1. Doran Mix1 Joseph Featherall2
Pulsatile Hemodynamic Circuit Simulation of Access-Related Distal Ischemia and a Potential Mechanism for the Distal Revascularization-Interval Ligation Corrective Procedure
Doran Mix1
Joseph Featherall2
University of Rochester School of Medicine and Dentistry1
Rochester Institute of Technology2

2. Disclosure:
None

3. Objectives: Model physiologic pulsatile blood flow in a
Brachial-Cephalic arterovenous fistula
Observe retrograde blood flow in the arterial segment distal to AVF as a surrogate of access related distal ischemia (ARI)
Observe effect of capacitance and resistance produced by the Distal Revascularization-Interval Ligation procedure (DRIL)

4. Hypothesis:
Pulsatile retrograde blood flow in the arterial segment distal to the AVF is a function of arterial collateral resistance and capacitance.
Distal Revascularization will promote retrograde blood flow to the distal limb by decreasing collateral resistance and increasing capacitance.
Interval Ligation is needed to prevent retrograde blood flow.

5. Clinical Application
May 2009: 179,113 patients used AVF for hemodialysis
52.6% of RRT population
Rate of Distal Ischemia after fistula creation ~1.6-8%
Future reimbursement
based on outcomes

6. Limitations:
Retrograde blood flow in the arterial segment distal to the AVF is neither necessary nor sufficient for ARI.

7. Method:
Convert pulsatile arterial blood flow into an electric circuit diagram of an upper arm AVF
Pressure  Voltage
Flow  Current
Vessel Radius and Length  Resistance
Vessel Volume  Capacitance
Fluid Inertia  Inductance
Change resistance and capacitance of collaters
Hemodynamics in segment distal to AVF

8. Arterial Windkessel Model

9. Bridge: Hemodynamic  Circuit
Ohms Law: P = Q * R
Poiseuille’s Equation :
Vessel Capacitance:
Fluid Inertia:

11. The Wheatstone Bridge:

12. The Wheatstone Bridge

13. Balancing the Bridge
Anterograde:
No Flow:
Retrograde:

14. DRILing the Bridge
Anterograde:
No Flow:
Retrograde:

15. Objective#1: Circuit Model

16. Objective #1: Pulsatile

17. Objective#2: Distal Flow

18. Objective#3: DRIL Effect Collateral
Pressure (mmHg)
Flow In (cc/min)
Collateral
Radius (cm)
Rcollateral
Ccollateral
Flow Distal
(cc/min)
95/28
0.16
0.1210
0.0001
860.47
0.18
0.0728
860.51
0.14
0.1989
No Flow:
Retrograde:
Anterograde:

19. Conclusion:
Retrograde flow is promoted by Distal Revascularization: decreasing collateral resistance
Anterograde flow is promoted by Distal Revascularization: decreasing resistance of proximal segment
Interval Ligation removes the distal conduit and effectively removes retrograde flow
Collateral ligation supports anterograde flow

20. Objectives:
Model physiologic pulsatile blood flow in a
Brachial-Cephalic AVF
Observe retrograde blood flow in the arterial segment distal to AVF as a surrogate of access related distal ischemia (ARI)
Observe effect of capacitance and resistance produced by the Distal Revascularization-Interval Ligation procedure