Case 11: Diagnosis & Conclusions -

Diagnosis: Exposed Arteriovenous Graft (AVG)

Case Summary: Scary case! Even without the patient’s history and medical comorbidities, one look at this patient’s arm should prompt us to send him to the hospital for urgent evaluation. An exposed graft puts this patient at high risk for vascular access rupture, a life threatening emergency. Let’s take a minute to review AVGs.

Both arteriovenous fistulas (AVFs) and AVGs attempt to create a connection between an artery and a vein. While AVFs (on left below) are a direct anastomosis between an artery and a vein, the AVG utilizes a piece of tubing (the graft, seen below on the right) to facilitate this connection.

Arteriovenous fistula (AVF)

Arteriovenous graft (AVG)

The grafts can be constructed from prothetic or biologic materials, though prosthetic grafts are more commonly used (click below!):

Prosthetic grafts

*These grafts are commonly made out of expanded polytetrafluoroethylene (PTFE) and are 4 – 8 mm in diameter. Not all PTFE grafts are the same – they can be straight or looped, standard or thin walled, heparin bonded, externally supported, or tapered.
*The HeRO (Hemodialysis Reliable Outflow) graft is a special type of PTFE graft that is reinforced with a nitinol-outflow catheter. The nitinol catheter can be directly connected to the large outflow vein and the venous-end anastomosis seen above can be avoided.

Biologic grafts

Options include cryopreserved femoral veins and bovine arteries/veins/ureter – though not often used. Tissue-engineered grafts present and exciting option and have been tested in humans, but are not yet available for commercial use.

Here’s another look at our patient’s exposed PTFE graft – hopefully we don’t see this again! Remember – this is a surgical emergency!

For more, take a look here:

Case 11 Index
Case 11 Introduction
Case 11 Physical Exam
NephSim