Infected Aortic Graft 主动脉支架周围感染

医学词汇注释与简要讲解

Key Facts

Synonym: Postoperative graft infection.

Definition: Infection of aortic prosthetic graft.

Classic imaging appearance: Perigraft fluid, soft-tissue density, or ectopic gas beyond four weeks after surgery.

prosthetic 义肢、假体的

perigraft 支架（移植物）周围

ectopic 异位的

Other key facts

Incidence about 1%-6% of all postoperative aortic graft patients.

Serious complication with mortality rates of 25%-75%.

Graft infection is 3 times more common if aorta is ruptured preoperatively.

Most common organism is staphylococcus epidermis.

Hematoma after graft placement should resolve within 3 months.

Aortic enteric fistula is a subset of aortic graft infections.

staphylococcus epidermis 表皮葡萄球菌

hematoma 血肿

enteric fistula 小肠瘘

Imaging Findings

Best imaging clue: Perigraft fluid, soft-tissue mass, increasing or persisting months after graft placement.

Perigraft air more prevalent with an aortoenteric fistula.

CT Findings：(1) NECT: Perigraft fluid, perigraft soft tissue density . Ectopic perigraft gas represents aortoenteric fistula; (2) CECT: Perigraft inflammatory enhancement. Leakage of contrast into pseudoaneurysm, most pseudoaneurysms not infected.

pseudoaneurysm 假动脉瘤

MR Findings: Perigraft soft-tissue mass, fluid collection low signal on T1WI.Perigraft fluid collection high signal intensity on T2WI. Contrast-enhancement of perigraft inflammatory mass. Look for evidence of inflammatory changes in psoas muscles.

psoas 腰肌

Other Modality Findings

UItrasound not very helpful in evaluating aortic graft infection. Nuclear medicine: Indium-111 labeled white blood cell, Gallium scans. Angiography only for preoperative road map of arteries for extra-anatomic grafting.

Indium 铟

Gallium 镓

Imaging Recommendations

Unenhanced and enhanced CT as first imaging test

In-111 labeled white blood cell scan important test if CT ambiguousMRA, CTA, or conventional angiography is very helpful to establish the status of vessels distal to the graft, for possible secondary repair (i.e. axillaryfemoral bypass procedure).

axillary 腋（窝）的

femoral 股骨的

Fig 1 Graft infection. a) Axial nonenhanced CT, b) axial enhanced CT and c) coronal CT reconstruction imagings show fluid collection with enhanced rim and ectopic air(arrow) around aortic graft.

本例为腹主动脉瘤支架置入后，可见支架周围液体聚集，其内见游离气体，提示支架周围感染。

Differential Diagnosis

Anastomotic pseudoaneurysm: Caused by failure of graft repair at suture line, placing excessive tension on anastomosis. Anastomotic pseudoaneurysms may result as a secondary complication of infection of graft.

Aortoenteric fistula: Breakdown of graft repair with erosion of aortic contents into bowel. Duodenum is most comon location of aortoenteric fistula.

Normal postoperative resolution of perigraft hematoma: Complete resolution of hematomas should occur within 3 months.Ectopic gas in early postoperative period is suspicious but not diagnostic,gas should be resorbed in 3-4 weeks.

anastomotic pseudoaneurysm 吻合口假性动脉瘤

anastomosis 吻合、连接

aortoenteric fistula 主动脉小肠瘘

perigraft hematoma 支架周围血肿

Pathology

General: Most infections are believed to be a result of contamination from the abdominal incision. Hematogenous seeding secondary to bacteremia may be a cause of late graft infection.

Etiology-pathogenesis:Most common organism is staphylococcus epidermidis.Produces a slime that adheres to the graft and protects organism from host and from antibiotics, very difficult to eradicate.

Many of organisms are fastidious and may require 14 days to culture.

contamination 污染、 毒害

incision 切口

hematogenous seeding 血源性种植、播散

slime 黏和剂

eradicate 根除

Clinical Issues

Signs and symptoms are not specific: Fever, malaise, back or abdominal pain, gastrointestinal bleeding, elevated sedimentation rate, palpable mass and draining sinus.

Patients may present days to years following surgery.

malaise 不适，萎靡不振

sedimentation rate 血沉

Treatment：Antibiotic therapy often not curative.

Percutaneous aspiration of fluid around graft: diagnostic, obtain fluid for microbiology examination; occasionally therapeutic; installation of thrombolytics has been tried to help clear staph epidermidis Infection.

Graft excision and placement of extraanatomic bypass:Occasionally autogenous vein in situ, or very rarely rifampin-bonded prosthesis in situ.

thrombolytics 溶栓药

autogenous 自发的

rifampin-bonded prosthesis 药物（利福平）涂布假体

Prognosis: High morbidity and mortality associated with operative repair of infected graft.