Design and implementation of multicenter pediatric and congenital studies with cardiovascular magnetic resonance: Big data in smaller bodies

Cardiovascular magnetic resonance (CMR) has become the reference standard for quantitative and qualitative assessment of ventricular function, blood flow, and myocardial tissue characterization. There is a preponderance of large CMR studies and registries in adults; However, similarly powered studies are lacking for the pediatric and congenital heart disease (PCHD) population. To date, most CMR studies in children are limited to small single or multicenter studies, thereby limiting the conclusions that can be drawn. Within the PCHD CMR community, a collaborative effort has been successfully employed to recognize knowledge gaps with the aim to embolden the development and initiation of high-quality, large-scale multicenter research. In this publication, we highlight the underlying challenges and provide a practical guide toward the development of larger, multicenter initiatives focusing on PCHD populations, which can serve as a model for future multicenter efforts.

CMR reference values of right ventricular volumetric variables in patients with hypoplastic left heart syndrome

BACKGROUND

Cardiovascular magnetic resonance (CMR) has established itself as the gold standard for serial assessment of systemic right ventricular (RV) performance but due to the lack of standardized RV reference values for HLHS patients, the interpretation of RV volumetric data in HLHS remains difficult. Therefore, this study aimed to close this gap by providing CMR reference values for the systemic RV in HLHS patients.

METHODS

CMR scans of 160 children, adolescents and young adults (age range 2.2 to 25.2 years, 106 males) with HLHS were retrospectively evaluated. All patients were studied following total cavopulmonary connection. Short axis stacks were used to measure RV end-diastolic and end-systolic volumes (RVEDV, RVESV), stroke volume (RVSV), ejection fraction (RVEF) and end-diastolic myocardial mass (RVEDMM). Univariable and multiple linear regression analyses was performed to assess associations between RV parameters and demographic and anthropometric characteristics. Following the results of the regression analysis, reference graphs and tables were created with the LMS-method.

RESULTS

Multiple linear regression analysis showed strong associations between body height and RVEDV, RVESV as well as RVSV. Age was highly associated with RVEDMM. Therefore, percentile curves and tables were created with respect to body height (RVEDV, RVESV, RVSV) and age (RVEDMM). The influence of demographic and anthropometric parameters on RVEF was mild, thus no percentile curves and tables for RVEF are provided.

CONCLUSION

We were able to define CMR reference values for RV volumetric variables for HLHS patients. These data might be useful for the assessment and interpretation of CMR scans in these patients and for research in this field.

Organisation of paediatric echocardiography laboratories and governance of echocardiography services and training in Europe: current status, disparities, and potential solutions. A survey from the Association for European Paediatric and Congenital Cardiology (AEPC) imaging working group

BACKGROUND

There is limited data on the organisation of paediatric echocardiography laboratories in Europe.

METHODS

A structured and approved questionnaire was circulated across all 95 Association for European Paediatric and Congenital Cardiology affiliated centres. The aims were to evaluate: (1) facilities in paediatric echocardiography laboratories across Europe, (2) accredited laboratories, (3) medical/paramedical staff employed, (4) time for echocardiographic studies and reporting, and (5) training, teaching, quality improvement, and research programs.

RESULTS

Respondents from forty-three centres (45%) in 22 countries completed the survey. Thirty-six centres (84%) have a dedicated paediatric echocardiography laboratory, only five (12%) of which reported they were European Association of Cardiovascular Imaging accredited. The median number of echocardiography rooms was three (range 1-12), and echocardiography machines was four (range 1-12). Only half of all the centres have dedicated imaging physiologists and/or nursing staff, while the majority (79%) have specialist imaging cardiologist(s). The median (range) duration of time for a new examination was 45 (20-60) minutes, and for repeat examination was 20 (5-30) minutes. More than half of respondents (58%) have dedicated time for reporting. An organised training program was present in most centres (78%), 44% undertake quality assurance, and 79% perform research. Guidelines for performing echocardiography were available in 32 centres (74%).

CONCLUSION

Facilities, staffing levels, study times, standards in teaching/training, and quality assurance vary widely across paediatric echocardiography laboratories in Europe. Greater support and investment to facilitate improvements in staffing levels, equipment, and governance would potentially improve European paediatric echocardiography laboratories.

Assessment for learning of paediatric cardiology trainees in 41 centres from 19 European countries

BACKGROUND

Limited data exist on how trainees in paediatric cardiology are assessed among countries affiliated with the Association of European Paediatric and Congenital Cardiology.

METHODS

A structured and approved questionnaire was circulated to educationalists/trainers in 95 Association for European Paediatric and Congenital Cardiology training centres.

RESULTS

Trainers from 46 centres responded with complete data in 41 centres. Instructional design included bedside teaching (41/41), didactic teaching (38/41), problem-based learning (28/41), cardiac catheterisation calculations (34/41), journal club (31/41), fellows presenting in the multidisciplinary meeting (41/41), fellows reporting on echocardiograms (34/41), clinical simulation (17/41), echocardiography simulation (10/41), and catheterisation simulation (3/41). Assessment included case-based discussion (n = 27), mini-clinical evaluation exercise (mini-CEX) (n = 12), directly observed procedures (n = 12), oral examination (n = 16), long cases (n = 11), written essay questions (n = 6), multiple choice questions (n = 5), and objective structured clinical examination (n = 2). Entrustable professional activities were utilised in 10 (24%) centres. Feedback was summative only in 17/41 (41%) centres, formative only in 12/41 (29%) centres and a combination of formative and summative feedback in 10/41 (24%) centres. Written feedback was provided in 10/41 (24%) centres. Verbal feedback was most common in 37/41 (90 %) centres.

CONCLUSION

There is a marked variation in instructional design and assessment across European paediatric cardiac centres. A wide mix of assessment tools are used. Feedback is provided by the majority of centres, mostly verbal summative feedback. Adopting a programmatic assessment focusing on competency/capability using multiple assessment tools with regular formative multisource feedback may promote assessment for learning of paediatric cardiology trainees.

Ablation of atrial flutter in a patient after Fontan procedure: a case report of challenging access to the common atrium

Background

In patients with a total cavopulmonary connection in Fontan circulation, the access to the common atrium (CA) during a catheter ablation can be challenging, even in the presence of fenestration in an intra-atrial lateral tunnel (IALT). In our department, the fenestration is typically marked with metal clips (MCs). To the best of our knowledge, there is no previous report of balloonoplasty of clipped fenestration.

Case summary

A 19-year-old male with hypoplastic left heart syndrome (HLHS) was scheduled for catheter ablation of recurrent atrial tachycardia. He was diagnosed with HLHS prenatally and underwent a stepwise surgical palliation. Fontan circulation was completed with the creation of a fenestrated IALT. The fenestration was marked by four MCs. During the ablation procedure, the passage of the steerable sheath with mapping catheter to the CA was prevented by a small fenestration size and rigidness of the edges of the fenestration caused by the MCs. Multiple attempts to dilate the fenestration using a peripheric angioplasty balloon failed. Only angioplasty with the 'balloon-against-dilator' technique was finally successful. Activation map showed a counterclockwise atrial flutter in the CA; successful ablation was performed.

Discussion

We present a case of challenging access to the CA through a clipped fenestration in a polytetrafluoroethylene baffle for atrial tachycardia ablation. Even though a tunnel fenestration in Fontan patients facilitates access to the CA, the passage of a steerable introducer with a mapping catheter may be challenging due to diameter mismatch and the rigidity of its edges caused by MCs. The balloon-against-dilator technique might be helpful when conventional balloon angioplasty fails.

Detection of hypoplastic left heart syndrome anatomy from cardiovascular magnetic resonance images using machine learning

OBJECTIVE

The prospect of being able to gain relevant information from cardiovascular magnetic resonance (CMR) image analysis automatically opens up new potential to assist the evaluating physician. For machine-learning-based classification of complex congenital heart disease, only few studies have used CMR.

MATERIALS AND METHODS

This study presents a tailor-made neural network architecture for detection of 7 distinctive anatomic landmarks in CMR images of patients with hypoplastic left heart syndrome (HLHS) in Fontan circulation or healthy controls and demonstrates the potential of the spatial arrangement of the landmarks to identify HLHS. The method was applied to the axial SSFP CMR scans of 46 patients with HLHS and 33 healthy controls.

RESULTS

The displacement between predicted and annotated landmark had a standard deviation of 8-17 mm and was larger than the interobserver variability by a factor of 1.1-2.0. A high overall classification accuracy of 98.7% was achieved.

DISCUSSION

Decoupling the identification of clinically meaningful anatomic landmarks from the actual classification improved transparency of classification results. Information from such automated analysis could be used to quickly jump to anatomic positions and guide the physician more efficiently through the analysis depending on the detected condition, which may ultimately improve work flow and save analysis time.

Clinical course and follow-up of pediatric patients with COVID-19 vaccine-associated myocarditis compared to non-vaccine-associated myocarditis within the prospective multicenter registry-"MYKKE"

BACKGROUND

Since the onset of widespread COVID-19 vaccination, increased incidence of COVID-19 vaccine-associated myocarditis (VA-myocarditis) has been noted, particularly in male adolescents.

METHODS

Patients <18 years with suspected myocarditis following COVID-19 vaccination within 21 days were enrolled in the PedMYCVAC cohort, a substudy within the prospective multicenter registry for pediatric myocarditis "MYKKE." Clinical data at initial admission, 3- and 9-months follow-up were monitored and compared to pediatric patients with confirmed non-vaccine-associated myocarditis (NVA-myocarditis) adjusting for various baseline characteristics.

RESULTS

From July 2021 to December 2022, 56 patients with VA-myocarditis across 15 centers were enrolled (median age 16.3 years, 91% male). Initially, 11 patients (20%) had mildly reduced left ventricular ejection fraction (LVEF; 45%-54%). No incidents of severe heart failure, transplantation or death were observed. Of 49 patients at 3-months follow-up (median (IQR) 94 (63-118) days), residual symptoms were registered in 14 patients (29%), most commonly atypical intermittent chest pain and fatigue. Diagnostic abnormalities remained in 23 patients (47%). Of 21 patients at 9-months follow-up (259 (218-319) days), all were free of symptoms and diagnostic abnormalities remained in 9 patients (43%). These residuals were mostly residual late gadolinium enhancement in magnetic resonance imaging. Patients with NVA-myocarditis (n=108) more often had symptoms of heart failure (P = .003), arrhythmias (P = .031), left ventricular dilatation (P = .045), lower LVEF (P < .001) and major cardiac adverse events (P = .102).

CONCLUSIONS

Course of COVID-19 vaccine-associated myocarditis in pediatric patients seems to be mild and differs from non-vaccine-associated myocarditis. Due to a considerable number of residual symptoms and diagnostic abnormalities at follow-up, further studies are needed to define its long-term implications.

Adult congenital heart disease training in Europe: current status, disparities and potential solutions

OBJECTIVES

This study aimed to determine the status of training of adult congenital heart disease (ACHD) cardiologists in Europe.

METHODS

A questionnaire was sent to ACHD cardiologists from 34 European countries.

RESULTS

Representatives from 31 of 34 countries (91%) responded. ACHD cardiology was recognised by the respective ministry of Health in two countries (7%) as a subspecialty. Two countries (7%) have formally recognised ACHD training programmes, 15 (48%) have informal (neither accredited nor certified) training and 14 (45%) have very limited or no programme. Twenty-five countries (81%) described training ACHD doctors 'on the job'. The median number of ACHD centres per country was 4 (range 0-28), median number of ACHD surgical centres was 3 (0-26) and the median number of ACHD training centres was 2 (range 0-28). An established exit examination in ACHD was conducted in only one country (3%) and formal certification provided by two countries (7%). ACHD cardiologist number versus gross domestic product Pearson correlation coefficient=0.789 (p<0.001).

CONCLUSION

Formal or accredited training in ACHD is rare among European countries. Many countries have very limited or no training and resort to 'train people on the job'. Few countries provide either an exit examination or certification. Efforts to harmonise training and establish standards in exit examination and certification may improve training and consequently promote the alignment of high-quality patient care.

Impact of compressed sensing (CS) acceleration of two-dimensional (2D) flow sequences in clinical paediatric cardiovascular magnetic resonance (CMR)

OBJECTIVES

Two-dimensional (2D) through-plane phase-contrast (PC) cine flow imaging assesses shunts and valve regurgitations in paediatric CMR and is considered the reference standard for Clinical quantification of blood Flow (COF). However, longer breath-holds (BH) can reduce compliance with possibly large respiratory manoeuvres altering flow. We hypothesize that reduced BH time by application of CS (Short BH quantification of Flow) (SBOF) retains accuracy while enabling faster, potentially more reliable flows. We investigate the variance between COF and SBOF cine flows.

METHODS

Main pulmonary artery (MPA) and sinotubular junction (STJ) planes were acquired at 1.5 T in paediatric patients by COF and SBOF.

RESULTS

21 patients (mean age 13.9, 10-17y) were enrolled. The BH times were COF mean 11.7 s (range 8.4-20.9 s) vs SBOF mean 6.5 s (min 3.6-9.1 s). The differences and 95% CI between the COF and SBOF flows were LVSV -1.43 ± 13.6(ml/beat), LVCO 0.16 ± 1.35(l/min) and RVSV 2.95 ± 12.3(ml/beat), RVCO 0.27 ± 0.96(l/min), QP/QS were SV 0.04 ± 0.19, CO 0.02 ± 0.23. Variability between COF and SBOF did not exceed intrasession variation of COF.

CONCLUSION

SBOF reduces breath-hold duration to 56% of COF. RV flow by SBOF was biased compared to COF. The variation (95% CI) between COF and SBOF was similar to the COF intrasession test-retest 95% CI.

Pulmonary valve reconstruction for acquired pulmonary regurgitation in patients with treated congenital heart disease

OBJECTIVES

Pulmonary valve regurgitation is a common problem after relief of right ventricular outflow tract (RVOT) obstruction with a transannular patch. Pulmonary valve replacement with a homograft or xenograft is the routine treatment. Longevity of biological valves and the availability of homografts are limited. Alternatives to restore RVOT competence are evaluated. The goal of this study was to present intermediate-term results for pulmonary valve reconstruction (PVr) in patients with severe regurgitation.

METHODS

PVr was performed in 24 patients (August 2006‒July 2018). We analysed perioperative data, pre- and postoperative cardiac magnetic resonance (CMR) imaging studies, freedom from valve replacement and risk factors for pulmonary valve dysfunction.

RESULTS

The underlying diagnoses were tetralogy of Fallot (n = 18, 75%), pulmonary stenosis (n = 5, 20.8%) and the double outlet right ventricle post banding procedure (n = 1, 4.2%). The median age was 21.5 (14.8-23.7) years. Main (n = 9, 37.5%) and branch pulmonary artery procedures (n = 6, 25%) and surgery of the RVOT (n = 16, 30.2%) were often part of the reconstruction. The median follow-up after the operation was 8.0 (4.7-9.7) years. Freedom from valve failure was 96% at 2 and 90% at 5 years. The mean longevity of the reconstructive surgery was 9.9 years (95% confidence interval: 8.8-11.1 years). CMR before and 6 months after surgery showed a reduction in the regurgitation fraction [41% (33-55) vs 20% (18-27) P = 0.00] and of the indexed right ventricular end-diastolic volume [156 ml/m2 (149-175) vs 116 ml/m2 (100-143), P = 0.004]. Peak velocity across the pulmonary valve (determined by CMR) half a year after surgery was 2.0, unchanged.

CONCLUSIONS

PVr can be achieved with acceptable intermediate-term results and may delay pulmonary valve replacement.

Short-term outcome of late gadolinium changes detected on cardiovascular magnetic resonance imaging following coronavirus disease 2019 Pfizer/BioNTech vaccine-related myocarditis in adolescents

BACKGROUND

Rare cases of cardiac inflammation following vaccination for severe acute respiratory coronavirus 2 (SARS-CoV-2) have been reported.

OBJECTIVE

To study paediatric patients with clinical findings of acute inflammation post coronavirus disease 2019 (COVID-19) Pfizer/BioNTech vaccination using cardiovascular magnetic resonance imaging (MRI) in acute and subacute phases.

MATERIALS AND METHODS

We enrolled adolescents younger than 18 years who presented at one of two institutions between July 2021 and August 2022 with clinical and laboratory findings of acute myocarditis shortly following COVID-19 Pfizer/BioNTech vaccination. They all underwent cardiovascular MRI using the institutional myocarditis protocol.

RESULTS

Five adolescents (four boys) underwent eight scans between 3 days and 109 days (mean 49 days) after the onset of symptoms following COVID-19 vaccination. Myocardial oedema appeared on short tau inversion recovery (STIR) T2-weighted images in three adolescents at presentation (3-12 days after symptom onset). In these children, the myocardial oedema/acute inflammation had resolved at follow-up cardiovascular MRI (53-68 days after first MRI). However, in all three adolescents, a persistent area of late gadolinium enhancement was evident at follow-up, suggesting post-myocarditic fibrosis. One adolescent scanned only once, 66 days after being symptomatic, had no acute inflammation but persistent fibrotic changes. This last adolescent, who underwent the first scan 109 days after symptom onset, had findings compatible with an episode of previous myocarditis, with mild ongoing regional myocardial oedema/inflammation.

CONCLUSION

This study on post-vaccine myocarditis demonstrates residual lesions with persistent areas of late gadolinium enhancement/myocardial fibrosis with ongoing myocardial oedema after resolution of the initial myocardial oedema a few weeks after Pfizer/BioNTech vaccination. There is an urgent need to recognise and fully investigate the outcome of post-vaccination myocarditis.

Characterization of Aortic Flow Patterns by High-Frame-Rate Blood Speckle Tracking Echocardiography in Children

Background Blood speckle tracking echocardiography allows for direct quantification of interventricular and aortic flow profiles, principally in children. Here, we sought to demonstrate the feasibility and reproducibility of blood speckle tracking echocardiography in the aortas of healthy children. Methods and Results One hundred healthy White children evaluated for the screening of congenital heart disease were prospectively enrolled. Echocardiographic examinations were performed using a Vivid E 95 ultrasound system, with blood speckle tracking from a focused and zoomed view of the aortic root and the ascending aorta. Vortex position, height (mm), width (mm), sphericity index, and area (cm2) were measured and indexed by body surface area. Median (interquartile range) age was 8.2 (5.6-11.0) years, median (interquartile range) weight was 28 (19-35) kg, and median (interquartile range) body surface area was 1.01 (0.79-1.16) m2. Vortices were visualized in only a single phase of the cardiac cycle in 25 subjects-14 (56.0%) were evident in early diastole and 11 (44.0%) in late systole. Vortices visualized in diastole had a mean area of 0.27±0.1 cm2/m2, while those in systole had a mean area of 0.34±0.12 cm2/m2. In a subset of 20 patients, inter- and intraobserver coefficient of variation and intraclass correlation coefficients were determined and showed good reproducibility. Conclusions We demonstrate feasibility and reproducibility of blood speckle tracking and identified vortical flow patterns in the aortic root and ascending aorta in healthy children. These data may serve as a baseline for evaluating aortic flow patterns in children with congenital and acquired heart disease.

Genetic Screening Reveals Heterogeneous Clinical Phenotypes in Patients with Dilated Cardiomyopathy and Troponin T2 Variants

Background: Cardiomyopathies (CMs) are a heterogeneous and severe group of diseases that shows a highly variable cardiac phenotype and an incidence of app. 1/100.000. Genetic screening of family members is not yet performed routinely. Patients and methods: Three families with dilated cardiomyopathy (DCM) and pathogenic variants in the troponin T2, Cardiac Type (TNNT2) gene were included. Pedigrees and clinical data of the patients were collected. The reported variants in the TNNT2 gene showed a high penetrance and a poor outcome, with 8 of 16 patients dying or receiving heart transplantation. The age of onset varied from the neonatal period to the age of 52. Acute heart failure and severe decompensation developed within a short period in some patients. Conclusion: Family screening of patients with DCM improves risk assessment, especially for individuals who are currently asymptomatic. Screening contributes to improved treatment by enabling practitioners to set appropriate control intervals and quickly begin interventional measures, such as heart failure medication or, in selected cases, pulmonary artery banding.

Pediatric Cardiac Magnetic Resonance Reference Values for Biventricular Volumes Derived From Different Contouring Techniques

BACKGROUND

Measurement of ventricular volumes and function using MRI is an important tool in pediatric congenital heart disease. However, normal values for children are sparce and analysis methods are inconsistent.

PURPOSE

To propose biventricular reference values in children for two MRI postprocessing (contouring) techniques.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 154 children from two institutions (13.9 ± 2.8 years; 101 male) that were referred for a clinical MRI study.

FIELD STRENGTH/SEQUENCE

1.5 T; balanced steady-state free precession (bSSFP) sequence.

ASSESSMENT

Left ventricular (LV) and right ventricular (RV) end-diastolic and end-systolic volumes (LVEDV, LVESV, RVEDV, RVESV) and end-diastolic and end-systolic myocardial mass (LVEDMM, LVESMM, RVEDMM, RVESMM) were measured from short-axis images using two contouring techniques: 1) papillary muscles, trabeculations and the moderator band were included in the ventricular blood volume and excluded from the myocardial mass, 2) papillary muscles, trabeculations and the moderator band were excluded from the ventricular volume and included in the ventricular mass.

STATISTICAL TESTS

Univariable and multivariable linear regression models were used to evaluate relationships between sex, weight, height, body surface area (BSA) and age and volumetric results. Reference graphs and tables were created with the LMS-method. Contouring techniques were compared by intraclass correlation, regression analysis and Bland-Altman plots. A P value < 0.05 was considered statistically significant.

RESULTS

Height and BSA were significantly associated with LVESV (method 1) and with LVEDV and RVEDV (method 2). LVESV (method 2), RVESV (both methods), RVEDV (method 1), and LVEDMM and RVEDMM (both methods), showed significant associations with height and weight. LVSV and RVSV (both methods) were significantly associated with BSA and weight. RVESV (method 1) was significantly associated with age. Gender showed significant associations for all parameters.

DATA CONCLUSION

The proposed pediatric reference values can be used in the diagnosis and follow-up of congenital or acquired heart disease and for research purposes.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Reference Values for Pediatric Atrial Volumes Assessed by Steady-State Free-Precession Magnetic Resonance Imaging Using Monoplane and Biplane Area-Length Methods

BACKGROUND

Measurement of atrial volumes by MRI is becoming increasingly important in pediatric cardiac disorders. However, MRI normal values for atrial volumes in children are lacking.

PURPOSE

To establish pediatric reference values for atrial volumes.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 155 healthy children from two large institutions (103 male, age 13.9 ± 2.8 years, range 4-18 years).

FIELD STRENGTH/SEQUENCE

A 1.5 T; balanced steady-state free precession (bSSFP) sequence.

ASSESSMENT

The monoplane and biplane area-length methods were used to measure minimal and maximal left and right atrial volumes (LAmin , LAmax , RAmin , and RAmax ) from four-chamber (4ch) and two-chamber (2ch) MR cine images. Centile charts and tables for atrial volumes were created.

STATISTICAL TESTS

Descriptive statistics, lambda-mu-sigma (LMS)-method of Cole and Green, univariable and multivariable linear regression models. A P value < 0.05 was considered to be statistically significant.

RESULTS

In the multivariable linear model, body surface area was significantly associated with all atrial volumes and sex was significantly associated with RA volumes, LA volumes measured in the 2ch-view as well as biplane LAmax. Average atrial volumes measured: monoplane 4ch: LAmin 13.1 ± 4.8 mL/m2 , LAmax 33.4 ± 8.8 mL/m2 , RAmin 18.5 ± 6.8 mL/m2 , RAmax 33.2 ± 9.6 mL/m2 ; monoplane 2ch: LAmin 12.7 ± 4.9 mL/m2 , LAmax 30.5 ± 9.5 mL/m2 ; biplane: LAmin 12.3 ± 4.5 mL/m2 , LAmax 30.9 ± 8.7 mL/m2 .

DATA CONCLUSION

Pediatric MRI reference values for atrial volumes have been provided.

TECHNICAL EFFICACY

2 EVIDENCE LEVEL: 4.

Myocardial Deformation in the Pediatric Age Group: Normal Values for Strain and Strain Rate Using 2D Magnetic Resonance Feature Tracking

BACKGROUND

Myocardial deformation can be assessed from routine cardiac magnetic resonance (MR) images using two-dimensional feature tracking (2D-FT). Although reference values are essential for implementation of strain imaging in clinical practice, data for the healthy pediatric age group are limited.

PURPOSE

To provide pediatric MR reference values for strain and strain rate for all four heart chambers.

STUDY TYPE

Retrospective.

SUBJECTS

One hundred and fifty-seven healthy children from two institutions (102 male, age 4.7-18 years).

FIELD STRENGTH/SEQUENCE

1.5 T; balanced steady-state free precession sequence.

ASSESSMENT

Left ventricular (LV) global and regional longitudinal, circumferential, and radial strain and strain rate as well as right ventricular (RV) and atrial global and regional longitudinal strain and strain rate were measured in two-, three-, and four-chamber views and the short axis stack. The relationships between strain parameters and age, height, weight, and gender were investigated. Age- and height-specific centile curves and tables were created for LV strain and strain rate. For all other global strain parameters, the mean was calculated as a reference.

STATISTICAL TESTS

Lambda-mu-sigma (LMS)-method of Cole and Green, univariable, and multivariable linear regression models. A P value <0.05 was considered to be statistically significant.

RESULTS

Age, height and weight had a significant influence on LV global strain values. These parameters also showed an influence on RV strain but only in boys (girls P = 0.12) and none of the variables had a significant influence on atrial strain (P = 0.19-0.49). Gender differences were only found for RV strain values.

DATA CONCLUSION

Pediatric potential reference values for myocardial deformation parameters of both ventricles and atria are provided. The values may serve as a reference in future studies and clinical practice.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 5.

Family screening of hypertrophic cardiomyopathy in children: a case report

Background

Paediatric hypertrophic cardiomyopathy (HCM) caused by sarcomere protein gene mutations is more common than previously thought. We present the case of a 9-year-old boy that was diagnosed with HCM during family screening.

Case summary

We present a case of a 9-year-old boy with a family history of sarcomeric HCM who was diagnosed with hypertrophic obstructive cardiomyopathy (HOCM) during clinical screening. Echocardiography and cardiovascular magnetic resonance imaging revealed asymmetric left ventricular hypertrophy with a maximum wall thickness of 18–19 mm. Cardiovascular magnetic resonance late gadolinium enhancement imaging showed patchy fibrosis within the area of maximum wall thickness. Genetic testing confirmed the presence of the familial mutation in the MYL2 gene. The patient was started on bisoprolol. Furthermore, risk stratification was performed and a recommendation for implantable cardioverter-defibrillator implantation was made.

Discussion

This case demonstrates that significant HCM can already start in childhood and discusses the recommendations for family screening on the basis of recently published studies and the present European Society of Cardiology guideline.

Performance of Cardiac MRI in Pediatric and Adult Patients with Fontan Circulation

Cardiac MRI has become a widely accepted standard for anatomic and functional assessment of complex Fontan physiology, because it is noninvasive and suitable for comprehensive follow-up evaluation after Fontan completion. The use of cardiac MRI in pediatric and adult patients after completion of the Fontan procedure are described, and a practical and experience-based cardiac MRI protocol for evaluating these patients is provided. The current approach and study protocol in use at the authors' institution are presented, which address technical considerations concerning sequences, planning, and optimal image acquisition in patients with Fontan circulation. Additionally, for each sequence, the information that can be obtained and guidance on how to integrate it into clinical decision-making is discussed. Keywords: Pediatrics, MRI, MRI Functional Imaging, Heart, Congenital © RSNA, 2022.

Effect of Leisure Sports on Exercise Capacity and Quality of Life in Patients with a Fontan Circulation

Despite improvement in survival, patients with a Fontan circulation are at risk for numerous complications, and exercise capacity and quality of life are usually reduced compared with healthy controls. However, only a few studies have assessed the impact of the amount of sporting activity on exercise capacity and health-related quality of life. We analyzed cardiopulmonary exercise tests (CPET) in a large cohort of patients with a Fontan circulation. Questionnaires were used to assess health-related quality of life and sporting activity. A total of 79 patients with a median age of 13.0 (6.5 to 34.4) years at CPET were included (female, n = 31). Questionnaires revealed that 80% of patients (n = 63) do leisure sports with 43% (n = 27) exercising more than 2 hours per /week. In a subgroup analysis on pediatric patients (n = 52) we found that nearly all participate in school sports (n = 51) and report good subjective health (n = 48). In the pediatric subgroup, oxygen uptake at the anaerobic threshold and peak oxygen uptake correlated with subjective health (p <0.05) and the amount of leisure sports activity (p <0.01). In the overall cohort, running time and running distance were significantly associated with the hours of sports per week (p <0.01). CPET results did not significantly differ between single right and single left ventricle patients. Furthermore, an open fenestration was not associated with reduced exercise capacity. In conclusion, most patients with a Fontan circulation participate in leisure sports and report good subjective healthiness. In pediatric patients, increased sports activity is associated with better exercise capacity and subjective healthiness.

Serial Assessment of Right Ventricular Deformation in Patients With Hypoplastic Left Heart Syndrome: A Cardiovascular Magnetic Resonance Feature Tracking Study

Background As right ventricular dysfunction is a major cause of adverse outcome in patients with hypoplastic left heart syndrome, the aim was to assess right ventricular function and deformation after Fontan completion by performing 2-dimensional cardiovascular magnetic resonance feature tracking in serial cardiovascular magnetic resonance studies. Methods and Results Cardiovascular magnetic resonance examinations of 108 patients with hypoplastic left heart syndrome (female: 31) were analyzed. Short-axis cine images were used for right ventricular volumetry. Two-dimensional cardiovascular magnetic resonance feature tracking was performed using long-axis and short-axis cine images to measure myocardial global longitudinal, circumferential, and radial strain. All patients had at least 2 cardiovascular magnetic resonance examinations after Fontan completion and 41 patients had 3 examinations. Global strain values and right ventricular ejection fraction decreased from the first to the third examination with a significant decline in global longitudinal strain from the first examination to the second examination (median, first, and third quartile: -18.8%, [-20.5;-16.5] versus -16.9%, [-19.3;-14.7]) and from the first to the third examination in 41 patients (-18.6%, [-20.9;-15.7] versus -15.8%, [-18.7;-12.6]; P-values <0.004). Right ventricular ejection fraction decreased significantly from the first to the third examination (55.4%, [49.8;59.3] versus 50.2%, [45.0;55.9]; P<0.002) and from the second to the third examination (53.8%, [47.2;58.7] versus 50.2%, [45.0;55.9]; P<0.0002). Conclusions Serial assessment of cardiovascular magnetic resonance studies in patients with hypoplastic left heart syndrome after Fontan completion demonstrates a significant reduction in global strain values and right ventricular ejection fraction at follow-up. The significant reduction in global longitudinal strain between the first 2 examinations with non-significant changes in right ventricular ejection fraction suggest that global longitudinal strain measured by 2-dimensional cardiovascular magnetic resonance feature tracking might be a superior technique for the detection of changes in myocardial function.

Complex adult congenital heart disease on cross-sectional imaging: an introductory overview

Congenital heart disease is the most common group of congenital pathology. Over the past few decades, advances in surgical treatment have resulted in a rising population of adult patients with repaired complex congenital heart disease. Although the quality of life has greatly improved, a significant proportion of morbidities encountered in clinical practice is now seen in adults rather than in children. These patients often have significant haemodynamic pathophysiology necessitating repeat intervention. CT and MRI are excellent imaging modalities, which help elucidate potential complications that may need urgent management. Although imaging should be performed in specialised centres, occasionally patients may present acutely to emergency departments in hospitals with little experience in managing potentially complex patients. The purpose of this article is to provide an introductory overview to the radiologist who may not be familiar with complex congenital heart disease in adult patients. This educational review has three main sections: (1) a brief overview of the post-operative anatomy and surgical management of the most common complex conditions followed by (2) a discussion on CT/MRI protocols and (3) a review of the various complications and their CT/MRI findings.

Moderate excess alcohol consumption and adverse cardiac remodelling in dilated cardiomyopathy

OBJECTIVE

The effect of moderate excess alcohol consumption is widely debated and has not been well defined in dilated cardiomyopathy (DCM). There is need for a greater evidence base to help advise patients. We sought to evaluate the effect of moderate excess alcohol consumption on cardiovascular structure, function and outcomes in DCM.

METHODS

Prospective longitudinal observational cohort study. Patients with DCM (n=604) were evaluated for a history of moderate excess alcohol consumption (UK government guidelines; >14 units/week for women, >21 units/week for men) at cohort enrolment, had cardiovascular magnetic resonance and were followed up for the composite endpoint of cardiovascular death, heart failure and arrhythmic events. Patients meeting criteria for alcoholic cardiomyopathy were not recruited.

RESULTS

DCM patients with a history of moderate excess alcohol consumption (n=98, 16%) had lower biventricular function and increased chamber dilatation of the left ventricle, right ventricle and left atrium, as well as increased left ventricular hypertrophy compared with patients without moderate alcohol consumption. They were more likely to be male (alcohol excess group: n=92, 94% vs n=306, 61%, p=<0.001). After adjustment for biological sex, moderate excess alcohol was not associated with adverse cardiac structure. There was no difference in midwall myocardial fibrosis between groups. Prior moderate excess alcohol consumption did not affect prognosis (HR 1.29, 95% CI 0.73 to 2.26, p=0.38) during median follow-up of 3.9 years.

CONCLUSION

DCM patients with moderate excess alcohol consumption have adverse cardiac structure and function at presentation, but this is largely due to biological sex. Alcohol may contribute to sex-specific phenotypic differences in DCM. These findings help to inform lifestyle discussions for patients with DCM.

Impact of Right Ventricular Pressure Load After Repair of Tetralogy of Fallot

Background Right ventricular outflow tract (RVOT) stenosis after repair of tetralogy of Fallot has been linked with favorable right ventricular remodeling but adverse outcomes. The aim of our study was to assess the hemodynamic impact and prognostic relevance of right ventricular pressure load in this population. Methods and Results A total of 296 patients with repaired tetralogy of Fallot (mean age, 17.8±7.9 years) were included in a prospective cardiovascular magnetic resonance multicenter study. Myocardial strain was quantified by feature tracking technique at study entry. Follow-up, including the need for pulmonary valve replacement, was assessed. The combined end point consisted of ventricular tachycardia and cardiac death. A higher echocardiographic RVOT peak gradient was significantly associated with smaller right ventricular volumes and less pulmonary regurgitation, but lower biventricular longitudinal strain. During a follow-up of 10.1 (0.1-12.9) years, the primary end point was reached in 19 of 296 patients (cardiac death, n=6; sustained ventricular tachycardia, n=2; and nonsustained ventricular tachycardia, n=11). A higher RVOT gradient was associated with the combined outcome (hazard ratio [HR], 1.03; 95% CI, 1.00-1.06; P=0.026), and a cutoff gradient of ≥25 mm Hg was predictive for cardiovascular events (HR, 3.69; 95% CI, 1.47-9.27; P=0.005). In patients with pulmonary regurgitation ≥25%, a mild residual RVOT gradient (15-30 mm Hg) was not associated with a lower risk for pulmonary valve replacement. Conclusions Higher RVOT gradients were associated with less pulmonary regurgitation and smaller right ventricular dimensions but were related to reduced biventricular strain and emerged as univariate predictors of adverse events. Mild residual pressure gradients did not protect from pulmonary valve replacement. These results may have implications for the indication for RVOT reintervention in this population.

Exercise-dependent changes in ventricular-arterial coupling and aortopulmonary collateral flow in Fontan patients: a real-time CMR study

AIMS

Inefficient ventricular-arterial (V-A) coupling has been described in Fontan patients and may result in adverse haemodynamics. A varying amount of aortopulmonary collateral (APC) flow is also frequently present that increases volume load of the single ventricle. The aim of the study was to assess changes in V-A coupling and APC flow during exercise CMR.

METHODS AND RESULTS

Eighteen Fontan patients (age 24 ± 3 years) and 14 controls (age 23 ± 4 years) underwent exercise CMR using a cycle ergometer. Ventricular volumetry and flow measurements in the ascending aorta (AAO), inferior (IVC), and superior (SVC) vena cava were assessed using real-time sequences during stepwise increases in work load. Measures of systemic arterial elastance Ea, ventricular elastance Ees, and V-A coupling (Ea/Ees) were assessed. APC flow was quantified as AAO - (SVC + IVC). Ea remained unchanged during all levels of exercise in both groups (P = 0.39 and P = 0.11). Ees increased in both groups (P = 0.001 and P < 0.001) with exercise but was lower in the Fontan group (P = 0.04). V-A coupling was impaired in Fontan patients at baseline (P = 0.04). Despite improvement during exercise (P = 0.002) V-A coupling remained impaired compared with controls (P = 0.001). Absolute APC flow in Fontan patients did not change during exercise even at maximum work load (P = 0.98).

CONCLUSIONS

Inefficient V-A coupling was already present at rest in Fontan patients and aggravated during exercise due to a limited increase in ventricular contractility which demonstrates the importance of a limited functional reserve of the single ventricle. APC flow remained unchanged suggesting no further increase in volume load during exercise.

Myocardial deformation assessed by CMR in children after multisystem inflammatory syndrome (MIS-C)

BACKGROUND

Short-term sequelae of Multisystem Inflammatory Syndrome in Children (MIS-C), recently published by our institution, showed rapid improvement of the cardiac abnormalities within a few weeks after the onset of the disease. However, subtle residual abnormalities, affecting mainly the myocardial interstitium, were shown in some of the patients. The current study aimed to assess myocardial deformation with CMR shortly after MIS-C.

METHODS

Sixty children were included into the study; 30 following MIS-C (onset-to-scan mean 27 days, SD 11) and 30 controls. Strain values were compared between patients and controls and additionally to published paediatric normal CMR values. U-Mann Whitney test was used for comparison of the myocardial deformation between patients and controls.

RESULTS

Median age of the patients was 9.0 years (range 0.99-14.4) and controls 9.8 years (range 4.7-14.9). All conventional CMR parameters in patients were in normal range. Strain values were significantly lower in patients than in controls. When compared to published centile graphs, radial and circumferential global strain was within 2.5th and 97.5th centile in all patients. Eleven patients had global longitudinal strain between 2.5th centile and 50th centile, 1 patient was below 2.5th centile and all the others above 50th centile. Only 3 controls had global longitudinal strain between 2.5th centile and 50th centile, all other had higher strain.

CONCLUSIONS

This study demonstrates that myocardial deformation indices measured by CMR are within normal range in the vast majority of the patients within a few weeks after the onset of MIS-C. However, when compared to healthy controls, all strain parameters were lower in patients.

Abnormal torsion and helical flow patterns of the neo-aorta in hypoplastic left heart syndrome assessed with 4D-flow MRI

BACKGROUND

The Norwood procedure is the first stage of correction for patients with hypoplastic left heart syndrome (HLHS) and may lead to an abnormal neoaortic anatomy. We prospectively studied the neoaorta's fluid dynamics and the abnormal twist of the neoaorta by MRI examinations of HLHS patients in Fontan circulation. This study for the first time investigates the hypothesis that the neoaorta twist is associated with increased helical flow patterns, which may lead to an increased workload for the systemic right ventricle (RV) and ultimately to RV hypertrophy.

METHODS

A group of forty-two HLHS patients with a median age of 4.9 (2.9-17.0) years, at NYHA I was studied along with a control group of eleven subjects with healthy hearts and a median age of 12.1 (4.0-41.6). All subjects underwent MRI of the thoracic aorta including ECG-gated 2D balanced SSFP cine for an axial slice stack and 4D-flow MRI for a sagittal volume slab covering the thoracic aorta. The twist of the neoaortic arch was quantified by the effective geometric torsion, defined as the product of curvature and geometric torsion. Fluid dynamics and geometry in the neoaorta, including the flow helicity index, were evaluated using an in-house analysis software (MeVisLab-based). Myocardial mass of the systemic ventricle at end-diastole was estimated by planimetry of the short-axis stack.

RESULTS

Compared to the control group, the neoaorta in the HLHS patients shows an increased twist (P=0.04) and higher peak helicity density (P=0.03). The maximum helicity density was correlated with maximum effective torsion of the ascending neoaorta (P<0.001). The degree of maximum twist correlated with the increase in RV myocardial mass (P<0.01).

CONCLUSIONS

This study shows that the abnormal twist of the neoaortic arch in HLHS patients is associated with abnormal helical flow patterns, which may contribute to increased RV afterload and may adversely affect the systemic RV by stimulation of myocardial hypertrophy. These findings suggest that further improvements of surgical aortic reconstruction, guided by insights from 4D-flow MRI, could lead to better neoaortic fluid dynamics in patients with HLHS.

Serial assessment of right ventricular function and deformation in patients with hypoplastic left heart syndrome: a cardiovascular magnetic resonance study

Background

In patients with hypoplastic left heart syndrome (HLHS), right ventricular (RV) dysfunction and failure is a major cause of adverse outcome. Most studies have assessed RV function and size during staged palliation but serial data about RV deformation and function after completion of the Fontan circulation are rare. We assessed RV function and deformation by analysing serial cardiovascular magnetic resonance (CMR) studies in a large cohort of HLHS patients after completion of the total cavopulmonary connection (TCPC).

Methods

CMR examinations of 105 HLHS patients (female: 31, male: 74) were retrospectively analysed. Short axis cine images were used to measure RVEF and end-diastolic myocardial mass indexed to body surface area (RVMMi). 2-dimensional CMR feature tracking (2D-CMR-FT) was performed using long-axis and short axis cine images to measure myocardial global longitudinal, circumferential and radial strain (GLS, GCS, GRS) values.

Results

From 105 patients, all had at least two CMR examinations after TCPC completion (mean age at TCPC: 2.7±0.8 years; mean interval between examinations 5.4±1.6 years). 36 patients had three examinations (mean interval between first and third scan 9.9±2.2 years). The first scan was performed at a mean age of 5.6±2.9 years. Global strain values and RVEF decreased from the first to the third examination with a significant decline in GLS from the first examination to the second examination (median and interquartile range (IQR): −18.6%, IQR −20.4 to −16.3 vs. −16.8%, IQR −19.2 to −14.7) and from the first to the third examination in 36 patients (−18.6%, IQR −20.8 to −16.1 vs. −15.9%, IQR −18.3 to −12.4) (all p-values &lt;0.004). RVEF decreased significantly from the first to the third examination (55.9%, IQR 50.2–59.8 vs. 50.4%, IQR 45.0–57.6; p&lt;0.002) and from the second to the third examination (55.1%, IQR 47.1–58.7 vs. 50.4%, IQR 45.0–57.6; p&lt;0.0004). The decrease in RVEF between the first and second scan and the changes in GCS and GRS across the examinations did not reach statistical significance. Median RVMMi increased significantly between the first and second scan (47.4 g/m2, IQR 39.0–55.3 vs. 50.2 g/m2, IQR 42.6–61.7; p&lt;0.0007) and slightly but not significantly between the first and third scan in patients with three examinations (47.4 g/m2, IQR 39.5–56.2 vs. 50.1 g/m2, IQR 45.3–60.4). Negative correlations between GCS and RVEF (r=−0.57 to −0.76; p all &lt;0.0001) as well as between GLS and RVEF (r=−0.31 to −0.59; p all &lt;0.002) at all three time points could be demonstrated.

Conclusion

Serial assessment of CMR studies in HLHS patients after TCPC completion demonstrates a significant reduction in global strain values and RVEF at mid-term follow-up. The significant reduction in GLS between the first two examinations with non-significant changes in RVEF suggest that 2D-CMR-FT might be a suitable technique for the detection of early myocardial dysfunction.

Funding Acknowledgement

Type of funding sources: None.

Normal values for paediatric atrial volumes assessed by steady-state free-precession cardiovascular magnetic resonance

Background

Measurement of atrial volumes by steady-state free precession (SSFP)cardiovascular magnetic resonance (CMR) is becoming increasingly important in the treatment and follow-up of paediatric congenital heart disease. It has prognostic value in terms of heart failure and cardiovascular death. However, CMR normal values for the clinically often used mono- and biplane area-length method in children are lacking.

Aims

We sought to create paediatric normal values for atrial volumes using the mono- and biplane area-length method.

Methods

In a retrospective study design, CMR data sets of 157 healthy children with an age range between 4 and 18 years from two centers in the UK and Germany were evaluated. In a four-chamber (4ch-) view, left and right atrial (LA, RA) endocardial borders were segmented during end-diastole and end-systole to calculate minimal and maximal atrial volumes (LAmin, LAmax, RAmin, RAmax) using the monoplane area-length method. Additionally, end-diastolic and end-systolic LA endocardial borders were segmented in a two-chamber (2ch-) view. Using the measurements from the 2ch- and 4ch-views, minimal and maximal LA volumes were calculated using the biplane area-length method. Atrial volumes were normalized for body surface area (BSA in m2). Sex-specific reference curves were created using the lambda mu sigma method.

Results

The median age was 13.8±2.81 years (53 girls).

In children from 4–10 years average atrial volumes measured: monoplane 4ch: LAmin 10.2±3.5 ml/m2, LAmax 28.8±7.4 ml/m2, RAmin 14.1±6.3 ml/m2, RAmax 27.0±11.4 ml/m2; monoplane 2ch: LAmin 10.9±4.1 ml/m2, LAmax 27.0±6.1 ml/m2; biplane: LAmin 10.2±3.3 ml/m2, LAmax 27.4±5.7 ml/m2.

In children from 11–18 years average atrial volumes measured: monoplane 4ch: LAmin 13.6±4.9 ml/m2, LAmax 34.1±9.1 ml/m2, RAmin 19.2±6.8 ml/m2, RAmax 34.2±9.6 ml/m2; monoplane 2ch: LAmin 13.2±4.9 ml/m2, LAmax 31.4±9.7 ml/m2; biplane: LAmin 12.9±4.4 ml/m2, LAmax 31.8±8.8 ml/m2.

Separate centile charts and centile tables for boys and girls for all volumetric parameters were created.

Conclusion

We provide paediatric CMR reference values for atrial volumes. They can be used in the diagnosis and follow-up of congenital or acquired heart disease in children and for research purposes.

Funding Acknowledgement

Type of funding sources: None.

Normal values for paediatric biventricular volumes, ejection fraction and mass – influence of cardiovascular magnetic resonance analysis techniques

Background

Measurement of ventricular volumes and function by steady-state free precession (SSFP) cardiovascular magnetic resonance (CMR) is an important diagnostic tool in the treatment and follow-up of paediatric congenital heart disease. However, normal values are rare and the CMR analysis methods are inconsistent.

Aims

We sought to create two sets of ventricular normal values for different CMR analysis (contouring) methods.

Methods

In a retrospective study design, CMR data sets of 154 healthy children with an age range between 4 and 18 years from two centers in the UK and Germany were evaluated. Left and right ventricular end-diastolic and end-systolic volumes (LVEDV, LVESV, RVEDV, RVESV), ejection fraction (RVEF, LVEF) and myocardial mass (LVMM, RVMM) were analysed from short axis steady-state free precession images by using two different analysis techniques: 1) papillary muscles, myocardial trabeculations and the moderator band were included in the ventricular volume and excluded from the ventricular mass (Figure 1), 2) papillary muscles, myocardial trabeculations and the moderator band were excluded from the ventricular volume and included in the ventricular mass (Figure 2). Sex-specific reference curves were created separately for both ventricular contouring methods using the lambda mu sigma method. Correlations between variables were analyzed with the Spearman's rank correlation. Contouring methods were compared through Bland-Altman analysis.

Results

The mean age was 13.85±2.8 years (53 girls).

In children from 4 to 10 years average ventricular volumes and mass normalized for body surface area (BSA) measured:

In children from 11 to 18 years average ventricular volumes and mass measured:

Separate centile charts and centile tables for boys and girls for all cardiac parameters were created.

Conclusion

We provide paediatric CMR reference values for biventricular volumes, ejection and masses for two different CMR contouring methods. They can be used in the diagnosis and follow-up of congenital or acquired heart disease in children and for research purposes.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Bioelastic properties of the aorta in children, adolescents and young adults after cardiac transplantation: a cardiovascular magnetic resonance study

Background

Long-term complications after cardiac transplantation are common and typically include arterial hypertension and coronary allograft vasculopathy. Few studies also suggested that heart transplant recipients have an increased arterial stiffness.

Purpose

This prospective study aimed to assess the bioelastic properties of the aorta as well as LV function, morphology and structure in children and young adults after cardiac transplantation.

Methods

CMR studies from 34 patients (median age: 17.1 years, range: 8–24 years) who underwent cardiac transplantation in childhood were analysed. Aortic anatomy and distensibility were assessed at five locations of the thoracic aorta using steady-state free precession cine sequences. Pulse wave velocity (PWV) of the aortic arch and the descending thoracic aorta was measured from 2-dimensional phase contrast images. Size and function of the left atrium and the ventricles were assessed from a stack of short axis slices. Myocardial T1 times were determined using a standard MOLLI sequence.

Results

Cross-sectional areas of the ascending aorta and the aortic arch tended to be lower in patients compared to controls (ascending aorta 464.5±172.5 mm2 vs. 515.3±186.3 mm2, aortic arch 342.4±113.3 mm2 vs. 376.9±148.5 mm2) whereas cross-sectional areas of the descending aorta tended to be higher (aortic isthmus 283.7±102.1 mm2 vs. 257.9±89.5 mm2, aorta descendens diaphragmal 218.4±75.8 mm2 vs. 214.2±75.0 mm2) and showed a correlation with systolic blood pressure (r=0.33). PWV was higher in the aortic arch (4.8±2.4 m/s vs. 3.6±0.7 m/s).

Aortic distensibility was slightly higher at all measuring points in the study population compared to the control group and showed an increase with rising distance from the heart (ascending aorta 10.5±5.8 10–3 mm Hg-1, aortic isthmus 13.1±7.5 10–3 mm Hg-1, descending aorta 16.6±6.8 10–3 mm Hg-1). Biventricular volumes were slightly reduced in the patient group compared to the control group but this was not statistically significant. Only left ventricular mass messured during the systolic phase was higher in the study population compared to the control group (males 55.1 g/m2 vs. 53.0 g/m2, females 46.2 g/m2 vs. 45.2 g/m2). T1 mapping demonstrated increased T1 times in the heart-transplanted group compared to published data in healthy adults. In particular, T1 times of the lateral and inferior myocardial segments were higher.

Conclusion

Patients who underwent cardiac transplantation in childhood seem to have a reduced bioelasticity of the thoracic aorta. Increased myocardial T1 times suggesting alterations in myocardial structure.

Funding Acknowledgement

Type of funding sources: None.

Myocardial Perfusion in Hypoplastic Left Heart Syndrome

BACKGROUND

The status of the systemic right ventricular coronary microcirculation in hypoplastic left heart syndrome (HLHS) is largely unknown. It is presumed that the systemic right ventricle's coronary microcirculation exhibits unique pathophysiological characteristics of HLHS in Fontan circulation. The present study sought to quantify myocardial blood flow by cardiac magnetic resonance imaging and evaluate the determinants of microvascular coronary dysfunction and myocardial ischemia in HLHS.

METHODS

One hundred nineteen HLHS patients (median age, 4.80 years) and 34 healthy volunteers (median age, 5.50 years) underwent follow-up cardiac magnetic resonance imaging ≈1.8 years after total cavopulmonary connection. Right ventricle volumes and function, myocardial perfusion, diffuse fibrosis, and late gadolinium enhancement were assessed in 4 anatomic HLHS subtypes. Myocardial blood flow (MBF) was quantified at rest and during adenosine-induced hyperemia. Coronary conductance was estimated from MBF at rest and catheter-based measurements of mean aortic pressure (n=99).

RESULTS

Hyperemic MBF in the systemic ventricle was lower in HLHS compared with controls (1.89±0.57 versus 2.70±0.84 mL/g per min; P<0.001), while MBF at rest normalized by the rate-pressure product, was similar (1.25±0.36 versus 1.19±0.33; P=0.446). Independent risk factors for a reduced hyperemic MBF were an HLHS subtype with mitral stenosis and aortic atresia (P=0.017), late gadolinium enhancement (P=0.042), right ventricular diastolic dysfunction (P=0.005), and increasing age at total cavopulmonary connection (P=0.022). The coronary conductance correlated negatively with systemic blood oxygen saturation (r, -0.29; P=0.02). The frequency of late gadolinium enhancement increased with age at total cavopulmonary connection (P=0.014).

CONCLUSIONS

The coronary microcirculation of the systemic ventricle in young HLHS patients shows significant differences compared with controls. These hypothesis-generating findings on HLHS-specific risk factors for microvascular dysfunction suggest a potential benefit from early relief of frank cyanosis by total cavopulmonary connection.

Ventricular and atrial function and deformation is largely preserved after arterial switch operation

OBJECTIVE

To test the hypothesis that ventricular and atrial function are different between patients with transposition of the great arteries (TGA) after arterial switch operation (ASO) and healthy controls.

METHODS

103 consecutive patients with TGA (median age: 16.7 years, 4.3-39.6 years, 71.8% male) were compared with 77 controls (median age: 15.4 years, 6.3-43.2 years, 66.2% male). Biventricular and biatrial function were assessed using standard cardiovascular magnetic resonance (CMR) techniques and feature tracking. Group comparison was performed with conventional non-parametrical statistics and machine learning methods to find the variables most discriminative between patients and controls. These variables were used to build a multivariable logistic regression model to assess the case-control status.

RESULTS

Markers of left and right ventricular function (LV; RV) (ejection fraction, MAPSE, TAPSE, LV long-axis strain) as well as LV global longitudinal (-20.7 (-24.1; -17.9) vs -23.7 (-26.1; -21.6), p<0.001), circumferential (-29.4 (-32.2; -26.5) vs -30.5 (-33.6; 29), p=0.001) and atrial longitudinal strain (left atrium (LA): 23.3 (18.6; 28.8) vs 36.7 (30.7; 44), p<0001; right atrium: 21.7 (18.2; 27.8) vs 34.9 (26.9; 40.3), p<0.001) were reduced in patients compared with controls using non-parametrical testing. The logistic regression model including the most discriminative variables from univariate and machine learning analysis demonstrated significant differences between patients and controls only for TAPSE and LA global longitudinal strain.

CONCLUSIONS

Biventricular and biatrial function are largely preserved after ASO for TGA. Using a comprehensive CMR protocol along with statistical machine learning methods and a regression approach, only RV longitudinal function and LA function are significantly impaired.

Left ventricular noncompaction in pediatric population: could cardiovascular magnetic resonance derived fractal analysis aid diagnosis?

BACKGROUND

Cardiovascular magnetic resonance (CMR) derived fractal analysis of the left ventricle (LV) has been shown in adults to be a useful quantitative measure of trabeculation with high reproducibility and accuracy for the diagnosis of LV non-compaction (LVNC). The aim of this study was to investigate the utility and feasibility of fractal analysis in children.

METHODS

Eighty-four subjects underwent CMR: (1) 28 patients with LVNC (as defined by the Petersen criteria with NC/C ratio [Formula: see text] 2.3); (2) 28 patients referred by clinicians for assessment of hyper-trabeculation and found not to qualify as LVNC (NC/C [Formula: see text] 1.8 and < 2.3); (3) 28 controls. The fractal scores for each group were presented as global and maximal fractal dimension as well as for 3 segments of the LV: basal, mid, and apical. Statistical comparison of the fractal scores between the 3 groups was performed.

RESULTS

Global fractal dimension (FD) was higher in the LVNC group than in the hyper-trabeculated group: 1.345 (SEM 0.053) vs 1.252 (SEM 0.034), p < 0.001 and higher in hyper-trabeculated group than in controls: 1.252 (SEM 0.034) vs 1.158 (SEM 0.038), p < 0.001. The highest maximum FD was in the apical portion of the LV in the LVNC group, (1.467; SEM 0.035) whereas it was in the mid ventricle in the hyper-trabeculated (1.327; SEM 0.025) and healthy groups (1.251; SEM 0.042). Fractal analysis showed lower intra- and interobserver variability than the Petersen and Jacquier methods.

CONCLUSIONS

It is technically feasible to perform fractal analysis in children using CMR and that it is quick, accurate and reproducible. Fractal scoring accurately distinguishes between LVNC, hyper-trabeculation and healthy controls as defined by the Petersen criteria.