Ann Thorac Surg 2007;84:2108-2110. doi:10.1016/j.athoracsur.2007.04.081
© 2007 The Society of Thoracic Surgeons
Case Reports
Severe Chronic Pulmonary Hypertension Caused by Pulmonary Embolism of Hydatid Cysts
Semih Buz, MD*,
Christoph Knosalla, MD, PhD,
Sead Mulahasanovic, MD,
Rudolf Meyer, MD, PhD,
Roland Hetzer, MD, PhD
Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum Berlin, Berlin, Germany
Accepted for publication April 20, 2007.
* Address correspondence to Dr Buz, Deutsches Herzzentrum Berlin, Department of Cardiothoracic and Vascular Surgery, Augustenburger Platz 1, Berlin, D-13353, Germany (Email: buz{at}dhzb.de).
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Abstract
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Severe pulmonary hypertension caused by chronic pulmonary thromboembolism may still present an indication for lung transplantation. We report a rare case in which severe pulmonary hypertension developed after pulmonary embolism of hydatid cysts. Successful treatment in this patient was achieved by complete pulmonary endarterectomy of the hydatid cysts.
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Introduction
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Pulmonary embolism caused by hydatid cysts is a rare complication of cardiac or hepatic echinococcosis. To date, there have only been a few cases reported and most of these involved acute embolisms. Herein, we report a rare case of severe pulmonary hypertension caused by pulmonary hydatid cyst embolization. The patient was referred to our institution for evaluation for lung transplantation after the appearance of right-sided heart failure. Treatment by pulmonary endarterectomy was successful.
A 30-year-old woman originating from a Mediterranean country who had severe pulmonary hypertension and right heart failure was referred to our institution for evaluation for lung transplantation. She had a history of excision of a hydatid cyst by resection of the right lateral segment of the liver at the age of 19. During this operation, the inferior caval vein was accidentally injured and she was put on mebendazole (Vermox; Janssen-Cilag GmbH, Neuss, Germany). On postoperative day 2, a fulminant pulmonary artery embolism occurred. As a thromboembolic event was suspected, the patient was treated with intravenous heparin. She was able to compensate, recovered well, and was clinically fit for the next 10 years, after which progressive right heart failure became apparent. On admission to our institution she presented with severe ascites and peripheral edema and was in New York Heart Association functional class III. Physical examination showed poor ventilation of the right lower lung and liver enlargement. An enzyme-linked immunosorbent assay test for serum-anti-echinococcal antibodies was positive with a titer of 1:3200 (negative control < 1:100). Right heart catheterization revealed severe pulmonary hypertension with a pulmonary artery pressure of 120/60 mm Hg (mean, 80 mm Hg), which equalled systemic blood pressure. Mean right atrial pressure was 35 mm Hg and cardiac index was 1.9 L/min/m2. Arterial blood PO
2 was 48% and CO
2 was 38 mm Hg, with O2 saturation of 88%. Electrocardiographic recordings showed a right axis deviation and signs of right ventricular hypertrophy. Echocardiography showed no cysts in the cardiac chambers or pericardial cavity, but documented mild tricuspid valve insufficiency and distended pulmonary artery with severe distension and hypertrophy of the right ventricle. Magnetic resonance imaging (MRI) of the chest with contrast enhancement revealed complete occlusion of the right pulmonary artery (Fig 1), with all segments of the left lung visualized. No evidence of hydatid cysts was found in the abdomen.
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Fig 1. Magnetic resonance imaging of the chest with contrast enhancement. Complete occlusion of the right pulmonary artery by the hydatid cyst.
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The patient was scheduled for pulmonary endarterectomy. Surgery was performed using standard cardiopulmonary bypass through a median sternotomy with cannulation of the ascending aorta and cannulation of the superior and inferior caval veins for drainage. Deep hypothermia of 16°C was induced, followed by intermittent circulatory arrest (total time, 28 minutes) without cardioplegic solution. A left ventricular vent was inserted through the right upper pulmonary vein. After protection of the adjacent tissues with wet sponges soaked with hypertonic saline solution, the main pulmonary artery and the right pulmonary artery were incised longitudinally between the ascending aorta and superior caval vein. The main right pulmonary artery was occluded by several hydatid vesicles of different sizes, some of them attached to the vascular endothelium. These vesicles (Fig 2a) were carefully dissected from the endothelium and removed down to the pulmonary artery subsegments and submitted to bacteriologic and histologic examination. The pulmonary artery tree was irrigated with hypertonic saline solution and the arteriotomy was closed with a 5-0 polypropylene running suture. Inhaled nitric oxide (40 ppm) was administered prophylactically during weaning from the cardiopulmonary bypass. Early postoperative pulmonary artery pressure was reduced to 50/27 mm Hg (mean, 38 mm Hg). Histology confirmed the diagnosis of hydatid cyst caused by Echinococcus granulosus (Fig 2b). The patient recovered well after surgery and was discharged 2 weeks later.
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Fig 2. (a) Part of the vesicular mass removed from the right pulmonary artery. (b) Histologic examination of the hydatid cyst (Elastic van Gieson stain) showing chitin membranes (arrows).
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Comment
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Hydatid disease is caused by a parasitic infection with Echinococcus granulosus in the larval stage and is endemic in many sheep-rearing regions of the world, especially in Mediterranean countries. Parasites can reach any part of the body, but the organs most often affected are the liver by 75% and the lung by 15%, whereas cardiac involvement is encountered in less than 2% of all cases.
Pulmonary or systemic embolism caused by hydatid cysts or vesicles rupturing into the venous or arterial system is extremely rare [1]. The origin of pulmonary emboli is the right ventricle, the right atrium, or the liver. According to the clinical presentation, hydatid pulmonary embolism has three possible outcomes: (1) early death due to acute embolism, (2) subacute pulmonary hypertension with death in less than 1 year, and (3) chronic pulmonary hypertensive cases. In our case, embolism was most likely caused during the first operation on the liver 10 years ago when the inferior caval vein was injured. Unexpectedly, cardiac hydatidosis had not occurred. Hydatidosis was suspected because of the medical history of the patient and a significant titer of anti-echinonococcal antibodies, but the definitive diagnosis was only made intraoperatively after histopathologic examination.
Two-dimensional echocardiography, spiral computed tomographic scan, MRI, and possibly conventional pulmonary angiography are the diagnostic procedures of choice for the investigation of patients with suspected hydatid pulmonary embolism. The presence of anti-echinococcal antibodies and eosinophilia in blood tests make the diagnosis more likely and hydatid pulmonary embolism should be suspected even if there is no previous history of hydatid disease.
Echocardiography is the imaging method of choice for cardiac and pericardial cysts, but it rarely enables direct visualization of a pulmonary embolus. Transesophageal echocardiography may visualize massive emboli in the main pulmonary arteries [2]. Spiral computed tomographic scan and MRI are more useful in the diagnosis of extracardiac echinococcosis, and MRI is more advantageous than a spiral computed tomographic scan for examination of the heart and large vessels, with images in multiple phases giving a more complete anatomic picture [3]. In our case, preoperative MRI revealed an occlusion of the right pulmonary artery with free peripheral branches, which is important for the success of surgical therapy in pulmonary embolism. However, MRI failed to differentiate between thromboembolism and hydatid cyst.
Chronic pulmonary embolism results in pulmonary hypertension and eventually pulmonary and heart failure [4], as in the case we describe herein. Without intervention, chronic embolic pulmonary hypertension is a progressive and lethal disease for which pulmonary endarterectomy is the treatment of choice. Lung transplantation is only indicated in a few cases when pulmonary endarterectomy is not feasible. Surgery under cardiopulmonary bypass, profound hypothermia, and circulatory arrest is the therapy of choice with good long-term results. Although outcome in patients exhibiting a mean pulmonary artery pressure greater than 60 mm Hg or pulmonary vascular resistance higher than 1,000 dynes/s–1/cm–5 is poor [5, 6], surgical treatment was successful in our patient despite severe pulmonary hypertension (mean pulmonary artery pressure, 80 mm Hg). We believe that inhaled nitric oxide therapy contributed to this success because of its selective effectiveness as a pulmonary vasodilator. In conclusion, this case shows that hydatid cysts as a cause of pulmonary hypertension need to be suspected even 10 years after primary diagnosis. Pulmonary endarterectomy of the hydatid cysts may make it unnecessary for lung transplantation. Scrupulous precautions are necessary both intraoperatively and perioperatively to avoid spreading of the hydatid cysts.
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Acknowledgments
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We thank Anne Gale, editor in the life sciences, for her editorial assistance.
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References
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- Gougoulakis D, Moulopoulos LA, Alexanrou K, et al. A rare cause of respiratory failure: Echinococcus of the pulmonary artery Am J Roentgenol 1998;171:1163-1164.
- Martin R. Acute embolism 1: pathophysiology, clinical presentation and diagnosis Heart 2001;85:229-240.[Free Full Text]
- Desnos M, Brochet E, Cristofini P, et al. Polyvisceral echinococcosis with cardiac involvement imaged by two dimensional echocardiography, computed tomography and nuclear magnetic resonance imaging Am J Cardiol 1987;59:383-384.[Medline]
- Riedel M, Stanek V, Widimsky J, et al. Long term follow-up of patients with pulmonary thromboembolism: late prognosis and evaluation of hemodynamic and respiratory data Chest 1982;81:151-158.[Medline]
- Ando M, Okita Y, Tagusari O, et al. Surgical treatment for chronic thromboembolic pulmonary hypertension under profound hyperthermia and circulatory arrest in 24 patients J Card Surg 1999;14:377-385.[Medline]
- Jamieson SW, Kapelanski DP, Sakakibara N, et al. Pulmonary enderterectomy: experience and lessons learned in 1,500 cases Ann Thorac Surg 2003;76:1457-1464.[Abstract/Free Full Text]
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Abstract
Introduction
