Mycotic aneurysm of a native brachiocephalic fistula

Daniel J Higgs; Arun Ariyarathenam; Jacob A Akoh

doi:10.4103/1319-2442.157409

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LETTER TO THE EDITOR

Year : 2015 | Volume : 26 | Issue : 3 | Page : 594-596

Mycotic aneurysm of a native brachiocephalic fistula

Daniel J Higgs, Arun Ariyarathenam, Jacob A Akoh
Gastroenterology, Surgery and Renal Services Directorate, Plymouth Hospitals NHS Trust, Derriford Hospital, Plymouth, PL6 8DH, United Kingdom

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Date of Web Publication

20-May-2015

How to cite this article:
Higgs DJ, Ariyarathenam A, Akoh JA. Mycotic aneurysm of a native brachiocephalic fistula. Saudi J Kidney Dis Transpl 2015;26:594-6

How to cite this URL:
Higgs DJ, Ariyarathenam A, Akoh JA. Mycotic aneurysm of a native brachiocephalic fistula. Saudi J Kidney Dis Transpl [serial online] 2015 [cited 2021 Jan 20];26:594-6. Available from: https://www.sjkdt.org/text.asp?2015/26/3/594/157409

To the Editor,

Native arteriovenous fistulas (AVFs) are considered the gold standard for providing access for hemodialysis (HD) by the National Kidney Foundation Kidney Disease Outcome Quality Initiative (NKF K-DOQI) ^[1] as a result of their superior patency, lower morbidity and greater cost effectiveness. ^{[2],[3],[4],[5],[6],[7]} We would like to share our experience with a rare case of infection of a native AVF leading to aneurysmal dilatation (mycotic aneurysm), managed by excision of vascular access. A 72-year-old female with established renal failure due to hypertensive ischemic nephropathy was admitted to the hospital with poor flow through her threeyear-old brachio-cephalic fistula (BCF). Her past medical history included collagenous colitis treated with a defunctioning loop ileostomy, parastomal hernia repair, cholecystectomy, appendectomy, severe osteoporosis, disabling fibromyalgia, secondary hypertension and peripheral neuropathy. A Doppler ultrasound scan revealed extensive thrombosis of the AVF. Targeted thrombolysis using recombinant tissue plasminogen activator restored fistula function but left a small proximal residual thrombus. The patient was subsequently commenced on 60 mg of enoxaparin daily, while HD was performed using a temporary tunneled central venous catheter inserted via the internal jugular vein. One week later, the temporary line was removed as the BCF was once again used as the vascular access for dialysis. The patient was initiated on warfarin therapy initially at a dose of 2 mg/3 mg on alternate days with a target International Normalized Ratio (INR) of 2.5.

Five weeks later, the fistula became erythematous and larger in size with a raised Creactive protein (CRP) level of 74mg/L but normal white cell count (WCC) of 9.2 × 10 ⁹ /L. A diagnosis of AVF infection/aneurysm was made and the patient was initiated on a oneweek course of vancomycin. The vascular access imaging by means of duplex ultrasound revealed several large dilatations within a patent BCF. Three weeks after the diagnosis of AVF infection, the patient was referred urgently to the surgical outpatient clinic with significant dilatation of her BCF, overlying erythema and a localized collection of pus [Figure 1]. Blood cultures yielded no bacterial growth. Her INR of 1.8 was further reduced to 1.4 prior to surgery with the use of 1 mg of oral vitamin K. At surgery, the aneurysmatic fistula with purulent discharge from the over-lying necrotic skin exhibited features of imminent rupture [Figure 2]. The aneurysm was exposed along its length via a longitudinal incision and excised with the ends ligated and transfixed. A wound swab obtained at the time of surgery cultured coagulase-negative Staphylococcus.

Figure 1: Mycotic aneurysmal dilatation of the left brachiocephalic fistula.

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Figure 2: Exposed aneurysmal fistula via a longitudinal incision.

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Histology confirmed a 25-mm mycotic aneurysm of the excised native BCF with reactive inflammatory changes within its wall secondary to thrombus formation. There was a 6mm patch of necrotic skin over the aneurysmatic fistula.

This case highlights the ravaging effects of vascular access infection, irrespective of the type of vascular access. Vascular access infections account for approximately one-third of all bacterial infections, ^[8] and bacteremia due to vascular access infection is associated with a mortality rate of 6% and 9% in non-diabetic and diabetic populations, respectively. ^[9]

Aneurysmal dilatation occurs in approximately 5.5-6.7% of AVF, ^{[10],[11],[12]} and usually results from repeated trauma to the fistula from needling. ^[13] However, in our case, the aneurysmal dilatation developed over a five-week period after thrombolysis in combination with infection of the fistula, despite good inflow and outflow. It can be postulated that the combined risk of graft thrombosis leading to weakening of the vessel wall and vascular access infection resulted in damage of the integral structure of the fistula and the formation of a rapidly dilating mycotic aneurysm. Routine inspection of the fistula site, which is most frequently performed by dialysis nurses, is therefore essential to ensure that complications such as infection and aneurysm formation are highlighted early and treated effectively. Although rare, AVF infections associated with aneurysmal dilatation, infected thrombosis or septic embolization require excision of vascular access.

Conflict of Interest: None declared.

References

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