Asian Cardiovasc Thorac Ann 1998;6:224-226
© 1998 Asia Publishing EXchange Pte Ltd
Post-Enteric Mycotic Aneurysm of Abdominal Aorta with Total Disruption
Rajendar Krishan Suri, MS,
Neerod Kumar Jha, MCh,
Katragadda Lakshmi Narasimha Rao, MCh1,
Mandeep Singh, DM2,
Pramila Chari, MD3
Department of Cardiovascular & Thoracic Surgery
1 Department of Pediatric Surgery
2 Department of Cardiology
3 Department of Anaesthesia Postgraduate Institute of Medical Education and Research Chandigarh, India
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For reprint information contact: Rajendar Krishan Suri, MS Department of Cardiovascular & Thoracic Surgery Postgraduate Institute of Medical Education and Research Chandigarh 160012, India Tel: 91 172 54 1031 Ext. 302 Fax: 91 172 54 0401
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ABSTRACT
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We report an extremely rare case of suprarenal mycotic aneurysm of the abdominal aorta below the origin of the superior mesenteric artery, secondary to Salmonella infection in a 3-year-old boy, which was associated with total disruption of the aortic wall. This case was successfully managed surgically with debridement and interposition of a double velour Dacron graft in the involved segment of aorta. A high degree of suspicion, angiographic evaluation supported by noninvasive investigations, and a planned surgical approach are required for a successful outcome.
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INTRODUCTION
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Aneurysms of the abdominal aorta are very rare and congenital abnormalities, inflammation, and trauma are the most common causes.1,2 In children, mycotic aneurysms are uncommon arterial lesions that arise usually as a complication of septicemia resulting from subacute bacterial endocarditis or umbilical artery catheterization.3,4 Mycotic abdominal aortic aneurysm secondary to salmonella infection is extremely rare, particularly in a child.5,6 Such aneurysms tend to involve the aorta with an alarming tendency to rupture early.7 We report a successfully managed case of suprarenal mycotic aneurysm of the abdominal aorta secondary to enteric fever in a 3-year-old child, which was associated with total disruption of the aortic wall below the origin of the superior mesenteric artery.
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CASE REPORT
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A 3-year-old boy was referred to us for evaluation of an abdominal lump. The child was in excellent health until 2 months prior to admission when he began to have continuous moderate grade fever with intermittent rigors and chills. The blood Widal test was suggestive of enteric fever due to Salmonella typhi. After a full course of intravenous ciprofloxacin (200 mg 3 times daily) his fever subsided. However, within one week, he developed a painful lump in the abdomen. The lump progressively increased in size from 6 to 12 cm over a period of one month. On admission, the child was toxic and cachectic. His weight was 8 kg and his blood pressure was 140/100 mm Hg in the upper limbs with absent pulses in both lower extremities. A tender pulsatile lump approximately 12 x 12 cm in size was found extending into the umbilical, epigastric, and hypogastric regions without an audible bruit. Other systems appeared to be normal. His blood pressure was controlled with nifedipine 5 mg 3 times daily. Hematological screening showed polymorphonuclear leukocytosis. However, repeated blood cultures were sterile. Computed tomography and magnetic resonance imaging scans of the abdomen revealed a massive dilatation of the abdominal aorta measuring 98 x 48 mm with swirling internal echoes. The wall of the sac was thickened and nodular, suggestive of thrombus formation. There was a breach in continuity of the wall of the abdominal aorta in the suprarenal section associated with extravasation of blood into a false sac as depicted by signal intensity of blood on the T1 weighted image. The right kidney was found to be relatively small (Figures 1 and 2
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Figure 1. Contrast computed tomography scan of the abdomen showing the abdominal aortic aneurysm with thickened wall and nodules suggestive of thrombus formation. The right kidney is relatively small in size.
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Figure 2. Magnetic resonance scan of the abdomen (lateral view) showing massive dilatation of the abdominal aorta with swirling internal echoes and feature of leakage.
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A transbrachial abdominal aortogram revealed an aortic aneurysm arising just below the origin of the celiac trunk and demonstrated leakage into a false sac with swirling of the contrast medium within the sac. Neither the kidneys nor the renal arteries were opacified. However, in delayed films, passive filling of the bifurcation of the distal aorta and two common iliac arteries could be seen (Figure 3). In view of the reduced size of the right kidney on computed tomography scan and doubt regarding the status of the renal arteries, a renal radionuclide scan was performed, which showed a nonfunctioning right kidney.
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Figure 3. Abdominal aortogram showing the aortic aneurysm just below the origin of the celiac trunk with leakage into a false sac and swirling of the contrast medium within the sac. There are indications of disruption of the aortic wall. Inset: delayed film showing passive filling of the bifurcation of the distal aorta and two common iliac arteries.
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Surgical exploration was carried out via a left thoracoabdominal incision. A large false aneurysmal sac surrounded by nonpulsatile mesentery of the small and large bowel was seen extending from the diaphragm to the pelvic cavity. The gross size of the false anerysmal sac was 20 x 16 cm. The aneurysm involved the abdominal aorta below the origin of the superior mesenteric artery and extended 5 cm distally to just above the origin of the renal arteries. The aorta was totally disrupted and continuity of flow was maintained through a channel created by the wall of the false sac and the surrounding mesenteric adhesions. Faint pulsation of the left renal artery could be felt but the right renal artery could not be palpated due to surrounding inflammatory adhesions of mesentery and the aneurysmal sac.
After proximal and distal control of the aorta, debridement of the aneurysmal sac was performed and continuity of the aorta was restored by interposition of a 4-cm long preclotted double velour Dacron graft of 20 mm in diameter anastomosed end-to-end between the origin of the superior mesenteric artery and the renal arteries. A 4/0 polypropylene suture was used for interposition of the graft. The suture was placed in a continuous manner in the posterior section of the aorta and interrupted sutures were used in the anterior section to facilitate anastomotic growth. Once continuity of the aorta was achieved, blood flow to the distal aorta and its branches was restored and mesenteric vessels became pulsatile. Histopathologic examination of the wall of the aneurysmal sac revealed features of a mycotic aneurysm showing capillary proliferation, destruction of the adventitia, lymphocytic infiltration, and lines of Zahn. Cultures of samples of the wall of the aneurysmal sac were reported to be sterile. A renal radionuclide scan 6 weeks postoperatively showed improved renal function on both sides. The patient continues to have hypertension controlled by medical therapy. After 2 years of follow-up, magnetic reasonance imaging showed patency of the vascular graft and good visceral and distal flow in the abdominal aorta. Another study will be undertaken at a later follow-up for subsequent right renal revascularization.
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DISCUSSION
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The pathogenesis of mycotic aneurysm is thought to be embolomycotic, or due to extension either directly or via lymphatics, or from hematogenous seeding of the arterial wall during bacteremia leading to destruction of the vessel wall, aneurysm formation, and rupture.5,6,8 The aneurysm is due to gram-negative organisms in 18% to 35% of cases and those associated with salmonella infection present a formidable surgical problem as they exhibit a greater tendency towards early rupture with a very high mortality.5,6 The introduction of better antibiotics and refinements in surgical technique have changed the clinical outlook for infections and resultant mycotic aneurysms.3 In this patient, the blood Widal test was strongly positive but cultures from blood and the wall of the involved segment were negative, possibly due to previous heavy antibiotic dosage. However, all the classical features of a mycotic aneurysm were present and histopathologic examination of the aortic wall from the disrupted site confirmed the diagnosis. In this case, the mesentery of the small and large gut was adherent to the aneurysmal sac, thus temporarily protecting it from gross rupture and intra-abdominal bleeding.
The various surgical procedures described in the literature for the management of these aneurysms include debridement and bypass grafting, debridement with extraanatomical bypass, and ligation and excision of the sac.5,6 Considering the age of this child, it was mandatory to use a vascular graft of sufficient diameter to avoid a future iatrogenic coarctation of the involved segment of the aorta due to the physical growth of the child. The possible explanation for the diminished size and function of the right kidney and persistent renovascular hypertension could be congenital stenosis or distortion of the right renal artery due to adhesions or the aneurysmal sac. At the time of surgery, the right renal artery was not explored because of extensive adhesions and inflammatory edema around the aneurysm as well as the risk of damage to the surrounding structures.
An earlier report of attempted surgical repair of a disrupted mycotic abdominal aortic aneurysm described a fatal outcome due to an exsanguinating hemorrhage before proximal and distal control of the abdominal aorta could be achieved.1 We consider that a high degree of suspicion, thorough angiographic evaluation supported by noninvasive investigations, and a planned surgical approach are required for a successful outcome in such patients.
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REFERENCES
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ABSTRACT
INTRODUCTION
