The Potential use of 3-D Ultrasound for Arteriovenous Fistula
Flow Dynamics Assessment
Eoin A Murphy1, Rose A Ross2, Shona Z Matthew1,
and John Graeme Houston1
This project has received funding
from the European Union’s Seventh
Framework Programme for research,
technological development and
demonstration under grant
agreement no 324487.
1Division of Cardiovascular and Diabetes Medicine, School of Medicine, Ninewells Hospital, Dundee, DD1 9SY.
2 NHS Tayside Vascular Department, Ninewells Hospital, DD1 9SY, UK.
Image References
[1] T. Vachharajani, Atlas of dialysis vascular access, School of Medicine. Wake Forest. Univ. (2010).
[2] A. Brahmbhatt, A. Remuzzi, M. Franzoni, S. Misra, The molecular mechanisms of hemodialysis vascular access failure, Kidney Int. 89 (2016) 303–316.
doi:10.1016/j.kint.2015.12.019.
Introduction Haemodialysis is the most common treatment for end stage renal
disease. An arteriovenous fistula (AVF) is considered the preferred
vascular access needed for haemodialysis, although, up to 50% fail
to mature. One theory as to why AVFs fail to mature is adverse local
haemodynamics. To study the local haemodynamics computational
fluid dynamics (CFD) is used. 3-D ultrasound could potentially pro-
vide a cheap and accessible means to generate the patient-specific
geometries needed for this study.
The ReDVA Project— Combat the problem of renal dialysis
vascular access failure
Goals – Develop clinical technologies and methodologies that improve long-term performance of VA techniques
– Knowledge exchange
AVF Creation
Fistula surgically created by joining an artery to a vein.
One commonly used fistula type is a radiocephalic (radial
artery and cephalic vein).
Radiocephalic Fistula [1]
AVF Failure—Get with the Flow
Local non-physiological haemodynamics
within a fistula are theorised to encourage
intimal hyperplasia, causing fistula failure.
(a) Unidirectional WSS—physiological
(b) Disturbed WSS—non-physiological
Wall Shear Stress (WSS) and
Endothelial Cells (ECs)
ECs sense the local haemodynamics and
release mitogens and cytokines that regu-
late the proliferation and migration of cells
into and within the vessel wall, as shown
in figure on the right.[2]
CFD Analysis of AVFs
Biological processes within fistula occur at very small scale and cur-
rently unable to get an accurate view of local haemodynamics in vi-
vo.
Therefore, CFD software used to model and assess the haemody-
namics within patient-specific AVFs.
Geometries of patients’ AVFs needed for CFD currently acquired us-
ing magnetic resonance imaging (MRI) at five time-points:
pre-surgery, and post-surgery at 2-4 weeks, 4-6 weeks, 6-8 weeks
and 6 months
Problems
MRI Problems: expensive and time-consuming
Patient Problems: difficult for renal patients to commit to five
extra hospital visits (in addition to dialysis sessions) for MRI scan-
ning, some potential patients find MRI claustrophobic, frailty of pa-
tients (difficult to lie still for one hour).
Geometry Problems: loss of signal around fistula region; therefore,
geometry difficult to acquire in specific region of interest.
Solution—Ultrasound
Ultrasound is already used to assess renal patients pre-surgery, and post-surgery at
regular intervals in Ninewells. 3-D ultrasound could offer a viable alternative to MRI
for patient AVF geometry acquisition. Advantages: no additional patient visits are
needed, assessment is non-invasive, accessible, cheap, good resolution is attainable,
flow measurements can be acquired, and 3-D geometries can be attained.
Sample
Ultrasound
Images
Doppler Ultrasound showing
disturbed flow in fistula
Ultrasound image of fistula with
velocity profile over cardiac cycle
Email: Eoin A Murphy—[email protected]
Foreseeable Issues
Ultrasound is operator dependent. Also, specific ultrasound machine needed capable
of 3-D image acquisition, and position and orientation of images need to be known.
