Translating In-vitro and Computational Multi-scale Models for the Vascular Surgeon

Transcription

1 Translating In-vitro and Computational Multi-scale Models for the Vascular Surgeon Benjamin A. Eslahpazir MS, BSME 1, Kyle W. Beggs 2, Zoe M. Lauters 2 Alain J. Kassab PhD 2 William M. DeCampli MD, PhD 1,3 1 College of Medicine, University of Central Florida, Orlando, FL 2 Department of Mechanical Engineering, University of Central Florida, Orlando, FL 3 Division of Cardiothoracic Surgery, Arnold Palmer Hospital for Children, Orlando, FL

2 Disclosures The authors report no disclosures

3 Introduction Hemodynamic in-vitro circulatory systems and computational counterparts serve as useful instruments of knowledge for the vascular practice: 1. Post-operative hemodynamic outcomes 2. Novel surgical maneuvers 3. Behavior of complex pathology Multi-scale modeling of the vascular system permits the addition of vascular impedance downstream

4 Hemodynamic Vascular Modeling Organizing Principles 1. Cardiac Output

5 Hemodynamic Vascular Modeling Organizing Principles 1. Cardiac Output 2. Vessel Geometry

6 Hemodynamic Vascular Modeling Organizing Principles 1. Cardiac Output 2. Vessel Geometry 3. Downstream Domain

7 Hemodynamic Vascular Modeling Downstream Domain

8 Hemodynamic Vascular Modeling Downstream Domain

9 Hemodynamic Vascular Modeling Downstream Domain = Impedance

10 Vascular Impedance

11 Construction and Incorporation of the 2-Element Arterial Windkessel for In-vitro Impedance

12 Creation of In-vitro Vascular Impedance: Resistance from Blood Viscosity 6:4 water-glycerol mix with μ = 4.19±0.48 cp Compares to complex, non-newtonian whole blood at physiological shear rates (4-6 cp).

13 Creation of In-vitro Vascular Impedance: Resistance from Geometry Borosilicate Glass Capillary Tubes In-vitro Validation PVC Conduit with Standard NPT Pipe Connections

14 Creation of In-vitro Vascular Impedance: Resistance Established: flow-independent resistance High level of accuracy: Error < 1.5% (Q 1.0 L/min) Laminar Flow at 2L/min: Reynolds Number < 145 << 2000 EXPERIMENTAL REFERENCE Kung E, Cardiovasc Eng and Tech (2010) 2, 2-14

15 Creation of In-vitro Vascular Impedance: Compliance

16 Creation of In-vitro Vascular Impedance: 2-Element Hydraulic Windkessel

17 Creation of In-vitro Vascular Impedance: 2-Element Hydraulic Windkessel Theoretical Pressure Flow Theoretical Pressure Measured Pressure Measured Pressure

18 Hemodynamic Vascular Modeling 3 Organizing Principles 1. Cardiac Output 2. Vessel Geometry 3. Downstream Domain

19 Cardiac Output: CPU-Controlled Solenoid Motor SHELLY MEDICAL PHYSIO-PULSE 100 FLOW SYSTEM

20 Hemodynamic Vascular Modeling 3 Organizing Principles 1. Cardiac Output 2. Vessel Geometry 3. Downstream Domain

21 Vessel Geometry THORACIC CT W/ CONTRAST

22 Vessel Geometry THORACIC CT W/ CONTRAST VESSEL ISOLATION

23 Vessel Geometry THORACIC CT W/ CONTRAST VESSEL ISOLATION LUMEN EXPORT & GRAFT CONNECTION

24 Vessel Geometry THORACIC CT W/ CONTRAST VESSEL ISOLATION LUMEN EXPORT & GRAFT CONNECTION MODIFY AORTA GEOMETRY FOR IN-VITRO APPLICATIONS

25 Vessel Geometry THORACIC CT W/ CONTRAST VESSEL ISOLATION LUMEN EXPORT & GRAFT CONNECTION 3D PRINT PROTOTYPE MODIFY AORTA GEOMETRY FOR IN-VITRO APPLICATIONS

26 Vessel Geometry THORACIC CT W/ CONTRAST VESSEL ISOLATION LUMEN EXPORT & GRAFT CONNECTION 3D PRINT PROTOTYPE 3D PRINT ACCURA 60 TRANSPARENT POLYCARB MODIFY AORTA GEOMETRY FOR IN-VITRO APPLICATIONS

27 Hemodynamic Vascular Modeling Complete In-vitro Model 1. Cardiac Output 2. Vessel Geometry 3. Downstream Domain

28 Hemodynamic Vascular Modeling Complete In-vitro Model SUBCLAVIAN, VERTEBRAL, & COMMON CAROTID ARTERY WINDKESSELS DESCENDING THORACIC AORTA WINDKESSEL PULSATILE PUMP VASCULAR GEOMETRY

29 Measurements Pressure Transducers

30 Measurements In-Line Impeller Flow Meters

31 Controls Gated Coronary Solenoid Valve

32 Digital Control & Measurements SHELLY MEDICAL CARDIAC PUMP CONTROLLER POWER SUPPLY SOLID STATE RELAY SWITCH 16-CHANNEL ADINSTRUMENTS POWERLABS ADINSTRUMENTS LabChart

33 Pressure Flow Output Flows and Pressures of the Thoracic Aorta Ascending Aorta Outflow Graft Left Subclavian Right Subclavian Left Common Carotid Right Common Carotid Left Vertebral Right Vertebral Descending Aorta Coronaries Subclavians Common Carotids Vertebrals Descending Aorta Phase Delay

34 Pressure Flow Output Flows and Pressures of the Thoracic Aorta Ascending Aorta Outflow Graft Left Subclavian Right Subclavian Left Common Carotid Right Common Carotid Left Vertebral Right Vertebral Descending Aorta Coronaries Subclavians Common Carotids Vertebrals Descending Aorta Phase Shift

35 Flow Meter Parasitic Resistance Impeller Flow Meter Electromagnetic Flow Meter dp = 5 mmhg dp = 120 mmhg

36 Conclusion Impedance can be accurately recreated using the 2- element Windkessel construct. Vascular impedance is a principle consideration for pressure-flow relationships in the multi-scale model. Fidelity of in-vitro studies for the vascular practice can benefit from the multi-scale model.

37 References 1. N. Westerhof, J.W. Lankhaar, et.al., The arterial Windkessel, Medical and Biological Engineering and Computing, 2009, 47: M. Mehta, F. Veith, et. al., Significance of endotension, endoleak, and aneurysm pulsatility after endovascular repair, Journal of Vascular Surgery, 2003, 37: HA. Orra, P. Puech-Leiio, et al., Aneurysm Pulsatility after endovascular exclusion an experimental study using human aortic aneurysms, Clinics, 2008;63(1): N. Varble, S. Day, et al., In vitro hemodynamics model of the arm arteriovenous circulation to study hemodynamics of native arteriovenous fistula and the distal revascularization and interval ligation procedure, Journal of Vascular Surery, 2014;59: H. Veger, J. Westenberg, et al., The role of branch vessels in aortic type B dissection: an in-vitro study, European Journal of Endovascular Surgery, 2015;49: W. Clark, B. Eslahpazir, et al., In-vitro modeling provides consistent results with computational fluid dynamics for reduced ventricular assist device embolization rates in cerebral vessels, Cardiovascular Engineering and Technology, 2015;6(3):

38 Thank You