CURRENT PROCJECTS The Effect of AVF Size and Position on Distal Perfusion

1. # 71 28 100 63 70 65 67 67 35 65 47 97 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 Aorta 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. Mean Aortic Flow: 4.2 L/min • 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 4.58 L/min Ventricular Compliance Chamber Valve Viewing Chamber Buffing Chamber Body Resistance 1310 mL/min 1410 mL/min Subclavian V. Subclavian A. Intersection of Arm Vasculature Methods and Materials 1317 mL/min • Hollow Tygon tubing • Features: Tubing length and thickness match vessel compliance and anatomy and includes venous return • Glycerin and Water • Features: Match blood viscosity • Connectors with fabricated pressure taps • Features: Non- Compliant tubing, capable of acquiring • pressure measurements at each junction through • pressure transducers, one-way valve included in • venous return • Hand compliance chamber • Features: Column of water below column of • pressurized air, accurately mimics compliance and • resistance of hand capillary bed • Heart Simulator • Features: Ventricular and Venous Compliance chamber, ventricular and buffing chamber, two artificial valves, driven by Servo motor, outputs pulsatile flow Current and Future Work Axillary A. • CURRENT PROCJECTS • The 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) Modeling • Focus: 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. 1375 mL/min • SC A.: 125/55 mmHg (90.47 mmHg) 1260 mL/min Axillary V. • SC V.: 17.63 mmHg Ventricular Chamber Venous Compliance Chamber 1280 mL/min Collateral 136 mL/min Brachial 1260 mL/min 84 mL/min One-Way Check Valve CFD Model of brachial artery bifurcated with AVF 29 mL/min Distal Arm V. Brachial A.: 121/54 mmHg (91.92 mmHg) 29 mL/min Ulnar • Distal Venous Return: 41.30 mmHg -20 mL/min Compliance Chamber 39 mL/min Radial Mean Flows and Pressures are labeled at the appropriate vessels and connectors above. Pressures [mmHg] are indicated by balloons: 65 mL/min In vitro upper extremity vascular simulator with pressure waveforms at specified locations Retrograde Flow