Doran Mix1 Joseph Featherall2

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Presentation transcript:

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

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 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

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 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

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 Bridge Anterograde: No Flow: Retrograde:

Objective#1: Circuit Model

Objective #1: Pulsatile

Objective#2: Distal Flow

Objective#3: DRIL Effect Collateral Pressure (mmHg) Flow In (cc/min) Collateral Radius (cm) Rcollateral Ccollateral Flow Distal (cc/min) 95/28 860.243 0.16 0.1210 0.0001 -1.20523 860.47 0.18 0.0728 -89.1715 860.51 0.14 0.1989 95.4482 No Flow: Retrograde: Anterograde:

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 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