Invasive Arterio-Venous Fistula Blood Pressure Monitoring & Fluid Dynamics Study

Study Overview
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Brief Summary
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The surgical formation of an AVF offers a unique example of vascular remodelling and adaption. Yet, the specific factors which elicit remodelling events which determine successful maturation or failure have not been unambiguously determined. Computational fluid dynamic (CFD) simulations are increasingly been employed to investigate the interaction between local haemodynamics and remodelling and can potentially be used to assist in clinical risk assessment of maturation or failure. However, these simulations are inextricably linked to their prescribed boundary conditions and are reliant on in vivo measurements of flow and pressure to ensure their validity. This study will compare in vivo measurements of the pressure distribution across an AVF against a representative numerical model.

Detailed Description
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Most patients with End Stage Renal Disease (ESRD) will require haemodialysis. Several studies have recognized a well-functioning Arterio-Venous Fistula (AVF) as the best modality for access in patients with ESRD undergoing haemodialysis. A mature AVF has lower incidence of thrombosis and stenosis compared to the other two available modalities of the Arterio-Venous Graft (AVG) and Central Venous Catheter (CVC). This translates into prolonged patency rates and lower risk of infection. The use of AVF's are also associated with lower mortality, and costs. However, significant numbers of AVFs [20% to 60 %] are known to fail to mature into functioning fistulas. Issues such as impaired vein remodelling, intimal hyperplasia, technical problems, unrecognized stenosis within the outflow vein, inflow problems, or steal syndromes can all lead to failure of achieving a mature AVF. The aim of the study is to examine the relationship between the pressure gradient within the surgically formed AVF and its' maturation and functioning status.

Official Title
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Invasive Arterio-Venous Fistula Blood Pressure Monitoring & Fluid Dynamics Study

Conditions
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Arterio-venous Fistula

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients undergoing AVF formation surgical procedure or AVF intervention surgery. Willing and capable of signing an informed consent form. Exclusion Criteria: Patients unable to provide informed consent. Patients under the age of 18 Patients who are deemed unsuitable due to any circumstances as deemed appropriate by the P.I.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Effects of pressure gradient within AVF on maturation and functioning of the AVF. | Pressure measurements obtained intra-operatively will be examined alongside pre and post operative ultrasound imaging of the veins and arteries. | 2 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of in-vivo and ex-vivo perfusion with validation of CFD solutions. | The two models will be compared for validation purposes. | 2 years |