current procjects the effect of avf size and position on distal perfusion focus: alter diameter,...

CURRENT PROCJECTSThe Effect of AVF Size and Position on Distal Perfusion

Focus: Alter diameter, length and position of fistula and monitor changes in hemodynamics of system

CFD (Computational Fluid Dynamics) ModelingFocus: Alteration of fistula diameter and the resulting changes in flow patterns

FUTURE PROJECTS The Hemodynamics of AVF and DRIL Bypass Focus: Understand hemodynamics of system with AVF and DRIL, study hemodynamics of DRIL and optimal treatment for ischemic steal.

Mean Aortic Flow: 4.2 L/min

Hollow Tygon tubingFeatures: Tubing length and thickness match vessel compliance and anatomy and includes venous return

Glycerin and WaterFeatures: Match blood viscosity

Connectors with fabricated pressure tapsFeatures: Non- Compliant tubing, capable of acquiring pressure measurements at each junction through pressure transducers, one-way valve included in venous return

Hand compliance chamberFeatures: Column of water below column of pressurized air, accurately mimics compliance and resistance of hand capillary bed

Heart SimulatorFeatures: Ventricular and Venous Compliance chamber, ventricular and buffing chamber, two artificial valves, driven by Servo motor, outputs pulsatile flow

Complete in Vitro Model of the Pulsatile Upper Extremity Arteriovenous Circulation: a Platform for Hemodynamic Testing and Modeling

Ankur Chandra, MD1, Nicole A. Varble, BS2, Dan B. Phillips, Ph.D.2, Steven W. Day, Ph.D.2, Karl Schwarz, M.D.1, Karl A. Illig, M.D.1. 1University of Rochester Medical Center, Rochester, NY, USA, 2Rochester Institute of Technology, Rochester, NY, USA.

Introduction Results Conclusions

Methods and Materials

Current and Future Work

Venous Compliance Chamber

Ventricular Compliance Chamber

Valve Viewing Chamber

Buffing Chamber

Ventricular Chamber

Intersection of Arm

Vasculature

Subclavian A.

Aorta

Axillary A.

Brachial

Ulnar

Radial

Compliance Chamber

Distal Arm V.

One-Way Check Valve

Axillary V.

Subclavian V.

Body Resistance

Collateral

The experimental study of pulsatile arterial and venous hemodynamics is challenging. Mathematical modeling struggles to accurately represent the capillary bed/venous circulation while in vivo animal models are expensive and labor intensive.

We hypothesized that an in vitro, physiologic model of the extremity arteriovenous (AV) circulation could be created as a platform for hemodynamic modeling and testing.

In vitro upper extremity vascular simulator with pressure waveforms at specified locations

Physiologically representative, in vitro, fluid model of the extremity AV circulation which incorporates:• Vessel wall compliance• Blood viscosity• Capillary bed physiology• Variation of all aspects of input hemodynamics (B.P., C.O., and SV) with

heart simulator Applications:Ideal tool to study complex hemodynamics of dialysis access and steal physiology, device testing, surgical simulation

1004.58 L/min

1310 mL/min

1317 mL/min

1260 mL/min

1280 mL/min

29 mL/min

29 mL/min

39 mL/min-20 mL/min

65 mL/min

136 mL/min

1375 mL/min

1410 mL/min

1260 mL/min84 mL/min

97

71

67

65

70

65

67

63

47

35

28

Mean Flows and Pressures are labeled at the appropriate vessels and connectors

above. Pressures [mmHg] are indicated by balloons: #

0 0.5 1 1.5 2 2.5 30

20

40

60

80

100

120

140

time

mm

Hg

P2- Subclavian Artery

0 0.5 1 1.5 2 2.5 30

20

40

60

80

100

120

140

time

mm

Hg

P7: Radial- Ulnar Bifurcation

0 0.5 1 1.5 2 2.5 30

20

40

60

80

100

120

140

time

mm

Hg

P12- Venous Return

0 0.5 1 1.5 2 2.5 30

20

40

60

80

100

120

140

time

mm

Hg

P14- Venous Return

Retrograde Flow

Brachial A.: 121/54 mmHg (91.92 mmHg)

SC V.: 17.63 mmHg

Distal Venous Return: 41.30 mmHg

SC A.: 125/55 mmHg (90.47 mmHg)

CFD Model of brachial artery bifurcated with AVF