INTRODUCTION

The retrieval of a foreign body in vessels or body cavities is a common procedure in the department of interventional radiology. Most of the retained foreign bodies are the fragments of a fractured central venous catheter or a drainage catheter (1-3). Although the incidence rate of catheter fractures in the body is low,those cather fragments may cause a variety of complications, including thrombosis, arrhythmia, and infection (4-6). In most cases, the retained foreign bodies can be removed with a snare (gooseneck or en-snare), basket catheter, or forceps technique.However, in some cases, the retrieval can be very difficult due to the special angle or position of the foreign bodies. We described here the in situ formation of the loop snare technique applied by the combining a gooseneck snare and a loach guide wire to retrieve foreign bodies.

MATERIALS AND METHODS

This is a retrospective study that was approved by the institutional review board (IRB). Informed consent was obtained before the procedures. All of the retained fractured catheter fragments were diagnosed before the procedures.

From July 2009 to August 2014, 2 males and 4 females with an average age of 55 years, (range,22-89 y) were included in this study. There were 4 patients with a ruptured peripherally inserted central venous catheter (PICC) and 2 patients with catheter fractures of an implantable venous access port catheter(IVAP). The demographic and clinical information is listed in the Table 1.

在工程施工中，材料是实际项目管理中第一要点，进场材料的质量好坏，将直接影响工程的施工质量。因此加强对施工现场的材料验收能够有效的提升工程整体的施工质量，避免工程质量问题的发生。通过严格验收，能够直接有效的对工程施工的源头进行材料质量上的管理与控制，在保障安全的前提下，最大限度地保证项目的施工质量水平。

In situ formation of the loop snare technique: A new loop snare was formed by combining a 0.035-inch loach guide wire (Terumo Coroporation, Tokyo, Japan)with a 2.5-cm diameter Amplatz gooseneck snare(Covidien, Irvine, CA, US). First, the gooseneck snare and the guide wire were introduced via an 11-Fr introducer sheath (Bard Access System, Salt Lake City, UT, US). Then the snare and the guide wire were placed on the two sides of the fractured central vein catheter. Next, the gooseneck snare was used to snare the tip of the guide wire, and then a new loop snare was created around the fractured catheter (Figure 1).Then the sheath was pushed forward to affix the new loop snare in place of the gooseneck snare. The gooseneck snare, sheath, and guide wire were pulled out of the vessel together.

RESULTS

A total of 6 foreign bodies were retrieved with the combined gooseneck snare and loach guide wire.There were 4 fractured Groshong NXT PICC catheters(Bard Access System, Salt Lake City, UT, US) and 2 X-Port isp™ implantable port catheters (Bard Access System, Salt Lake City, UT, US).

If the end of the fractured catheter floats in large blood vessels, such as in the superior vena cava, the free end can be easily captured with a gooseneck snare.However, in some cases, the distal end of the fractured catheter may move to the right atrium or the pulmonary artery, while the proximal end remains in the subclavian vein. In this situation, surgery in the right atrium or pulmonary artery with a gooseneck snare increases the risk of valve injury and may cause fatal complications (13,14). It has been reported that the gooseneck snare may damage the tricuspid valve when the catheter has moved to the right atrium (14).As in the 4 patients with a fractured PICC reported here, it is difficult to capture the fractured catheters with the gooseneck snare because there are no free ends. However, with the technique we described, the physician can control the loach guide wire, which makes the process easier than using the gooseneck snare alone. Although crocodile squeezers are convenient to operate, not all departments have access to them, and their use is limited by the diameter of the foreign body. There have been some case reports of port catheter displacement, but it is a moderately uncommon complication (3,15-18). We developed this technique from the report for the retrieval of a foreign bodies without free ends (19). This technique was first used in patients in our interventional radiology department who had fractured port catheters that could not be captured with a goose neck snare alone (20). This process can prevent injury to the heart valves. Another advantage is the three components of the guide wire, snare, and the foreign body in the tangent plane of the foreign body. The Texan foreign body retrieval device is similar in that the orientation of loop does not change when the snare is used to capture the foreign body (3). The in situ formation loop technique has the similar characteristic of the guide wire or the snare when the guide wire and snare are placed on each side of the foreign body. The guide wire was fixed and captured with the snare in our series of patients.

The retrieval of foreign bodies is a common procedure in interventional radiology departments.Although a variety of techniques, including stone basket extraction and cardiac biopsy, has been used,and new devices have been developed for the retrieval of foreign bodies, the gooseneck snare has been the most widely used device in retrieving foreign bodies(3,7). The fracture of central venous catheters isuncommon yet serious. The fractured catheters always move with the refluxed blood flow to the right atrium,some as far as the pulmonary artery. Severe complications such as cardiac arrest, pulmonary embolism, and perforation of the heart and blood vessels may occur and lead to serious results(3,6,8-12).

DISCUSSION

导师很可能因为同是在校生的身份而不被实践团队普遍认可。因此，强化导师的角色是个关键，如:通过创造更多的机会展示朋辈导师的个人魅力;课程实践指导教师通过课堂途径加大对朋辈导师角色的解读力度;通过文体形式、心理疏导等活动增强导师现身的频次等，以增强实践团队成员对朋辈导师的认可度。

Table 1 Profile of 6 patients with foreign body and time of operation.

Patient Gender Age Etilogy Catheter Proximal end Distal end Duration of foreignbody(day)Duration of the operation(min)1 Female 22 Leukemia Port catheter Right subclavian vein Right atrium 10 3 2 Male 48 Leukemia Port catheter Superior vena cava Right atrium 1 2 3 Male 89 Colon cancer PICC Left axillary vein Right atrium 1 3 4 Female 37 Ovarian cancer PICC Right subclavian vein Lower left PA 10 4 5 Female 61 Cervical cancer PICC Right subclavian vein Lower right PA 1 3 6 Female 71 Ovarian cancer PICC Left subclavian vein Lower right PA 1 4

Figure 1. (A) One end of the fractured peripherally inserted central venous catheter (PICC) was located in the left subclavian vein and the other end in the right pulmonary artery. (B) We placed the 0.035 inch guide wire on one side of the PICC. (C) We then placed the gooseneck catheter on the other side to snare the guide wire. (D) We dragged the snare and the guide wire together back to the guiding catheter. (E)Finally, we dragged the guiding catheter out.

No free ends were present on the fractured catheters.The proximal end of the fractured PICC was located in the right subclavian vein, left subclavian vein, or the axillary vein (Figure 2), and the distal end was located in the right atrium (Figure 3), the right inferior pulmonary artery, or the left inferior pulmonary artery.Two patients had fractured catheter fragments, both of the port catheter. In one patient, the aforementioned fracture occurred 10 days after implantation into the left subclavian area, and an X-ray showed that the catheter had fractured and migrated. The catheter’s tip had migrated to the right subclavian vein while the broken end had migrated to the right atrium. In the other patient, the fracture occurred 64 days after the catheter was implanted into the right subclavian area.The catheter moved to the superior vena cava and right atrium. With the loop snare technique, it took 2-4 min to snare the foreign body. The entire operation took 15 to 32 min (from femoral venous puncture to hemostasis), and no serve complications were observed during or after the surgery.

Figure 2. Female, 22 years old; implantable venous access port catheter (IVAP) fracture 10 days implantation. (A) The proximal end of the catheter had migrated to the right subclavian vein (white arrow) while the broken end had migrated to the right atrium (black arrow). (B) We introduced the 0.035-in loach guide wire through the 10F guiding catheter (white arrowhead). (C) We placed the gooseneck snare (white arrow) on one side of the IVAP (black arrow) to snare the guide wire (white arrowhead) on the other side. (D) We arranged the guide wire(white arrow) to form a circle structure, and the catheter of IVAP (black arrowhead) should be in this circle structure. (E) We used the gooseneck snare capture the end of the guide wire, then dragged the guidewire into the guiding catheter, and the fractured catheter was then dragged back into the guiding catheter. (F) Finally, we removed the guiding catheter (black arrowhead).

Figure 3. Male, 89 years old, 1 day after the fracture of the peripherally inserted central venous catheter (PICC). (A) The distal end of the fractured PICC is located in the right atrium (white arrow) while the proximal end in the left axillary vein. (B) Use the looping technique by combining the gooseneck snare (black arrowhead) with the loach guide wire (black arrow) together, we successfully dragged the fractured catheter (whiter arrow) back into the guiding catheter. (C) We then dragged the guiding catheter out of the blood vessel, and no residual fragments were found.

In conclusion, the looping technique combining the gooseneck snare with the guide wire can make it easier and safer to retrieve foreign bodies. The technique proves effective for retrieving foreign bodies of different diameters by providing a very sturdy retrieval apparatus that helps prevent the catheter from falling off. This new technique can help interventional physicians use simple instruments to perform tough tasks.

For retrieval of fractured PICCs like those described in our study, we suggest that using the looping technique immediately is the best choice.

式中：QL，QR分别为服务于IOL和IOR的堆垛机执行出库任务运行时间的数学期望;Pijk和分别为存储在第k排货架，第i列、第j行货位的货物的出/入库频率和最短出库时间；E，e共同描述当货位中货物出/入库交由用时最短的堆垛机时，两堆垛机的工作区域，即第1列～第E列货位由左端堆垛机负责，第e列～第I列货位由右端堆垛机负责；xijk为判断第k排货架，第i列、第j行货位是否为空的决策变量。

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