Primary aortoenteric fistula related to septic aortitis

ABSTRACT CONTEXT: Primary aortoenteric fistulas usually result from erosion of the bowel wall due to an associated abdominal aortic aneurysm. A few patients have been described with other etiologies such as pseudoaneurysm originating from septic aortitis caused by Salmonella. OBJECTIVE: To present a rare clinical case of pseudoaneurysm caused by septic aortitis that evolved into an aortoenteric fistula. CASE REPORT: A 65-year-old woman was admitted with Salmonella bacteremia that evolved to septic aortitis. An aortic pseudoaneurysm secondary to the aortitis had eroded the transition between duodenum and jejunum, and an aortoenteric fistula was formed. In the operating room, the affected aorta and intestinal area were excised and an intestine-to-intestine anastomosis was performed. The aorta was sutured and an axillofemoral bypass was carried out. In the intensive care unit, the patient had a cardiac arrest that evolved to death.


INTRODUCTION
Aortoenteric fistulas are classified as primary 1 and secondary, 2 (after aortic repair by means of an arterial prosthesis).This condition involves arterial rupture and infection of vascular areas. 3Primary fistulas are in most cases (90%) 4 the result of erosion of the bowel wall, caused by abdominal aortic aneurysm.Septic aortitis is also one of the most challenging problems that confront the vascular surgeon.Transient bacteremia allows lodgment of bacteria on the inner arterial surface and permits the formation of an aneurysm or false aneurysm.5][6][7][8][9] The aim of this work is to present the case report of a patient with a pseudoaneurysm due to Salmonella aortitis, which originated an aortoenteric fistula.

CASE REPORT
A 65-year-old black woman with a twenty-year history of diabetes mellitus was admitted with diffuse abdominal pain and fever.The abdomen was distended without palpable abdominal masses.Her blood pressure was 220 x 120 mmHg, temperature 38.2ºC, and the white blood cell count was 23,000 leukocytes per mm 3 .Abdominal radiography and ultrasonography were unremarkable.A blood culture grew Salmonella nontyphymurium, and she was treated intravenously with ceftriaxone and discharged on the 11 th day.Cerriaxone was substitute for oral amoxicillin.
Thirty days after discharge, the patient returned with diffuse abdominal pain, associated with fever (39 ºC).Physical examination brought into evidence a pulsatile, epigastric and periumbilical abdominal mass.Bmode ultrasound scanning showed an infrarenal aortic aneurysm, 5.7 cm in diameter.While waiting for abdominal tomography (CT scan), to make an examination of the aortic dilation, the patient had three hematemesis episodes.Endoscopy was repeated three times and only in the last of these was a pulsatile lesion shown in the fourth portion of the duodenum.In order to analyze the anatomy of the aneurysm, an emergency CT scan was performed, which displayed a large pseudoaneurysm with gas close to the arterial wall (Figure 1).Eighteen hours after the first bleeding, the patient was submitted to a midline laparotomy, which revealed a large retroperitoneal hematoma densely adhering to the duodenum-jejunum transition.After proximal aortic control the fistula was closed off and a large intestinal defect was detected.The affected intestinal area was removed and intestine-to-intestine anastomosis was performed.The infected aorta and the large hematoma were excised, and the proximal aorta and iliac common arteries were oversewn.A right axillobifemoral bypass graft with prosthesis was constructed.
Eight hours after the end of the surgery, the patient had cardiac arrest and was unresponsive to resuscitative maneuvers.Necropsy could not identify the cause of death and a metabolic origin was considered.The infrarenal aortic specimen exhibited the presence of some fatty streaks, but there was

OBJECTIVE:
To present a rare clinical case of pseudoaneurysm caused by septic aortitis that evolved into an aortoenteric fistula.

CASE REPORT:
A 65-year-old woman was admitted with Salmonella bacteremia that evolved to septic aortitis.An aortic pseudoaneurysm secondary to the aortitis had eroded the transition between duodenum and jejunum, and an aortoenteric fistula was formed.In the operating room, the affected aorta and intestinal area were excised and an intestine-to-intestine anastomosis was performed.The aorta was sutured and an axillofemoral bypass was carried out.In the intensive care unit, the patient had a cardiac arrest that evolved to death.no massive atherosclerotic disease.

DISCUSSION
Classifications used for describing arterial infection include several different names, such as mycotic aneurysm, infected aneurysm, aortitis, cryptogenic aortitis, bacterial aortitis and microbial arteritis. 2Microbial arteritis is an infectious process that attacks a non-aneurysmal artery and develops an aneurysm or arterial rupture with pseudoaneurysm 2 (Figure 2).Our patient presented microbial arteritis caused by Salmonella.Fever, abdominal distension and pain were some of the common aortitis diagnostic findings in our patient.When aortic infection leads to aneurysm or pseudoaneurysm formation, there may be a pulsatile mass present.In the initial phase of the aortitis, there may not be any remarkable findings from either ultrasound or tomography.In our clinical case, the first ultrasound showed a normal aorta, but a large pseudoaneurysm was detected one month later.
Standardized diagnosis of primary fistulas, as well as the management of such patients, is especially difficult 10 because primary fistulas are not frequent (Table 1).When the primary fistula has an etiology other than an aneurysm, such as aortitis, [4][5][6][7][8] or when it is idiopathic, [16][17][18][19] diagnosis difficulties increase.For two-thirds of the patients, the diagnosis is made in the operating room 15 (Table 2).The classic trio of abdominal pain, palpable mass and gastrointestinal bleeding only occurs in 6% to 12% of patients. 3,4 th regard to aortoenteric fistula, hematemesis and melena form the most com- mon symptoms (32% to 78%). 13,20When the etiology is an aortic aneurysm, a palpable mass can be found in 25% to 70% of the patients. 1,4,13ndoscopy is essential.However, it has the potential risk of inducing massive hemorrhage by dislodging fresh thrombus in the fistula. 16,17n our case, the endoscopy was repeated in order to achieve a diagnosis.We believed that making the patient undergo a laparotomy without diagnosis would be hazardous.Rarely can angiography demonstrate the fistula, as the bleeding is usually not active at the time of the examination. 16,18 e outcome will depend upon the timeliness of diagnosis, the patient's general state, the degree of contamination, and the anatomical site of the aorta involved.The conventional treatment of infrarenal aortic infection includes primary intestinal suture or resection and intestinal anastomosis, excision and drainage of infection with the oversewing of the infrarenal aorta, combined with axillofemoral bypass grafting. 21The alternative of extraanatomical grafting is used in situations where the above cannot be performed, i.e. in infectious aneurysms of the aorta that involve the visceral branches. 22In these cases, the synthetic prosthesis is placed in situ.In the infrarenal aortic segment, in the absence of gross pus at the site of the fistula, in situ prosthesis grafting could be performed. 23,24 ternative reconstruction methods have been proposed and consist of in situ replacement with an antibiotic-bonded prosthesis, 25 homografts, 26 and reconstruction with femoral veins. 27Additional maneuvers to prevent prosthesis infection include the use of viable pedicles of the greater omentum between aortic grafts and intestinal suture, 23 and prolonged antibiotic therapy. 24In our case, the option  was for extra-anatomical reconstruction, owing to the high risk and difficulty of carrying out in situ prosthesis placement on an infected, friable aorta.Early diagnosis and aggressive surgical treatment are the best ways to achieve successful results in aorta-infected patients.The multifactorial features of this condition rule out one single approach, and the medical team must have knowledge of several forms for its presentation, as well as several options for dealing with this malady.

•
University Hospital, Universidade de São Paulo, São Paulo, Brazil CONTEXT: Primary aortoenteric fistulas usually result from erosion of the bowel wall due to an associated abdominal aortic aneurysm.A few patients have been described with other etiologies such as pseudoaneurysm originating from septic aortitis caused by Salmonella.

: 3 Figure 1 .
Figure 1.CT scan reveals a large pseudoaneurysm with air close to aortic wall (arrows).

Figure 2 .
Figure 2. Infectious aortitis could affect a normal aorta or aneurysmal aorta with different forms of presentation.