Pseudoaneurysmatic complication of an arteriovenous graft
Improvements in hemodialysis techniques have led to an extended life expectancy such that the number of patients with end-stage renal disease is increasing1. Complications regarding vascular access are the main causes of hospitalization in dialysis patients2,3.
Nowadays, it is recognised that autologous arteriovenous fistulas (AVF) lead to better long-term results when compared to other possible vascular accesses, including polytetrafluoroethylene (PTFE) grafts4–6. Although the creation of an AVF is a common practice, many patients require secondary or tertiary access procedures. Indeed, an important complication of AVFs is aneurismal dilatation of the venous end which can rupture and cause hemorrhages that can even be fatal7.
Pseudoaneurysm is also a relatively rare1 (2% to 10%) complication of dialysis access graft1 and comes from repeated needle punctures. An arteriovenous bridge graft, usually with PTFE, continues to be a reasonable alternative form of hemodialysis access1,8. The creation and maintenance of hemodialysis access occupies a significant portion of most vascular and general surgery practices9.
Presentation of the case
A 78-year-old Caucasian Greek man presented with a well defined round region of 2–3 cm diameter, with discoloration, swelling and pain in the arteriovenous graft anastomosis in his left upper extremity. He had been on hemodialysis for 6 years as a result of end-stage renal disease. Hemodialysis was originally initiated with an arteriovenous cimino fistula in his left arm, which provided low blood supply and was thus considered non-functional. The access was switched to a new arterio-venous fistula in his right upper arm, which thrombosed after 3 years. Eventually an arteriovenous graft was placed between the brachial artery and axillary vein in his left upper arm. After two years, upon physical examination, a pulsatile mass was found in the middle of the arteriovenous graft anastomosis. A murmur was detected on auscultation. The size of the pseudoaneurysm was approximately 2 × 3 cm. Within a month’s time, he presented with swelling and discolouration of the aneurismatic mass which had developed a purulent outflow. The patient was referred to surgeons who performed a longitudinal incision and explored the pseudoaneurysm sac.
Diagnosis and therapeutic intervention
An infection was confirmed after taking cultures when the aneurismal sac was opened. There was a destructed segment of about 6 cm in length at the initial AVG. The defect in the graft was repaired with the interposition of a second PTFE graft that was placed next to the initial graft and was anastomosed in an end-to-side fashion by performing a bypass procedure in the same section. The surgical procedure was successful and the patient was discharged without any complications on the same day. The patient continued hemodialysis sessions after this for three years without any complications.
Discussion
The progressive increase in the number of hemodialysis patients makes vascular access creation a common procedure. There are three different choices for hemodialysis access, an AVF, AVG and a central catheter. The brachiocephalic AVF in the forearm should be the first choice1. However, some patients lack available veins for AVF creation or have unsuitable superficial veins due to their use for repeated arteriovenous fistula procedures. In these cases, upon the exhaustion of all autologous AVF possibilities, a PTFE prosthetic graft becomes an alternative necessity in order to bridge arteries and veins. It is usually placed as an arm or forearm loop graft or even as an axillary-brachial bypass graft. A successful procedure requires adequate blood flow, and, therefore, the rotation or angulation of the prosthesis needs to be avoided.
Common complications of a vascular access include thrombosis, infection, venous hypertension, and aneurysmal degeneration10,11. Thrombosis is the most common complication in 90% of AVFs12. The use of antiplatelet agents, marcumar or other agents may reduce the risk of thrombosis13, but there is a risk of bleeding and further studies need to prove this hypothesis.
True aneurysms are most likely to occur in native AVFs, compared with AVGs where a pseudoaneurysm may occur. The indications for surgical intervention of venous aneurysms are progressively increasing size, thrombosis or an open skin lesion14.
Focal aneurysms can be managed either with manual ligation, embolization and thrombin injection under ultrasonographic guidance15, interposition, replacement with vein or a prosthesis, or resection and imbrication.
PTFE grafts can also lead to bleeding, dilatation, infection, pseudoaneurysm, seroma, steal, swelling, stenosis or thrombosis1,8. Duplex scans can define the exact nature and extension of the aneurysm1.
The development of a graft–related pseudoaneurysm is multifactorial16. Repeated canulations may cause disruption and fragmentation of the PTFE graft material16,17. Further, progressive enlargement of a pseudoaneurysm can lead to the breakdown of the overlying skin, spontaneous bleeding, and rupture16. Surgical repair is recommended16,18. The main treatment includes ligation and resection of the graft followed by insertion of a new interposition graft segment16,19.
In this case study, the aneurysm was infected to such an extent that it caused the patient’s arteriovenous graft to rupture. The surgeons repaired the graft with the interposition of a second PTFE AVG placed right next to the initial one. They performed a bypass procedure in the same section by anastomosing the second graft in an end-to-side fashion. After completing the resection procedure of the AVF aneurysm, the patient’s new AVG was canulated without any complications. Our patient was therefore satisfied with the outcome of the surgery.
Concluding, AV dialysis accesses are associated with multiple complications20. The traditional repair of hemodialysis graft pseudoaneurysms requires the surgical replacement of the segment that involves the PTFE graft material or autogenous vein16,19,21. Careful attention to technical detail is required, such as focusing on patients with development of arm swelling or discomfort after surgical access placement or hemodialysis sessions; decreased flow rates during dialysis, suspected of having a pseudoaneurysm; AVF/graft stenosis; or adjacent fluid collection and prolonged immaturity of a surgically created AVF, in order to avoid several diagnostic pitfalls22.
Consent
Written informed consent for publication of clinical details was obtained from the patient.
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