Marija Vukicevic

Cardiac 3D Printing and its Future Directions

Three-dimensional (3D) printing is at the crossroads of printer and materials engineering, noninvasive diagnostic imaging, computer-aided design, and structural heart intervention. Cardiovascular applications of this technology development include the use of patient-specific 3D models for medical teaching, exploration of valve and vessel function, surgical and catheter-based procedural planning, and early work in designing and refining the latest innovations in percutaneous structural devices. In this review, we discuss the methods and materials being used for 3D printing today. We discuss the basic principles of clinical image segmentation, including coregistration of multiple imaging datasets to create an anatomic model of interest. With applications in congenital heart disease, coronary artery disease, and surgical and catheter-based structural disease, 3D printing is a new tool that is challenging how wexa0image, plan, and carry out cardiovascular interventions.

3D Printed Modeling of the Mitral Valve for Catheter-Based Structural Interventions

As catheter-based structural heart interventions become increasingly complex, the ability to effectively model patient-specific valve geometry as well as the potential interaction of an implanted device within that geometry will become increasingly important. Our aim with this investigation was to combine the technologies of high-spatial resolution cardiac imaging, image processing software, and fused multi-material 3D printing, to demonstrate that patient-specific models of the mitral valve apparatus could be created to facilitate functional evaluation of novel trans-catheter mitral valve repair strategies. Clinical 3D transesophageal echocardiography and computed tomography images were acquired for three patients being evaluated for a catheter-based mitral valve repair. Target anatomies were identified, segmented and reconstructed into 3D patient-specific digital models. For each patient, the mitral valve apparatus was digitally reconstructed from a single or fused imaging data set. Using multi-material 3D printing methods, patient-specific anatomic replicas of the mitral valve were created. 3D print materials were selected based on the mechanical testing of elastomeric TangoPlus materials (Stratasys, Eden Prairie, Minnesota, USA) and were compared to freshly harvested porcine leaflet tissue. The effective bending modulus of healthy porcine MV tissue was significantly less than the bending modulus of TangoPlus (pxa0<xa00.01). All TangoPlus varieties were less stiff than the maximum tensile elastic modulus of mitral valve tissue (3697.2 ± 385.8xa0kPa anterior leaflet; 2582.1 ± 374.2xa0kPa posterior leaflet) (pxa0<xa00.01). However, the slopes of the stress-strain toe regions of the mitral valve tissues (532.8 ± 281.9xa0kPa anterior leaflet; 389.0 ± 156.9xa0kPa posterior leaflet) were not different than those of the Shore 27, Shore 35, and Shore 27 with Shore 35 blend TangoPlus material (pxa0>xa00.95). We have demonstrated that patient-specific mitral valve models can be reconstructed from multi-modality imaging datasets and fabricated using the multi-material 3D printing technology and we provide two examples to show how catheter-based repair devices could be evaluated within specific patient 3D printed valve geometry. However, we recognize that the use of 3D printed models for the development of new therapies, or for specific procedural training has yet to be defined.

3D Printed Modeling for Patient-Specific Mitral Valve Intervention Repair with a Clip and a Plug

A 62-year-old man with peripheral vascular disease, chronic kidney disease (glomerular filtration ratexa0<30 ml/min), previous coronary artery bypass grafting, and recent treatment forxa0bacterial endocarditis was referred for refractory decompensated congestive heart failure (New York Heart

Percutaneous Repair of Severe Eccentric Mitral Regurgitation Due to Medial Commissural Flail: Challenges for Imaging and Intervention

Graphical abstract

Percutaneous Repair for Recurrent Mitral Regurgitation After Surgical Repair: A Mitraclip Experience

ABSTRACT Background: The aim of our study was to evaluate the acute feasibility and short-term efficacy of mitral valve repair using the MitraClip device in patients with prior surgical repair. Mitral regurgitation (MR) may recur after surgical repair. Because reoperation is associated with significant mortality and morbidity, a transcatheter approach appears appealing. Methods: Between April 2015 and December 2016, 12 patients with MR after a previous surgical repair underwent the MitraClip procedure. Procedural details, intraoperative echocardiographic features, and baseline and 30-day clinical follow-up data were analyzed and compared to those of patients undergoing MitraClip therapy with no prior surgical repair (n = 54) within the same timeframe. Results: Past medical history, MR severity, and NYHA class did not differ between the two groups. A MitraClip was deployed in all 12 patients in the surgical repair (SR) group and in 51 patients in the no surgical repair (NR) group. Induction of mitral stenosis precluding final device deployment occurred in one and two cases, respectively. The procedure was associated with successful reduction of MR to ≤ moderate in all SR patients and in 47 (96%) NR patients. Total procedural time, fluoroscopy time, time from transseptal access to first MitraClip release, and final diastolic gradients were not different between the groups. Clinical outcomes—NYHA class and KCCQ scores—were not different at 30 days. Conclusions: In selected patients with recurrent MR after surgical repair, the MitraClip procedure is feasible and effective without significant increase in procedural time, fluoroscopy time, diastolic mitral gradient compared to MitraClip therapy in patients without prior surgical repair.

Patient-specific 3D Valve Modeling for Structural Intervention

ABSTRACT Three-dimensional (3D) printing is an advanced manufacturing technique, recently introduced in the medical field to convert clinical imaging information of anatomical features into physical replicas built through digitally guided deposition of successive layers of material. This novel clinical instrument has emerged as a confluence of advances in imaging technology, 3D printing techniques, and structural heart interventions. Both digital and physical 3D modeling are now used to better visualize patient-specific anatomic features prior to catheter-based valve intervention. This review discusses common structural heart valve problems and the imaging challenges associated with catheter-based interventions. We highlight how 3D printed modeling can be used as a tool to overcome certain limitations of 2D visualization and how such modeling can be used to plan, practice, and predict success for increasingly complex catheter-based structural heart valve interventions. An overview of current 3D modeling techniques and advances are presented, including their limitations and future directions.

Transcatheter Aortic Valve Replacement

Three dimensional (3D) stereolithographic printing can be used to convert clinical imaging data into life size, patient-specific physical models replicating the anatomic characteristics of calcific aortic valve disease. Creation of these full-scale models requires a combination of several technologies including high spatial resolution electrocardiogram-gated computed tomography, computer-aided design software, and fused multimaterial 3D printing. By selecting specific print material properties, it is possible to replicate the geometry of the entire aortic root complex combining regions of compliant tissue with regions of hard and immobile “calcified” tissue. 3D printing of calcific aortic valve disease has been taken another step forward in replicating not only the anatomy but also the basic functional characteristics of these valves: stenosis and regurgitation. These functional models allow for accurate evaluation of diseased patient-specific physiology and represent a potentially very powerful new tool. Development of functional patient-specific models has several potential applications in medicine: training of medical teams for transcatheter aortic valve replacement (TAVR) procedures; investigating the flow dependency of aortic stenosis or regurgitation using flow phantoms; determining the accuracy and limitations of noninvasive imaging methods to quantify valve dysfunction; and evaluating patient-specific procedural adjustments a priori that may influence acute procedural success during catheter-based valve intervention. Functional 3D-printed models and accurate replication of patient-specific hemodynamics can create an environment for testing percutaneous valve devices and optimization of their design. Current effort is focused on applying these models to both predict and prevent paravalvular regurgitation.

3D PRINTED PATIENT-SPECIFIC MULTI-MATERIAL MODELING OF MITRAL VALVE APPARATUS

Background: We have reported that the approximate mechanical properties of mitral leaflet tissue can be replicated using multi-material 3D printing. We sought to create multi-material patient-specific replicas of the entire mitral valve (MV) apparatus.nnMethods: CT images (systolic and diastolic) of

3D Experimental and Computational Analysis of Eccentric Mitral Regurgitant Jets in a Mock Imaging Heart Chamber

Mitral valve regurgitation (MR) is a disorder of the heart in which the mitral valve does not close properly. This causes an abnormal leaking of blood backwards from the left ventricle into the left atrium during the systolic contractions of the left ventricle. Noninvasive assessment of MR using echocardiography is an ongoing challenge. In particular, a major problem are eccentric or Coanda regurgitant jets which hug the walls of the left atrium and appear smaller in the color Doppler image of regurgitant flow. This manuscript presents a comprehensive investigation of Coanda regurgitant jets and the associated intracardiac flows by using a combination of experimental and computational approaches. An anatomically correct mock heart chamber connected to a pulsatile flow loop is used to generate the physiologically relevant flow conditions, and the influence of two clinically relevant parameters (orifice aspect ratio and regurgitant volume) on the onset of Coanda effect is studied. A two parameter bifurcation diagram showing transition to Coanda jets is obtained, indicating that: (1) strong wall hugging jets occur in long and narrow orifices with moderate to large regurgitant volumes, and (2) short orifices with moderate to large regurgitant volumes produce strong 3D flow features such as vortex rolls, giving rise to the velocities that are orthogonal to the 2D plane associated with the apical color Doppler views, making them “invisible” to the single plane color Doppler assessment of MR. This is the first work in which the presence of vortex rolls in the left atrium during regurgitation is reported and identified as one of the reasons for under-estimation of regurgitant volume. The results of this work can be used for better design of imaging strategies in noninvasive assessment of MR, and for better understanding of LA remodeling that may be associated with the presence of maladapted vortex dynamics. This introduces a new concept in clinical imaging, which emphasizes that the quality and not only the quantity of regurgitant flow matters in the assessment of severity of mitral valve regurgitation.