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Introduction There have been reports of myocarditis following vaccination against COVID-19. We sought to describe cardiac magnetic resonance (CMR) findings among pediatric patients. Methods and Results Retrospective review at a large academic center of patients clinically diagnosed with post-vaccine myocarditis (PVM) undergoing CMR. Data collected included parametric mapping, ventricular function and degree of late gadolinium enhancement (LGE). Post processing strain analysis was performed using tissue tracking. Strain values, T1/T2 values and ventricular function were compared to age-and gender-matched controls with viral myocarditis using a Wilcoxon Signed Rank test. Among 12 patients with presumed PVM, 11 were male and 11 presented after the second vaccination dose, typically within 4 days. All presented with chest pain and elevated troponin. 10 met MRI criteria for myocarditis. All had LGE typically seen in the lateral and inferior walls; only five had prolonged T1 values. 10 met criteria for edema based on skeletal muscle to myocardium signal intensity ratio, and only 5 had prolonged T2 mapping values. Patients with PVM had greater short-axis global circumferential and radial strain, right ventricle function and cardiac output when compared to those with viral myocarditis. Conclusion Patients with PVM have greater short-axis global circumferential and radial strains compared to those with viral myocarditis. LGE was universal in our cohort. Signal intensity ratios between skeletal muscle and myocardium may be more sensitive in identifying edema than T2 mapping. Overall, the impact on myocardial strain by CMR is less significant in PVM compared to more classic viral myocarditis.

Background The value of MRI in pediatric congenital heart disease (CHD) is well recognized; however, the requirement for expert oversight impedes its widespread use. Four-dimensional (4D) multiphase steady-state imaging with contrast enhancement (MUSIC) is a cardiovascular MRI technique that uses ferumoxytol and captures all anatomic features dynamically. Purpose To evaluate multicenter feasibility of 4D MUSIC MRI in pediatric CHD. Materials and Methods In this prospective study, participants with CHD underwent 4D MUSIC MRI at 3.0 T or 1.5 T between 2014 and 2020. From a pool of 460 total studies, an equal number of MRI studies from three sites (n = 60) was chosen for detailed analysis. With use of a five-point scale, the feasibility of 4D MUSIC was scored on the basis of artifacts, image quality, and diagnostic confidence for intracardiac and vascular connections (n = 780). Respiratory motion suppression was assessed by using the signal intensity profile. Bias between 4D MUSIC and two-dimensional (2D) cine imaging was evaluated by using Bland-Altman analysis; 4D MUSIC examination duration was compared with that of the local standard for CHD. Results A total of 206 participants with CHD underwent MRI at 3.0 T, and 254 participants underwent MRI at 1.5 T. Of the 60 MRI examinations chosen for analysis (20 per site; median participant age, 14.4 months [interquartile range, 2.3-49 months]; 33 female participants), 56 (93%) had good or excellent image quality scores across a spectrum of disease complexity (mean score ± standard deviation: 4.3 ± 0.6 for site 1, 4.9 ± 0.3 for site 2, and 4.6 ± 0.7 for site 3; P < .001). Artifact scores were inversely related to image quality (r = -0.88, P < .001) and respiratory motion suppression (P < .001, r = -0.45). Diagnostic confidence was high or definite in 730 of 780 (94%) intracardiac and vascular connections. The correlation between 4D MUSIC and 2D cine ventricular volumes and ejection fraction was high (range of r = 0.72-0.85; P < .001 for all). Compared with local standard MRI, 4D MUSIC reduced the image acquisition time (44 minutes ± 20 vs 12 minutes ± 3, respectively; P < .001). Conclusion Four-dimensional multiphase steady-state imaging with contrast enhancement MRI in pediatric congenital heart disease was feasible in a multicenter setting, shortened the examination time, and simplified the acquisition protocol, independently of disease complexity. Clinical trial registration no. NCT02752191 © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Roest and Lamb in this issue.

PURPOSE Whole-heart MRA techniques typically target predetermined motion states, address cardiac and respiratory dynamics independently, and require either complex planning or computationally demanding reconstructions. In contrast, we developed a fast data-driven reconstruction algorithm with minimal physiological assumptions and compatibility with ungated free-running sequences. THEORY AND METHODS We propose a similarity-driven multi-dimensional binning algorithm (SIMBA) that clusters continuously acquired k-space data to find a motion-consistent subset for whole-heart MRA reconstruction. Free-running 3D radial data sets from 12 non-contrast-enhanced scans of healthy volunteers and six ferumoxytol-enhanced scans of pediatric cardiac patients were reconstructed with non-motion-suppressed regridding of all the acquired data ("All Data"), with SIMBA, and with a previously published free-running framework (FRF) that uses cardiac and respiratory self-gating and compressed sensing. Images were compared for blood-myocardium sharpness and contrast ratio, visibility of coronary artery ostia, and right coronary artery sharpness. RESULTS Both the 20-second SIMBA reconstruction and FRF provided significantly higher blood-myocardium sharpness than All Data in both patients and volunteers (P < .05). The SIMBA reconstruction provided significantly sharper blood-myocardium interfaces than FRF in volunteers (P < .001) and higher blood-myocardium contrast ratio than All Data and FRF, both in volunteers and patients (P < .05). Significantly more ostia could be visualized with both SIMBA (31 of 36) and FRF (34 of 36) than with All Data (4 of 36) (P < .001). Inferior right coronary artery sharpness using SIMBA versus FRF was observed (volunteers: SIMBA 36.1 ± 8.1%, FRF 40.4 ± 8.9%; patients: SIMBA 35.9 ± 7.7%, FRF 40.3 ± 6.1%, P = not significant). CONCLUSION The SIMBA technique enabled a fast, data-driven reconstruction of free-running whole-heart MRA with image quality superior to All Data and similar to the more time-consuming FRF reconstruction.

Children with single-ventricle congenital heart disease undergo a series of operations to maintain their pulmonary circulation including bidirectional Glenn (BDG) or hemi-Fontan in the second stage to create a superior cavopulmonary anastomosis. We aimed to optimize cardiovascular angiography protocols by determining optimal contrast timing of pulmonary and systemic circulation on magnetic resonance angiography (MRA) performed with the technique of time-resolved imaging with interleaved stochastic trajectories (TWIST).Cardiac TWIST MRA with lower extremity (LE) contrast injection was analyzed in 92 consecutive patients with a BDG or hemi-Fontan anastomosis. Contrast arrival time to inferior vena cava was set to zero to determine the relative time-to-peak (TTP) of the target vessels. Time-to-peak of each vessel was compared by age (2 or ≥2 y), ejection fraction (54% or ≥54%), the median values of heart rate (111 or ≥111 beats per minute), body surface area (BSA,0.59 or ≥0.59), cardiac index (6.04 or ≥6.04), and indexed ascending aorta flow (AscAo_i,5.3 or ≥5.3). The TTP of the vessels was also correlated with the volumetric parameters.The mean age of 92 patients (32 female, 60 male) was 3.1 years (0.7-5.6 years). With LE injection, the first peak was depicted in AscAo. Time-to-peak of the pulmonary arteries was approximately 9 seconds later than AscAo. The TTP difference between pulmonary arteries and AscAo was shorter in high heart rate group (8.3 vs 10 seconds, P0.001). The TTP difference between AscAo and the mean of pulmonary arteries was significantly shorter in high cardiac index group (8.4 vs 9.9 seconds, P0.01) and high AscAo_i group (8.7 vs 9.7 seconds, P = 0.03). The TTP differences were not significant by age, ejection fraction, and BSA. Cardiac index and AscAo_i were negatively correlated with all TTPs except AscAo. The ejection fraction, stroke volume, and atrioventricular regurgitation fraction did not correlate with the TTP.In patients with BDG or hemi-Fontan anastomosis, TTP of the pulmonary arteries on TWIST MRA via LE intravenous injection is approximately 9 seconds later than AscAo, approximately 8 and 10 seconds later in high and low heart rate groups, respectively. Cardiac index and AscAo_i have less effect on the TTP than the heart rate. There was no TTP difference of the pulmonary arteries by age, BSA, and ejection fraction and no correlation with ejection fraction, stroke volume, and atrioventricular regurgitation fraction. These data can be used to guide timing of pulmonary arterial enhancement of single-ventricle patients after BDG or hemi-Fontan anastomosis.

Single ventricle (SV) patients undergo multiple surgeries with subsequent changes in anatomy and hemodynamics. There are little cardiac magnetic resonance (CMR) data on serial changes in these patients. This study aimed to assess longitudinal changes of SV anatomy and hemodynamics in a large cohort.Anatomy and flow in SV patients with serial CMRs performed between 2008 and 2019 at a single institution were retrospectively reviewed. Mixed-effects linear regression was used to estimate changes over time at 3 to 9 months, 1 to 5 years, and5 years after Fontan.A total of 119 patients were included (51% with hypoplastic left heart syndrome; 77% underwent extracardiac Fontan). A total of 88 patients had 3 serial CMRs. Indexed right superior vena cava, inferior vena cava, neoaortic valve, and descending aorta area decreased over time (beta = -0.19, -0.44, and -0.23, respectively; P.01), as did indexed right superior vena cava, neoaorta and native aorta, and descending aorta flow (beta = -0.49, -0.53, and -0.59, respectively; P.0001). Inferior vena cava flow and its contribution to total caval flow increased (beta = 0.33; P.0001). Indexed right and left pulmonary artery flow did not change; however, indexed left pulmonary artery area decreased (beta = -0.16; P = .0014) with time. Systemic-to-pulmonary collateral flow remained unchanged before and early after Fontan (beta = -0.54; P = .42) but decreased with time from Fontan (beta = -0.22; P.0001).In this cohort of longitudinally followed SV patients, there are significant trends in vascular size and flow over time from Fontan. These findings can be used as a framework to interpret serial CMR data in the SV and noninvasively identify deviations from expected patterns before the development of clinical symptoms.

Introduction: Single ventricle patients develop aortopulmonary collaterals (APC) whose flow (APCF) has been shown, in a cross-sectional study, to be inversely proportional to cerebral blood flow (CBF). Serial longitudinal CBF and APCF data in Fontan patients taking into account brain injury (BI) has never been reported. Decreased CBF may adversely impact neurodevelopmental outcome. Methods: A prospective longitudinal cohort of 27 Fontan patients (age 10 + 1.9 years, 74% male) underwent cardiac and brain MRIs 3-9 months after Fontan and 6.0 + 1.86 years afterwards to measure CBF, APCF and to assess BI (grouped into focal brain injury (FBI), generalized insult (GI) and hemorrhage). CBF was measured using jugular venous flow and APCF was measured by the difference between aortic flow and caval return. A multivariate linear regression model was used to assess the relationship between change in APCF and change in CBF controlling for time since Fontan, sex, and changes in BI. Results: Demographics, flow and BI data are shown in table 1. A strong inverse relationship was found between CBF and APCF when CBF was indexed to aortic flow and APCF was indexed to BSA (R^2 = 0.72, P+ 11% and APCF decreased by 0.73 + 0.67 l/min/m^2 (12% when indexed to aortic flow). CBF and APCF were significantly and inversely related when adjusting for time since Fontan, sex, and change in the visibility of BI on MRI. Each one unit increase in APCF was associated with an 8% decrease in CBF. Change in CBF was smaller for those with longer times since Fontan and was larger for males. Change in CBF was larger for those whose FBI or GI became less visible, but smaller for those whose hemorrhages became less visible. See table 2. Conclusion: CBF and APCF are inversely related across serial imaging, adjusting for time from Fontan, sex and BI. This may adversely impact neurodevelopment. As APCs can be embolized, this may be a modifiable risk factor. A large scale trial is warranted.

Introduction: Patients with malaligned common atrioventricular (AV) canal (CAVC) are difficult to manage when one ventricle is borderline hypoplastic. The decision between the single ventricle pathway or attempting a biventricular repair depends upon pre-operative parameters which have previously been studied only by echocardiography. The purpose of this study was to determine the utility of cardiac magnetic resonance (CMR) in predicting success of a biventricular repair in CAVC. Methods: We performed a single center, retrospective cohort study of children with varying degrees of CAVC malalignment who underwent CMR prior to definitive repair (7/1/10 to 2/28/21). The primary outcome was successful biventricular repair. CMR measurements were performed by the investigators. To account for both dominant right ventricles (RV) and left ventricles (LV), ratios of ventricular and AV valve size were normalized as differences from their expected values. Associations were tested using univariable logistic regression. Multivariable regression models using combinations of two variables with p-values less than 0.2 were tested. Results: We included 28 patients (median age at CMR: 5.2 months, 43% male). Clinical and CMR variables are shown in Table 1. The optimal multivariable predictive model included the normalized LV end diastolic volume (EDV) to total ventricular EDV ratio and the LV-RV angle in diastole. Area under the receiver operator characteristic curve was 0.83 (p = 0.041). An LV EDV to total EDV ratio between 0.30 and 0.66 had a sensitivity of 92% and specificity of 63% for predicting successful biventricular repair. Including an LV-RV angle in diastole of less than 72 degrees resulted in a sensitivity of 83% and specificity of 81%. Conclusions: Multiple CMR measures were associated with surgical outcomes. CMR measures such as LV EDV to total ventricular EDV ratio and LV-RV angle in diastole can accurately predict successful biventricular canal repair.

Background. Surgical and catheter-based interventions for congenital heart disease require precise understanding of complex anatomy. The use of three-dimensional (3D) visualization techniques to enhance visuospatial understanding has been well documented, but integration of these methods into routine clinical practice has not been well described. We report the growth and development of a clinical 3D modeling service to inform procedural planning within a high-volume pediatric heart center.Methods. Clinical 3D modeling was performed using cardiac magnetic resonance (CMR) or computed tomography (CT) derived data. Image segmentation and post-processing was performed using FDA-approved software. Patient-specific anatomy was visualized using 3D printed models, digital flat screen models and virtual reality. Surgical repair options were digitally designed using proprietary and open-source computer aided design (CAD) based modeling tools. Results. From 2018 to 2020 there were 112 individual 3D modeling cases performed, 16 for educational purposes and 96 clinically utilized for procedural planning. Over the 3-year period, demand for clinical modeling tripled and in 2020, 3D modeling was requested in more than one-quarter of STAT category 3, 4 and 5 cases. The most common indications for modeling were complex biventricular repair (n = 30, 31%) and repair of multiple ventricular septal defects (VSD) (n=11, 12%). Conclusions. Using a multidisciplinary approach, clinical application of 3D modeling can be seamlessly integrated into pre-procedural care for patients with congenital heart disease. Rapid expansion and increased demand for utilization of these tools within a high-volume center demonstrate the high value conferred on these techniques by surgeons and interventionalists alike.

Background Patients with single ventricle (SV) may often undergo aortic reconstruction that creates a stiff large vessel, increasing afterload and affecting exercise performance. The objective of this study was to determine the relationship of pulse wave velocity (PWV) and distensibility in reconstructed and normal aortic arches after Fontan with exercise variables. Methods PWV and distensibility of the descending aorta at the level of the diaphragm (DAo) were calculated with real-time exercise cardiac magnetic resonance in 48 patients with SV after Fontan (18 after aortic reconstruction; 30 without aortic reconstruction) and compared with metabolic exercise stress test variables. Results PWV was greater in the reconstructed group than in the non-reconstructed group (median 4.4 m/s [range: 2.3 to 9.8 m/s] versus 3.6 [range: 2.6 to 6.3 m/s], respectively, p = 0.003). Statistically significant inverse correlations were found between PWV and end-diastolic, end-systolic, and stroke volumes at rest and at exercise in the reconstructed group. In addition, inverse correlations also existed in the reconstructed group between distensibility of the DAo and the exercise variables such as peak oxygen pulse (R = 0.56, p = 0.02), peak oxygen consumption (R = 0.63, p = 0.008), oxygen consumption at ventilatory anaerobic threshold (R = 0.48, p = 0.04), and peak work (R = 0.54, p = 0.02). Similar correlations were not seen in patients with non-reconstructed aortas. Conclusions Patients with SV with reconstructed aortas have increased aortic stiffness, increasing afterload on the ventricle. Native DAo stiffness distal to the reconstruction is inversely correlated with exercise performance, presumably to decrease impedance mismatch to maintain homogeneity of the aortic wall. This information suggests a possible mechanism for decreased exercise performance in patients with SV with aortic reconstructions.

Magnetic resonance imaging (MRI) and CT perform an important role in the evaluation of neonates with congenital heart disease (CHD) when echocardiography is not sufficient for surgical planning or postoperative follow-up. Cardiac MRI and cardiac CT have complementary applications in the evaluation of cardiovascular disease in neonates. This review focuses on the indications and technical aspects of these modalities and special considerations for imaging neonates with CHD.

Despite favorable short-term outcomes, Fontan palliation is associated with comorbidities and diminished quality of life (QOL) in the years after completion. We hypothesized that poor Fontan hemodynamics and ventricular function are associated with worse QOL.This was a single-center study of Fontan survivors aged more than 12 years. Subjects completed a cardiac magnetic resonance scan and QOL questionnaire. Cardiac magnetic resonance-derived variables included Fontan geometry, and hemodynamics. Computational fluid dynamics simulations quantified power loss, pressure drop, and total cavopulmonary connection resistance across the Fontan. Quality of life was assessed by completion of the Pediatric Quality of Life Inventory. Longitudinal and cross-sectional comparisons were made between cardiac magnetic resonance and computational fluid dynamics parameters with patient-reported QOL.We studied 77 Fontan patients, median age 19.7 years (interquartile range, 17.1 to 23.6), median time from Fontan completion 16 years (interquartile range, 13 to 20). Longitudinal data were available for 48 patients; median time between cardiac magnetic resonance and QOL was 8.1 years (interquartile range, 7 to 9.4). Median patient-reported Pediatric Quality of Life Inventory total score was 80 (interquartile range, 67.4 to 88). Greater power loss and smaller left pulmonary artery diameter at baseline were associated with worse QOL at follow-up. Greater pressure drop was associated with worse QOL at the same time point.For Fontan survivors, measures of computational fluid dynamics hemodynamics and geometry are associated with worse QOL. Interventional strategies targeted at optimizing the Fontan may improve QOL.

Purpose Biventricular repair of double-outlet right ventricle (DORV) necessitates the creation of a complex intracardiac baffle. Creation of the optimal baffle design and placement thereof can be challenging to conceptualize, even with 2-dimensional and 3-dimensional images. This report describes a recently developed methodology for creating virtual baffles to inform intraoperative repair. Description A total of 3 heart models of DORV were created from cardiac magnetic resonance images. Baffles were created and visualized using custom software. Evaluation This report demonstrates application of the tool to virtual planning of the baffle for repair of DORV in 3 cases. Models were examined by a multidisciplinary team, on screen and in virtual reality. Baffles could be rapidly created and revised to facilitate planning of the surgical procedure. Conclusions Virtual modeling of the baffle pathway by using cardiac magnetic resonance, creation of physical templates for the baffle, and visualization in virtual reality are feasible and may be beneficial for preoperative planning of complex biventricular repairs in DORV. Further work is needed to demonstrate clinical benefit or improvement in outcomes.

Introduction: Three-dimensional echocardiography (3DE) has been shown to be superior to 2DE when quantifying chamber dimensions. However, the clinical utility of 3DE has been limited by time-consuming analysis and need for 3D-specific training. This study aims to assess the clinical utility of a “hands-off,” artificial intelligence-driven software program, Philips Dynamic HeartModelA.I. (DHM), in a pediatric population. Hypothesis: We hypothesize that this program will be able to accurately calculate LVEF in children when compared to Cardiac MRI (CMRI) used as a gold standard. Methods: To date, 10 patients (Average Age 14.8±1.9) have undergone CMRI immediately followed by echocardiography at the Children’s Hospital of Philadelphia. Echocardiographic images were analyzed via DHM without manual editing and from full-volume 3D border tracing (3DEF). We excluded 3D imaging of 2 patients due to poor image quality. 2D LVEF was also evaluated visually in all patients by three experts, and by 2D Simpson’s Biplane method. All analyses were timed with a stopwatch. Each technique was correlated with CMRI. Results: Our results showed that LVEF measured via DHM was rapid and correlated very well with CMRI (R=0.85). DHM had a stronger correlation with CMRI than Biplane, 3DEF, and visual EF (R=0.56; R=0.68; R=0.57). Moreover, DHM analysis was faster than both Biplane and 3DEF (32±8 seconds vs 100±19 seconds, p Conclusions: Based on our pilot data, DHM analysis in children was faster than both 3DEF and biplane method likely due to its hands-off nature. Furthermore, its correlation with CMRI was superior to both 3DEF and Biplane. Based on further patient enrollment by us and others, this completely automated method will likely be clinically useful as it has potential to become a standard application in large volume, busy echo labs.

Introduction: Three-dimensional echocardiography (3DE) has been shown to be superior to two-dimensional echocardiography (2DE) for the quantification of chamber volumes and dimensions. However, the utility of 3DE in routine clinical practice has been restricted by time-consuming analysis and the need for 3D-specific training. This study aims to assess the accuracy and clinical utility of Philips Dynamic Heart ModelA.I. (DHM), a “hands off” automated software program, that may be used to measure LA chamber dimensions. This is notable, as indexed LA volume has been used as a predictor of heart failure in adults. Hypothesis: We hypothesize that DHM will be able to quickly and accurately calculate left atrial chamber volume when compared to Cardiac MRI (CMRI) used as a gold standard. Methods: To date, 10 patients (Average Age 14.8±1.9) have undergone clinically indicated CMRI, immediately followed by 3DE, at the Children’s Hospital of Philadelphia. 3D images were analyzed via DHM without manual editing (hands-off approach). DHM automatically calculated maximum LA volume. LA volume was also calculated from CMRI images using the biplane method. LA volume measurements by DHM were correlated with CMRI. Results: DHM was able to calculate LA volume in an average time of 32±8 seconds, without additional human input. Furthermore, inter-technique correlations showed that LA volume measurements made via DHM correlated very well with LA volume measurements made via CMRI (R=0.85, p Conclusions: In children, fully automated evaluation of LA volume based on artificial intelligence is a viable alternative to time-consuming 3D analysis when compared to a CMRI gold standard. This method of “hands-off” analysis may prove to be useful in situations where trained 3D personnel are unavailable. Furthermore, the utilization of this method may result in a greater integration of 3D LA volume into routine clinical practice.

The Fontan operation or the total cavopulmonary connection is a palliative surgery for single ventricle congenital heart disease where the systemic venous return circumvents a pumping chamber and flows directly into the pulmonary circuit. With surgical and medical advances, there has been improvement in life expectancy of these patients, however, it has also resulted in unique complications from the physiology that requires diligent surveillance. A critical component relies on optimal imaging for diagnosis and treatment of these complications. This article describes the normal anatomy of the Fontan circulation, current imaging modalities and techniques, and frequently encountered complications seen when imaging the patients who have undergone Fontan palliation.

Background Recent studies suggest that lymphatic congestion plays a role in development of late Fontan complications, such as protein‐losing enteropathy. However, the role of the lymphatic circulation in early post‐Fontan outcomes is not well defined. Methods and Results This was a retrospective, single‐center study of patients undergoing first‐time Fontan completion from 2012 to 2017. The primary outcome was early Fontan complication ≤6 months after surgery, a composite of death, Fontan takedown, extracorporeal membrane oxygenation, chest tube drainage >14 days, cardiac catheterization, readmission, or transplant. Complication causes were assigned to 1 of 4 groups: (1) Fontan circuit obstruction, (2) ventricular dysfunction or atrioventricular valve regurgitation, (3) persistent pleural effusions in the absence of Fontan obstruction or ventricular dysfunction, and (4) chylothorax or plastic bronchitis. T2‐weighted magnetic resonance imaging sequences were used to assess for lymphatic perfusion abnormality. The cohort consisted of 238 patients. Fifty‐eight (24%) developed early complications: 20 of 58 (34.5%) in group 1, 8 of 58 (14%) in group 2, 18 of 58 (31%) in group 3, and 12 of 58 (20%) in group 4. Preoperative T2 imaging was available for 126 (53%) patients. Patients with high‐grade lymphatic abnormalities had 6 times greater odds of developing early complications ( P =0.001). Conclusions There is substantial morbidity in the early post‐Fontan period. Half of those who developed early complications had lymphatic failure or persistent effusions unrelated to structural or functional abnormalities. Preoperative T2 imaging demonstrated that patients with higher‐grade lymphatic perfusion abnormalities were significantly more likely to develop early complications. This has implications for risk stratification and optimization of patients before Fontan palliation.

Objective We sought to evaluate contractile function in single-ventricle patients before and after imposition of Fontan physiology. Methods Single right ventricle (SRV; n = 38) and single left ventricle (SLV; n = 11) patients underwent cardiac magnetic resonance imaging pre and post Fontan operation. Global radial strain (GRS), global circumferential strain (GCS), and global longitudinal strain were measured along with ejection fraction (EF) and atrioventricular valve regurgitation (AVVR). Results Age at cardiac magnetic resonance imaging before the Fontan operation was 3.1 ± 1.3 years and after the Fontan procedure was 5.8 ± 2.7 years. There were no significant EF differences between SRV and SLV patients before and after the Fontan procedure, and EF did not deteriorate significantly after the Fontan operation. GRS was significantly lower for SRV patients than for SLV patients before (24.3% vs 32.1%; P = .048) and after (21.8% vs 29.7%; P = .045) the Fontan procedure. GRS and GCS of the SRV patients deteriorated significantly after the Fontan operation (GRS, P = .01; GCS, P = .009). Strains showed positive correlations before and after the Fontan operation with positive correlations among each strain. Within all patients, strains correlated positively with EF. Strains and EF negatively correlated with AVVR (GRS P = .03, r = −0.22; GCS P = .03, r = −0.23; EF P Conclusions Strains were lower for SRV than for SLV patients before and after the Fontan operation and deteriorated after the Fontan operation. Our study suggests that strain measures might detect ventricular deterioration earlier than EF. Because strains before and after the Fontan operation were positively correlated, and negatively correlated with AVVR, the early institution of myocardial protective therapy including AVVR management, especially for SRV patients, might have benefit.

The purpose of this study was to assess the safety and indications for cardiac magnetic resonance (CMR) with myocardial perfusion imaging (MPI) in a cohort of children and young adults. A retrospective review of 178 children and young adults who underwent CMR with MPI was performed. Studies were categorized based on study protocols as MPI with resting perfusion only, adenosine stress MPI, exercise-induced stress MPI, and MPI for cardiac mass diagnosis. Relevant clinical history, exam indications, and adverse reactions following gadolinium-based contrast agent and adenosine administration were recorded. Studies were reviewed for the presence of myocardial perfusion defects, wall motion abnormalities, and delayed myocardial enhancement. The most common indications from MPI were congenital heart disease (CHD), Kawasaki disease, anomalous coronary artery, or myocardial mass characterization. Of these, 51% were protocoled with adenosine stress, 23% without stress, 6% with exercise stress, and 20% for cardiac mass evaluation. Excluding patients for myocardial mass evaluation, MPI defects were present in 16% (14 with adenosine stress, 1 with exercise stress, 8 on resting studies only). For cardiac mass evaluation, a mass was confirmed in 58%. No adverse reactions occurred with intravenous administration of a gadolinium-based contrast agent. Three self-limited adverse reactions, 2 patients with chest pain, and 1 patient with bradycardia, occurred following adenosine administration. MPI is a safe modality for the evaluation of pediatric and young adults with minimal adverse events. The most common indications for MPI were for the evaluation of CHD, Kawasaki disease, anomalous coronary artery, or myocardial mass characterization.

Objective Exercise intolerance afflicts Fontan patients with total cavopulmonary connections (TCPCs) causing a reduction in quality of life. Optimising TCPC design is hypothesised to have a beneficial effect on exercise capacity. This study investigates relationships between TCPC geometries and exercise haemodynamics and performance. Methods This study included 47 patients who completed metabolic exercise stress test with cardiac magnetic resonance (CMR). Phase-contrast CMR images were acquired immediately following supine lower limb exercise. Both anatomies and exercise vessel flow rates at ventilatory anaerobic threshold (VAT) were extracted. The vascular modelling toolkits were used to analyse TCPC geometries. Computational simulations were performed to quantify TCPC indexed power loss (iPL) at VAT. Results A highly significant inverse correlation was found between the TCPC diameter index, which factors in the narrowing of TCPC vessels, with iPL at VAT (r=−0.723, p 2 ) at VAT (r=0.373, p=0.01), VO 2 at peak exercise (r=0.485, p=0.001) and work at VAT/weight (r=0.368, p=0.01). iPL at VAT was negatively correlated with VO 2 at VAT (r=−0.337, p=0.02), VO 2 at peak exercise (r=−0.394, p=0.007) and work at VAT/weight (r=−0.208, p=0.17). Conclusions Eliminating vessel narrowing in TCPCs and reducing elevated iPL at VAT could enhance exercise tolerance for patients with TCPCs. These findings could help plan surgical or catheter-based strategies to improve patients’ exercise capacity.

3D modeling clearly has the potential to enhance our understanding of cardiovascular disease. There is a growing body of evidence demonstrating its utility with regard to adult and congenital heart disease. However, it has not yet been widely adopted as a clinical tool. The generation of cardiac models is a multistep process and each step poses unique challenges that may hinder its incorporation into standard clinical practice. This chapter explores the challenges posed at the time of image acquisition, segmentation of the region of interest, and additive manufacturing. Additionally, obstacles faced in the practice of running a 3D printing lab are also discussed. Analysis of these specific issues may improve the ease with which 3D modeling can be utilized in everyday clinical practice.

BACKGROUND: Ferumoxytol is approved for use in the treatment of iron deficiency anemia, but it can serve as an alternative to gadolinium-based contrast agents. On the basis of postmarketing surveillance data, the Food and Drug Administration issued a black box warning regarding the risks of rare but serious acute hypersensitivity reactions during fast high-dose injection (510 mg iron in 17 seconds) for therapeutic use. Whereas single-center safety data for diagnostic use have been positive, multicenter data are lacking. PURPOSE: To report multicenter safety data for off-label diagnostic ferumoxytol use. MATERIALS AND METHODS: The multicenter ferumoxytol MRI registry was established as an open-label nonrandomized surveillance databank without industry involvement. Each center monitored all ferumoxytol administrations, classified adverse events (AEs) using the National Cancer Institute Common Terminology Criteria for Adverse Events (grade 1–5), and assessed the relationship of AEs to ferumoxytol administration. AEs related to or possibly related to ferumoxytol injection were considered adverse reactions. The core laboratory adjudicated the AEs and classified them with the American College of Radiology (ACR) classification. Analysis of variance was used to compare vital signs. RESULTS: Between January 2003 and October 2018, 3215 patients (median age, 58 years; range, 1 day to 96 years; 1897 male patients) received 4240 ferumoxytol injections for MRI. Ferumoxytol dose ranged from 1 to 11 mg per kilogram of body weight (≤510 mg iron; rate ≤45 mg iron/sec). There were no systematic changes in vital signs after ferumoxytol administration (P > .05). No severe, life-threatening, or fatal AEs occurred. Eighty-three (1.9%) of 4240 AEs were related or possibly related to ferumoxytol infusions (75 mild [1.8%], eight moderate [0.2%]). Thirty-one AEs were classified as allergiclike reactions using ACR criteria but were consistent with minor infusion reactions observed with parenteral iron. CONCLUSION: Diagnostic ferumoxytol use was well tolerated, associated with no serious adverse events, and implicated in few adverse reactions. Registry results indicate a positive safety profile for ferumoxytol use in MRI. © RSNA, 2019 Online supplemental material is available for this article.

BACKGROUND: The Fontan operation is performed for surgical palliation of single ventricle physiology. This operation is usually preceded by a superior cavopulmonary connection (SCPC); lymphatic abnormalities after SCPC may be demonstrated at MRI and prior to the Fontan operation. PURPOSE: To determine if the degree of neck and thoracic lymphatic abnormalities at T2-weighted MRI in patients after superior cavopulmonary connection (SCPC) correlated with surgical outcomes from the Fontan procedure. MATERIALS AND METHODS: Patients for whom SCPC was performed for palliation of single ventricle disease who underwent chest MRI between July 2012 and May 2015 at a single institution were retrospectively reviewed. T2-weighted images were scored as lymphatic type 1 (little or no T2 mediastinal and supraclavicular signal) to type 4 (T2 signal into both the mediastinum and the lung parenchyma). Fontan takedown, duration of post-Fontan hospitalization and pleural effusion, postoperative plastic bronchitis, need for transplant, and mortality were tabulated. The relationship between lymphatic type and clinical outcomes was evaluated by using analysis of variance (ANOVA), the Kruskal-Wallis H test, and the Fisher exact test. RESULTS: A total of 83 patients (mean age, 7.9 years ± 2.6) were evaluated. Among these 83 patients, 53 (64%) were classified with type 1 or 2 lymphatic abnormalities, 17 (20%) with type 3, and 12 (16%) with type 4. The rate of failure of Fontan completion was higher in patients with type 4 than in type 1 or 2 (54% vs 2%, respectively; P = .004). Need for cardiac transplant (one of 13 [8%]) and death (three of 13 [23%]) occurred only in type 4. Median postoperative length of stay was longer for patients with type 4 than for those with types 1 or 2 (29 days vs 9 days, respectively; P < .01). CONCLUSION: Greater MRI-based severity of lymphatic abnormalities in patients prior to planned Fontan procedure was associated with failure of Fontan completion and longer postoperative stay. © RSNA, 2019 Online supplemental material is available for this article.

Background Little is known of baseline anatomic, hemodynamic, and fluid dynamic cardiac magnetic resonance data in single-ventricle patients immediately after Fontan. A comparison from that time point to the teen years can demonstrate clinical course, potentially predict future events, and may shed some light regarding how to optimize outcome. This cross-sectional study is meant to characterize these variables from just after Fontan to the teenage years. Methods The anatomy, flows, and computational fluid dynamic modeling of 22 patients 3 to 9 months after Fontan (age 3 ± 1.1 years) and 25 teens (age 16 ± 1.8 years) were compared. Significance was defined as P less than .05. Results The percentage of Fontan pathway stenosis was greater with cardiac index and fenestration flow while caval return was lower in teens than in younger patients (for Fontan pathway stenosis, 43% vs 21%, P = .009); however, hepatic flow distribution was more evenly distributed in older patients. Pulmonary artery size kept up with somatic growth. In the teen group, indexed power loss (R = .39), percentage of Fontan pathway stenosis (R = .62), and particle resident time (R = .42) deteriorated as time from Fontan increased (P Conclusions There are mostly aspects of deterioration with a few bright spots of stability in anatomy, blood flow, and fluid dynamic variables in Fontan patients from the postoperative period to the teenage years. Most notably, Fontan pathway stenosis increases with decreasing flows while pulmonary artery size and hepatic flow distribution remain stable or improved. These data may be aid in designing improved Fontan reconstruction to optimize clinical outcome and to understand future complications.

Fontan surgical planning ranks proposed surgical options according to their hemodynamics assessed by computational fluid dynamic (CFD) modeling. CFD commonly utilizes blood flow acquired under breath-holding (BH) conditions. Ignoring the free-breathing (FB) effect on blood flow waveforms may impact the ranking of surgical options. This study investigates such a potential impact by including ten Fontan patients who had blood flow acquisitions under both BH and FB conditions. A virtual surgery platform was used to generate two surgical options for each patient: (1) a traditional Fontan conduit and (2) a Y-graft. These options were ranked based on clinically relevant hemodynamic metrics: power loss (PL) and hepatic flow distribution (HFD). No difference was found in the ranking of options between using FB and BH flow acquisitions. The findings indicated that decision-making is not affected by the types of flow acquisition for Fontan surgical planning.

A non-contractile transannular patch (TAP) in the right ventricular outflow tract (RVOT) contributes to ventricular dysfunction after tetralogy of Fallot (TOF) repair. We compared regional right ventricular (RV) strain in repaired TOF with valvar pulmonary stenosis (VPS) after balloon valvuloplasty to investigate the effects of TAP. Retrospective review of 26 cardiac magnetic resonance studies of TOF (n = 13) and VPS (n = 13) subjects matched by degree and duration of pulmonary regurgitation (PR). Feature tracking strain analysis was performed. Student's t tests, Pearson correlation, and linear regression were applied. RV ejection fraction (EF) was normal and similar between TOF and VPS (60 and 65%, respectively, p = 0.8). RV 4-chamber Lagrangian longitudinal strain (RV 4ch LS) was worse in both groups compared to normals but comparable to each other: -18.2 (95% CI -3.6 to -33) for TOF and -20.2 (95% CI -12.4 to -28) for VPS, p = 0.5. RVOT LS was worse than RV 4ch LS in TOF, p = 0.05, but not in VPS, p = 0.19. There were no significant differences in RVOT strain between groups, p = 0.18. RVOT strain and RV 4ch LS correlated positively with RV EF in VPS (r = 0.72, p = 0.003 and r = 0.55, p = 0.04). PR degree correlated negatively with RVOT LS for TOF and VPS. Longitudinal strain is diminished in VPS and TOF subjects with preserved RV EF. TAP could explain worse RVOT strain in TOF. Longitudinal studies are needed to ascertain if RV strain predicts worsening of RV EF.

Surgical optimization of the cavopulmonary connection and pharmacological therapy for dysfunctional Fontan physiology continue to advance, but these treatment approaches only slow the progression of decline to end-stage heart failure. The development of a mechanical cavopulmonary assist device will provide a viable therapeutic option in the bridging of patients to transplant or to stabilization. We hypothesize that rotational blood flow, delivered by an implantable axial flow blood pump, could effectively assist the venous circulation in Fontan patients by mimicking vortical blood flow patterns in the cardiovascular system. This study investigated seven new models of mechanical cavopulmonary assistance (single and dual-pump assist), created combinations of pump designs that deliver counter rotating vortical flow conditions, and analyzed pump performance, velocity streamlines, swirling strength, and energy augmentation in the cavopulmonary circuit for each support scenario. The model having an axial clockwise-oriented impeller in the inferior vena cava and an axial counterclockwise-oriented impeller rotating in the superior vena cava outperformed all of the support scenarios by enhancing the energy of the cavopulmonary circulation an average of 10.3% over the entire flow range and a maximum of 27.4% at %the higher flow rates. This research will guide the development of axial flow blood pumps for Fontan patients and demonstrated the high probability of %a cardiovascular benefit using counter rotating pumps in a dual support scenario, but found that this is dependent upon the patient-specific cavopulmonary anatomy.

Using cardiac magnetic resonance imaging (MRI) with virtual angioscopy, we sought to evaluate coronary anatomy, myocardial injury, and left ventricular function in children with interarterial anomalous aortic origin of coronary artery before and after surgery.We prospectively enrolled children 5 to 19 years old with interarterial anomalous coronary artery. Cardiac MRI was performed with respiratory-navigated steady-state free-precession 3-dimensional data set acquisition. Virtual angioscopy was used to evaluate the coronary ostia directly. Surgery consisted of the modified unroofing procedure.We enrolled 9 subjects between February 2009 and May 2015. Subjects were male, with an average age at surgery of 14.1 years. Anomalous coronary was right in 7 patients (77%) and left in 2. In all subjects, the proximal anomalous coronary arose tangential to the aorta with an elliptical, slitlike ostium. Before the operation, the proximal coronary artery was significantly smaller proximally than distally (2 vs 3.1 mm; P .0001. After the operation, neo-orifices were round and patent in 7 subjects; however, 2 subjects still had narrowed neo-orifices. New postoperative MRI findings included flattened septal wall motion (N = 1), small region of midmyocardial partial-thickness scar (N = 1), and dyskinetic septal wall motion with mild aortic insufficiency (N = 1). Left ventricular function was normal both before and after surgery (P = .85).Cardiac MRI with virtual angioscopy is an important tool for evaluating anomalous coronary anatomy, myocardial function, and ischemia and should be considered for initial and postoperative assessment of children with anomalous coronary arteries.

Mechanical circulatory support (MCS) options are limited for patients with dysfunctional single ventricle physiology. To address this unmet clinical need, we are developing an axial-flow blood pump to provide mechanical assistance to the cavopulmonary circulation. In this study, we investigate the use of high-resolution cardiac magnetic resonance imaging (MRI) to visualize the complex fluid flow conditions of mechanical circulatory assist in two patient-specific Fontan anatomies. A three-bladed axial-flow impeller coupled to a supportive cage with a four-bladed diffuser was positioned in the inferior vena cava (IVC) of each Fontan anatomy. Cardiac magnetic resonance (CMR) imaging and power efficiency studies were conducted at physiologic relevant parameters with cardiac outputs of 2, 3, and 4 L/min with impeller rotational speeds of 2000 and 4000 rpm. The axial-flow impeller was able to generate improved flow in the total cavopulmonary connection (TCPC). The higher rotational speed was able to redistribute flow in the TCPC anastomosis aiding in removing stagnant blood. No retrograde flow was observed or measured in the superior vena cava (SVC). As an extension of the CMR data, a scalar stress analysis was performed on both models and found a maximum scalar stress of approximately 42 Pa for both patient anatomies. The power efficiency experiments demonstrated a maximum energy gain of 8.6 mW for TCPC Anatomy 1 and 12.58 mW for TCPC Anatomy 2 for a flow rate of 4 L/min and at 4000 rpm. These findings support the continued development of axial blood pumps for mechanical cavopulmonary assist.

Background Pulmonary insufficiency is a consequence of transannular patch repair in Tetralogy of Fallot (ToF) leading to late morbidity and mortality. Transcatheter native outflow tract pulmonary valve replacement has become a reality. However, predicting a secure, atraumatic implantation of a catheter-based device remains a significant challenge due to the complex and dynamic nature of the right ventricular outflow tract (RVOT). We sought to quantify the differences in compression and volume for actual implants, and those predicted by pre-implant modeling. Methods We used custom software to interactively place virtual transcatheter pulmonary valves (TPVs) into RVOT models created from pre-implant and post Harmony valve implant CT scans of 5 ovine surgical models of TOF to quantify and visualize device volume and compression. Results Virtual device placement visually mimicked actual device placement and allowed for quantification of device volume and radius. On average, simulated proximal and distal device volumes and compression did not vary statistically throughout the cardiac cycle (P = 0.11) but assessment was limited by small sample size. In comparison to actual implants, there was no significant pairwise difference in the proximal third of the device (P > 0.80), but the simulated distal device volume was significantly underestimated relative to actual device implant volume (P = 0.06). Conclusions This study demonstrates that pre-implant modeling which assumes a rigid vessel wall may not accurately predict the degree of distal RVOT expansion following actual device placement. We suggest the potential for virtual modeling of TPVR to be a useful adjunct to procedural planning, but further development is needed.

There is an established association between tetralogy of Fallot and partial anomalous pulmonary venous connections. This association is important because surgically repaired tetralogy patients have increased risk of right heart failure. We hypothesize that partial anomalous venous connections increase right ventricular volumes and worsen right ventricular failure.We reviewed cardiac MRI exams performed at a tertiary pediatric hospital from January 2005 to January 2014. We identified patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection. We used age- and gender-matched repaired tetralogy patients without partial anomalous pulmonary venous connection as controls. We analyzed the MRI results and surgical course and performed comparative statistics to identify group differences.There were eight patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection and 16 controls. In all cases, the partial anomalous pulmonary venous connection was not detected on preoperative echocardiography. There were no significant differences in surgical course and body surface area between the two groups. Repaired tetralogy patients with unrepaired partial anomalous pulmonary venous connection showed significantly higher indexed right ventricular end diastolic volume (149 ± 33 mL/m(2) vs. 118 ± 30 mL/m(2)), right ventricle to left ventricle size ratios (3.1 ± 1.3 vs. 1.9 ± 0.5) and a higher incidence of reduced right ventricular ejection fraction compared to controls (3/8 vs. 0/16).Repaired tetralogy of Fallot with unrepaired partial anomalous pulmonary venous connection is associated with reduced right ventricular ejection fraction and more significant right ventricular dilation.

Background: Children with single ventricle heart disease are at risk for developing systemic to pulmonary arterial collateral vessels that adversely impact short-term outcomes, although the effect on long-term outcomes remains unclear. Collateral flow (CollF) can be quantified using cardiac magnetic resonance (CMR) flow quantification. The velocity–time integral (VTI), obtained from spectral Doppler tracings, has been used in “runoff” lesions like aortic regurgitation to quantify insufficiency. We hypothesized that the VTI ratio of the proximal descending aorta (DAo) after cavopulmonary anastomosis (CPA) would estimate CollF. Methods: A retrospective cross-sectional study was conducted. Patients who had a superior CPA or total CPA and underwent CMR between April 2008 and December 2012 were included. Those with greater than trivial semilunar valve insufficiency or aortic arch obstruction were excluded. In a subset (n = 88), spectral Doppler tracings of the DAo were analyzed to determine the VTI ratio. In another subset (n = 112), CMR was used to determine the ratio of retrograde to antegrade flow in the DAo. Results: There was no linear correlation between VTI ratio and CollF ( r2 = .006, P = .46). There was a weakly positive correlation with CollF ( r2 = .07, P = .007) and the CMR measured ratio of retrograde to antegrade flow. Holodiastolic flow reversal by echo did not predict higher CollF ( P = .40), but those with holodiastolic flow reversal by CMR had significantly higher CollF ( P = .04). Conclusions: The ratio of reverse to forward flow in the DAo as determined by Doppler echo does not accurately reflect CollF in children with single ventricle after CPA.

Growth hormone and its mediator, insulinlike growth factor 1 (IGF-1), are key determinants of growth in children and young adults. As patients with Fontan physiology often experience diminished longitudinal growth, we sought to describe IGF-1 levels in this population and to identify factors associated with IGF-1 deficiency. Forty-one Fontan subjects ≥5 years were evaluated in this cross-sectional study. Age- and gender-specific height Z scores were generated using national data. Laboratory testing included IGF-1 and brain natriuretic peptide (BNP) levels. IGF-1 levels were converted to age-, gender-, and Tanner stage–specific Z scores. BNP levels were log transformed to achieve a normal distribution (log-BNP). Medical records were reviewed for pertinent clinical variables. Predictors of IGF-1 Z score were assessed through the Student t test and Pearson's correlation. Median age was 11.1 years (range 5.1 to 33.5 years), and time from Fontan was 8.2 years (1.1 to 26.7). Mean height Z score was −0.2 ± 0.9 with a mean IGF-1 Z score of −0.1 ± 1.3. There was no association between IGF-1 Z score and height Z score. Longer interval since Fontan ( R = −0.32, p = 0.04), higher log-BNP ( R = −0.40; p = 0.01), and lower indexed systemic flow on cardiac magnetic resonance ( R = 0.55, p = 0.02) were associated with lower IGF-1 Z scores. In conclusion, in this cohort with Fontan physiology, higher BNP and lower systemic flow were associated with lower IGF-1 Z score. Longitudinal studies are needed to determine if these relations represent a mechanistic explanation for diminished growth in children with this physiology and with other forms of congenital heart disease.

Objective Poor total cavopulmonary connection (TCPC) hemodynamics have been hypothesized to be associated with long-term complications in Fontan patients. Image-based Fontan surgical planning has shown great potential as a clinical tool because it can pre-operatively evaluate patient-specific hemodynamics. Current surgical planning paradigms commonly utilize cardiac-gated phase contrast magnetic resonance (MR) imaging to acquire vessel flows. These acquisitions are often taken under breath-held (BH) conditions and ignore the effect of respiration on blood flow waveforms. This study investigates the effect of respiration-driven flow waveforms on patient-specific hemodynamics using real-time MR acquisitions. Methods Patient-specific TCPCs were reconstructed from cardiovascular MR images. Real-time phase contrast MR images were acquired under both free-breathing (FB) and breath-held conditions for 9 patients. Numerical simulations were employed to assess flow structures and hemodynamics used in Fontan surgical planning including hepatic flow distribution (HFD) and indexed power loss (iPL), which were then compared between FB and BH conditions. Results Differences in TCPC flow structures between FB and BH conditions were observed throughout the respiratory cycle. However, the average differences (BH – FB values for each patient, which are then averaged) in iPL and HFD between these conditions were 0.002 ± 0.011 (p = 0.40) and 1 ± 3% (p = 0.28), respectively, indicating no significant difference in clinically important hemodynamic metrics. Conclusions Respiration affects blood flow waveforms and flow structures, but might not significantly influence the values of iPL or HFD. Therefore, breath-held MR acquisition can be adequate for Fontan surgical planning when focusing on iPL and HFD.

Background As patients with a single-ventricle physiology age, long-term complications inherent to this population become more evident. Previous studies have focused on correlating anatomic and hemodynamic performance, but there is little information of how these variables change with time. Vessel growth and flow rate changes were quantified using cardiac magnetic resonance and their effects on hemodynamics were assessed, which could affect the long-term outcome. Methods Forty-eight patients with a lateral tunnel or extracardiac conduit Fontan who underwent two cardiac magnetic resonance scans (average interval, 5.1 ± 2.3 years) were studied. Total cavopulmonary connection anatomic and flow variables were reconstructed and normalized to body surface area 1/2 . Total cavopulmonary connection hemodynamic efficiency (indexed power loss) was obtained through computational fluid dynamic modeling. Results Absolute vessel diameters increased with time, normalized diameters decreased, and vessel mean flow rates remained unchanged. Indexed power loss changed significantly in the cohort, as well as in patients in whom the minimum normalized left pulmonary artery decreased. Age at first scan and connection type (lateral tunnel or extracardiac conduit) were not associated with changes in indexed power loss. Conclusions We present the largest serial cardiac magnetic resonance Fontan cohort to date. Although flow rates increased proportionally to body surface area, vessel diameters did not match somatic growth. As a result, energy losses increased significantly with time in the cohort analyzed.

Little data are available on the accuracy of phase-contrast magnetic resonance imaging (PC-MRI) velocity mapping in the vicinity of intravascular metal stents other than nitinol stents. Therefore, we sought to determine this accuracy using in vitro experiments. An in vitro flow phantom was used with 3 stent types: (1) 316L stainless steel, (2) nitinol self-expanding, and (3) platinum-iridium. Steady and pulsatile flow was delivered with a magnetic resonance imaging-compatible pump (CardioFlow 5000, Shelley Medical, London, Ontario, Canada). Flows were measured using a transit time flow meter (ME13PXN, Transonic, Inc, Ithaca, New York). Mean flows ranged from 0.5 to 7 L/min. For each condition, 5 PC-MRI acquisitions were made: within the stent, immediately adjacent to both edges of the stent artifact, and 1 cm upstream and downstream of the artifact. Mean PC-MRI flows were calculated by segmenting the tube lumen using clinical software (ARGUS, Siemens, Inc, Erlangen, Germany). PC-MRI and flow meter flows were compared by location and stent type using linear regression, Bland-Altman, and intraclass correlation (ICC). PC-MRI flows within the stent artifact were inaccurate for all stents studied, generally underestimating flow meter-measured flow. Agreement between PC-MRI and flow meter-measured flows was excellent for all stent types, both immediately adjacent to and 1 cm away from the edge of the stent artifact. Agreement was highest for the platinum-iridium stent (R = 0.999, ICC = 0.999) and lowest for the nitinol stent (R = 0.993, ICC = 0.987). In conclusion, PC-MRI flows are highly accurate just upstream and downstream of a variety of clinically used stents, supporting its use to directly measure flows in stented vessels.

ObjectiveWe previously described lower leg lean mass Z-scores (LLMZ) in Fontan patients associated with worse peak oxygen consumption on metabolic exercise testing. We hypothesised that LLMZ correlates with indexed systemic flow (Qsi) and cardiac index (CI) on exercise cardiac magnetic resonance (eCMR).MethodsThirteen patients had LLM measured by dual-energy X-ray absorptiometry within mean 40 (range 0–258) days of eCMR. LLM was converted to sex and race-specific Z-scores based on healthy reference data. Ventricular volumes and flow measurements of the ascending and descending (DAO) aorta and superior vena cava (SVC) were obtained by CMR at rest and just after supine ergometer exercise to a heart rate associated with anaerobic threshold on prior exercise test. Baseline and peak exercise measures of Qsi (SVC+DAO/BSA) and CI, as well as change in Qsi and CI with exercise, were compared with LLMZ by linear regression.ResultsLLMZ was not correlated with resting flows, stroke volume or CI. There was a strong linear correlation between LLMZ and change in both CI (r=0.77, p=0.002) and Qsi (r=0.73, p=0.005) from rest to exercise. There was also a significant correlation between LLMZ and Qsi at exercise (r=0.70, p=0.008). The correlation between LLMZ and CI at exercise did not reach significance (r=0.3, p=0.07).ConclusionsIn our cohort, there was a strong linear correlation between LLMZ and change in both CI and Qsi from rest to exercise, suggesting that Fontan patients with higher LLMZ may be better able to augment systemic output during exercise, improving performance.