences of the lesion can also be assessed. Echocardiography also excels in the demonstration of thin floating membranes, small daughter cysts and hydatid sand. The non-invasive nature of the modality and lack of cardiac motion artefacts (which both occur with MDCT and MRI) make echocardiography the modality of choice in imaging cardiac hydatid disease [4]. The potential limitations of this technique include operator dependence, relative difficulty in studying retrosternal lesions, and the lack of depiction of structures posterior to calcifications. Infected hydatid cysts can sometimes appear as echogenic lesions, resembling secondary cardiac tumours [5].
On MDCT, the mother cyst and multiple daughter cysts can be identified. The contents of the mother cyst — the hydatid matrix — are often of higher attenuation than those of the daughter cysts, which contain a water-like transudate. The cyst walls also enhance moderately with intravenous iodinated contrast [1]. A dead cyst can become totally calcified [1]. Multiplanar isotropic reconstructions allow accurate delineation of the anatomical site of the lesion and the relationship to adjacent cardiac chambers. Furthermore, the internal cystic structure posterior to calcifications may be demonstrated. Artefacts owing to cardiac motion have been reduced with the advent of MDCT. An additional advantage with CT is the ability to concurrently study the adjacent lung parenchyma.
The outer pericyst is fibrous and may contain calcifications. This can result in a hypointense rim on both T1 and T2 weighted sequences. This appearance is suggestive of a hydatid cyst, although a similar rim may occur in an abscess or haematoma in other organs [1]. The water-like nature of the contents of the daughter cyst results in a low signal on T1 weighted images and a high signal T2 weighted images, which allows for high contrast between the lesion and the adjacent cardiac soft tissue. The daughter cysts separated by the matrix form the spokewheel appearance, with the daughter cysts appearing more hyperintense than the cyst matrix [1]. Floating membranes that have a low signal on all sequences give rise to the "serpent sign" but this is more frequently described in hepatic lesions [1]. Gadolinium administration that allows delineation of the cyst from the myocardium can show enhancement of the cyst walls. This enhancement may aid in the differentiation of non-infective cysts from hydatid cysts [1]. The inability to demonstrate calcifications, however, is a potential drawback. Multiplanar imaging coupled with cardiac gating allows accurate delineation of the site of the lesion.
Several serological tests including Casoni's intradermal antigen test, complement fixation test, indirect haemagglutination test and enzyme-linked immunosorbent assay (ELISA) are available. The source of antigen for these tests is the hydatid cyst fluid obtained from sources such as bovine or equine hydatid [6]. The indirect haemagglutination test or ELISA for immunoglobulin G (IgG) [7] antibodies to E. granulosus hydatid fluid antigen has been employed as a screen for E. granulosus infection. This may be followed by confirmatory tests such as arc-5 immunoprecipitation or antigen B subunit 8 kD immunoblotting [8]. Total IgG (IgG1 and IgG2) has been shown to be sensitive for the disease at clinical presentation. Furthermore, assays for IgG2 antibody response have been found to correlate with disease activity during follow-up and may aid in the confirmation of disease cure or relapse [9, 10].
The accuracy of serological tests depends upon multiple factors. For example, the sensitivity and specificity depend upon the type and quality of preparation of the antigen and the method employed [6, 8]. False-positive results have occurred in the presence of hydatid disease elsewhere in the body, in the presence of cross-reacting cestode antigens and in the presence of tumours such as gastrointestinal neoplasms and lymphomas [8]. False-negative results have been obtained in several situations. As leakage of cyst fluid is believed to be essential for immunosensitization, an unruptured cyst can result in a false-negative result [8]. Calcified cysts in locations such as the lung have also resulted in negative serological results. Furthermore, it has been reported that serological tests may be negative in untreated patients [8].
Once the diagnosis of a hydatid cyst in the heart is made, immediate surgery is the treatment of choice because of the potential risk of rupture and anaphylaxis. The cysts may also rupture into the pericardial cavity and cause pericardial effusion or tamponade and the formation of daughter cysts [11].
Only high-risk patients or those with a small completely calcified cyst (indicating a dead cyst) and no haemodynamic complications have been considered for conservative therapy [11]. This often takes the form of oral therapy with albendazole. Albendazole was administered for both of our patients pre-operatively and continued post-operatively for 4 weeks, principally to prepare for possible cyst rupture and dissemination of daughter cysts during the surgical procedure. Leakage of cyst contents by spontaneous cyst rupture, either during surgery or during treatment with mebendazole, also carries the risk of anaphylaxis. A combination of corticosteroids, H1 and H2 receptor antihistamines and benzodiazepines have been advocated as cover for anaphylaxis [12, 13].
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Conclusions
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Cardiac hydatid is a very rare manifestation of hydatid disease. The diagnosis is suggested by the identification of daughter cysts in a multiseptated lesion, presence of hydatid sand, wall calcifications and the spokewheel appearance. Echocardiography is the modality of choice for the diagnosis of cardiac hydatid cysts, owing to its widespread availability, high sensitivity, superior resolution and the ability to analyse concurrent haemodynamic consequences. MDCT and MRI may aid in accurate localization of the lesion, detection of multiple lesions, study of concurrent lung lesions and detection of multiorgan involvement, as well as differential diagnosis and follow-up [14].
Received for publication May 4, 2005.
Revision received July 5, 2005.
Accepted for publication August 24, 2006.
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References
|
|---|
- Polat P, Kantarci M, Alper F, Suma S, Koruyucu MB, Okur A. Hydatid disease from head to toe. Radiographics 2003;23:475–94.[Abstract/Free Full Text]
- Thameur H, Abdelmoula S, Chenik S, Bey M, Ziadi M, Mestiri T, et al. Cardiopericardial hydatid cysts. World J Surg 2001;25:58–67.[CrossRef][Medline]
- Elangovan S, Harshavardan K, Meenakshi K, Swaminathan TS, Murthy P. Left ventricular hydatid cyst with myocardial infarction in a patient with severe rheumatic mitral stenosis. Indian Heart J 2004;56:664–7.[Medline]
- Siwach SB, Katyal VK, Jagdish. Cardiac echinococcosis — a rare echocardiographic diagnosis. Heart 1997;77:378–9.[Abstract/Free Full Text]
- Ceviz M, Becit N, Kocak H. Infected cardiac hydatid cyst. Heart 2001;86:E13[CrossRef][Medline]
- Irabuena O, Nieto A, Ferreira AM, Battistoni J, Ferragut G. Characterization and optimization of bovine Echinococcus granulosus cyst fluid to be used in immunodiagnosis of hydatid disease by ELISA. Rev Inst Med Trop Sao Paulo 2000;42:255–62.[Medline]
- Grimm F, Maly FE, Lu J, Llano R. Analysis of specific immunoglobulin G subclass antibodies for serological diagnosis of Echinococcosis by a standard enzyme-linked immunosorbent assay. Clin Diagn Lab Immunol 1998;5:613–6.[Medline]
- Poretti D, Felleisen E, Grimm F, Pfister M, Teuscher F, Zuercher C, et al. Differential immunodiagnosis between cystic hydatid disease and other cross-reactive pathologies. Am J Trop Med Hyg 1999;60:193–8.[Abstract]
- Bulut V, Ilhan F, Yucel AY, Onal S, Ilhan Y, Godekmerdan A. Immunological follow-up of hydatid cyst cases. Mem Inst Oswaldo Cruz 2001;96:669–71.[Medline]
- Lawn SD, Bligh J, Craig PS, Chiodini PL. Human cystic echinococcosis: evaluation of post-treatment serologic follow-up by IgG subclass antibody detection. Am J Trop Med Hyg 2004;70:329–35.[Abstract/Free Full Text]
- Akar R, Eryilmaz S, Yazicioglu L, Eren NT, Durdu S, Uysalel A, et al. Surgery for cardiac hydatid disease: an Anatolian experience. Anadolu Kardiyol Derg 2003;3:238–44.[Medline]
- Koppen S, Wejda B, Dormann A, Seesko H, Huchzermeyer H, Junghanss T. [Anaphylactic shock caused by rupture of an echinococcal cyst in a 25-year-old asylum seeker from Georgia]. Dtsch Med Wochenschr 2003;128:663–6.[CrossRef][Medline]
- Appell RG, Gundert D, Bartholome K, Wahn U. [Anaphylactic reactions in mediastinal echinococcosis]. Immun Infekt 1983;11:46–50.[Medline]
- Kurugoglu S, Kizilkilic O, Ogut G, Mihmanli I, Akman C, Tanrikulu H. Primary cardiac hydatid disease: cross-sectional imaging features. South Med J 2002;95:1140–4.[Medline]
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Abstract
Introduction
