Faculty Bibliography

Background: Hypoplastic left heart syndrome (HLHS) is of the highest risk lesions in congenital heart disease. The initial surgery typically involves the Norwood procedure, frequently with Sano modification. Despite surgical advances, interstage mortality remains approximately 10%, with diminished right ventricular (RV) systolic function a risk factor for death. Tricuspid regurgitation (TR) derived dP/dT has been shown to correlate with catheter derived dP/dT in patients with HLHS, and is frequently used in assessment of RV systolic function. However, in patients without an adequate TR Doppler signal, this modality cannot be used. The purpose of this study was to evaluate the correlation between a Sano derived RV dP/dT and TR derived RV dP/dT in the assessment of RV systolic function following Norwood operation with Sano modification. Methods: An echocardiographic retrospective review was performed in patients following a Norwood/Sano operation, and assessed for the presence of a continuous wave Doppler tracing across the tricuspid valve and Sano shunt. 46 studies met this criteria. A dP/dT for both methods was measured between 1 and 3 m/s, and a qualitative assessment of function was also assigned to each study. Results: The mean value of TR derived dP/ dT and Sano derived dP/dT was 979.9 mmHg/s and 1102.89 mmHg/s respectively. A linear relationship exists between a Sano and TR derived RV dP/dT, where the TR derived RV dP/dT = 387+0.73x, (p=0.001). There was also a statistically significant relationship between the Sano derived dP/dT and the qualitative analysis of RV systolic function, particularly in the higher values. Moderately diminished function was found to have a Sano derived dP/dT of 860 to 1093, mildly diminished 732 to 1325, and normal function 866 to 2048. Conclusions: Sano derived RV dP/dT can be effectively used as a surrogate for TR derived RV dP/dT, which may be of use in patients with inadequate TR. There is a statistically significant correlation between the Sano dP/dT and the qualitative assessment of function (Figure presented)

OBJECTIVES: Residual respiratory motion degrades image quality in conventional cardiac cine MRI (CCMRI). We evaluated whether a free-breathing (FB) radial imaging CCMRI sequence with compressed sensing reconstruction [extradimensional (e.g. cardiac and respiratory phases) golden-angle radial sparse parallel, or XD-GRASP] could provide better image quality than a conventional Cartesian breath-held (BH) sequence in an unselected population of patients undergoing clinical CCMRI. MATERIALS AND METHODS: One hundred one patients who underwent BH and FB imaging in a midventricular short-axis plane at a matching location were included. Visual and quantitative image analysis was performed by two blinded experienced readers, using a five-point qualitative scale to score overall image quality and visual signal-to-noise ratio (SNR) grade, with measures of noise and sharpness. End-diastolic and end-systolic left ventricular areas were also measured and compared for both BH and FB images. RESULTS: Image quality was generally better with the BH cines (overall quality grade for BH vs FB images 4 vs 2.9, p < 0.001; noise 0.06 vs 0.08 p < 0.001; SNR grade 4.1 vs 3, p < 0.001), except for sharpness (p = 0.48). There were no significant differences between BH and FB images regarding end-diastolic or end-systolic areas (p = 0.35 and p = 0.12). Eighteen of the 101 patients had poor BH image quality (grade 1 or 2). In this subgroup, the quality of the FB images was better (p = 0.0032), as was the SNR grade (p = 0.003), but there were no significant differences regarding noise and sharpness (p = 0.45 and p = 0.47). CONCLUSION: Although FB XD-GRASP CCMRI was visually inferior to conventional BH CCMRI in general, it provided improved image quality in the subgroup of patients with respiratory-motion-induced artifacts on BH images.

BACKGROUND: Pulmonary artery intimal spindle cell sarcomas are rare and carry with them a poor prognosis and high rate of recurrence. In extremely rare cases, this tumor can infiltrate the pulmonic valve and manifest as adult-onset pulmonic stenosis. CASE PRESENTATION: We report an unusual case of a patient with symptomatic, adult-onset severe pulmonic stenosis who was referred for possible balloon valvuloplasty but was subsequently found to have pulmonary artery intimal sarcoma infiltrating the pulmonary valve leading to progressive exertional dyspnea. CONCLUSION: The presence of adult-onset pulmonic stenosis should prompt the clinician to investigate further as most cases of pulmonic stenosis are congenital in nature and present early in life. Careful diagnostic evaluation in concert with multimodal imaging should take place to arrive at the correct and challenging diagnosis of sarcoma-induced adult-onset severe pulmonic stenosis. Given the poor prognosis and rapid progression of disease, early diagnosis is crucial.

Background/Hypothesis: The clinical importance of intracardiac echogenic foci(ICEF)on prenatal ultrasound remains debatable amongst pediatric cardiologists and obstetricians. It has previously been discredited as a marker of triploidy and no clear association with congenital heart disease (CHD) has been established. Yet it continues to be a frequent reason for referral for fetal echocardiogram. The aim of this study was to assess the presence of CHD in patients with ICEF and to determine if it represents echocardiographic artifact. We hypothesized that there is no significant association between ICEF and CHD and that ICEF represents echocardiographic artifact. Materials and Methods: The institutional fetal echocardiography database was retrospectively searched for reports containing the diagnosis of echogenic focus from November 2014-November 2016. Each study was evaluated by a single reviewer. The presence of ICEF in the 3 standard views analogous to the apical 4 chamber, parasternal short axis, and parasternal long axis views was recorded. In addition, the presence of CHD, pericardial effusion, and/or fetal arrhythmia for each study was documented. Statistical analysis was performed using cross-tabulation with chi-square analysis. Results: 55 patients, yielding 145 studies were reviewed. 6 patients (10.9%) had CHD, which included VSD(n= 3), PA/VSD(n =2), and vascular ring(n =1). ICEF was noted in all 3 views in 33 studies(23%), in 2 views in 45 studies(31%), in 1 view in 22 studies (15%), and resolved in 45 studies (31%)(see table). Of those studies with ICEF noted in all 3 views, 19%(n=6) were associated with CHD, indicating a significant association in this highly selective population (p =0.039). Conclusions: There is a higher incidence of CHD in fetuses with ICEF compared to the general population. The presence of ICEF was more likely to be identified in multiple views, suggesting it is unlikely echocardiographic artifact

Rapid prototyping may be beneficial in properly selected cases of complex congenital heart disease, providing detailed anatomical understanding that helps to guide potential surgical and cardiac catheterization interventions. We present a case of double-outlet right ventricle, where the decision to obtain a three-dimensional printed model helped for better understanding of the anatomy, with the additional advantage of surgical simulation in planning the surgical approach and type of surgical repair.

BACKGROUND: It is still thought by some that a common wall is to be found in the normal heart between the attachments of the caval and pulmonary veins, with absence of this wall underscoring the presence of sinus venosus defects. Recent findings using episcopic microscopy in developing mice have shown the deficiencies of this notion. Understanding that the superior rim of the oval fossa is a fold, rather than a true septum, which can be distorted in the presence of partially anomalous pulmonary venous drainage, has provided an alternative explanation for the morphogenesis of sinus venosus defects. METHODS: We reviewed our experience with patients suspected of having a sinus venosus defect from August, 2011, through October, 2015, analysing the findings in light of the current hypotheses used to explain the development of the defects, along with correlations made by inspection of autopsy specimens. RESULTS: We evaluated findings from 16 patients, with a mean age of 7.7 years, ranging from 2.7 to 15 years. Of the group, 13 were ultimately diagnosed with a superior sinus venosus defect, two with an inferior defect, and one with isolated anomalous pulmonary venous connection in the absence of an interatrial communication. Initially, two patients were thought to have oval fossa defects, one from each subtype, but were correctly diagnosed following cardiac magnetic resonance interrogation. Anomalous pulmonary venous connections were present in all cases. CONCLUSION: Appreciation of the changes occurring during normal cardiac development helps in understanding the anatomical substrate underscoring the spectrum of sinus venosus defects. The lesions are veno-venous connections due to partially anomalous pulmonary venous connections, producing interatrial communications outside the confines of the interatrial septum.

Rapid prototyping is quickly gaining utility in various complex forms of CHD. In properly selected cases, these printed models provide detailed anatomical understanding that help guide potential surgical and cardiac catheterisation interventions. We present a case of a tunnel-like ventricular septal defect referred for surgical repair, where the decision to obtain a three-dimensional printed model helped in better understanding of the anatomy, leading to delaying, and hopefully avoiding altogether, surgical repair.

We report an unusual presentation of a large left atrial myxoma in an eight-year-old girl who presented with the sudden onset of chorea. This case illustrates the fact that the presentation of chorea in nonendemic areas for rheumatic fever should raise suspicion for a myxoma. The chorea resolved soon after removal of the myxoma, supporting the hypothesis of an immune-mediated mechanism, or manifestation of paraneoplastic syndrome secondary to the myxoma.

Rapid prototyping facilitates comprehension of complex cardiac anatomy. However, determining when this additional information proves instrumental in patient management remains a challenge. We describe our experience with patient-specific anatomic models created using rapid prototyping from various imaging modalities, suggesting their utility in surgical and interventional planning in congenital heart disease (CHD). Virtual and physical 3-dimensional (3D) models were generated from CT or MRI data, using commercially available software for patients with complex muscular ventricular septal defects (CMVSD) and double-outlet right ventricle (DORV). Six patients with complex anatomy and uncertainty of the optimal management strategy were included in this study. The models were subsequently used to guide management decisions, and the outcomes reviewed. 3D models clearly demonstrated the complex intra-cardiac anatomy in all six patients and were utilized to guide management decisions. In the three patients with CMVSD, one underwent successful endovascular device closure following a prior failed attempt at transcatheter closure, and the other two underwent successful primary surgical closure with the aid of 3D models. In all three cases of DORV, the models provided better anatomic delineation and additional information that altered or confirmed the surgical plan. Patient-specific 3D heart models show promise in accurately defining intra-cardiac anatomy in CHD, specifically CMVSD and DORV. We believe these models improve understanding of the complex anatomical spatial relationships in these defects and provide additional insight for pre/intra-interventional management and surgical planning.

INTRODUCTION Melody transcatheter pulmonary valve (TPV) implantation is frequently considered in patients with Right Ventricle Outflow Tract (RVOT) conduit obstruction, as a minimally invasive alternative to open-heart surgery.1 However, TPV implantation is associated to a risk of coronary artery (CA) compression.2 In this work, an innovative Finite Element (FE) balloon dilatation model has been built to predict CA compression in order to avoid patient exposure to unnecessary risks. In this study four patients, who underwent MRI or CT in anticipation to receive TPV, were considered. Images were segmented to generate 3D models. A balloon dilatation FE simulation was implemented for each of the models. The balloon was represented as a deformable 3D cylinder positioned at the center of mass at the narrowest point of the conduit lumen. Then, radial displacement was applied uniformly until the balloon reached the dimension of a fully inflated balloon. A linear elastic constitutive model was chosen to describe all the vasculature, and parameters for it were retrieved from literature. A frictionless contact algorithm was implemented between the balloon and the conduit and between the conduit and the surrounding structures. The results of the simulations allowed analysis of important parameters that could play an active role in the determination of the angioplasty procedure outcome in terms of CA compression. MATERIALS AND METHODS Patient-Specific Models Patients who were candidates for Transcatheter Pulmonary Valve Replacement (TPVR) were included (n = 4). The investigators from Tandon School of Engineering were blinded to the results of the procedure. Each patient underwent pre-catheterization Magnetic Resonance Imaging (MRI) or Computerized Tomography scan (CT scan) and patient-specific models were created from these images using Mimics (Materialize, Belgium), Meshmixer (Autodesk, California) and Cubit (C Sim Software, Utah) software. Each model was constituted by the components of the cardiovascular system affected by the angioplasty procedure, the pulmonary artery (PA), the aorta and the coronary arteries (CA). A 60 mm long segment of PA was selected from the right ventricle outflow tract (RVOT) to the PA bifurcation so that the conduit was included. Similarly, a 60 mm long segment of aorta was selected from the aortic root to the aortic arch. Finally, left and right CAs were selected where visible. Our protocol required the CA branches to be at least 20 mm in length to be included in the study. The model thus obtained, was manipulated using 3D CAD tools available in Meshmixer to smooth the model and to generate a 3D hollow geometry from a model representing only the blood pool. The hollowing procedure required the definition of the thickness of the arterial wall, which was chosen to be 2 mm for the aorta and the RVOT conduit, and 1 mm for the CA branches,3 see Fig. 1A-D. Finally, the model was meshed using Cubit. The PA model was divided in three parts: a 30 mm long central section that defined the contact surfaces, internally with the balloon and externally with the aorta and CAs; and the two remaining parts, each 15 mm long, extending before and after the contact area. Tetrahedral elements where used for meshing the models, and in average, the number of elements used was 14,406 +/- 5875. The model thus obtained was then exported in ABAQUS (Dassault Systemes, RI) for the finite element simulations. Balloon Models In this study, two separate approaches were used to model the angioplasty balloon. In one case an analytical rigid surface is used to simulate the balloon, and the results of this approach are compared with a deformable balloon model. * Rigid Balloon In order to replicate folding of the angioplasty balloon into a catheter, the rigid balloon model was composed by 5 analytical rigid surfaces made in such a way that, after the applied radial displacement, the shells were forming a cylinder with a diameter matching that of an inflated angioplasty balloon, see Fig. 1E. * Deformable Balloon The deformable balloon model was created in ABAQUS. In this case, the balloon was modeled as a deformable 3D cylinder of 20 mm length, 1 mm of external diameter and 0.2 mm thickness.1 A mesh of 63 quadrilateral elements was generated and solved by employing reduced integration algorithms and large-strain formulation, see Fig. 1F. Material Models Human arterial tissue was modeled as a linear-elastic isotropic material with Young's modulus of 2.7 MPa and Poisson ratio of 0.49.4Duetothe lack of data on thematerialproperties of the conduit after implantation, the material properties of the conduit were assumed to be similar to those of the arterial tissue. Based on literature, the balloon was modeled as an isotropic, linear-elastic material, with a Young's modulus of 900 MPa and Poisson's ratio of 0.3.5-6 Contact Definition Each model surface was defined and surface-to-surface frictionless hard contact was imposed between the external surface of the balloon model and the internal surface of the conduit. Surface to surface frictionless hard contact was also imposed between the external pulmonary artery surface external surface of the aorta and the CA. The contact model used assumed that: (1) the surfaces transmit no contact pressure unless the nodes of the slave-surface contact the master-surface; (2) no penetration is allowed at each surface; (3) there is no limit to the magnitude of contact pressure that can be transmitted when the surfaces are in contact. The direct method was chosen as contact constraint enforcement method. Surface to surface contact was used such that the master role was given to the surface with the coarser mesh and/or larger area. For the analyses with analytical rigid surfaces, the master role was always given to the rigid shell. Boundary Conditions All the extremities of the conduit and of the aorta are constrained through an encastre. The extremity at the end of the CA is constrained as well through an encastre. Displacement Protocol The angioplasty intervention was simulated by displacing the balloon to the diameter used during the intervention. Although the TPVR standard protocol, states that the angioplasty balloon can be inflated to 110% of the original conduit diameter or 24 mm,1,2 whichever is greater, this protocol could be applied only to patient 2, see Fig. 1G. RESULTS For all the simulations, the balloon expanded under the imposed displacement conditions causing the conduit to deform. As the balloon displacement was increased, the central part of the conduit also expanded. It was also noticeable that once the balloon had reached its nominal diameter, the maximum stress value was localized in the portion of the conduit with the highest curvature for all four models. Rigid Balloon vs Deformable Balloon By comparing the two different approaches to model angioplasty, it was found that more stable results were obtained using the meshed cylinder balloon model rather than the one made of analytically rigid surfaces. However, it was possible to compare the results of the two models for deformations up to the 80% of the complete final angioplasty balloon diameter. Results on the conduit in terms of stress and deformation were strongly comparable. In fact, the average Von Mises stress varied by 0.76%, while the average displacement varied by 0.3%. In both cases the values obtained in the deformable model were smaller than the ones obtained in the rigid one. Angioplasty Outcomes For all the patient-specific models we evaluated whether CA compression could be modeled with this approach. The results show that in two cases the CA deforms, but there is no contact with the conduit. In these cases, we defined the CA to be distorted and not compressed as it deforms as a consequence of compression at the level of the aortic root, see Fig. 2A-D. DISCUSSION Segmentation of the patient geometries generated regular models, which made possible to complete the computational analysis. Overall, 50% of the sample population analyzed showed the risk of coronary deformation as a result of the angioplasty balloon expansion. Computational methods, such as the finite element method, represent an interesting alternative to the state-of-art catheterization lab evaluation, which have been found to have a low prediction value. The results of the four expansion simulations presented similar values of the maximum Von Mises stresses on the pulmonary arteries, while they present different results in terms of displacement and stresses in the coronary arteries, showing that coronary compression is strictly dependent on the specific geometry on the specific patient. CONCLUSIONS In this study, the effect of the balloon expansion during pre- TPV Angioplasty procedure was investigated by means of the FE method. Data of four patients who underwent attempted MelodyTM valve implantation were used. A deformable cylindrical balloon model was developed and compared with a balloon model constituted by analytical rigid shells to evaluate whether the choice of a different balloon model can be significant in terms of displacement results in the artery. The developed models allowed analysis of important parameters that could play a role in the determination on the angioplasty procedure outcome in terms of coronary compression. Finally, this work successfully identified a method to simulate a pre-TPVR procedure. Future work includes the analysis of a pressure based balloon expansion. This approach would be closer to the actual procedure and make possible the realization of a folded balloon model obtained by applying a negative pressure from a cylindrical configuration.(Table Presented)