Endovascular stent graft repair for infected thoracic aortic pseudoaneurysms—a durable option?

Patients and methods 

Between August 2000 and November 2005, seven consecutive patients with eight infected pseudoaneurysms of the thoracic aorta were treated with endovascular stent-graft repair. Surgical interventions were done to control sepsis and prevent rupture and bleeding. Patients were diagnosed based on a typical appearance of an infected pseudoaneurysm on imaging, including saccular morphology arising from a “breach” in the aortic wall (Fig 1) and rim enhancement over the pseudoaneurysm sac (Fig 2), together with a positive bacteriology culture or clinical evidence of sepsis. Patients were regularly reassessed postoperatively with clinical examination, hematologic tests, and follow-up computed tomography (CT) scans at 1 month and every 6 months thereafter.

View Large Image Download to PowerPoint

Fig 1. Computed tomography scan shows a typical infected pseudoaneurysm over the lower thoracic aorta (arrow).

View Large Image Download to PowerPoint

Fig 2. Computed tomography scan shows a typical infected thoracic aortic pseudoaneurysm. Note the contrast-enhanced pseudoaneurysm sac (arrow).

During the same period, two other patients with infected pseudoaneurysms of the thoracoabdominal aorta received open repair and in situ reconstruction. Endovascular stent grafts were not considered in these two patients because of the involvement of the visceral branches requiring bypasses. Both patients survived, although acute renal failure developed in one as a result of a thrombosed renal bypass graft requiring re-exploration and redo bypass.

The demographic data, investigation results including the bacteriology, surgical outcome, and follow-up data were prospectively collected.

Results 

There were six men and one woman with a median age of 68 years (range, 37 to 90 years) at operation. One patient had two synchronous infected aortic pseudoaneurysms. The demographic data and the medical comorbidities are listed in Table I.

Table I. The demographic data, medical comorbidities and the pathology of the patients with infected pseudoaneurysms of the thoracic aorta

	Patient	Sex/Age	Medical comorbidities	Organisms	Rupture
	1	M/87	AF	MRSA	AEF
	2	M/37	HT, CRF	MSSA	No
	3⁎	M/59	HT, DM, IHD, COAD	Salmonella enteritidis	No
	4	M/68	CaE†	Candida albicans	AJF
	5	M/77	COAD	Salmonella	No
	6	M/59	Inoperable CaE	—	AEF
	7	M/90	AF, HT, DM	—	No

AF, Atrial fibrillation; CaE, carcinoma of the esophagus; COAD, chronic obstructive airway disease; CRF, chronic renal failure requiring dialysis; DM, diabetes mellitus; HT, hypertension; IHD, ischemic heart disease; MRSA, methicillin-resistant Staphylococcus aureus; MSSA, methicillin-sensitive Staphylococcus aureus; AEF, aortoesophageal fistula; AJF, aortojejunal fistula.

⁎ The patient with two infected aortic pseudoaneurysms. † This patient had post-esophagectomy anastomotic leakage.

Surgical management and perioperative outcome 

Intravenous antibiotics were started once the diagnosis of infected aortic pseudoaneurysm was made. Patients with Salmonella infection were treated with ceftriaxone, 1 to 2 g every 12 hours. For patients with non-Salmonella infections, antibiotics were determined by culture results and sensitivity testing if available, with consultation with the microbiologist.

All the procedures were performed in the operating room, with six under general anesthesia and one with local anesthetic agents. With the image guidance of a mobile C-arm (Philips BV-29, Philips Medical System, The Netherlands) or OEC 9800 (General Electric Company, Fairfield, Conn), endovascular stent grafts were deployed successfully in all patients, with complete exclusion of the pseudoaneurysms. The type and size of the endografts used are listed in Table II.

Table II. Perioperative details, duration of follow-up, and the lifelong maintenance antibiotics prescribed

	Patient	Endovascular repair⁎	Hospital stay (days)	Follow-up duration (months)	Antibiotics (daily)
	1	AneuRx36/120	36	3†	—
	2	Talent32/100	105	38	Cephalexin 500 mg
	3‡	Talent32/100
		Talent§30/26/113	27	35	Levofloxacin 500 mg
	4	Talent32/115	81	34	Fluconazole 200 mg, Metronidazole 400 mg, Cephalexin 500 mg ×3
	5	Zenith34/152	11	7	Levofloxacin 250 mg
	6	Zenith34/77	19	3⁎	—
	7	Zenith30/120	11	4	Clindamycin 450 mg ×3

AneuRx and Talent (Medtronic AVE Inc, Santa Rosa, Calif); Zenith, (Cook, Bloomington, Ind).

⁎ Dimension of endografts shown in diameter/length in mm. † Deaths at follow-up. ‡ The patient with two infected aortic pseudoaneurysms. § Tapering graft.

In the three patients with aortoenteric fistula, hematemesis stopped immediately after the operation. Subsequent thoracotomy with mediastinal debridement was required in the patient with esophagojejunal anastomotic leakage to control the sepsis. The fistula in this patient subsequently closed with endoscopic injection of fibrin sealant directly into the fistula tract. We have previously reported this novel approach of combined endovascular stenting and endoscopic injection of fibrin sealant in the management of aortojejunal fistula.11

Intravenous antibiotics were then continued for 1 to 6 weeks and followed by lifelong maintenance oral antibiotics (Table II). There was no hospital death. The median hospital stay was 27 days (range, 11 to 105 days). Two patients stayed in the hospital for >2 months (Table II). In the patient with aortojejunal fistula and subsequent mediastinal debridement, prolonged hospital stay was required for daily irrigation of the mediastinal abscess via the tubal drain inserted until the fistula healed. Another patient stayed >3 months because of placement issues and arrangement of continued hemodialysis, which she required before admission. No paraplegia or other major complications occurred.

Follow-up 

There were two deaths at follow-up (Table II). The 87-year-old man who had a thoracic aortic pseudoaneurysm with aortoesophageal fistula refused further definitive surgical intervention after stabilization with endovascular stent graft repair. He died from sepsis 3 months after the initial procedure. The patient with aortoesophageal fistula who had inoperable carcinoma of the esophagus died 3 months later as a result of stent graft infection and presented with recurrent hematemesis. The other five patients remained well, with no evidence of graft infection at a median follow-up of 34 months (range, 4 to 38 months).

Follow-up CT scans were performed in all patients. Thrombosis of the pseudoaneurysm sac was noted, and no evidence of late graft infection was detected. A significant reduction in the diameter of the pseudoaneurysm sac (>5 mm) was observed after 12 months (Fig 3).

View Large Image Download to PowerPoint

Fig 3. Serial computed tomography scan in the patient with thoracic aortic pseudoaneurysm infected with a methicillin-sensitive Staphylococcus aureus after endovascular stent graft repair. Note the complete resolution of the pseudoaneurysm.

Discussion 

Endovascular stent graft repair has provided a viable, less-invasive alternative in the management of aortic diseases. Favorable results with reduced perioperative mortality and morbidity have been reported in endovascular repair of abdominal aorta aneurysms.4, 5 Its application has also been extended to the treatment of infected aortic pseudoaneurysms.6, 7, 8, 9 Stanley et al7 reported successful endovascular treatment of four patients with mycotic thoracic aortic aneurysms, and successful endovascular repair with complete regression of an infected abdominal aortic aneurysm has also been documented.6

A less-invasive approach may be particularly appealing in our patients who had thoracic aortic involvement. As shown by Moneta,12 the operative mortality is much higher in patients with mycotic aneurysms involving the suprarenal or thoracic aorta compared with infrarenal involvement (43% vs 10%). Endovascular stent graft repair obviates the need for thoracotomy, significant blood loss, aortic cross-clamping, and extracorporeal circulation in these already critically ill patients. This is well illustrated in this series of seven patients, where the technical success was 100% with no hospital deaths.

There has always been a concern about persistent infection by putting a stent graft in an infected field. In situ prosthetic reconstruction was often unavoidable, however, even with open repair. The safety, durability, and efficacy of in situ reconstruction in the presence of aortic sepsis have been described.13, 14 Chan13 reported 22 mycotic aortic aneurysms (including 21 with thoracic/suprarenal involvement) treated with in situ prosthetic graft reconstruction. Nineteen patients (86%) survived for periods ranging from 3 months to 8 years postoperatively, with only one recurrent graft infection.

Long-term follow-up (>30 months) data were available in three of our patients with four infected aortic pseudoaneurysms treated by endovascular means. There was no clinical evidence of sepsis, and the latest follow-up CT scans showed exclusion of the pseudoaneurysms with significant reduction in the sac size. We believe that potent antibiotics, together with lifelong maintenance, are essential because of the definite risk of graft contamination during implantation. In addition, regular surveillance with CT scans is also indispensable.

On the other hand, the risk of persistent infection may be important in the situation where sepsis and contamination is ongoing, such as in the presence of an aortoesophageal fistula. Owing to the persistent esophageal contamination, a poor outcome is not unexpected without further definitive surgery. This is well exemplified by the two follow-up deaths in this series. Both patients had a persistent esophageal lesion resulting in continued contamination of the stent-grafts. Both patients died of graft infection and hematemesis 3 months after the initial stent graft placement. This underscores the importance of eliminating continued graft contamination. As shown in the patient with aortojejunal fistula secondary to esophagojejunal anastomotic leakage, long-term survival is possible if the fistula heals.

Even in situation where the contamination cannot be controlled, endovascular repair can at least be used as a temporary measure to save the patient from exsanguinating hematemesis before definitive surgery. Successful management of an aortoesophageal fistula secondary to mycotic thoracic aortic aneurysm using endovascular repair, followed by subsequent definitive esophagectomy has been reported.15

Open repair of thoracic aortic pathologies always incurs a considerable risk of postoperative paraplegia. In the review of their extensive experience, Svensson et al16 reported a significant 16% incidence of paraplegia/paraparesis in a series of >1500 patients undergoing thoracoabdominal aortic repairs. With the absence of aortic cross-clamping, endovascular stent graft repair has a theoretic benefit of minimizing the ischemic injury to the spinal cord and hence decreased the risk of paraplegia.17 This was well shown by the absence of paraplegia/paraparesis in our patients.

Although randomized controlled trials may be the ultimate answer to the role of endovascular stent graft repair in infected aortic pseudoaneurysms, a sufficient number for a trial may be impossible given with the rarity of this entity. Case series such as this with longer-term follow-up data may be helpful in defining the role of endovascular repair in this difficult clinical situation.

Conclusion 

Endovascular stent graft repair is effective and may be a durable option for patients with infected pseudoaneurysms of the thoracic aorta. Even for patients in whom sepsis cannot be adequately controlled, it may serve as a temporary measure to save life before definitive surgery.

Author contributions