Abdominal aortic aneurysm, EVAR, consumptive coagulopathy

77 years old/female

A 77 years old female was admitted for anendovascular repair of asymptomatic abdominal aortic aneurysm. Her medical history included hypertension, chronic renal failure and renal artery stent placement 1 year previously.

Abdominal aortic aneurysm

Abdominal CT scan showed infrarenal abdominal aortic aneurysm (53mm in diameter) combined with left common iliac artery aneurysm (40mm). The length of proximal neck (26mm) was sufficient to apply EVAR and not significantly angulated (30 degree), but circumferential coverage of intramural thrombus (maximal thickness: 5.4mm) was noted in the proximal neck of aortic aneurysm just below both renal arteries.

The EVAR was performed under epidural anesthesia. Both femoral arteries were exposed by surgery. A 5000U of heparin was injected intravenously before insertion of stent-graft. We planned to extend contralateral stent-graft limb into the left external iliac artery for complete exclusion of left common iliac artery aneurysm so that we embolized left internal iliac artery to prevent type 2 endoleak. Thereafter, a bifurcated Zenith endovascular stent-graft device (Cook, Bloomington, IN) was deployed to the common iliac artery on the right and the external iliac artery on the left. No evidence of endoleak was noted on completion angiography, but a movable filling defect was demonstrated on the proximal margin of stent graft (just below renal artery) and embolic occlusion of right renal artery which were not recognized at that time. After repairing exposed both femoral arteries, patient complained left leg pain and both frank pain since epidural anesthetic effect fade out. The left femoral pulse was not palpated. Emergent CT scan revealed distorted proximal portion of stent-graft, total embolic occlusion of left femoral artery, right renal artery and multifocal infarction of left kidney. No emergent surgery was attempted to remove thromboemboli because patient refused. Fourteen hours later, left foot cyanosis and skin color change in the abdomen were developed. The platelet count was decreased into 38*10⁹/L. She died of disseminated intravascular coagulation (DIC) on 1 day after procedure.

Abdominal CT scan showed infrarenal abdominal aortic aneurysm (53mm in diameter) combined with left common iliac artery aneurysm (40mm in diameter).

Circumferential coverage of in tramural thrombus (maximal thickness: 5.4mm) was noted in the proximal neck of aortic aneurysm just below both renal arteries.

On completion angiography, no evidence of endoleak was noted, but a movable filling defect was demonstrated on the proximal margin of stent-graft (just below renal artery, arrow).

Emergent CT scan one day after EVAR showed distorted proximal portion of stent-graft and thrombus on the proximal margin of stent-graft.

DIC is a pathological activation of coagulation mechanisms that happens in response to a variety of diseases including aortic aneurysm. As the small clots consume coagulation proteins and platelets, normal coagulation is disrupted and abnormal bleeding occurs from the skin, the digestive tract, the respiratory tract and surgical wounds and may participate in the development of multiple organ failure, which may lead to death. DIC associated with EVAR has been rarely reported. The cause of DIC in our case was not clearly demonstrated, but we could postulate possible mechanisms of DIC in our case as follows. First, passage and deployment of endovascular stent-graft may perturb the endothelium and stimulate procoagulant activity. Second, embolus may precipitate in-situ thrombus formation which leads acute consumption of coagulation factors. Third, distorted stent-graft may result in shear stress of blood flow which can induce intravascular hemolysis. In summary, it is difficult to apply EVAR to aneurysm with hostile neck anatomy including neck angulation, neck length, and associated thrombus. Problem encountered with hostile neck anatomy include an inability to form a proximal seal with subsequent type 1 endoleak, graft migration, thrombosis or dissection of the renal artery, renal or distal embolization, and hemorrhage from excessive manipulation or over dilatation. Our case had significant thrombus in the proximal neck. We underestimated the risk of EVAR in this situation. We didn't manipulate endovascular instrument carefully and also didn't aware of possible embolic complication and consumptive strict indication, coagulopathy. Thus, strict indication, appropriate sizing and careful examination on completion angiography to detect possible complications performing EVAR are necessary to avoid adverse outcome.

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