Imaging Casebook Resolution of Multiple Aortic Aneurysms in a Neonate

Ryan M. McAdams, MD with bilateral pneumothoraces requiring chest tube placement Randy R. Richardson, MD and had a patent ductus arteriosus that was closed with Journal of Perinatology (2005) 25, 60–62. doi:10.1038/sj.jp.7211197 indomethcin treatment. On DOL 25, a routine complete blood count test showed an elevated white blood cell count, with subsequent bandemia and thrombocytopenia. The infant had blood INTRODUCTION and cerebral spinal fluid cultures drawn, which were positive for Staphylococcus aureus. The infant’s UAC was pulled and the tip The use of umbilical artery catheters (UAC) is common in the sent for culture, which also grew S aureus that was methicillin management of critically ill neonates, but may be associated with a sensitive. Despite treatment with oxacillin, gentamicin, and variety of complications including infection, thrombosis, aortic rifampin, his clinical course continued to deteriorate with dissection, hypoglycemia, umbilical artery rupture, and persistent thrombocytopenia, hypotension, and a worsening paraplegia.1 Aortic aneurysms, with reported high morbidity and 2–4 respiratory status requiring increased setting with high-frequency mortality, have also been reported in association with UAC’s. We oscillatory ventilation. report a case of a 24-week infant who developed multiple aortic A limited abdomen ultrasound performed on DOL 28 to evaluate aneurysms associated with use of an UAC complicated by a for an abscess or aneurysm was negative. The abdominal aorta was Staphylococcus aureus infection with subsequent spontaneous patent without evidence of thrombosis. An echocardiogram, resolution of aneurysms after 5 months. performed on DOL 36 to evaluate for endocarditis, showed a 3 mm fibrin clot on the left atrial appendage. An enhanced abdominal and pelvic-computed tomography scan on DOL 36 revealed three CASE PRESENTATION aneurysms of the abdominal aorta and one aneurysm of the right A 665-g-infant male was born to a 22-year-old gravida 1, para 0 iliac artery, as well as a small left kidney with abnormally mother at 24 weeks gestation by emergent Cesarean section decreased, patchy enhancement. On DOL 38, an abdominal and secondary to placental abruption. Maternal pregnancy was pelvic magnetic resonance angiography (MRA) scan using complicated by 2 weeks of preterm labor for which she received gadolinium bolus technique revealed multiple large aneurysms: a indomethacin tocolysis, a full course of dexamethasone, as focal posterior aneurysm measuring 3.5 mm in the thoracic aorta well as antibiotic prophylaxis. Upon delivery, the infant was above the hemidiaphragm, a 8.1 Â 6.7 mm2 aneurysm above the noted to have severe respiratory depression requiring endotracheal celiac artery take-off, a 10.6 Â 6.3 mm2 left-sided aneurysm below tube intubation, surfacant administration, and mechanical the superior mesenteric artery take-off with a smaller 2.1 mm ventilation. An umbilical vein catheter was placed, the tip of which aneurysm identified just inferior to the larger aneurysm, a was in the proximal inferior vena cava at the level of T9. 4.2 Â 7mm2 aneurysm above the bifurcation, and a 4.6 x 7.9 mm A UAC was also placed, the tip of which was in the thoracic aneurysm at the origin of the right common iliac artery (Figure 1). aorta at the level of T7–8. Ampicillin and gentamicin antibiotics The MRA also revealed minimal contrast enhancement of the left- were empirically started for sepsis and were stopped on day sided kidney (Figure 2). of life (DOL) 7, after initial blood culture was negative. The After surgical consultation, it was decided to manage the infant infant’s course was initially complicated by hypotension requiring nonoperatively, since his multiple aneurysms coupled with his dopamine, dobutamine, epinephrine, and hydrocortisone (two unstable respiratory status made him an unfavorable surgical doses of 1 mg/kg/dose) with pressor support weaned off by candidate. The infant’s meningitis was treated with a 2-week DOL 8. The infant developed pulmonary interstitial emphysema course of oxacillin, gentamicin, and rifampin with negative repeat cerebral spinal fluid studies. He was treated a total of 6 weeks with oxacillin for his endocarditis and multiple aneurysms with resolution of his bacteremia, and improvement in his clinical Department of Pediatrics, (R.M.M.), Wilford Hall Medical Center, San Antonio, TX, USA; and Department of Pediatric Radiology, (R.R.R.), Wilford Hall Medical Center, San Antonio, TX, USA. condition. He never developed or required treatment for hypertension. Dynamic imaging of the kidneys at 2 months of life The opinions expressed in this paper are solely those of the authors and do not represent the views of the United States Air Force, Department of Defense, or the United States Government. by a technetium-99m mercaptoacetyltriglycerine scan revealed no

Address correspondence and reprint requests to Ryan M. McAdams, Department of Pediatrics, discernible left renal activity, consistent with probable infarction, Wilford Hall Medical Center, 2200 Berquist Dr Suite 1, Lackland AFB, TX 78236, USA. with normal activity on the right side.

Figure 1. Three-dimensional reconstruction from a gadolinium bolus Figure 3. Three-dimensional reconstruction from a gadolinium bolus MRA showing ﬁve saccular aneurysms off the abdominal aorta and one MRA showing complete resolution of aneurysms with only mild off of the right common iliac artery (arrows). tortuosity of the abdominal aorta (arrow). Note the absence of the left renal artery from complete infarction of the left kidney.

A follow-up MRA at 6 months of life showed resolution of all aneurysms (Figure 3) with mild vessel tortuosity of the abdominal aorta where aneurysms were previously located. No left renal artery was seen; however, a normal appearing right renal artery was noted. The infant, now 12 months old, had laser surgery for bilateral retinopathy of prematurity and has moderate developmental delay, but is otherwise doing well.

DISCUSSION Sequential development of multiple aortic aneurysms in a neonate associated with UAC placement is very rare, but has been reported.5 However, to our knowledge, this is the ﬁrst reported case of a neonate with documented imaging demonstrating spontaneous resolution of multiple aortic aneurysms, especially over such a Figure 2. Coronal image from a gadolinium bolus MRA showing short duration. Although surgical intervention is normally large sacular abdominal aortic aneurysms. There was complete advocated due to the high risk for aneurysm rupture, occlusion of the left renal artery manifested here as lack of especially thoracic aneurysms, and death in untreated cases, enhancement of the left kidney, with the right kidney showing our case demonstrates that aortic aneurysms may enhancement. self-resolve.2,3,6–9

Journal of Perinatology 2005; 25:60–62 61 McAdams and Richardson Aortic Aneurysms

Umbilical artery catheter placement in neonates is indicated for aneurysm progression. More detailed imaging modalities, such as blood gas or laboratory sample analysis, continuous blood pressure computed tomography or MRA, provide useful information for monitoring, exchange transfusions, and medication infusions.10 planning surgical intervention or for monitoring nonsurgical UACs are placed in 10.8 to 64.4% of neonatal intensive care unit management. admissions, and 2% of all births.1 Aortic aneurysm formation following UAC placement, which is rare, may be associated with hypertension, uncontrolled sepsis, cardiorespiratory deterioration, References and death. The incidence of complications associated with UAC use 1. Hogan MJ. Neonatal vascular catheters and their complications. Radiol Clin appears to be related to the duration of time that the catheter is left North Am 1999;37(6):1109–25. in place.11,12 In our case, the prolonged duration of UAC use may 2. Cribari C, Meadors FA, Crawford ES, Coselli JS, Safi HJ, Svensson LG. have been a contributing risk factor to the development of Thoracoabdominal aortic aneurysm associated with umbilical artery infection, and subsequent aneurysm formation. The institution of catheterization: case report and review of the literature. J Vasc Surg guidelines in neonatal intensive care units for the discontinuation 1992;16(1):75–86. of UACs after a set duration of time may help reduce the potential 3. Mendeloff J, Stallion A, Hutton M, Goldstone J. Aortic aneurysm resulting complications associated with prolonged use. from umbilical artery catheterization: case report, literature review, and There is a strong association with infection, mainly S aureus, management algorithm. J Vasc Surg 2001;33(2):419–24. 4. Drucker DE, Greenfield LJ, Ehrlich F, Salzberg AM. Aorto–iliac aneurysms and subsequent aneurysm formation.3,4,13 The precise mechanisms following umbilical artery catheterization. J Pediatr Surg 1986;21(8): leading to aneurysm formation remain unclear. Mechanical 725–30. trauma from a UAC tip routinely produces aortic endothelial injury 5. Kirpekar M, Augenstein H, Abiri M. Sequential development of multiple 14 which leads to thrombus formation. In the presence of aortic aneurysms in a neonate post umbilical arterial catheter insertion. bacteremia or an infected UAC tip, the susceptible vascular Pediatr Radiol 1989;19(6–7):452–3. endothelium may become infected, resulting in weakening of the 6. Sarkar R, Coran AG, Cilley RE, Lindenauer SM, Stanley JC. Arterial vessel wall due to inflammation, and subsequent aneurysm aneurysms in children: clinicopathologic classification. J Vasc Surg formation. Although the location of the UAC tip has been shown to 1991;13(1):47–56, discussion 56–7. be associated with the site of future aneurysm formation,4 this does 7. Lobe TE, Richardson CJ, Boulden TF, Swischuk LE, Hayden CK, Oldham KT. not explain the formation of aneurysms distal to the UAC tip, as Mycotic thromboaneurysmal disease of the abdominal aorta in preterm seen in our case. The development of a fibrin sheath involving the infants: its natural history and its management. J Pediatr Surg arterial wall along the length of the UAC may lead to vessel wall 1992;27(8):1054–9, discussion 1059-60. 8. Millar AJ, Gilbert RD, Brown RA, Immelman EJ, Burkimsher DA, Cywes S. inflammation with subsequent disruption of intimal integrity upon 4,15 Abdominal aortic aneurysms in children. J Pediatr Surg 1996;31(12): UAC removal. This could potentially lead to aneurysm 1624–8. formation anywhere along the length of the UAC. Aortic aneurysms 9. Guzzetta PC. Congenital and acquired aneurysmal disease. Semin Pediatr may develop in the abdominal aorta (43%), thoracic aorta (30%), Surg 1994;3(2):97–102. iliac artery (15%), and thoracoabdominal aorta (12%) with most 10. Cohen RS, Ramachandran P, Kim EH, Glasscock GF. Retrospective analysis aneurysms being of the saccular type.3 of risks associated with an umbilical artery catheter system for continuous Any neonate with UAC placement and S aureus sepsis should be monitoring of arterial oxygen tension. J Perinatol 1995;15(3):195–8. considered at increased risk for aortic aneurysm development. 11. Bryant BG. Drug, fluid, and blood products administered through the These infants should have their UACs removed, appropriate umbilical artery catheter: complication experiences from one NICU. antibiotics started, and be followed serially with ultrasound to Neonatal Network 1990;9(1):27–32, 43–6. monitor for the development of aortic aneurysms. If hypertension 12. Symansky MR, Fox HA. Umbilical vessel catheterization: indications, develops, it needs to be adequately controlled, since it may lead to management and evaluation of the technique. J Pediatr 1972;80(5):820–6. 13. Bell P, Mantor C, Jacocks MA. Congenital abdominal aortic aneurysm: a expansion of existing aneurysms,8 and increased risk for rupture. case report. J Vasc Surg 2003;38(1):190–3. Since the extent of aortic damage and the amount of arterial 14. Chidi CC, King DR, Boles Jr ET. An ultrastructural study of the intimal reaction to injury seem to correlate with the duration of UAC injury induced by an indwelling umbilical artery catheter. J Pediatr Surg placement, prompt removal of catheters, when feasible, is 1983;18(2):109–15. 14 advocated to prevent complications. Aortic aneurysms require 15. Kristt DA, Rosenberg KA, Engel BT. Effect of prolonged intra-arterial close observation with serial ultrasound scans to monitor for catheterization on arterial wall. Johns Hopkins Med J 1974;135(1):1–8.

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