P-059 - TOWARDS 3D-PRINTING OF REALISTIC AORTIC PHANTOMS: MODELLING OF MECHANICAL POLYMER CHARACTERISTICS TO MIMICK AORTIC TISSUE

TOPIC:
New vascular techniques and devices
AUTHORS:
Dorweiler B. (Department of Vascular Surgery, University Medical Center Cologne ~ Cologne ~ Germany) , Wegner M. (Department of Vascular Surgery, University Medical Center Cologne ~ Cologne ~ Germany) , Hannah R. (Anamos GmbH ~ Munich ~ Germany) , Niehoff A. (Deutsche Sporthochschule ~ Cologne ~ Germany) , Salem O. (Department of Vascular Surgery, University Medical Center Cologne ~ Cologne ~ Germany)
Introduction:
Current applications of 3D-printing technology for generation of patient-specific anatomical models of aortic disease mainly use rigid printing polymers. There is the aim to develop flexible polymers, that will enable generation of more realistic models and herein we report our results of modelling and mechanical testing of flexible polymers for 3D-printing of aortic anatomy.
Methods:
Test objects made of flexible printing polymers of varying hardness (ShoreA 20: highly flexible to ShoreA 40: medium flexibility) were generated by either using the Stratasys Objet350 ConnexIII-platform or silicone (ACEO® GP series, Wacker Chemie AG) and compared to biologic tissue (fresh porcine aorta, bovine pericardium). Test objects included patches (dumbbell-shape, length 25mm, thickness 2mm) and tubes (length 60mm, diameter 25mm, thickness 2mm) and were either used intact or cut in half and sutured using 4/0 propylene suture. Test objects were subjected to mechanical stress/strain tests using a Zwick Roell Z2.5/TN1S device.
Results:
The tensile strength (in N/mm2) of synthetic polymer for intact patches was between 3,3 and 4,1 for Shore-hardness 20-40. Polymer-compositions of increased hardness (Shore 50-80) exhibited increased strength but reduced elasticity (elongation). Bovine pericardium and aortic tissue showed a max. tensile strength of 3,0 and 1,6, respectively. Using sutured patches, tensile strength was reduced to 0,9 to 1,1 (ShoreA 20-40), but still slightly higher than aortic tissue (0,4). For the sutured tubes, tensile strength (in N/mm2) was 0,8 to 1,0 while bovine pericardium and aortic tissue showed a tensile strength of 1,2 and 0,7, respectively. Assessment of haptic feedback (needle-puncture/suture pull-through) revealed that ShoreA 20 and 30 were most closely resembling aortic tissue.
Conclusion:
Flexible printing polymers enable the next step towards generation of high-fidelity 3D-printed models of aortic anatomy: By adjustment of Polymer-composition and subsequent stress-testing it could be confirmed that mechanical behavior mimicking that of aortic tissue can be achieved. This in turn offers the future direction of realistic training and simulation models of aortic anatomy/pathology.