Three-dimensional printing in congenital heart disease: Considerations on training and clinical implementation from a teaching session

In light of growing interest for three-dimensional printing technology in the cardiovascular community, this study focused on exploring the possibilities of providing training for cardiovascular three-dimensional printing in the context of a relevant international congress and providing considerations on the delivery of such courses. As a second objective, the study sought to capture preferences in relation to three-dimensional printing uses and set-ups from those attending the training session. A survey was administered to n = 30 professionals involved or interested in three-dimensional printing cardiovascular models following a specialised teaching session. Survey results suggest the potential for split training sessions, with a broader introduction for those with no prior experience in three-dimensional printing followed by a more in-depth and hands-on session. All participants agreed on the potential of the technology in all its applications, particularly for aiding decision-making around complex surgical or interventional cases. When exploring setting up an in-house three-dimensional printing service, the majority of participants reported that their centre was already equipped with an in-house facility or expressed a desire that such a facility should be available, with a minority preferring consigning models to an external third party for printing.

Long term cardiovascular magnetic resonance phenotyping of anthracycline cardiomyopathy

BACKGROUND

Anthracycline cardiomyopathy contributes to the morbidity and mortality of cancer survivors but long-term data are lacking. This study sought to describe the phenotype of long-term anthracycline cardiomyopathy, the prevalence of myocardial fibrosis and its association with cardiac remodeling, systolic function and clinical outcomes.

METHODS AND RESULTS

We undertook contrast-enhanced CMR in 81 cancer survivors at median 5 years after anthracycline (mean dose 279 SD 89 mg/m²). Participants were aged 55 SD 14 years; 68% were female. Mean LVEF was impaired (49 SD 12%), driven by a pathological increase in iLVESV (47 SD 23 ml/m²). 19% of participants exhibited LGE, which was associated with significant adverse left ventricular remodeling and reduced systolic function (iLVEDV: 102 SD 34 vs 83 SD 21 ml/m², p = 0.03; iLVESV 61 SD 32 vs 43 SD 20 ml/m², p = 0.03; LVEF: 43 SD 11 vs 50 SD 12%, p = 0.03). In subgroup analysis of 36 patients, 36% had elevated native T1 measurements, which was associated with significant adverse left ventricular remodeling (iLVEDV: 97 SD 22 vs 74 SD 19 ml/m², p = 0.002; iLVESV: 56 SD 22 vs 35 SD 15 ml/m², p = 0.005), reduced systolic function (LVEF 44 SD 13 vs 55 SD 9%, p = 0.01), and hospitalizations for heart failure (38% vs 9%, p = 0.03). Absolute native T1 measurements correlated significantly with iLVEDV (p ≤ 0.001, R² 0.33), iLVESV (p < 0.001, R² 0.36), LVEF (p < 0.001, R² 0.35), LAVi (p = 0.04, R² 0.12) and MAPSE (p = 0.02, R² 0.14).

CONCLUSIONS

Long-term anthracycline cardiomyopathy is characterized by pathologically increased iLVESV. Both LGE and elevated native T1 measurements were associated with significant adverse cardiac remodeling and reduced systolic function, and the latter with heart failure hospitalizations.

Evaluating 3D-printed models of coronary anomalies: a survey among clinicians and researchers at a university hospital in the UK

OBJECTIVE

To evaluate the feasibility of three-dimensional (3D) printing models of coronary artery anomalies based on cardiac CT data and explore their potential for clinical applications.

DESIGN

Cardiac CT datasets of patients with various coronary artery anomalies (n=8) were retrospectively reviewed and processed, reconstructing detailed 3D models to be printed in-house with a desktop 3D printer (Form 2, Formlabs) using white resin.

SETTING

A University Hospital (division of cardiology) in the UK.

PARTICIPANTS

The CT scans, first and then 3D-printed models were presented to groups of clinicians (n=8) and cardiovascular researchers (n=9).

INTERVENTION

Participants were asked to assess different features of the 3D models and to rate the models' overall potential usefulness.

OUTCOME MEASURES

Models were rated according to clarity of anatomical detail, insight into the coronary abnormality, overall perceived usefulness and comparison to CT scans. Assessment of model characteristics used Likert-type questions (5-point scale from 'strongly disagree' to 'strongly agree') or a 10-point rating (from 0, lowest, to 10, highest). The questionnaire included a feedback form summarising overall usefulness. Participants' imaging experience (in a number of years) was also recorded.

RESULTS

All models were reconstructed and printed successfully, with accurate details showing coronary anatomy (eg, anomalous coronary artery, coronary roofing or coronary aneurysm in a patient with Kawasaki syndrome). All clinicians and researchers provided feedback, with both groups finding the models helpful in displaying coronary artery anatomy and abnormalities, and complementary to viewing 3D CT scans. The clinicians' group, who had substantially more imaging expertise, provided more enthusiastic ratings in terms of models' clarity, usefulness and future use on average.

CONCLUSIONS

3D-printed heart models can be feasibly used to recreate coronary artery anatomy and enhance understanding of coronary abnormalities. Future studies can evaluate their cost-effectiveness, as well as potentially explore other printing techniques and materials.

Prognostic Role of CMR and Conventional Risk Factors in Myocardial Infarction With Nonobstructed Coronary Arteries

OBJECTIVES

This study sought to assess the prognostic impact of cardiac magnetic resonance (CMR) and conventional risk factors in patients with myocardial infarction with nonobstructed coronaries (MINOCA).

BACKGROUND

Myocardial infarction with nonobstructed coronary arteries (MINOCA) represents a diagnostic dilemma, and the prognostic markers have not been clarified.

METHODS

A total of 388 consecutive patients with MINOCA undergoing CMR assessment were identified retrospectively from a registry database and prospectively followed for a primary clinical endpoint of all-cause mortality. A 1.5-T CMR was performed using a comprehensive protocol (cines, T2-weighted, and late gadolinium enhancement sequences). Patients were grouped into 4 categories based on their CMR findings: myocardial infarction (MI) (embolic/spontaneous recanalization), myocarditis, cardiomyopathy, and normal CMR.

RESULTS

CMR (performed at a median of 37 days from presentation) was able to identify the cause for the troponin rise in 74% of the patients (25% myocarditis, 25% MI, and 25% cardiomyopathy), whereas a normal CMR was identified in 26%. Over a median follow-up of 1,262 days (3.5 years), 5.7% patients died. The cardiomyopathy group had the worst prognosis (mortality 15%; log-rank test: 19.9; p < 0.001), MI had 4% mortality, and 2% in both myocarditis and normal CMR. In a multivariable Cox regression model (including clinical and CMR parameters), CMR diagnosis of cardiomyopathy and ST-segment elevation on presentation electrocardiogram (ECG) remained the only 2 significant predictors of mortality. Using presentation with ECG ST-segment elevation and CMR diagnosis of cardiomyopathy as risk markers, the mortality risk rates were 2%, 11%, and 21% for presence of 0, 1, and 2 factors, respectively (p < 0.0001).

CONCLUSIONS

In a large cohort of patients with MINOCA, CMR (median 37 days from presentation) identified a final diagnosis in 74% of patients. Cardiomyopathy had the highest mortality, followed by MI. The strongest predictors of mortality were a CMR diagnosis of cardiomyopathy and ST-segment elevation on presentation ECG.

Three-Dimensional Printing of Fetal Models of Congenital Heart Disease Derived From Microfocus Computed Tomography: A Case Series

This article presents a case series of n = 21 models of fetal cardiovascular anatomies obtained from post mortem microfocus computed tomography (micro-CT) data. The case series includes a broad range of diagnoses (e.g., tetralogy of Fallot, hypoplastic left heart syndrome, dextrocardia, double outlet right ventricle, atrio-ventricular septal defect) and cases also had a range of associated extra-cardiac malformations (e.g., VACTERL syndrome, central nervous system anomalies, renal anomalies). All cases were successfully reconstructed from the microfocus computed tomography data, demonstrating the feasibility of the technique and of the protocols, including in-house printing with a desktop 3D printer (Form2, Formlabs). All models were printed in 1:1 scale as well as with the 5-fold magnification, to provide insight into the intra-cardiac structures. Possible uses of the models include education and training.

Use of 3D Models in the Surgical Decision-Making Process in a Case of Double-Outlet Right Ventricle With Multiple Ventricular Septal Defects

3D printing has recently become an affordable means of producing bespoke models and parts. This has now been extended to models produced from medical imaging, such as computed tomography (CT). Here we report the production of a selection of 3D models to compliment the available imaging data for a 12-month-old child with double-outlet right ventricle and two ventricular septal defects. The models were produced to assist with case management and surgical planning. We used both stereolithography and polyjet techniques to produce white rigid and flexible color models, respectively. The models were discussed both at the joint multidisciplinary meeting and between surgeon and cardiologist. From the blood pool model the clinicians were able to determine that the position of the coronary arteries meant an arterial switch operation was unlikely to be feasible. The soft myocardium model allowed the clinicians to assess the VSD anatomy and relationship with the aorta. The models, therefore, were of benefit in the development of the surgical plan. It was felt that the clinical situation was stable enough that an immediate intervention was not required, but the timing of any intervention would be dictated by decreasing oxygen saturation. Subsequently, the oxygen saturation of the patient did decrease and the decision was made to intervene. A further model was created to demonstrate the tricuspid apparatus. An arterial switch was ultimately performed without the LeCompte maneuver, the muscular VSD enlarged and baffled into the neo aortic root and the perimembranous VSD closed. At 1 month follow up SO₂ was 100%, there was no breathlessness and no echocardiogram changes.

Current and future applications of 3D printing in congenital cardiology and cardiac surgery

Three-dimensional (3D) printing technology in congenital cardiology and cardiac surgery has experienced a rapid development over the last decade. In presence of complex cardiac and extra-cardiac anatomies, the creation of a physical, patient-specific model is attractive to most clinicians. However, at the present time, there is still a lack of strong scientific evidence of the benefit of 3D models in clinical practice and only qualitative evaluation of the models has been used to investigate their clinical use. 3D models can be printed in rigid or flexible materials, and the original size can be augmented depending on the application the models are needed for. The most common applications of 3D models at present include procedural planning of complex surgical or interventional cases, in vitro simulation for research purposes, training and communication with patients and families. The aim of this pictorial review is to describe the basic principles of this technology and present its current and future applications.

Wave intensity analysis in the internal carotid artery of hypertensive subjects using phase-contrast MR angiography and preliminary assessment of the effect of vessel morphology on wave dynamics

Objective: Hypertension is associated with reduced cerebral blood flow, but it is not known how this impacts on wave dynamics or potentially relates to arterial morphology. Given the location of the internal carotid artery (ICA) and risks associated with invasive measurements, wave dynamics in this artery have not been extensively assessed in vivo. This study explores the feasibility of studying wave dynamics in the internal carotid artery non-invasively. Approach: Normotensive, uncontrolled and controlled hypertensive participants were recruited (daytime ambulatory blood pressure  <135/85 mmHg and  >135/85 mmHg, respectively; n  =  38). Wave intensity, reservoir pressure and statistical shape analyses were performed on the right ICA and ascending aorta high-resolution phase-contrast magnetic resonance angiography data. Main results: Wave speed in the aorta was significantly lower in normotensive compared to hypertensive participants (6.7  ±  1.8 versus 11.2  ±  6.2 m s⁻¹ for uncontrolled and 11.8  ±  4.6 m s⁻¹ for controlled hypertensives, p  =  0.02), whilst there were no differences in wave speed in the ICA. There were no significant differences between the groups for the wave intensity or reservoir pressure. Interestingly, a significant association between the anatomy of the ICA and wave energy (FCW and size, r²  =  0.12, p  =  0.04) was found. Significance: This study shows it is feasible to study wave dynamics in the ICA non-invasively. Whilst changes in aortic wave speed confirmed an expected increase in arterial stiffness, this was not observed in the ICA. This might suggest a protective mechanism in the cerebral circulation, in conjunction with the effect of vessel tortuosity. Furthermore, it was observed that ICA shape correlated with wave energy but not wave speed.

Enlightening the Association between Bicuspid Aortic Valve and Aortopathy

Bicuspid aortic valve (BAV) patients have an increased incidence of developing aortic dilation. Despite its importance, the pathogenesis of aortopathy in BAV is still largely undetermined. Nowadays, intense focus falls both on BAV morphology and progression of valvular dysfunction and on the development of aortic dilation. However, less is known about the relationship between aortic valve morphology and aortic dilation. A better understanding of the molecular pathways involved in the homeostasis of the aortic wall, including the extracellular matrix, the plasticity of the vascular smooth cells, TGFβ signaling, and epigenetic dysregulation, is key to enlighten the mechanisms underpinning BAV-aortopathy development and progression. To date, there are two main theories on this subject, i.e., the genetic and the hemodynamic theory, with an ongoing debate over the pathogenesis of BAV-aortopathy. Furthermore, the lack of early detection biomarkers leads to challenges in the management of patients affected by BAV-aortopathy. Here, we critically review the current knowledge on the driving mechanisms of BAV-aortopathy together with the current clinical management and lack of available biomarkers allowing for early detection and better treatment optimization.

Robust Revascularization in Models of Limb Ischemia Using a Clinically Translatable Human Stem Cell-Derived Endothelial Cell Product

Pluripotent stem cell-derived differentiated endothelial cells offer high potential in regenerative medicine in the cardiovascular system. With the aim of translating the use of a human stem cell-derived endothelial cell product (hESC-ECP) for treatment of critical limb ischemia (CLI) in man, we report a good manufacturing practice (GMP)-compatible protocol and detailed cell tracking and efficacy data in multiple preclinical models. The clinical-grade cell line RC11 was used to generate hESC-ECP, which was identified as mostly endothelial (60% CD31⁺/CD144⁺), with the remainder of the subset expressing various pericyte/mesenchymal stem cell markers. Cell tracking using MRI, PET, and qPCR in a murine model of limb ischemia demonstrated that hESC-ECP was detectable up to day 7 following injection. Efficacy in several murine models of limb ischemia (immunocompromised/immunocompetent mice and mice with either type I/II diabetes mellitus) demonstrated significantly increased blood perfusion and capillary density. Overall, we demonstrate a GMP-compatible hESC-ECP that improved ischemic limb perfusion and increased local angiogenesis without engraftment, paving the way for translation of this therapy.

Involving patients, families and medical staff in the evaluation of 3D printing models of congenital heart disease

OBJECTIVE

To develop a participatory approach in the evaluation of 3D printed patient-specific models of congenital heart disease (CHD) with different stakeholders who would potentially benefit from the technology (patients, parents, clinicians and nurses).

METHODS

Workshops, focus groups and teaching sessions were organised, targeting different stakeholders. Sessions involved displaying and discussing different 3D models of CHD. Model evaluation involved response counts from questionnaires and thematic analysis of audio-recorded discussions and written feedback.

RESULTS

Stakeholders’ responses indicated the scope and potential for clinical translation of 3D models. As tangible, three-dimensional artefacts, these can have a role in communicative processes. Their patient-specific quality is also important in relation to individual characteristics of CHD. Patients indicated that 3D models can help them visualise ‘what’s going on inside’. Parents agreed that models can spark curiosity in young people. Clinicians indicated that teaching might be the most relevant application. Nurses agreed that 3D models improved their learning experience during a CHD course.

CONCLUSION

Engagement of different stakeholders to evaluate 3D printing technology for CHD identified the potential of the models for improving patient– doctor communication, patient empowerment and training.

PRACTICE IMPLICATIONS

A participatory approach could benefit the clinical evaluation and translation of 3D printing technology.

A Mock Circulatory System Incorporating a Compliant 3D-Printed Anatomical Model to Investigate Pulmonary Hemodynamics

A realistic mock circulatory system (MCS) could be a valuable in vitro testbed to study human circulatory hemodynamics. The objective of this study was to design a MCS replicating the pulmonary arterial circulation, incorporating an anatomically representative arterial model suitable for testing clinically relevant scenarios. A second objective of the study was to ensure the system's compatibility with magnetic resonance imaging (MRI) for additional measurements. A latex pulmonary arterial model with two generations of bifurcations was manufactured starting from a 3D-printed mold reconstructed from patient data. The model was incorporated into a MCS for in vitro hydrodynamic measurements. The setup was tested under physiological pulsatile flow conditions and results were evaluated using wave intensity analysis (WIA) to investigate waves traveling in the arterial system. Increased pulmonary vascular resistance (IPVR) was simulated as an example of one pathological scenario. Flow split between right and left pulmonary artery was found to be realistic (54 and 46%, respectively). No substantial difference in pressure waveform was observed throughout the various generations of bifurcations. Based on WIA, three main waves were identified in the main pulmonary artery (MPA), that is, forward compression wave, backward compression wave, and forward expansion wave. For IPVR, a rise in mean pressure was recorded in the MPA, within the clinical range of pulmonary arterial hypertension. The feasibility of using the MCS in the MRI scanner was demonstrated with the MCS running 2 h consecutively while acquiring preliminary MRI data. This study shows the development and verification of a pulmonary MCS, including an anatomically correct, compliant latex phantom. The setup can be useful to explore a wide range of hemodynamic questions, including the development of patient- and pathology-specific models, considering the ease and low cost of producing rapid prototyping molds, and the versatility of the setup for invasive and noninvasive (i.e., MRI) measurements.

Utility of Cardiovascular Magnetic Resonance-Derived Wave Intensity Analysis As a Marker of Ventricular Function in Children with Heart Failure and Normal Ejection Fraction

OBJECTIVE

This study sought to explore the diagnostic insight of cardiovascular magnetic resonance (CMR)-derived wave intensity analysis to better study systolic dysfunction in young patients with chronic diastolic dysfunction and preserved ejection fraction (EF), comparing it against other echocardiographic and CMR parameters.

BACKGROUND

Evaluating systolic and diastolic dysfunctions in children is challenging, and a gold standard method is currently lacking.

METHODS

Patients with presumed diastolic dysfunction [n = 18; nine aortic stenosis (AS), five hypertrophic, and four restrictive cardiomyopathies] were compared with age-matched control subjects (n = 18). All patients had no mitral or aortic incompetence, significant AS, or reduced systolic EF. E/A ratio, E/E' ratio, deceleration time, and isovolumetric contraction time were assessed on echocardiography, and indexed left atrial volume (LAVi), acceleration time (AT), ejection time (ET), and wave intensity analyses were calculated from CMR. The latter was performed on CMR phase-contrast flow sequences, defining a ratio of the peaks of the early systolic forward compression wave (FCW) and the end-systolic forward expansion wave (FEW).

RESULTS

Significant differences between patients and controls were seen in the E/E' ratio (8.7 ± 4.0 vs. 5.1 ± 1.3, p = 0.001) and FCW/FEW ratio (2.5 ± 1.6 vs. 7.2 ± 4.2 × 10^-5 m/s, p < 0.001), as well as-as expected-LAVi (80.7 ± 22.5 vs. 51.0 ± 10.9 mL/m², p < 0.001). In particular, patients exhibited a lower FCW (2.5 ± 1.6 vs. 7.2 ± 4.2 × 10^-5 m/s, p < 0.001) in the face of preserved EF (67 ± 11 vs. 69 ± 5%, p = 0.392), as well as longer isovolumetric contraction time (49 ± 7 vs. 34 ± 7 ms, p < 0.001) and ET/AT (0.35 ± 0.04 vs. 0.27 ± 0.04, p < 0.001).

CONCLUSION

This study shows that the wave intensity-derived ratio summarizing systolic and diastolic function could provide insight into ventricular function in children, on top of CMR and echocardiography, and it was here able to identify an element of ventricular dysfunction with preserved EF in a small group of young patients.