Total occlusion of EVAR graft in a patient with acute pancreatitis

A 66-year-old male with a history of chronic kidney disease and nephrotic syndrome, arterial hypertension, subrenal abdominal aortic aneurysm and EVAR intervention in 2019 referred to emergency hospital with acute pain in upper abdomen lasting for several hours, nausea and vomiting. Initial CT examination confirmed acute pancreatitis. Few hours later the patient developed severe pain and cold feeling in lower limbs and lower abdomen, CT angiography of neck, body, limbs was performed.

First contrast-enhanced CT of abdomen performed in portal venous phase showed typical picture of acute pancreatitis with diffusely enlarged pancreas, peripancreatic fluid and fat stranding (Figure 1a, 1b, 1c, 1d). Additionally already on first CT visible features of EVAR stent thrombosis that include direct visualization of hypoattenuating thrombotic masse in the left limb of the stent (Figure 1d, orange arrow, EVAR without signs of structural abnormality, beginning of thrombosis in right EVAR limb and mural thrombus in endograft’s main body. There was still sufficient collateral circulation in both a. iliaca externa and a. iliaca interna (white arrows).

Second CT arteriography of neck, body, limbs performed in arterial phase 11 hours after first imaging, when the patient started exhibiting signs of lower limbs ischaemia, showed total stent occlusion from subrenal level and caudal, including total occlusion of both stent limbs (Figure 2a, 2b, 2c).

Background

Endovascular repair is an effective and minimally invasive radiological procedure, where the lumen of aneurism is substituted by stent and excluded from blood circulation. One of the common systemic long term complications includes ischaemia that can be caused by arterial thrombosis, embolism, arterial dissection or arterial obstruction occurring as a result of endograft kinking or collapse. The majority of ischemic complications after EVAR represent acute arterial ischemia of lower extremities [1]. Total occlusion of a stent-graft occurs in approximately in 4% of cases compared to the total amount of complications [2] Majority of thrombotic events tend to occur early after EVAR, according to authors as a result of either anatomical or stent features [3]. However, thrombosis can also occur later in clinical course, particularly in a presence of various transitory and permanent hypercoagulable states [4].

Clinical and Imaging Perspective

Early detection of ischemic complications after EVAR is crucial, as such complication make a source of increased mortality and disability for patients with aortic endograft. Use of regular follow-up imaging programs and antiplatelet treatment can minimize occurrence of serious ischemic complications and initiate necessary early surgical or therapeutic interventions [5]. Regular follow-up imaging for patients, who underwent EVAR intervention, is CT with contrast in arterial phase. First, follow up imaging, in this case, happened half a year after EVAR and showed no structural abnormalities of endograft or signs of thrombosis.  

In a setting of acute imaging, non-related to EVAR follow-up, radiologist should be especially aware of implanted body devices, and should not be satisfied with a finding of only initial abnormality, in this case acute pancreatitis. It is a common error, knows as “satisfaction of search”. In this case, thrombosis of the left limb of aorto-iliac endograft was visible on the first abdominal imaging but unfortunately not included in report. By the time that the patient developed signs of acute arterial ischaemia, total endograft occlusion had occurred (Figure 2a, 2b, 2c). Total thrombosis of EVAR could be explained by combination of patient’s pre-existing Minimal Change Disease and nephrotic syndrome and acute pancreatitis, where both conditions can cause state of hypercoagulability and arterial thrombosis [6, 7, 8] There was no signs of structural abnormalities in EVAR endograft.

Outcome

With increasing incidence of EVAR treatment there is also increasing data about late complications. Many of these complications carry risk for serious disability and mortality for the patients, if not detected early enough. In a setting of thrombotic complications, minimally invasive repair can be difficult because of big thrombotic masse, stent deformation and malposition, and can require extensive or repeated surgeries [1, 2] In this case, after CT-angiography and diagnosis of total stent occlusion, transfemoral intervention with endovascular thrombectomy and femoro-femoral crossover bypass was performed, unfortunately, unsuccessful due to big thrombotic masse and distal thrombosis in small arterial branches. Irreversible loss of lower limbs vitality occurred, and the patient died few hours later.

Teaching point.

Systematic approach to interpretation of radiological examinations is important and can promote early detection of clinically significant systemic and device-related complications after EVAR interventions.