Table 2.
3D printed model construction and key characteristics
| Reference | Model construction | 3D printer | Material | Time | Cost | Model characteristics | |
|---|---|---|---|---|---|---|---|
| Imaging | Anatomy | ||||||
| Schmauss et al., 2012 [39] | Cardiac CT | Aortic root, aortic arch and the ascending aorta | Polyjet | N/A | N/A | N/A | N/A |
| Ripley et al., 2016 [32] | ECG gated Cardiac CT, images at peak systole | Aortic root and LVOT. Valve leaflets not included | SLA | Clear flexible photosensitive resin | 5 h | N/A | Agreement of minimum and maximum annulus diameter measurements between 3D model and patient's imaging data |
| Fujita et al., 2016 [43] | CT | Ascending aorta, aortic valve, prosthetic mitral valve and LVOT | SLA | Photosensitive resin | N/A | N/A | N/A |
| Qian et al., 2017 [37] | Contrast-enhanced CT, images taken at systolic phase |
Aortic root, aortic annulus, LVOT and valve leaflets |
Polyjet |
Photopolymers: Stiff sinusoidal fibres—VeroBlackPlus® (RGD875) Elastic matrix—TangoPlus® (FullCure 930) |
Segmentation of anatomical structures: 5–10 min Formation of digital files for printing: 5 min 9–10 h to print ten 3D models Post-printing processing time: 45 min |
Cost of printing materials per model: $150 to $200 |
Model imitates, to some degree, the strain-stiffening characteristic of human soft tissue Model submerged in water at 37 °C to mimic temperature of body, ensured full expansion of the valve |
| Hosny et al., 2018 [36] | ECG gated cardiac CTA, images taken at diastolic phase | Aortic root, annulus, LVOT, valve leaflets with calcifications | Polyjet |
Photopolymers: Calcified leaflets and valve sizer printed with rigid white VeroWhitePlus (RGD835), aortic root/ non-calcified leaflets printed with flexible transparent TangoPlus® (FLX930) |
N/A | N/A |
Agreement in annulus diameter measurements between 3D model and patient's imaging data Mechanical properties of human tissue were approximated but, strain-stiffening behaviour of human aortic tissue not replicated |
| Tanaka et al., 2018 [33] | ECG gated multi-detector CT, images taken at end-diastole | aortic annulus with valve leaflets, aortic root, LVOT, thoracic and abdominal aorta, iliofemoral arteries | SLA—for all structures except aortic annulus | Printed material not specified. Aortic annulus with three leaflets constructed using silicone moulding | N/A | N/A |
Elasticity of calcified regions and mechanical stiffness of aortic annulus were adjusted to those of human tissue Pulsatile flow circulation system replicated HR and mAP of patients |
| Yaku et al., 2018 [42] | CT | N/A | SLA |
Photosensitive resin: Aortic wall printed with Polyurethane resin. Intramural haematoma was made using epoxy resin (hard material) |
N/A | N/A | Pressure gauge measure pressure exerted onto aortic wall |
| Hatoum et al., 2019 [40] | Cardiac CT, image taken at diastole | LVOT, aortic annulus with valve leaflets, aortic root and ascending aorta | Polyjet |
Photopolymers: Calcified leaflets printed with rigid white VeroWhitePlus (RGD835), soft tissues printed with flexible transparent TangoPlus® (FLX930) |
N/A | N/A | Model connected to pulse duplicator left heart simulator that replicated mAP and HR |
| Zhang et al., 2019 [38] | ECG gated cardiac CTA, images at systolic phase | Aortic root, valve leaflets with calcifications and LVOT | N/A |
HeartPrint® Flex for non-calcified regions: transparent, flexible, mimicking modulus of elasticity of human arterial tissue Material for hard calcifications—N/A |
N/A | N/A | Calcifications printed with a different coloured material to allow visualisation |
| Haghiashtiani et al., 2020 [41] | Cardiac CT | Aortic wall, aortic annulus, valve leaflets with calcifications, LVOT | Custom-built 3D printing system (AGS1000, Aerotech) | Silicone sealant and silicone grease mixed at various specified weight ratios to print (a) Myocardium and leaflets and (b) aortic wall. Speckling material for calcifications on vales. Colouring agent marked the intermediate implantation depth | 3D models left in ambient air for 5 to 7 days after printing, to complete curing | N/A | Young's modulus of meta-materials fall within the range of moduli values for human tissue. Materials failed to represent strain-stiffening behaviour of human tissue at high strains |
| Reiff et al., 2020 [35] | ECG gated CT, images at systolic phase |
LVOT, aortic root and ascending aorta Native leaflets not included |
FDM | Thermoplastic polyurethane (Ninjaflex flexible) | N/A | N/A | Model approximates the modulus of elasticity of the human aorta |
| Thorburn et al., 2020 [34] | ECG gated cardiac CT |
Aortic root, the coronary artery ostia and LVOT Native leaflets not included |
FDM |
Thermoplastic polyurethane (Ninjaflex flexible) Sealant material |
Printing time alone: 4 h / model | N/A | Closed pressure system. Saline to represent blood. Radiopaque marker on the annulus to allow them to replicate implantation depth as in vivo |
| Redondo et al., 2021 [44] | ECG gated cardiac CT | Thoracic aorta, aortic arch, descending aorta, aortic root and coronary ostia | SLA | Photosensitive resin with flexible silicone-like characteristics | N/A | N/A | N/A |
CTA Computed Tomography Angiography, ECG Electrocardiogram, FDM Fused Deposition Modelling, HR Heart Rate, LVOT Left ventricular outflow tract, mAP mean Arterial Pressure