Descarga (PDF 12.8Mb)
Transcription
Descarga (PDF 12.8Mb)
El cateterismo del futuro: ¿ver y tocar? Antonio J Cartón Servicio de Cardiología Pediátrica Hospital Universitario La Paz Madrid, España h"p://www.cardiopa.aslapaz.com Necesidades percibidas h"p://www.cardiopa.aslapaz.com Visualización 3D de estructuras anatómicas h"p://www.cardiopa.aslapaz.com cross-sectional area of the stent at the smaller section, stretching of the aortic root [18]. The aortic roots were it wasan moved 4.2 mm proximally towards the left ventricle devices were modelled using elasto-plastic con• obstruction of the coronary arteries, evaluated accord(EP; 3Fig. 4), and 4.2 mm distally towards the aortic arch stitutive law (density 8,300 kg/m , Young’s modulus ing to the minimum distance of the Sapien device/aortic Table 1 summarises the number of Elements elements used forModel each of TAVI stent was drawn resembling(Ethe ; Edwards Fig. 4). Part 189,600 MPa, yield stress 760D MPa, ultimate stress valve leaflets from the coronary ostia, The Sapien stent TM was designed in its expanded configmodel. Sapien device; theMPa). presence of the valve wasframes excluded from • comparison of maximum principal stress distribution in 1,160 The polymeric of Soprano and Patient-specific model uration this study. ThisTMstent is characterised by 12 units, and eachcrimped onto the balloon to the size of the the arterial walls. Epic valves were described by elasto-plastic parameters A 6,875 mm diameter) using a coaxial cylindrical sur2.2 Bioprosthetic aortic valves formed by 4 zigzag elements 3 (Fig. 3). Acatheter vertical(8bar (density 9,120 kg/m , Young’s modulus 2,840 MPa, yield B 8,675 face. The stent divides each unit and a perforated bar is positioned every 4 deployment was divided into two different stress 65.4 MPa, ultimate stress steps: 358 MPa). C 11,325 balloon pressurisation (0.342 MPa) with resulting a nominal The metal frames of the four bioprosthetic valves units. were The TAVI device was chosen to have The (=26 threemm) aortic valve leaflets wereexpansion included in the each FE and balloon deflation with 3 Results stent LVOT, D external diameter [ the internal diameter of the in reconstructed from the CT images to8,347 identify their position model of valves; the prosthetic valve. Leaflets ofthe bovine pericarsubsequent stent recoil. In all patients, the LVOT/aortic E 18,890 failing bioprosthetic the height and thickness of Med Biol Eng Comput (2012) 50:183–192 inside the patients’ outflow tracts. Bioprosthetic valve TM At the end of all simulations, the TAVI stent was virtually diumwere origin the root Soprano and(upper Perimount extremities and lower aortic sections and corBioprostheses (stent ? DOI leaflet) expanded stent 16 are andmounted 0.3 mm, on respectively. 188 Med Biol Eng Comput (2012) 50:183–192 geometries were10.1007/s11517-012-0864-1 then re-drawn with CAD software TM implanted in the five patient-specific aortic root models. onary terminal sections) were constrained in all directions Perimount Magna 44,048 ? 29,021 valves, while of porcine leaflets arewas usedbased in the valve. Mechanical behaviour the stent material on Epic (Rhinoceros 4.0, Robert McNeel, Seattle, WA, USA) to TM O R I G I N A L A R T I C L51,372 E Inside the four models with bioprosthetic valves (A–D), the (circumferential, radialwith and alongitudinal) in order to mimic Soprano ? 28,667 Both isotropic, bovine and porcine leaflets were simplified a homogeneous, elasto-plastic austenitic stainless recreate a complete model of the corresponding commer3 stent deployed symmetrically against the sewing rings and connection with biological structures. Boundary conPerimount 44,048 ? 29,021 elastic model (bovine: 1,120 kg/m , Young’s steel. The linear, adopted constitutive law wasdensity atheVon Mises cial device used in the patients, and placed in the same 3 3 valve leaflets, with no contact with the native aortic wall ditions on the balloon were placed to mimic the bond with EpicTM 51,372 ? 28,667 plasticity model (density 8,000 kg/m , Young’s modulus modulus 6 MPa; porcine: density 1,120 kg/m , Young’s position as that identified from CT images. Each design and/or other cardiac structure (Fig. 5). In model E, the the catheter. TAVI device 193,000 MPa, yield stress 205 MPa, ultimate stress modulus 7.5 MPa) by elaborating the results of experiPatient-specific simulations transcatheter aortic valve stent included different sewing rings and192,920 valve leaflets: 515of Sapien stent MPa) mental with an studies initial linear elastic response followed [19, 47]. Calcification of the leaflets was implantation 8,160Magna valve by Balloon isotropic behaviour fromand thickness, created by hardening increasing Young’sobtained modulus • The Carpentier-Edwards Perimount hada aplastic Fig. 5 TAVI stent final configuration (end of balloon deflation) for models A–D and E experimental data [2]. ThetoMed stent withmm 192,920 186 of 2 mm in height with a rectangular, Engmeshed Comput Fig. 450:183–192 Balloon and TAVI stentof respectively, 10Biolwas MPa and (2012) 1.4 in the region lower ring 0.5 • E. Cerri • J. Nordmeyer • elements, following mesh sensitivity hexahedral theanalysis. three analysed positions device assumed an asymmetrical configuration for the three In models A–D, the axial connector elements repreCapelli •The G. M. Bosisupport commissures [22], where ain weld constraint was also mm thickC.section. upper had a circular 2.3the positions, more open distally than proximally (EM in senting the welding constraint caused by the calcification at inside the native aortictested valve: TAVI device Table Mesh number •ofP.elements of the parts involved in the FE • • F. T.1Odenwald Bonhoeffer Migliavacca the leaflet commissure levels were broken during the 5).were In all three cases, the interaction between the TAVI applied; 16 connector elements per commissure sectionsimulations with a diameter of 0.5 mm. The total height of the central section of Fig. the stent 2.4 Balloon A. M. Taylor • S. Schievano system. Geometric orifice and placed inassigned correspondence thethe native implantation site was well confined inflation of the stent–balloon added. An stent axial,wasrigid behaviour was todevice theofthe conof TAVI drawn resembling the Edwards the valve Part was 14.5 mm and the diameter Elements23 mm Model area increased from 1.2 cm2 to 3.4 and 3.6 cm2 in models within LVOT and aortic root portion of the patient’s leaflet commissures (EM); Sapien device; the presence of the valve was excluded from nectors, allowing to maintain fixed distancemorphology, betweenthus reducing the potential risk of heart block A and B, respectively, and from 1.4 to 3.7 cm2 in models (Fig. 2). The geometry of the balloonthem was drawn in moved thea expanded 4.2 mm proximally Patient-specific model 2.3 TAVI mount device Table 1 Mesh number of elements of the parts involved in the FE meshed with 3D triangular shell general-purpose elements. simulations Simulaciones (realidad virtual) M Med Biol Eng Comput (2012) 50:183–192 this study. This stent is characterised by 12 units, each and mitral valve leaflet entrapment. C and D. The final geometric orifice areas in the three ); towards the bar left ventricleStent (EPradial configuration geometry recoil was recorded after balloon deflation. positions EM, EP and ED were, respectively, 4.7, 3.7 and formedtobyresemble 4 zigzagthe elements (Fig.of3).the A commercial vertical and, 4.2 mm distally towards In all the models including bioprosthetic valves the maxi5.3 cm2 compared to an initial orifice of 3.7 cm2. each unit, and a perforated bar is positioned 4 balloon divides (Z MED IITM NuMed Inc., Hopkinton, NY,every USA) the aortic arch (ED) mum recoil was measured in the distal sections towards the The minimum distances between the closest stent strut/ C Received: 20 May 2011 / Accepted: 2 January 11,3252012 / Published online: 29 January 2012was Thepractice TAVI device to have a nominal used in units. clinical [17]. Thechosen nominal length of the aortic arch (model A = 17.0%, model B = 13.2%, model bioprosthetic valve leaflet and coronary ostia are reported D ! International Federation for Medical and 8,347 Biological Engineering 2012 external diameter (=26 mm) [ the internal diameter of the C = 11.7%, model D = 10.8%). Recoil was absent or low in Table 2. In none of the models, direct obstruction of the expanded balloon was 50 mm; the cylindrical body that is E 18,890 failing bioprosthetic valves; the height and thickness of the proximally, at the level of the bioprosthetic valves’ annulus coronaries occurred; neither the TAVI stent nor the bioin contact with the stent had a nominal diameter of Bioprostheses (stent ? leaflet) expanded stent were 16 and 0.3 mm, respectively. (model A = 0.0%, model B = 1.7%, model C = 1.7%, prosthetic valve leaflets occluded the ostia. The stent were higher in the model with native outflow tract. FE Abstract implantation (TAVI) 21.85 mm and length of 30 mm. The geometry of the Perimount MagnaTranscatheter aortic valve 44,048 ? 29,021 model D = 0.0%). In the model with the native valve, the positioned in model D was the closest (5.5 mm) to the Mechanical behaviour of the stent material was based on TM treatment of aortic stenosis with no need for open recoil was measured proximally, in the portions coronaries amongst those with bioprosthetic valves. The analyses canelasto-plastic both refineaustenitic patient selection andmaximum characterise enables deflated a balloon was obtained according to previously Soprano 51,372 ? 28,667 homogeneous, isotropic, stainless of stent mostly interacting with the LVOTs (model distal position of the stent implanted in model ED was device constitutive mechanicallaw performance TAVI, overall impactheart surgery. According to current only Perimount 44,048 ?guidelines, 29,021 steel. The[13]. adopted was a VoninMises published work EM = 14.9%; the closest to the right coronary artery (3.1 mm) amongst 188 model EP = 20.2%; model ED = 11.4%). Med Biol Eng Comput (2012) 50:183–192 TM 3 Epic ? 28,667 plasticity (density 8,000 , Young’s ing on procedural safety in the modulus early introduction of perpatients considered at high surgical 51,372 risk can be A treated with model homogeneous, isotropic, linearkg/m elastic Nylon11 was the three positions tested. The highest Von Mises stresses occurred at the strut 3 TAVI device In this study, patient-specific analyses were 193,000 MPa, yield stress 205 MPa, ultimate stress In all models with bioprosthetic valves, the principal junctions for all the models. The maximum reached values cutaneous heart valve devices in new patient populations. TAVI. peradopted as per manufacturer’s data (density 1,256 kg/m , stress state in the aortic root reached the maximum value of were included between 414 MPa (model ED) and 477 MPa Sapien stent 192,920 515 MPa) with an initial linear elastic response followed formed to explore the feasibility of TAVI inYoung’s morphologies, modulus 450 MPa). The balloon was meshed with 0.1 MPa, while in model E the maximum principal stress in (model EP, in Fig. 6). Stress values throughout the length of 123 Balloon 8,160 by a plastic isotropic hardening behaviour obtained from Fig. 2 Carpentier-Edwards Perimount Magna bioprosthetic Keywords Stent finite element analysis ! Aortic valve which are currently borderlinevalve casesFEfor a0.03 percutaneous the LVOT was higher, showing how the implanted biothe stent zigzags and vertical bars were lower than 250 MPa. mmexperimental thick membrane an average size of data [2].elements The stent with was meshed with 192,920 model and dimensions (mm): lower (purple) and upper (blue) support prostheses act as a scaffold for the TAVI stent. By comMaterial plasticisation occurred at the points of maximum stenosisfollowing ! Transcatheter implantation ! Patient-specific approach. patients were(yellow) recruited: with elements, rings; valve leaflets (grey) and Five connector elements to four patients hexahedral mesh sensitivity analysis. paring the stress distribution induced by the three stent stresses, i.e. at the junctions between zigzag and vertical failed bioprosthetic valves (stenosis) and one patientpatients’ aortic roots simulate the1calcification (colour figure online)aorticreconstructions positions in patient E, higher stresses were found in the bars, thus guaranteeing a final open configuration of the stent. Fig. From left to right, 3D volumetric of the five selected with an incompetent, native aortic valve. Three-dimen2.4 Balloon sional models of the implantation sites were reconstructed 1 Introduction Fig. 6 Von Mises stress The geometry of the balloon was drawn in the expanded computed images. Within these realistic Fig. 5 TAVI TAVIstent stent final configuration (end of balloon deflation) for models A–D and EM the two nodes until afrom threshold forcetomography was reached—equal to distribution in the configuration to resemble the geometry of the commercial after balloon valve deflation in model Aortic stenosis (AS) is currently the most common geometries, TAVI with an Edwards Sapien stent was 0.92 N [22] along the direction joining the 2 nodes—and EP balloon (Z MED IITM, NuMed Inc., Hopkinton, NY, USA) simulatedvalue usingwas finite elementmimicking (FE) modelling. Engineering pathology in Europe and USA, where increased lifeassumed an asymmetrical configuration for the three device In models A–D, the axial connector elements reprethen fail after this threshold reached used in clinical practice [17]. The nominal length of the outcomes assessed. FE balloon expectancy is the associated degenerative diseases tested positions, more open distally than proximally (EM in senting the welding constraint caused by the calcification at expanded was 50 mm; cylindrical with body that is calcification failure.and Theclinical thickening and were welding of the In all patients, affecting cardiac Surgical valve replacethat TAVI was orifice morphologically feasible. the leaflet commissure levels were broken during the Fig. 5). In all three cases, the interaction between the TAVI in contact with the stent had structures a nominal [25]. diameter of failing valve leafletsanalysis producedproved aortic valve geometric inflation of the stent–balloon system. Geometric orifice device and the native implantation site was well confined 21.85 mm and length of 30 considered mm. The geometry ofstandard the After the implantation, stress distribution showed no risks ment has been the gold for effectively areas equal to those measured in the selected patients area increased from 1.2 cm2 to 3.4 and 3.6 cm2 in models withinofthe LVOT and aortic root portion of the patient’s was AS obtained according the to previously of and immediate failure and rigid geometric orificedeflated areas balloon treating [6]; however, intrinsic invasive nature (1.2 cm2 for A and B, 1.4 cm2device for C and D). The morphology, thus reducing the potential risk of heart block A and B, respectively, and from 1.4 to 3.7 cm2 in models published work [13]. open heart surgery exposes patients to high risks and slow increased with lowusing risk 8-node of obstruction supports of the valves were meshed linear of the coronary and mitral valve leaflet entrapment. C and D. The final geometric orifice areas in the three A homogeneous, isotropic, linear elastic Nylon11 was Maximum principal stresses walls recovery. Over the last decade, less invasive techniques hexahedral elementsarteries. with reduced integration with a num-in the arterialadopted Stent radial recoil was recorded after balloon deflation. positions EM, EP and ED were, respectively, 4.7, 3.7 and as per manufacturer’s data (density 1,256 kg/m3, have450 been introduced to was insert cardiac all the models including bioprosthetic valves the maxi5.3 cm2 compared to an initial orifice of 3.7 cm2. Young’s modulus MPa). The balloon meshed withvalves usingIncatheber of elements varying from 28,667 to 29,021 according to Fig. 2 Carpentier-Edwards Perimount Magna bioprosthetic valve FE ter-based In 2002, the first intervention mum recoil was measured in the distal sections towards the The minimum distances between the closest stent strut/ 0.03 mm thick membraneinterventions elements with [5]. an average size of the model (Tablemodel 1). The valve leaflets were meshed with and dimensions (mm): lower (purple) and upper (blue) support C. valve Capellileaflets and G. M. Bosi contributed equally(yellow) to this publication. of transcatheter aortic valve implantation (TAVI) was aortic arch (model A = 17.0%, model B = 13.2%, model bioprosthetic valve leaflet and coronary ostia are reported rings; (grey) and connector elements to 4-node, quadrilateral, shell elements with reduced integra123 Fig. 3 CAD model and dimensions of the recreated Edwards Sapien simulate the calcification (colour figure online) = 11.7%, model D = 10.8%). Recoil was absent or low in Table 2. In none of the models, direct obstruction of the successfully performed [9]. The possibility to Creplace tion and large-strainC.formulation stent! (mm) Capelli (&) (Fig. ! G. M.2).Bosi ! E. Cerri ! T. Odenwald coronaries occurred; neither the TAVI stent nor the biocardiac valves using less invasive procedures has proximally, been a at the level of the bioprosthetic valves’ annulus P. Bonhoeffer ! A. M. Taylor ! S. Schievano (model A = 0.0%, model B = 1.7%, model C = 1.7%, prosthetic valve leaflets occluded the ostia. The stent disruptive innovation and has revolutionised the treatment for Cardiovascular Institute of to model D = 0.0%). In the model h"p://www.cardiopa.aslapaz.com with the native valve, the positioned in model D was the closest (5.5 mm) to the the Centre two nodes until a thresholdImaging, force wasUCL reached—equal 123 of patients with severe AS. Almost 10 years after the first Cardiovascular Science, Great Ormond Street Hospital for maximum recoil was measured proximally, in the portions coronaries amongst those with bioprosthetic valves. The 0.92 N [22] along the direction joining the 2 nodes—and Children, Great Ormond Street, London WC1N 3JH, UK case, two devices are commercially available forofTAVI then fail after this threshold value was reached mimicking stent mostly interacting with the LVOTs (model distal position of the stent implanted in model ED was e-mail: c.capelli@ucl.ac.uk (Edwards Sapien, Edwards Lifesciences, Irvine, CA,EMUSA; calcification failure. The thickening and welding of the the closest to the right coronary artery (3.1 mm) amongst = 14.9%; model EP = 20.2%; model ED = 11.4%). " CoreValve , Medtronic, Minneapolis, MN, USA) The withhighest Von Mises stresses occurred at the strut failing valve leaflets produced aortic valve geometric orifice the three positions tested. G. M. Bosi ! E. Cerri ! F. Migliavacca areas equal toofthose measured in the selected Structural patients In all models with bioprosthetic valves, the principal junctions for all the models. The maximum reached values over 40,000 cases reported and over 200 studies published, Laboratory Biological Structure Mechanics, A B 6,875 8,675 123 h"p://www.cardiopa.aslapaz.com D C E The F n e w e ng l a n d j o u r na l o f m e dic i n e Trachea Carina A B Aorta SVC D C G E F Trachea Carina Figure 1. Placement of the Printed Airway Splint in the Patient. Aorta SVC Panel A shows the airway in expiration before placement of the splint; the image was reformatted with minimumintensity projection. Panel B shows the patient-specific computed tomography–based design of the splint (red). Panel C shows an image-based three-dimensional printed cast of the h"p://www.cardiopa.aslapaz.com patient’s airway without the splint in place, and Panel D shows the cast with the splint in place. Panel E shows intraoperative placement of the splint (green arrow) overlying the malacic left mainstem bronchial segment. SVC denotes superior vena cava. Panel F shows the bronchoscopic view, from the carina, of the left mainstem bronchus after placement of the splint. Panel G shows the airway in ex- Construcción de realidades tridimensionales ¡PODEMOS TOCAR! h"p://www.cardiopa.aslapaz.com Impresión 3D C. Hull (3D Systems Corp, 1984) h"p://www.cardiopa.aslapaz.com the workstation, 3D segmentation and visualization are performed and a Computer-Aided Design (CAD) model of the segmented structures can be generated. Such data can then be used by rapid prototyping machines to create the 3D solid object by the addition of material layers Impresión 3D Table 1 Overview of established rapid prototyping techniques used in the medical arena Accuracy Cost Advantages Disadvantages Stereolithography (SLA) +++ $$ Large part size Moderate strength Selective Laser Sintering (SLS) ++ $$$ Large part size, variety of materials, good strength High cost, powdery surface Fused Deposition Modeling (FDM) ++ $ Low cost, good strength Low speed Laminated Object Manufacturing (LOM) + $ Low cost, large part size Limited materials Inkjet printing techniques + $ Low cost, high speed, multimaterial capability Moderate strength The characteristics can vary depending on the specific printing system used dispended by a piston, the parts of this layer belonging to the 3D object are bonded by an adhesive liquid deposited by another piston. Inkjet printing techniques can also be used to generate a 3D scaffold with different types of tissue by printing living cells and biomaterials simultaneously [12,13]. Some fabrication techniques use two materials in the course of constructing parts. The first material is the part material and the second is the support material (to support overhanging features during construction), the support material is later removed by heating or dissolved with a solvent or water. This is not required in techniques where a powder bed provides the support such as in SLS and inkjet printing techniques. Depending on the fabrication technique it is also possible to combine materials of different elasticity or color in one model. This can be useful to create more realistic models for educational or research purposes, or for naturally including individual patient care, research and as an educational and training tool. Individual patient care Surgical planning Rapid prototyping has recently been introduced into the surgical arena as a tool for better understanding of complex underlying anomaly. This can improve and facilitate the diagnostic quality and help in pre-surgical planning. Its application and benefith"p://www.cardiopa.aslapaz.com in craniofacial and maxillofacial surgery [14–20] has been proven. First studies in pelvic surgery [21,22], neurosurgery (Fig. 2) [23,24], spine surgery [25], Adquisición de la imagen Alta resolución espacial: 0.5*0.5*0.5 mm (TC) Vóxels isotrópicos Formato DICOM (Digital Imaging and Communications in Medicine) h"p://www.cardiopa.aslapaz.com Postprocesado Malla triangular 3D Software CAD Archivos DICOM (datos crudos [raw data]) Modelo para imprimir (Sterero Lithography, .stl) h"p://www.cardiopa.aslapaz.com Los problemas clínicos ¿PODEMOS PLANIFICAR MEJOR? ¿PODEMOS INVESTIGAR MEJOR? ¿PODEMOS ENSEÑAR MEJOR? ¿PODEMOS INTERVENIR MEJOR? Int J CARS (2010) 5:335–341 DOI 10.1007/s11548-010-0476-x REVIEW ARTICLE 3D printing based on imaging data: review of medical applications h"p://www.cardiopa.aslapaz.com F. Rengier · A. Mehndiratta · H. von Tengg-Kobligk · C. M. Zechmann · R. Unterhinninghofen · H.-U. Kauczor · F. L. Giesel Fig. 1. The Fab@Home 3D printer connected to a laptop running Fab@Home V_0.21 software. CAD model can be seen in Fig. 2b. The geometry of the sinuses of Valsalva was modeled partially following the ARTICLE IN PRESS description of Reul and colleagues w15x and was treated as an epitrochoid. ‘An epitrochoid is a roulette traced by a doi:10.1510/icvts.2008.194134 point attached to a circle of radius r rolling around the outside of a fixed circle of radius R, where the point is a distance d from the center of the exterior circle’ – defiInteractive CardioVascular and Thoracic Surgery 8 (2009) 182–186 nition of an epitrochoid from www.wikipedia.org. In brief www.icvts.org the sinuses were described as an epitrochoid with an Work in progress report - Experimental Rs13.2 mm, rs4.4 mm and ds2.8 mm (Fig. 3). It has to Rapid prototyping of compliant human aortic roots for be noted that in order to have three sinuses R has to be Rapid prototyping of compliant, life-size anatomical models with LE IN PRESS equal to 3r. The X, Y coordinates the respective curve assessment of valved stents ARTICLE IN ofPRESS the 3D printer is feasible – it is very quick compared wereFab@Home calculated in Microsoft Excel software using the ARTICLE INMartins PRESS Kalejs*, Ludwig183 Karl von Segesser CardioVascular and Thoracic Surgery 8 (2009) 182–186 equations which can be seen in Fig. 3. Later the calculated previous casting methods. M.to Kalejs, L.K. von Segesser / Interactive CardioVascular and Thoracic Surgery 8 (2009) 182–186 183 Department of Cardio-Vascular Surgery, Centre Hospitalier Universitaire Vaudois, CHUV, Rue du Bugnon 46, CH-1011 Lausanne, Lausanne, Switzerland points were saved in an ASCII text file as X, Y, Z coordinates M. Kalejs, L.K. von Segesser / Interactive CardioVascular and Thoracic Surgery 8 (2009) 182–186 183 Received 15 September 2008; accepted 15 October 2008 and imported into SolidWorks. Abstract The model geometry was saved in STL format (Stereolithography) and printed using an open-source rapid prototyping Adequate in-vitro training in valved stents deployment as well as testing of the latter devices requires compliant real-size models of the human aortic root. The casting methods utilized up to now are multi-step, time consuming and complicated. We pursued a goal of building system developed by the Fab@Home project (http:yyfabaa flexible 3D model in a single-step procedure. We created a precise 3D CAD model of a human aortic root using previously published anatomical and geometrical data and printed it using a novel rapid prototyping system developed by the Fab@Home project. As a material thome.orgy) and distributed by Koba Industries (Albuquerfor 3D fabrication we used common house-hold silicone and afterwards dip-coated several models with dispersion silicone one or two times. que, NM, USA) which main components are a deposition To assess the production precision we compared the size of the final product with the CAD model. Compliance of the models was measured and compared with native porcine aortic root. Total fabrication time was 3 h and 20 min. Dip-coating one or two times with dispersion tool with a syringe moved by several stepper motors. For silicone if applied took one or two extra days, respectively. The error in dimensions of non-coated aortic root model compared to the CAD printing we used a syringe tip with a diameter of 0.84 mm. design was -3.0% along X, Y-axes and 4.1% along Z-axis. Compliance of a non-coated model as judged by the changes of radius values in the radial direction by 16.39% is significantly different (P-0.001) from native aortic tissue – 23.54% at the pressure of 80–100 mmHg. The printing setup can be seen on Fig. 1. As a material for Rapid prototyping of compliant, life-size anatomical models with the Fab@Home 3D printer is feasible – it is very quick compared to previous casting methods. 3D fabrication we used common house-hold (sanitary) sili! 2009 Published by European Association for Cardio-Thoracic Surgery. All rights reserved. cone (Forbo international, Schoenenwerd, Switzerland) Keywords: Aortic root; 3D print; Stereolitography; Stent valve; Trancatheter valve replacement which took around 4 h to dry and is semitransparent. Afterwards we dip-coated several models with dispersion silicone Technology, Carpinteria, USA) one or two M. Kalejs, L.K. von ering Segesser / Interactive CardioVascular and(Nusil Thoracic Surgery 8 CA, (2009) 182–186 1. Introduction the rapid advancement of transcatheter procedures w12x, there is a certain need for flexible hollow models e.g. times making a pause of at least 16 h between dipping to With advancement of diagnostic imaging techniques capaa model of aorta or aortic root for endovascular and valvedallow the previous layer to dry completely. ble of producing three-dimensional virtual reconstructions stents procedures training and new device testing. of human body parts from stacks of multi-planar images, We compared the elastic properties of the constructed There are several methods to create such models but all 3D imaging has rapidly entered the clinical world. It is used of them include several steps and are time consuming. The models with a fresh porcine aortic root harvested within routinely not just for diagnostic purposes but also for most detailed and precise flexible models can be made by ome 3D printer connected to a laptop running Fab@Home Fig. 1. The Fab@Home 3D printer 6 connected a laptop running intervention planning and guidance in fields of radiology, h posttomortem. We Fab@Home performed a test using a roller pump combining rapid prototyping for creating molds and tradime V_0.21 software. neurosurgery and cranio-facial surgery w1–3x. The before tional casting of silicone w5, 13x. Recently, a new rapid Fig. 2. (a) View of the CAD design of the aortic root in Solidworks 2008 SE to pressurize the models with three sonomicrometry probes mentioned specialties were pioneering this field, but very prototyping system has become available, created by the software (see Video 1 for a rotation view of the model in 3D); (b) Dimensions quickly the benefits provided by 3D visualization were (Sonometrics, London, Canada) fixed on the outer surface Fab@Home project (Fig. 1) which to our best knowledge is in millimeters of the CAD design compared to the dimensions of final product appreciated and accepted n be seen in Fig. 2b. The geometry of also the by other medical specialties the only 3D printer capable of using any viscous substance the2b. models at the level of commissures. Mathematical CAD model can be seen inofFig. The geometry of the (after slash). (c) View of the final product – a flexible life-size aortic root including cardiologists and cardiovascular surgeons. It is as a building material. salva was modeled partially following the he being used for diagnostic purposes, for operation planning analysis of the data was performed off-line with a software model made in silicone. sinuses of forValsalva was modeled partially following the Aiming to reduce the complexity and time needed w x Reul and colleagues 15 and was treated as w x as well as for education and training 4–7 . he creating a compliant physical model ofdescription aortic root we of Reul and colleagues w15x and was treated as More recently traced with decreasing . ‘An epitrochoid is a roulette by a prices and increasing overdecided to pursue a goal of building a 3D model in a singleas an epitrochoid. ‘An epitrochoid is a roulette traced by a all popularity and availability of rapid prototyping devices step procedure without employing the somewhat time d to a circle of radius r rolling around the also called 3D printers, the virtual 3D representation on a point attached to a circle of radius r rolling around the consuming and rather unpredictable casting techniques. xed circle of radius the R, where thefound pointitsisrealization a screen has in solid replica of outside of a fixed circle of radius R, where the point is a he m the center of theanatomical exterior structures circle’ –– life-size, defi- rigid physical models w8– 2. Materials and methods distance d from the center of the exterior circle’ – defia 11x which contribute In to brief the realism, facilitate perception pitrochoid from www.wikipedia.org. and recognition of the 3D structures w10x, hence improving nition of an epitrochoid from www.wikipedia.org. In brief iWe used Solidworks 2008 SE (SolidWorks Corporation, ere described as an epitrochoid w9x. In an clinical performancewith cardiovascular surgery, considConcord, MA, USA) for creating a precise 3D model (Fig. 2a were described as an epitrochoid with an the sinuses ef s4.4 mm and ds2.8 mm (Fig. 3). It has to and Video 1) of the aortic root in silico Rs13.2 using previously *Corresponding author. Center of Cardiac Surgery, Pauls Stradins Clinical mm, rs4.4 mm and ds2.8 mm (Fig. 3). It has to sinuses R has to be anin order to have three published anatomical and geometrical data with minimal University Hospital, Pilsonu str. 13, Riga, LV-1002, Latvia. bein noted modifications w14, 15x. The dimensions used creating that the in order to have three sinuses R has to be E-mail address: martins.kalejs@stradini.lv he X, Y coordinates of the respective curve (M. Kalejs). to ! 2009software Published by European equal to 3r. The X, Y coordinates of the respective curve ed in Microsoft Excel usingAssociation the for Cardio-Thoracic Surgery be were calculated in Microsoft Excel software using the h can be seen in Fig. 3. Later the calculated ve equations which can be seen in Fig. 3. Later the calculated ved in an ASCII text file as X, Y, Z coordinates he points were saved in an ASCII text file as X, Y, Z coordinates nto SolidWorks. ed ideo 1. saved A rotation of the aortic root CAD model in 3D. and imported into SolidWorks. Video 2. A time-lapse movie of rapid prototyping of an aortic root using the ometry was in STL formatview (Stereolithoes inted using an open-source rapid prototyping The model geometry was saved in STL format (Stereolitho- ped by the Fab@Home project (http:yyfabaond distributed by Koba Industries (Albuquer) which main components are a deposition ng ringe moved by several stepper motors. For aed r- a syringe tip with a diameter of 0.84 mm. etup can be seen on Fig. 1. As a material for on we used common house-hold (sanitary) silior international, Schoenenwerd, Switzerland) ARTICLE IN PRESS Fab@Home 3D printer. graphy) and printed using an open-source rapid prototyping system developed by the Fab@Home project (http:yyfabathome.orgy) and distributed by Koba Industries (Albuquerque, NM, USA) which main components are a deposition tool with a syringe moved by several stepper motors. For printing we used a syringe tip with a diameter of 0.84 mm. The printing setup can be seen on Fig. 1. As a material for h"p://www.cardiopa.aslapaz.com To prove the appropriateness of the built mockup for close to real-life simulations in artificial circulatory systems we In inspection two patients, models were used for aneurysmecheart and the use of the model during the surgical proceintraoperativel of thethe ventricle leads to identification of scarred dure influenced preoperative planning and facilitated the tomy and LV reshaping (Fig. 4). Preoperative measand viable myocardium. Transmural palpation LVESV, of contractkinetic volume 2 non-viable operation. Due to the massive volume of the tumor and uredingby muscle delineates the junction of viable and echocardiography, was 139.9 mlym and 125.0 the template c 2 the infiltration to the tricuspid valve (Fig. 3), the access mlym tissue. An encircling suture at this junction excludes the . The surgeon could reshape the LV around the reshaping the to the target was chosen through the right ventricle instead residual scar from thetemplate ventricular cavity anddecrease creates the a pursed volume (Fig. 1) and LVESV dimensional (2 IN PRESS A complete mass reducof access through theARTICLE right atrium. opening. A Dacron patch is secured onto this opening and tion of the histological poor differentiated sarcoma was eliminates the akinetic or dyskinetic segment w12x. The achieved including the tricuspid valve, which had to be identification of the scarred and viable tissue on the replaced. Due to enabling identification of risk structures arrested or fibrillating heart is based on experience but like the right ventricular wall and the right ventricular misidentification can occur. In addition, creation of an Work in progress report - Experimental outflow tract (RVOT), the surgeon was guided through the elliptical ventricle is demanding. Standardized preshaped 3D-Imaging of cardiac structures using 3D heart models for planning operation andin could determine the malignant tissue (distinelliptical balloons (Chase Medical, Dallas, TX; The Blue heart surgery: a preliminary study guish myocardium andGrunert malignant tissue). Afterwards a Egg!, BioVentrix) may help to size and configure the Stephan Jacobs *, Ronny , Friedrich W. Mohr , Volkmar Falk echocardio8 Cryoablation was done. Postoperatively S. Jacobs et al.the / Interactive CardioVascular and Thoracic Surgery 7 (2008)a6–9 ventricle, but do not provide patient’s individual solution. graphy showed properly the size of the right ventricle with The 3D RPT method tries to support the transfer of 2D Abstract no obstruction of the RVOT. images into a 1:1 geometric model, which can beThese used resid2 2 to 64.5 mlym and 58.3 mlym postoperatively. The aim of the study was to create an anatomical correct 3D rapid prototyping model (RPT) for patients with complex heart disease and In two patients, the models were used for aneurysmecintraoperatively. Once the viable ventricular cavity (rest altered geometry of the atria or ventricles to facilitate planning and execution of the surgical procedure. Based on computer tomography ual volumes are in line with the current literature w11x. (CT) and magnetic resonance imaging (MRI) images, regions of interest were segmented using the Mimics 9.0 software (Materialise, Leuven, Belgium). The segmented were the target volume (Fig. and structures at risk.Preoperative After generating an STL-file (StereoLithography file) out tomy and regions LV reshaping 4). LVESV, measkinetic volume of the LV) is printed out as a RPT model, of the patient’s data set, the 3D printer Z" 510 (4D Concepts, Gross-Gerau, Germany) created a 3D plaster model. The patient individual The postoperative images show a complete resection of the 3Dured printed RPT-models used to plan the resection of a left ventricular aneurysm139.9 and right ventricular tumor.2The and surgeon was 125.0 able to by wereechocardiography, was mlym the template can potentially be used for patient individual identify risk structures, assess the ideal resection lines and determine the residual shape after a reconstructive procedure (LV remodelling, akinetic and dyskinetic target tissue and an elliptical veninfiltrating tumor resection). Using a 3D-print of the LV-aneurysm, reshaping of the left ventricle ensuring sufficient LV volume was easily mlym2The. useThe could the aneurysm LV and around the reshaping the left ventricle. This method converts a twoaccomplished. of the 3D surgeon rapid prototyping model (RPT-model) reshape during resection of ventricular malignant cardiac tumors may facilitate the surgical procedure due to better planning and improved orientation. tricular geometry. !residual 2008 Published by European Association template for Cardio-Thoracic Surgery. All rights1) reserved. volume (Fig. and decrease the LVESV dimensional (2D) image into a three-dimensional (3D) strucdoi:10.1510/icvts.2007.156588 Interactive CardioVascular and Thoracic Surgery 7 (2008) 6–9 www.icvts.org ARTICLE IN PRESS a, b a a Herzzentrum Leipzig, Department of Cardiac Surgery, University Leipzig, Germany b Innovation Center Computer Assisted Surgery, Leipzig, Germany a Received 25 March 2007; received in revised form 15 September 2007; accepted 17 September 2007 The time to segment the CT data set semi-automatically with a layer thickness of 0.5 mm took about 3 h compared 1. Introduction will be limited w4x. Beside the rest volume of the ventricle, the geometry is important. Ventricular volume should be Fig. 3. Rapid prototyping model showsperformed a massive cardiac-tumor infiltrato the segmentation manuallywith with a layer Fig. 4. Rapid proto The use of imaging techniques for preoperative planning reduced in its septal and anterior components without is helpful to improve the results of complex surgical tion to thickness the right ventricular wall and the tricuspid valve. deforming the chamber. In normal hearts, myocardial fibers of 0.5 mm which took about 8 h. The segmenta- Segmentation was interventions. have a spiral direction from the base to the apex with two opposite layers and well-defined intersection angles w5x. tion performed manually with a layer thickness of 1.0 mm When the spiral architecture is lost due to resection of the 1.1. Congestive heart failure and ventricular aneurysm aneurysm especially at the apex, ventricular function is In case of anterior myocardial infarction, the ventricular impaired and ejection fraction and stroke volume decrease. required 5 h. shape and volume changes w1x and there is loss of contracAn elliptical ventricle decreases lateral force (stress) tion of the anterior wall and septum. Ventricular dysfunccompared to a longitudinal one with a spherical rounded Quality of resolution of the semi-automatically segmented tion and eventually aneurysm formation may lead to apex w6x. Standardized preshaped elliptical balloons (Chase congestive heart failure (CHF). Surgical methods for aneuMedical, Dallas, TX; The Blue Egg", BioVentrix) have CT data set and the coarsely layered thickness of 1.0 mm w x rysm resection and left ventricular reshaping vary from helped to size and configure the ventricle 7 . volume reduction only if a dyskinetic scar is present, to 1.2. Cardiac tumors surgical repair of the postinfarction dyskinetic, dilated was unsurprisingly less. Regarding time needed for segmenventricle with simple excision and closure to Jatene’s Primary tumors of the heart are exceedingly rare. The septal exclusion technique w2x. In 1984, Dor et al. w3x tation and quality of target area and structures at risk, angiosarcoma is the most common primary malignant tumor reduction of ventricular size by excluding the of the heart in models adults with a uniformly prognosis . Fig.suggested 2. 3D solid anatomical rapid prototyping (RPT)dismal show anw8xinside non-contracting segment with an intraventricular patch. If Besides echocardiography, magnetic resonance imaging and only segmentation performed manually with a layer thickthe residual volume is too small, the resultcardiac will be cata-structures with the aneurysm and the LVview of resulting patients computed tomography are beneficial in the diagnostic The use ofindividual the 3D rapid prototyping model (RPT-model) strophic, in the physiology of a restricted cardiowork-up w9x. These imaging modalities are particularly myopathy. If the residual chamber is too large,was the benefit ness of 0.5 mm showed acceptable results in terms of residual-volume. The model segmented out a cardiac datatumors set with helpful in manually defining the extent to of which during resection of ventricular aneurysm and malignant infiltrate surrounding structures. Complete surgical reseca layer thickness of 0.5 mm. w x identifying all target areas and structures at risk. is required for improved survival 10 . However, by its cardiac tumors may facilitatetionthe surgical procedure due Keywords: Imaging; Ventricular remodeling; Cardiac tumor; 3D print *Corresponding author. Klinik für Herzchirurgie, Universität Leipzig, Herzzentrum, Strümpellstr. 39, 04289 Leipzig, Germany. Tel.:q49-341-865-1433; fax: q49-341-865-1452. E-mail address: stjacobs@aol.com (S. Jacobs). very location, radical complete resection is rarely possible. Optimal management strategies have not been defined to better planning and improved orientation. 3. Results ! 2008 Published by European Association for Cardio-Thoracic Surgery Fig. 3. Rapid prototyping model shows a massive cardiac-tumor with infiltration comparison to the right ventricular the tricuspid The of thewall 3Dand heart modelvalve. with the real open heart and the use of the model during the surgical procedure influenced preoperative planning and facilitated the operation. Due to the massive volume of the tumor and the infiltration to the tricuspid valve (Fig. 3), the access 4. Discussion Fig. 4. Rapid prototyping model shows an enlarged LV with an aneurysm. Segmentation was performed manually with a layer thickness of 1.0 mm. Performing an aneurysmectomy or Dor-plasty, visual inspection of the h"p://www.cardiopa.aslapaz.com ventricle leads to identification of scarred and viable myocardium. Transmural palpation of contracting muscle delineates the junction of viable and non-viable tissue. An encircling suture at this junction excludes the h"p://www.cardiopa.aslapaz.com h"p://www.cardiopa.aslapaz.com h"p://www.cardiopa.aslapaz.com h"p://www.cardiopa.aslapaz.com h"p://www.cardiopa.aslapaz.com h"p://www.cardiopa.aslapaz.com h"p://www.cardiopa.aslapaz.com h"p://www.cardiopa.aslapaz.com h"p://www.cardiopa.aslapaz.com Comentarios El protoVpado tridimensional de estructuras anatómicas es posible a parVr de los datos de pruebas radiológicas indicadas clínicamente. Existe un potencial enorme de planificación, invesVgación, docencia y mejora de intervenciones sobre nuestros complejos pacientes. h"p://www.cardiopa.aslapaz.com