Operative Thrombectomy for Acute Thrombosis of Lower Extremity Bypass Grafts



Operative Thrombectomy for Acute Thrombosis of Lower Extremity Bypass Grafts



Neal S. Cayne and Frank J. Veith


When a synthetic graft used to treat lower extremity arterial occlusive disease becomes occluded, a patient’s symptoms can vary from complete absence to acute limb-threatening ischemia. Depending on the severity of symptoms, treatment options include observation, percutaneous thrombectomy or lysis, open operative thrombectomy with or without graft revision, and reconstruction of a new bypass.


Most causes of graft failure, in particular failure of expanded polytetrafluoroethylene (ePTFE) conduits, have been shown to involve the distal anastomosis or progressive distal disease. Therefore, when operative intervention is required to open an occluded graft, older teachings suggested dissecting out the distal anastomosis primarily. Open access to the distal anastomosis would allow exposure for operative repair of an outflow problem once a thrombectomy is performed. This approach usually required general anesthesia. In addition, operating in a scarred field made for a more difficult dissection, with greater blood loss and a higher risk of postoperative infection. A technique for open thrombectomy of acutely thrombosed lower extremity PTFE bypass grafts that can be performed under local anesthesia, while avoiding a difficult dissection in a scarred field, to treat inflow or outflow lesions using interventional techniques has distinct advantages.



Preoperative Planning


If time permits, a good preoperative computed tomography angiogram (CTA) or magnetic resonance angiogram (MRA) can be very useful in identifying inflow lesions, outflow lesions, and progressive atherosclerotic disease. It can also help identify the location and course of the graft for planning a surgical access site. Prior operative notes should be reviewed to ascertain the location of the proximal and distal anastomoses, the course of the graft, and any difficulties encountered during the original procedure. If the graft thrombosis is less than 2 weeks old and time permits, percutaneous lysis may be considered. Discussions should be undertaken with the patient and the family about the possible operative risks (including possible limb loss), possible need for fasciotomy if ischemia has been prolonged, and the possible need for a new revascularization if the thrombectomy does not work.



Technique


Usually, both groins and the ipsilateral leg are fully prepped, including the majority of the foot. A clear sterile isolation bag can be placed on the foot to aid in evaluating perfusion of the foot after revascularization. Cases should be performed in a fluoroscopy-capable room with digital subtraction angiography available, ideally in a hybrid operating suite.


The majority of cases using this technique can be performed under local anesthesia with sedation. Prior operative notes and imaging should be reviewed to choose an appropriate graft access site. The chosen incision site should be made over an easily accessible virginal area of the graft. A subcutaneous graft is usually easily located by palpation. Otherwise, the upper thigh is a convenient access site if the graft is tunneled anatomically under the sartorius muscle. This exposure allows easy access to the graft and can allow muscle coverage of the exposed portion of graft. If the graft is difficult to locate, intraoperative ultrasound can be very useful. Ring-enforced ePTFE grafts are usually easy to identify under ultrasound guidance.


Local anesthesia is administered and a length of about 5 to 10 cm of graft is exposed. Double-looped umbilical tape or vessel loops are placed at either end for hemostasis during the procedure (Figure 1). Rubber-lined Fogarty hydrogrip clamps should also be available for graft hemostasis. The patient is then systemically anticoagulated, usually to achieve an activated clotting time of longer than 250 seconds.


image
FIGURE 1 Exposure of the polytetrafluoroethylene graft.

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Aug 25, 2016 | Posted by in CARDIOLOGY | Comments Off on Operative Thrombectomy for Acute Thrombosis of Lower Extremity Bypass Grafts

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