Doran Mix1

Joseph Featherall2

University of Rochester School of Medicine and Dentistry1

Rochester Institute of Technology2

Disclosure:None

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)

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.

Clinical ApplicationMay 2009: 179,113 patients used AVF for

hemodialysis52.6% of RRT populationRate of Distal Ischemia after fistula creation

~1.6-8%Future reimbursement

based on outcomes

Limitations:Retrograde blood flow in the arterial

segment distal to the AVF is neither necessary nor sufficient for ARI.

Method:Convert pulsatile arterial blood flow into an

electric circuit diagram of an upper arm AVFPressure VoltageFlow CurrentVessel Radius and Length ResistanceVessel Volume CapacitanceFluid Inertia Inductance

Change resistance and capacitance of collaters Hemodynamics in segment distal to AVF

Arterial Windkessel Model

Bridge: Hemodynamic Circuit

Ohms Law: P = Q * R

Poiseuille’s Equation :

Vessel Capacitance:

Fluid Inertia:

The Wheatstone Bridge:

The Wheatstone Bridge

Balancing the Bridge

Anterograde:

No Flow:

Retrograde:

DRILing the BridgeAnterograde:

No Flow:

Retrograde:

Objective#1: Circuit Model

Objective #1: Pulsatile

Objective#2: Distal Flow

Objective#3: DRIL Effect CollateralPressure (mmHg)

Flow In (cc/min)

CollateralRadius (cm)

Rcollateral

Ccollateral

Flow Distal(cc/min)

95/28 860.243 0.16 0.1210 0.0001 -1.20523

95/28 860.47 0.18 0.0728 0.0001 -89.1715

95/28 860.51 0.14 0.1989 0.0001 95.4482

Anterograde:

No Flow:

Retrograde:

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

Objectives:Model physiologic pulsatile blood flow in a

Brachial-Cephalic AVFObserve 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