The efficacy of immediate bridging thoracic endovascular aortic repair for ruptured infected thoracic aortic aneurysms.

Herein we describe four cases of ruptured infected thoracic aortic aneurysm. All patients underwent emergent thoracic endovascular aortic repair to stabilize hemodynamics. After controlling infection, stent graft removal and in situ reconstruction with radical debridement were performed in all but one case. All patients survived during the median 31-month follow-up period, and only one exhibited infection reactivation, which occurred 294 days after initial endoaortic repair. That particular patient underwent open repair. The current cases suggest that emergent bridging endovascular repair for ruptured infected thoracic aortic aneurysm is feasible and, after controlling infection, open repair should be performed as soon as possible.

Infected thoracic aortic aneurysm (ITAA) is a rare, life-threatening disorder that can only be treated via surgery. Aneurysm rupture increases the perioperative mortality rate of ITAA. The main strategies used to treat ruptured ITAA at our institution are (1) emergent thoracic endovascular aortic repair (TEVAR) to stabilize hemodynamic status when the anatomy is conducive, (2) efficient administration of antibiotic and adjunctive procedures (eg, drainage of infective foci) for several weeks to control infection, and (3) in situ reconstruction after radical debridement of infected tissue. We reviewed the details of the cases presented herein to assess the outcomes of these strategies. All patients provided written informed consent for the publication of this case series.

Case reports

From January 2002 to March 2017, a total of 21 patients underwent surgery for primary ITAA at our institution. Computed tomography (CT) findings on admission revealed aneurysmal rupture in eight patients. Through 2012, the therapeutic approach for ruptured ITAA was emergent open surgical repair. However, two of four patients treated using this strategy died within 3 months postoperatively. One of these deaths was due to aortic rupture at the site of anastomosis and the other was a case of unexplained sudden death. Therefore, the treatment strategies for ruptured ITAA were changed to those that we currently use. The TEVAR component was determined by the aortic team at our institution, and the TEVAR devices used were the GORE TAG (W.L. Gore and Associates, Flagstaff, Ariz) and Zenith TX2 (Cook Medical Inc., Bloomington, Ind). We retrospectively reviewed the cases of four patients who had undergone emergent TEVAR as a bridge before definitive open surgical repair since 2013. Table I summarizes the demographic characteristics of these four patients. All presented with fever and three experienced localized chest pain. Case 3 exhibited hemoptysis owing to aortobronchial fistula, but only case 2 exhibited a positive blood culture preoperatively.

Table I

Demographic characteristics

Case	Age, years	Sex	Probable etiology	Causative microorganism/culture	Location and size of aneurysm	Type of rupture
1	69	Female	Dental therapy	MSSA/abscess	DAA, 56 mm	Contained
2	64	Male	Atopic dermatitis	MRSA/blood	DAA, 78 mm	Contained
3	59	Male	Unknown	Unknown	TD, 72 mm + 60 mm, PV, 67 mm	Into an organ
4	72	Female	Dental therapy	Unknown	DAA, 58 mm	Contained

DAA, Distal aortic arch; MSSA, methicillin-sensitive Staphylococcus aureus; PV, paravisceral; TD, thoracic descending.

CT findings suggested that all aneurysms were saccular. In addition, three of the four patients exhibited a single contained ruptured aneurysm. Case 3 exhibited multiple aneurysms, and one thoracic descending aortic aneurysm had ruptured into the bronchial tube (Fig 1, A). Emergent TEVAR was performed immediately after admission (Fig 1, B). In case 4, carotid-carotid bypass and retrograde in situ branched stent grafting were performed to preserve cerebral perfusion (Fig 2, A-C).

Fig 1

Computed tomography (CT) scans of the patient in case 3. A, CT revealed multiple aneurysms from the thoracic descending aorta to the abdominal aorta at the time of admission. B, A stent graft was implanted to cover the thoracic descending aortic aneurysm.

Fig 2

Computed tomography (CT) scans of the patient in case 4. A, A ruptured, infected aneurysm of the aortic arch (red arrow). B, CT scan taken after emergent endovascular repair with cervical bypass. C and D, The distal landing zone of the stent graft at 6 days (C; blue arrowhead) and at 7 months (D; yellow arrowhead) after endovascular repair. E, In situ reconstruction of the aortic arch with total neck vessels.

Although an antibiotic had been administered at admission, intravenous administration of effective antibiotics was initiated in accordance with recommendations from the infection control team at our institution. The details of case 2 have been reported previously. In this case, a pigtail drainage catheter was placed into the aneurysmal cavity under CT guidance with daily irrigation using 0.02% gentian violet solution, which is reportedly highly effective against methicillin-resistant Staphylococcus aureus. The median maximum C-reactive protein level before TEVAR was 21.8 mg/dL (range, 15.8-29.8 mg/dL), and it had decreased to 2.23 mg/dL (range, 1.56-8.50 mg/dL) before open surgery.

Surgical repair and stent graft removal were performed under temporary control of potential ITAA rupture, except in one case, after a median waiting period of 16 days (range, 8-19 days). Intravenous antibiotics were continued postoperatively for 33 days (range, 28-38 days), and oral antibiotics were maintained in all patients. Intraoperatively obtained specimens (aortic wall, surrounding necrotic tissue, and explanted stent graft) from each patient were cultured; however, only 25% of cultures were positive.

In case 4, in accordance with the patient's preference, second-stage surgery was not performed within weeks because the infection was controlled via continuous oral antibiotic administration. Surgery was performed 294 days after TEVAR in that case, however, because the distal aortic arch at the distal landing zone was expanding in conjunction with elevated inflammation (Fig 2, D and E).

The procedures used in each patient are shown in Table II. The TEVAR strategy was discussed by the aortic team at our institution. Notably, no complications—including spinal cord injury—were observed after TEVAR. After cardiopulmonary bypass was established, in situ reconstruction using a gelatin-sealed Dacron graft soaked in rifampicin was performed under circulatory arrest at a nasopharyngeal temperature of 25°C. The stent graft was subsequently removed without any difficulty in all patients.

Table II

Summary of surgical interventions

Case	TEVAR device	Landing zone	Duration between TEVAR and OSR, days	OSR
1	TAG 40 × 150 mm	2	8	DAA resection, in-situ grafting with LSCA reconstruction, and omental flapping
2	TX2 36 × 152 mm	2	19	DAA resection, in-situ grafting with LSCA reconstruction, and omental flapping
3	TX2 28 × 80 mm + TX2 28 × 120 mm	4	16	Thoracoabdominal replacement with ICA reconstruction
4	TAG 37 × 200 mm	0	294	DAA resection and in-situ grafting with total neck vessels reconstruction

DAA, Distal aortic arch; ICA, intercostal artery; LSCA, left subclavian artery; OSR, open surgical repair; TEVAR, thoracic endovascular aortic repair.

Three of the four patients (cases 1, 3, and 4) were intubated postoperatively for more than 72 hours. Although cerebral infarction occurred in case 3, performance status remained unaffected at discharge. No other postoperative complications were observed. All patients survived without any evidence of recurrent aortic infection during a median follow-up period of 31 months (range, 13-54 months).

Discussion

Although ruptured ITAA requires emergency surgery, patient condition is usually substantially compromised owing to active infection, which affects survival during conventional open surgery. The perioperative mortality rate in patients with a free ruptured ITAA is reportedly 37.5% to 100.0%.4, 5, 6 Some recent studies have reported acceptable short-term outcomes of TEVAR for ITAA. Semba et al reported the successful management of ruptured ITAAs with endovascular repair.

Although TEVAR is a less invasive therapeutic option, particularly for aneurysmal rupture, implanting a foreign body in an infected field is a major concern. Ishida et al reported a major type I endoleak the day after performing TEVAR, despite successful stent graft placement. They concluded that TEVAR for ruptured ITAA may be associated with a substantial risk of endoleak owing to active infection. Further, Kan et al evaluated stent graft implantation of aneurysmal rupture, which is a significant independent predictor of persistent infection.

We experienced a case wherein aortic diameter enlargement occurred in conjunction with placement of the inner stent graft in the late phase, which may have been caused by persistent infection. We believe the infection was difficult to control completely despite continued antibiotic administration after stent graft implantation for the ruptured ITAA. Hence, open surgical repair after bridging TEVAR is recommended as soon as possible after hemodynamic stability and infection control are achieved. Tamura et al reported the first clinical case of the use of bridging TEVAR for infected aneurysm of the aortic arch. They performed staged open reconstruction 2 weeks after TEVAR, resulting in a successful postoperative course without any evidence of infection.

Conclusions

Bridging TEVAR followed by definitive open surgical repair is feasible in patients with ruptured ITAA. Performing open surgical repair as soon as possible after hemodynamic stability has been achieved and infection has been controlled is recommended, to maximize the likelihood of successful outcomes.