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MMCTS
(April 25, 2005). doi:10.1510/mmcts.2004.000307 Copyright © 2005 European Association for Cardio-thoracic Surgery
Procedure Resection of intrathoracic and subdiaphragmatic hydatid cystsSureyyapasa Thoracic and Cardiovascular Diseases Teaching and Investigation Hospital, Maltepe, 81530 Istanbul, Turkey * Corresponding author: * Tel.: +90-532-2660234, Fax: +90-216-3520954. E-mail: semihh{at}atlas.net.tr
The goal of surgical therapy in pulmonary hydatid disease is to remove the cyst while preserving as much lung tissue as possible. The surgical method may be different in the intact (simple) and ruptured (complicated) cysts. The operation has two steps: a) removal of the germinative layer, b) management of the residual pulmonary cavity. Simple cysts are generally removed after needle aspiration or enucleation without needle aspiration. Enucleation cannot be performed in ruptured cysts. The lung cavity that remains after removal of the cyst may be left as it is or obliterated by sutures from within the cavity in regard to the size and location of the cyst. However, the bronchial openings in the cavity must be closed by sutures in all cases. Rarely, hydatid cysts can occur in other thoracic structures such as pulmonary artery, chest wall or diaphragm. Those cysts located on the liver dome are operated by transthoracic–transdiaphragmatic approach. The surgical methods performed for the resection of hydatid cysts located in the chest or in the subdiaphragmatic area are presented with an overview of the literature.
Key Words: Hydatid cyst • Pulmonary • Pulmonary artery • Chest wall • Liver
The cyst Hydatid disease is a parasitic infection caused by Echinococcus granulosus [1]. The cyst lodges most commonly in the liver and the lungs, respectively. Morphologically, hydatid cyst consists of three layers and hydatid fluid. The first layer is the pericyst or adventitia which is the host tissue formed by the lung as a reaction to the foreign body (parasite). The other two layers, the laminated membrane (external layer of the cyst) and the germinative layer (inner layer of the cyst), belong to the parasite (Photo 1). The cyst fluid (Photo 2) resembles water in appearance which may contain daughter vesicles.
The cysts exist in different forms: intact (Photo 3) or ruptured (Photos 4, 5), single (Photo 4) or multiple (Photos 3, 6), unilateral or bilateral, solely located in the lung or concomitantly in other organ lodgements (especially in the liver).
General principles of the operation The aim of surgery in pulmonary hydatid cyst is to remove the cyst completely while preserving the lung tissue as much as possible [2,3,4,5]. Lung resection is performed only if there is an irreversible and disseminated pulmonary destruction. Careful manipulation of the cyst and adherence to the precaution to avoid the contamination of the operative field with the cyst content is the imperative part of the operation. The cysts located on the liver dome are easily accessible and resected via right thoracotomy with the transdiaphragmatic approach [4,6].
Finding the cyst Once the chest is opened, the lung is palpated gently to avoid the rupture of the cyst. The anaesthesiologist deflates the lung in the operated site and the surgeon finds the cyst located in the depth of the lung tissue easily if it is not very small or if it is located superficially (Video 1). The smaller cyst located within the parenchyma is found by gentle palpation of the lobe that is obtained to have the cyst in computerized tomography of the chest.
Covering the adjacent lung with the towels Because there is always a risk of spillage of daughter vesicles into the operating field during the operation, the lung should be surrounded by sterile towels immediately at the beginning of the operation. Only the area of the cyst-containing lung must be in the operating field before any attempt be made to remove the cyst or aspirate the cystic fluid (Video 2).
Removal of the cyst The intact cysts are removed in one of the two ways: removal of the cyst following aspiration of the cystic fluid, or by enucleation of the cyst without aspiration of the fluid. Ruptured cysts can only be removed by aspiration of the cyst content, then by the removal of the cyst membrane [2,3,4,5]. 1. Removal of the cyst following aspiration of the cystic fluid. The intact cysts may contain living vesicles suspending in the cystic fluid. A careful aspiration of the fluid prevents the dissemination of the vesicles into the chest or to the bronchus. The aspiration is performed with a syringe adapted to a 3-valved aspiration catheter. Ten percent povidone iodine may be injected into the cyst through the same catheter to kill the living vesicles within the cyst (Video 3).
When minimal fluid is left in the cystic cavity, the needle insertion site is enlarged and suction apparatus is inserted into the cyst to aspirate the residual fluid completely. After the aspiration has been completed, the edges of the pericyst are enlarged in an extent so that the laminated membrane can easily be taken out. The assistant grasps the edges of the pericyst and the surgeon takes the laminated membrane (which is generally disrupted) out of the cavity (Video 4). 2. Enucleation of the intact cyst without needle aspiration. Enucleation is performed by removing the intact cyst from the cystic cavity by a careful dissection between the pericyst and the laminated membrane. Pericystic layer is incised or cut superficially until the laminated membrane of the cyst is seen. This incision is then extended to a certain length so that the delivery of the cyst is possible. The pericyst is separated from the laminated membrane patiently by sharp and blunt dissections. Inflating the lung by the anaesthesiologist and gentle and adjusted manual pressure over the surrounding lung by the surgeon assist the delivery (Video 5). The cyst is delivered over the gauze steeped in povidone iodine and then taken out of the chest with the gauze (Video 6).
Management of the residual cavity When the cyst is removed, the remaining pulmonary cavity is cleaned completely with sterile gauze and, observed for the presence of air leakage. Air leakage can be seen by direct observation and also by filling the cavity with sterile saline solution. The cavity is filled with the fluid only after closure of the major bronchial opening(s) has been performed (Video 7).
The simple alveolar air leakage is not an important issue, which can easily be managed during the obliteration of the cavity with imbricating sutures. The obliteration (capitonnage) is made by circumferential imbricating separated sutures with a 3-0 chromic catgut or a 3-0 coated polyglactin from within the cavity (Video 8) [3,4].
When two steps of the resection of the cyst(s) have been accomplished, the towels surrounding the lung are taken out from the chest using the grasping instruments. Because the towels may contain cystic material, the hands must not be used in their removal from the operative field (Video 9).
Transthoracic–transdiaphragmatic approach to the subdiaphragmatic hydatid cysts Not infrequently, thoracic surgeons are asked for the management of hydatid cysts located at the upper part (subdiaphragmatic location) of the liver (Photo 7). A thoracotomy provides better exploration and access to the cyst located in this area when compared to the laparotomy [4,6].
The principal of the resection of liver cyst is similar with the pulmonary cyst; however, there are important technical differences between the two operations: the hepatic cysts contain daughter vesicles more commonly than the pulmonary cysts [7]. For this reason, a scolocidal agent (to kill the parasite) such as hypertonic saline solution or 10% povidone iodine must be injected through the diaphragm into the cyst to prevent the spreading of the living vesicles in the abdomen or thorax before the opening and removal of the cyst. The diaphragm is cut using a scissors and its muscle is separated from the cyst by blunt and sharp dissections with no pressure over the cyst. When the intracystic pressure has been lowered, the cyst is opened from the uppermost part of the cyst and its content is aspirated by a large holed suction device (Video 10).
Because the cyst contains numerous daughter vesicles that are not technically possible to aspirate with a suction device or take out by a grasper, a spoon is used to evacuate the cavity completely (Video 11).
A rubber tube is inserted into the cavity and taken out from the skin under the diaphragm. The edges of the cyst's fibrous capsule are closed with mattress sutures [6,8].
Removal of the hydatid cysts from the main pulmonary artery
Resection of the hydatid cyst located on the thoracic wall The chest wall is one of the unusual locations (Photo 11) of the hydatid cyst [10]. Because there is no cavity left after the removal of the cyst on the chest wall, the surgical technique includes only the removal of the cyst.
The assistance provided by the team is greatly appreciated: Surgical assistance: Volkan Baysungur, Erdal Okur and Mertol Gokce. Video imaging: Leyla Tuncer. Technical assistance in adjustment of the videos and photographs to the required specifications: Koray Tuncer.
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