Ruptured Pericardial Hydatid Cyst Causing Mitral Annulus Distortion With Severe Mitral Regurgitation and Tamponade-like Symptoms: A Case Report

Introduction

Hydatid disease, a parasitic zoonotic infection caused by Echinococcus granulosus, is characterized by the formation of multiple cysts in various organs. Transmission occurs via the fecal–oral route. The disease is endemic in regions where livestock farming is common, including rural areas of the Mediterranean, Africa, the Middle East, and South America. The liver and lungs are the most commonly affected organs, with reported involvement rates of 50% to 70% and 20% to 30%, respectively. In rare cases, cardiac involvement occurs (0.5–2%) [1]; the left ventricle is most frequently affected due to its rich blood supply. Cysts may occur in any cardiac location; however, pericardial involvement is particularly uncommon, representing approximately 7% of cardiac cases [2].

Pericardial hydatid cysts may remain asymptomatic for prolonged periods; however, rupture can result in life-threatening complications, including anaphylaxis, acute pericarditis, cardiac tamponade, and pulmonary edema. These clinical manifestations are often nonspecific and may mimic other cardiac emergencies, thereby complicating diagnosis given the rarity of the condition. We report an unusual presentation of mitral annular distortion and severe mitral regurgitation secondary to rupture of a pericardial hydatid cyst. This case highlights the diagnostic complexity and critical management considerations of cardiac hydatid disease, particularly when presentation is acute and atypical.

Case Report

INVESTIGATIONS:

Laboratory evaluation revealed leukocytosis (white blood cell count: 13000 cells/μL; local normal range, 4000–11000 cells/μL) and elevated inflammatory markers, including C-reactive protein and erythrocyte sedimentation rate. Subsequent serologic testing for E. granulosus yielded positive results. Blood cultures were negative. Cardiac biomarkers demonstrated minimally elevated troponin I with normal creatine kinase–MB levels. The brain natriuretic peptide concentration was 107 pg/mL (local normal range, <29 pg/mL). Mild elevations in liver enzymes and mild renal impairment were also noted. Electrocardiography showed sinus tachycardia with low-voltage QRS complexes and no ischemic changes (Figure 1). Chest radiography demonstrated mild cardiomegaly with bilateral alveolar infiltrates (Figure 2).

Transthoracic echocardiography revealed an ill-defined mass encroaching on the posterior aspect of the mitral annulus, causing at least moderate mitral regurgitation (Figure 3A–3C). Transesophageal echocardiography confirmed a ruptured cyst within the pericardium, leading to distortion of the mitral annulus and severe mitral regurgitation (Figure 4A–4C; Videos 1, 2). Contrast-enhanced echocardiography findings were negative for left ventricular free wall rupture.

Abdominal computed tomography demonstrated 2 hepatic cysts highly suggestive of hydatid disease (Figure 5). Chest computed tomography confirmed a multiloculated cystic lesion within the pericardial sac; there was evidence of rupture and multiple daughter cysts within the pericardial fluid compressing the mitral valve apparatus (Figure 6). Computed tomographic angiography showed patent pulmonary arteries.

Based on the clinical presentation and the results of these investigations, alternative diagnoses, including pulmonary embolism, acute coronary syndrome, aortic dissection, and papillary muscle rupture, were excluded. Accordingly, a working diagnosis of ruptured pericardial hydatid cyst causing anaphylaxis and tamponade-like symptoms was established. Compression of the posterior mitral annulus led to distortion of the mitral valve apparatus, followed by severe mitral regurgitation and pulmonary edema.

MANAGEMENT:

Symptomatic severe mitral regurgitation constitutes a class I indication for mitral valve replacement according to the American College of Cardiology/European Society of Cardiology guidelines for management of valvular heart disease. Accordingly, surgical excision of the cyst with concomitant mitral valve replacement was planned. The patient was stabilized with diuretics, corticosteroids, antihistamines, vasodilators, and supplemental oxygen. Antihelminthic therapy with albendazole was initiated. Subsequently, the patient underwent open-heart surgery via median sternotomy. Intraoperatively, the cyst was adherent to the posterior mitral annulus, with partial extension into the atrioventricular groove. Evacuation and complete excision of the ruptured pericardial hydatid cyst were conducted (Figure 7). Debridement and irrigation of the pericardial space with hypertonic saline were performed to avoid recurrence. Restoration of mitral annular geometry was achieved, followed by mitral valve replacement with a 31-mm mechanical prosthesis (Figure 8).

Recovery was uneventful. Histopathological examination confirmed hydatid disease. Five days after surgery, the patient was discharged on albendazole (400 mg twice daily for 6 months). Follow-up echocardiography at 3 months demonstrated a well-functioning mitral valve without residual pericardial effusion. At the 12-month follow-up, no recurrence was detected, and he remained asymptomatic (Videos 3, 4;Figure 9).

Discussion

Cardiac hydatid disease is exceedingly rare – cysts are most commonly located in the left ventricle and infrequently involve the pericardium. In the literature, hydatid cysts associated with mitral regurgitation are typically intramyocardial and encompass structures such as the left atrium, left ventricle, or papillary muscles [3–5]. To our knowledge, a single report has described a pericardial hydatid cyst causing mitral regurgitation [6].

In the present case, the unusual pericardial location adjacent to the mitral annulus resulted in annular distortion, severe mitral regurgitation, and subsequent pulmonary edema. Additionally, rupture of the cyst into the pericardial space led to anaphylaxis and tamponade-like symptoms.

Given that cardiac hydatidosis is uncommon, a high index of suspicion is required for diagnosis. Imaging represents the preferred diagnostic approach because no specific laboratory tests exist for this condition. Echocardiography remains the mainstay of diagnosis due to its noninvasive nature and absence of radiation exposure. Computed tomography and magnetic resonance imaging may also be used to better delineate lesion location and to differentiate among various types of cardiac masses [7].

Surgical resection is the treatment of choice, even in asymptomatic patients, because rupture may result in life-threatening complications. Complete cyst excision is essential to reduce the risk of dissemination or anaphylaxis [8]. Postoperative albendazole therapy is recommended to decrease the risk of recurrence; it may also serve as the sole treatment when surgery is not feasible [9].

Conclusions

This case adds to the limited literature on pericardial hydatid cysts and their potential to cause acute valvular dysfunction. It highlights the importance of considering parasitic etiologies in the differential diagnosis of acute mitral regurgitation, particularly in endemic regions. Moreover, it illustrates how external valvular distortion originating from an extracardiac source may mimic more common structural causes. These findings emphasize the need for comprehensive imaging and multidisciplinary collaboration in diagnosis and management.