AVAS Patient Information

What is the AVAS?

The AVAS is a long-term vascular access system that can be attached to an artery or a vein. The device is capable of accepting multiple catheters simultaneously and can be repeatedly accessed on a daily bases. The unprecedented capabilities of the AVAS have enabled clinicians to develop new treatment options for patients who require frequent and long-term infusion. The first application is for the targeted delivery of anti-cancer agents to tumours in the liver.

 

Implantation

A vascular surgeon or general surgeon implants the AVAS. The procedure is preformed under general anaesthetic and takes approximately 90 minutes.

 

Application 1 – Vascular Organ Isolation Chemotherapy with Extraction (VOICE) for primary and secondary liver cancer

VOICE is a treatment developed using the AVAS for primary and secondary liver cancer. The aim of VOICE is to target tumours in the liver with localised high-dose chemotherapy infusions. 

The problem VOICE aims to solve

When administering chemotherapy for cancer in the liver, the standard delivery technique is intravenous. This means that a clinician will inject chemotherapy into a patient’s vein. As most patients will have up to twenty chemotherapy injections over many months, a port-catheter system will be surgically implanted into a patient’s vein in the shoulder. The port-catheter allows clinicians to administer chemotherapy without having to re-harm the patient’s vein for each new injection.

The problem with delivering chemotherapy into the vein is that the drug will circulate throughout the whole body destroying not only tumour cells but also healthy cells. When healthy cells are destroyed patients usually become very sick. In most cases clinicians have to limit the dose of chemotherapy to ensure the patient’s overall health. Whilst limiting the dose is necessary for the patient’s health, it is also problematic because for most patients the limited dose will not completely eradicate all tumour cell activity.  

How VOICE aims to solve the problem

There are 3 main principles to the VOICE procedure

1. Targeted chemotherapy infusions
2. Organ isolation
3. Chemotherapy dose frequency

1. Targeted chemotherapy infusions

The first aim of VOICE is to avoid chemotherapy circulating throughout the body before it reaches the tumour(s) in the liver. The VOICE procedure directly accesses the liver using the AVAS, which is attached onto a patient’s artery near the shoulder. By attaching the AVAS to the artery, clinicians can insert infusion catheters that run directly into the liver and thus the tumour. Once catheters are in place, chemotherapy can be infused directly into the tumour. (Figure2). 

2. Isolation

Whilst infusing chemotherapy directly into the liver reduces the residual leakage of chemotherapy into the body, new blood passing through the liver will ultimately washout the unbound chemotherapy, which will cause similar side effects as the intravenous method mentioned above. The VOICE procedure aims to stop any chemotherapy washout by isolating the liver’s blood supply from the rest of the body. This is done by inserting multiple balloon catheters through the AVAS and into specific arteries that supply the liver with blood (Figure 3). Once all balloon catheters are positioned into the appropriate arteries they can be inflated to stop the blood flowing into the liver. Blood flow to the liver can safely be obstructed for up to 40 minutes at a time. 

3. Chemotherapy dose frequency

Because VOICE aims to minimise whole body toxicity, patients should be well enough to receive treatment more frequently. The AVAS enables clinicians to freely access the patient’s arteries on a daily basis if need be.

 

The AVAS is being used in a clinical trial treating liver cancer at Macquarie University Hospital in Sydney. The Trial is listed on the Australian and New Zealand Clinical Trial Registry ACTRN Number: 12611001273976 

To find out more please refer to the ANZCTR website

https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12611001273976

 

Lane RJ, Phillips M, McMillan D, Huckson M, Liang SW, Cuzzilla M.

Hypertensive extracorporeal limb perfusion (HELP): A new technique for managing critical lower limb ischemia

Journal of Vascular Surgery Volume 48, Issue 5, November 2008, Pages 1156–1165 http://www.sciencedirect.com/science/article/pii/S0741521408010410 

 

Khin NY, Dijkstra ML, Huckson M, Phillips M, McMillan D, Itoh S, Roger G, Lane RJ

Hypertensive extracorporeal limb perfusion for critical limb ischemia

Journal of Vascular Surgery 2013 Nov;58(5):1244-53. doi: 10.1016/j.jvs.2013.05.004. Epub 2013 Jul 2

http://www.ncbi.nlm.nih.gov/pubmed/23830315