Imaging findings of fatal embolic hemorrhagic stroke secondary to right ventricular hydatid cyst: A case report

Abstract

Cystic echinococcosis (CE) is a zoonotic infection caused by Echinococcus granulosus, primarily involving the liver and lungs. Cardiac involvement is rare (0.5%-2% of cases), and cerebral complications from cardiac CE are exceptionally uncommon but often fatal. A 19-year-old Afghan male with significant zoonotic exposures presented with progressive left flank pain, fever, nausea, and vomiting. Laboratory studies revealed elevated liver enzymes and thrombocytopenia. Thoracoabdominal computed tomography (CT) demonstrated a multiseptate hepatic hydatid cyst in segment III, and unexpectedly revealed a concomitant cardiac hydatid cyst in the right ventricle, which was further characterized by transthoracic echocardiography. The patient was scheduled for cardiac surgery and initiated on preoperative albendazole. However, hours before the procedure, he acutely developed right-sided hemiparesis and loss of consciousness. Emergent brain CT revealed an intracerebral hemorrhage (ICH) in the left middle cerebral artery (MCA) territory with intraventricular extension. Despite external ventricular drain placement, the patient died shortly thereafter. This case represents a rare fatal outcome of cardiac CE originating in the right ventricle, where cerebral embolization was the probable cause of the left MCA territory ICH. It underscores the critical need for high clinical suspicion of cardiac involvement in all CE patients and emphasizes the urgency of early surgical intervention to prevent catastrophic neurological sequelae.

Introduction

Human cystic echinococcosis (CE) is a zoonotic parasitic infection primarily caused by the larval stage of Echinococcus granulosus [1]. The life cycle of Echinococcus involves wild and domestic canids as definitive hosts and ungulates such as cattle, goats, sheep, and pigs as intermediate hosts that harbor hydatid cysts or the larval form of the parasite [2]. Humans are accidental hosts, and are usually infected by consuming water or food that has been contaminated with parasite eggs [3]. CE is highly prevalent in rural regions of Afghanistan and the Middle East, where canids have easy access to offal containing hydatid cysts from infected intermediate hosts [4]. The prevalence of CE in the human population of this region has been reported to be as high as 15.6% [5]. CE represents a major public health concern in developing nations such as Iran [6]. The disease carries a considerable economic burden, with costs estimated at approximately 0.03% of the country's gross domestic product [7]. Furthermore, CE accounts for roughly 1% of all hospital surgeries performed in Iran, underscoring its substantial impact on the healthcare system [8]. In approximately 80% of CE cases, a single organ is involved, with the liver and lungs being the most frequently affected sites (73.4% and 19.6% of cases respectively) [9]. Cardiac involvement is rare, occurring in only 0.5%-2% of all CE cases [10]. Although central nervous system (CNS) involvement accounts for only 2%-3% of all hydatid cyst cases worldwide, the consequences are particularly severe due to CNS's vulnerability, often resulting in debilitating neurological symptoms and life-threatening complications [11]. We describe a rare fatal case of CE involving the liver and heart, in which the cardiac cyst in the right ventricle was the presumed source of probable embolic cerebral involvement of the middle cerebral artery (MCA), leading to intracerebral hemorrhage (ICH) and death.

Case presentation

This report describes the case of a 19-year-old Afghan male who worked as a plasterer. His history was notable for significant zoonotic and dietary exposures in Afghanistan, where he lived in close contact with dogs and sheep and consumed raw meat and groundwater. Two years prior to his presentation, he had relocated to Iran.

His initial complaint was of progressive, colicky pain in the left flank, accompanied by fevers, nausea, and vomiting, approximately one month prior to admission. Physical examination on admission revealed a scar at the McBurney point; however, no medical records were available to confirm a history of appendectomy. Examination also elicited tenderness in the right lower quadrant, but was otherwise unremarkable.

Laboratory evaluations showed elevation in aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, prothrombin time, and international normalized ratio (158 U/L, 254 U/L, 190 U/L, 18.3 s, and 1.5 respectively). The complete blood count was unremarkable except for mild platelet deficiency at 128000 cells/mm³. Additional tests including blood sugar, electrolytes, procalcitonin, and erythrocyte sedimentation rate were normal. Two sets of blood cultures were obtained, both of which remained negative. Given the patient's clinical presentation, a stepwise radiological evaluation was performed to determine the extent of hepatic involvement.

Initially, an abdominal ultrasound assessment revealed a spleen measuring 92 mm in diameter. The liver parenchyma appeared normal; however, it was remarkable for a 33 × 41 mm multiseptate cystic lesion with a rosette-like appearance in segment III.

Further evaluation with non-enhanced thoracoabdominal computed tomography (CT) confirmed a 36 × 42 × 27 mm hydatid cyst in liver segment III, characterized by a calcified wall and the presence of internal daughter cysts. Critically and as an unexpected finding, the study also revealed a similar cystic lesion located in the right ventricle of the heart (Fig. 1).

Fig. 1.

Non-enhanced thoracoabdominal CT scan. (A) Axial abdominal CT image demonstrating a round hypodense well-defined, multilocular cystic lesion in liver segment III (36 × 42 × 27 mm), which exhibits thin wall calcification and internal daughter cysts, highly suggestive of a hydatid cyst (red arrow). (B, C) Axial and coronal thoracic CT scans reveal an incidental multiseptate cystic lesion in the right ventricle, consistent with a cardiac hydatid cyst (yellow arrow).

To assess the cardiac function, a transthoracic echocardiography (TTE) was performed. The study revealed normal left and right ventricular size and function. However, multiseptate cyst-like lesions were observed at the right ventricle. The cyst appeared to be intramural with a thin layer of myocardium surrounding it, and the endocardial surface overlying the cyst was intact with no evidence of erosion or direct communication with the ventricular cavity. No pedunculated or mobile intracardiac components were observed.

Following the confirmation of a cardiac hydatid cyst, the patient was scheduled for surgical intervention and received pre-operative albendazole therapy. However, 48 hours after diagnosis, and approximately 4 hours prior to the planned surgical start time, he acutely developed right-sided hemiparesis followed by a progressive loss of consciousness over the subsequent 30 minutes. An emergency brain CT scan, performed approximately 90 minutes after symptom onset revealed an ICH within the left frontoparietal lobe, in the territory of the left MCA, with extension into the adjacent lateral ventricle (Fig. 2). An external ventricular drain was placed approximately 3 hours after the CT scan. Despite these measures, the patient died approximately 12 hours after the initial neurological deterioration, with the ICH presumed to be the cause of death. No vascular imaging (such as CT angiography or digital subtraction angiography) was performed to evaluate for a mycotic aneurysm or arterial occlusion. No TTE or transesophageal echocardiographic shunt study (eg, bubble study) was performed to evaluate for a patent foramen ovale or other right-to-left shunt. An autopsy was not performed due to cultural and religious beliefs of the patient's family.

Fig. 2.

Axial non-enhanced brain CT scan after the development of right-sided hemiparesis demonstrates an ICH within the left frontoparietal lobe, involving the territory of the left MCA, with extension into the adjacent lateral ventricle (blue arrow). Significant mass effect and midline shift are observed.

Discussion

This case describes a patient with multi-organ CE involving the liver and heart, in which presumed embolization from the cardiac cyst to the left MCA territory likely resulted in fatal hemorrhagic infarction.

Cardiac involvement is a rare manifestation of Echinococcus granulosus infection [12]. Cardiac CE typically result from the larvae reaching the myocardium via hematogenous dissemination through the coronary arteries [13]. The distribution of cardiac hydatid cysts likely reflects regional coronary blood flow, with the most vascularized areas being the most susceptible [14]. Accordingly, the left ventricle is the most common site of involvement (55%-60% of cases), followed by the right ventricle (10%-15%) [15]. In our case, the CT scan identified a cardiac hydatid cyst in the right ventricle, confirmed by TTE.

Most patients with cardiac CE remain asymptomatic for long periods, due to the slow growth of hydatid cysts, with growth typically limited to 1 cm per year [16]. When symptoms do manifest, they are typically nonspecific and vary based on cyst location, size, and interaction with adjacent structures [17]. Common clinical presentations include chest pain, palpitations, cough, and dyspnea, which may result from pericardial stretching or compression of the coronary arteries [14]. However, an emergency arises when the hydatid cyst grows toward the endocardium or epicardium, as constant mechanical shear stress can lead to cyst rupture [18]. Spillage of cyst contents into the bloodstream or pericardial sac may then cause vascular events such as ischemic stroke, limb ischemia, abdominal aortic occlusion or splenic and renal infarctions, as well as potentially fatal anaphylactic reactions [16]. To avoid the complications of rupture, cardiac cysts should be treated without delay [19]. Our patient presented with nonspecific symptoms, including left flank pain, fever, nausea, and vomiting. Although he was scheduled for cardiac cyst surgery promptly following diagnosis, he ultimately died, most probably from an embolic stroke, in the absence of an anaphylactic reaction.

In endemic areas, relying on epidemiology and imaging patterns is essential in diagnosing CE [20], as serological test may lack specificity and sensitivity in these areas [21]. Echocardiography, CT scan, and magnetic resonance imaging (MRI) are the imaging modalities used in the diagnosis of cardiac hydatid cysts [22]. Transthoracic two-dimensional echocardiography is currently the preferred imaging test for the diagnosis of cardio-pericardial hydatid cysts [23]. TTE allows for the identification of cysts, determination of their location, assessment of potential complications, and evaluation of both regional and global left ventricular diastolic and systolic function [24]. On CT and MRI, cardiac hydatid cysts typically appear as well-defined, spherical, homogeneous cystic lesions with smooth and thin walls, without perilesional edema [25]. The cyst wall typically does not show contrast enhancement; however, enhancement may be seen in cases of superimposed infection [26]. CT is particularly effective for detecting daughter cysts, calcifications, and multivesicular architecture [27]. Furthermore, thoracoabdominal CT allows for the identification of possible involvement of other organs [26].

Uncommon localizations of echinococcosis often mimic inflammatory, congenital, or neoplastic lesions [28]. Several cardiac conditions can cause confusion in diagnosing a cardiac hydatid cyst, including left ventricular aneurysm, myxoma, fibroma, rhabdomyoma, cardiac sarcoma, intracardiac thrombus, and pericardial calcifications from other etiologies [26]; therefore, differential diagnosis plays a central role, and radiological imaging becomes the cornerstone of evaluation. In our case, radiological evaluation revealed a calcified, multiseptate hepatic hydatid cyst with daughter cysts and a concomitant multiseptate cystic lesion in the right ventricle on CT, confirmed by TTE.

Cerebral echinococcal embolism originating from a cardiac source has been previously described in the literature and typically occurs in the distribution of the terminal branches of the middle cerebral artery [29]. This can culminate in ischemic stroke due to cerebral artery occlusion [24,[30], [31], [32], [33]]. Interestingly, El Malih et al. [34] report a case of multiple infarcts involving both cerebral hemispheres and ICH in a patient with a left ventricular cardiac cyst and associated mobile vegetations, with the hemorrhage determined to be secondary to a ruptured mycotic aneurysm. In our case, ICH occurred in the left MCA territory. While the precise cause is unknown, possible explanations include hemorrhagic transformation of an echinococcal embolic infarct or rupture of a mycotic aneurysm. The former mechanism may be particularly relevant here, as thrombocytopenia is a recognized risk factor for hemorrhagic transformation following cerebral ischemia [35].

An interesting aspect of our case is the paradoxical finding that, although the hydatid cyst was situated in the right ventricle, the patient developed a left MCA territory hemorrhagic stroke that we presume to be of probable embolic origin. This seemingly paradoxical phenomenon may be hypothesized to occur via several potential mechanisms. The most likely, in our view, being paradoxical embolism via an undiagnosed patent foramen ovale or another right-to-left shunt, which would allow embolic material to bypass the pulmonary circulation and enter the systemic arterial system. Alternative hypothetical mechanisms include the transpulmonary passage of small parasitic elements through the capillary bed, or, in rare cases, direct cyst extension into the left ventricular cavity through the interventricular septum. Furthermore, a coincidental arteriovenous malformation (AVM) or other vascular malformation—as AVMs are the leading structural etiology of ICH in adults younger than 40 years [36]—cannot be excluded as another possible cause of the ICH. We emphasize that definitive proof of any of these mechanisms—such as vascular imaging, echocardiographic shunt evaluation, autopsy confirmation or antemortem imaging evidence of a right-to-left shunt—was not obtained in this case. Nonetheless, this case demonstrates that right-sided cardiac hydatid cysts might carry a risk of systemic embolization and should not be considered benign despite their anatomical location.

Conclusion

We reported a fatal case of multi-organ CE complicated by probable embolic hemorrhagic stroke presumably originating from a hydatid cyst in the right ventricle. The hemorrhage, localized to the left MCA territory (frontoparietal region), exhibited a pattern that we hypothesize to be consistent with an embolic origin from the cardiac hydatid cyst. This fatal outcome reinforces the need for clinicians to consider the heart not just as another site of disease in multi-organ CE, but as a potential source for devastating embolic phenomena, including hemorrhagic stroke.

Ethical approval

As a case report, our study did not require an approval from our institutional clinical ethics committee.

Patient consent

Written informed consent was obtained from the patients next of kin after his death for the publication of this case report.