Twenty-Year Experience and Outcomes in a National Pediatric Pulmonary Hypertension Service

Rationale: Pediatric pulmonary hypertension is an important cause of childhood morbidity and mortality, but there are limited data on the range of associated diseases, contributions of different pulmonary hypertension subtypes, therapeutic strategies, and clinical outcomes in children. Objectives: To report the 20-year experience of a large UK National Pediatric Pulmonary Hypertension Service focusing on epidemiology and clinical outcomes. Methods: Consecutive patients presenting between 2001 and 2021 were included, and survival analysis was performed for incident patients. Measurements and Main Results: Of 1,353 patients assessed, a pulmonary hypertension diagnosis was made in 1,101 (81.4%) patients (51% female, median age, 2.6 [interquartile range, 0.8-8.2] years). The most common form was pulmonary arterial hypertension in 48%, followed by 32.3% with pulmonary hypertension due to lung disease. Multiple contributory causes of pulmonary hypertension were common, with 16.9% displaying features of more than one diagnostic group. The annual incidence of childhood pulmonary hypertension was 3.5 (95% confidence interval [CI], 3.3-3.8) per 1 million children, and the prevalence was 18.1 (95% CI, 15.8-20.4) per 1 million. The incidence was highest for pulmonary hypertension due to lung disease in infancy (15.0 [95% CI, 12.7-17.2] per 1 million per year). Overall, 82.4% patients received pulmonary arterial hypertension therapy, and escalation to triple therapy during follow-up was required in 13.1%. In 970 (88.1%) incident patients, transplant-free survival was 86.7% (95% CI, 84.5-89%) at 1 and 68.6% (95% CI, 64.7-72.6%) at 10 years. Pulmonary hypertension due to left heart disease had the lowest survival (hazard ratio, 2.0; 95% CI, 1.36-2.94; P < 0.001). Conclusions: Clinical phenotypes of pediatric pulmonary hypertension are heterogeneous and overlapping, with clinical phenotypes that evolve throughout childhood. Despite widespread use of pulmonary arterial hypertension therapy, the prognosis remains poor.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease : Endorsed by The American Heart Association

Cardiovascular magnetic resonance (CMR) has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of CMR in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of CMR in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the Use of Cardiac Magnetic Resonance in Pediatric Congenital and Acquired Heart Disease: Endorsed by The American Heart Association

Cardiovascular magnetic resonance has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of cardiovascular magnetic resonance in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of cardiovascular magnetic resonance in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Ongoing Exercise Intolerance Following COVID-19: A Magnetic Resonance-Augmented Cardiopulmonary Exercise Test Study

Background Ongoing exercise intolerance of unclear cause following COVID-19 infection is well recognized but poorly understood. We investigated exercise capacity in patients previously hospitalized with COVID-19 with and without self-reported exercise intolerance using magnetic resonance-augmented cardiopulmonary exercise testing. Methods and Results Sixty subjects were enrolled in this single-center prospective observational case-control study, split into 3 equally sized groups: 2 groups of age-, sex-, and comorbidity-matched previously hospitalized patients following COVID-19 without clearly identifiable postviral complications and with either self-reported reduced (COVID_reduced) or fully recovered (COVID_normal) exercise capacity; a group of age- and sex-matched healthy controls. The COVID_reducedgroup had the lowest peak workload (79W [Interquartile range (IQR), 65-100] versus controls 104W [IQR, 86-148]; P=0.01) and shortest exercise duration (13.3±2.8 minutes versus controls 16.6±3.5 minutes; P=0.008), with no differences in these parameters between COVID_normal patients and controls. The COVID_reduced group had: (1) the lowest peak indexed oxygen uptake (14.9 mL/minper kg [IQR, 13.1-16.2]) versus controls (22.3 mL/min per kg [IQR, 16.9-27.6]; P=0.003) and COVID_normal patients (19.1 mL/min per kg [IQR, 15.4-23.7]; P=0.04); (2) the lowest peak indexed cardiac output (4.7±1.2 L/min per m²) versus controls (6.0±1.2 L/min per m²; P=0.004) and COVID_normal patients (5.7±1.5 L/min per m²; P=0.02), associated with lower indexed stroke volume (SVi:COVID_reduced 39±10 mL/min per m² versus COVID_normal 43±7 mL/min per m² versus controls 48±10 mL/min per m²; P=0.02). There were no differences in peak tissue oxygen extraction or biventricular ejection fractions between groups. There were no associations between COVID-19 illness severity and peak magnetic resonance-augmented cardiopulmonary exercise testing metrics. Peak indexed oxygen uptake, indexed cardiac output, and indexed stroke volume all correlated with duration from discharge to magnetic resonance-augmented cardiopulmonary exercise testing (P<0.05). Conclusions Magnetic resonance-augmented cardiopulmonary exercise testing suggests failure to augment stroke volume as a potential mechanism of exercise intolerance in previously hospitalized patients with COVID-19. This is unrelated to disease severity and, reassuringly, improves with time from acute illness.

Glycoprotein Acetyls: A Novel Inflammatory Biomarker of Early Cardiovascular Risk in the Young

Background Low-grade inflammation in the young may contribute to the early development of cardiovascular disease. We assessed whether circulating levels of glycoprotein acetyls (GlycA) were better able to predict the development of adverse cardiovascular disease risk profiles compared with the more commonly used biomarker high-sensitivity CRP (C-reactive protein). Methods and Results A total of 3306 adolescents and young adults from the Avon Longitudinal Study of Parents and Children (mean age, 15.4±0.3; n=1750) and Cardiovascular Risk in Young Finns Study (mean age, 32.1±5.0; n=1556) were included. Baseline associations between inflammatory biomarkers, body composition, cardiovascular risk factors, and subclinical measures of vascular dysfunction were assessed cross-sectionally in both cohorts. Prospective risk of developing hypertension and metabolic syndrome during 9-to-10-year follow-up were also assessed as surrogate markers for future cardiovascular risk. GlycA showed greater within-subject correlation over 9-to-10-year follow-up in both cohorts compared with CRP, particularly in the younger adolescent group (r=0.36 versus 0.07). In multivariable analyses, GlycA was found to associate with multiple lifestyle-related cardiovascular disease risk factors, cardiometabolic risk factor burden, and vascular dysfunction (eg, mean difference in flow-mediated dilation=-1.2 [-1.8, -0.7]% per z-score increase). In contrast, CRP levels appeared predominantly driven by body mass index and showed little relationship to any measured cardiovascular risk factors or phenotypes. In both cohorts, only GlycA predicted future risk of both hypertension (risk ratio [RR], ≈1.1 per z-score increase for both cohorts) and metabolic syndrome (RR, ≈1.2-1.3 per z-score increase for both cohorts) in 9-to-10-year follow-up. Conclusions Low-grade inflammation captured by the novel biomarker GlycA is associated with adverse cardiovascular risk profiles from as early as adolescence and predicts future risk of hypertension and metabolic syndrome in up to 10-year follow-up. GlycA is a stable inflammatory biomarker which may capture distinct sources of inflammation in the young and may provide a more sensitive measure than CRP for detecting early cardiovascular risk.

Reduced exercise capacity in patients with systemic sclerosis is associated with lower peak tissue oxygen extraction: a cardiovascular magnetic resonance-augmented cardiopulmonary exercise study

BACKGROUND

Exercise intolerance in systemic sclerosis (SSc) is typically attributed to cardiopulmonary limitations. However, problems with skeletal muscle oxygen extraction have not been fully investigated. This study used cardiovascular magnetic resonance (CMR)-augmented cardiopulmonary exercise testing (CMR-CPET) to simultaneously measure oxygen consumption and cardiac output. This allowed calculation of arteriovenous oxygen content gradient, a recognized marker of oxygen extraction. We performed CMR-CPET in 4 groups: systemic sclerosis (SSc); systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH); non-connective tissue disease pulmonary hypertension (NC-PAH); and healthy controls.

METHODS

We performed CMR-CPET in 60 subjects (15 in each group) using a supine ergometer following a ramped exercise protocol until exhaustion. Values for oxygen consumption, cardiac output and oxygen content gradient, as well as ventricular volumes, were obtained at rest and peak-exercise for all subjects. In addition, T1 and T2 maps were acquired at rest, and the most recent clinical measures (hemoglobin, lung function, 6-min walk, cardiac and catheterization) were collected.

RESULTS

All patient groups had reduced peak oxygen consumption compared to healthy controls (p < 0.022). The SSc and SSc-PAH groups had reduced peak oxygen content gradient compared to healthy controls (p < 0.03). Conversely, the SSc-PAH and NC-PH patients had reduced peak cardiac output compared to healthy controls and SSc patients (p < 0.006). Higher hemoglobin was associated with higher peak oxygen content gradient (p = 0.025) and higher myocardial T1 was associated with lower peak stroke volume (p = 0.011).

CONCLUSIONS

Reduced peak oxygen consumption in SSc patients is predominantly driven by reduced oxygen content gradient and in SSc-PAH patients this was amplified by reduced peak cardiac output. Trial registration The study is registered with ClinicalTrials.gov Protocol Registration and Results System (ClinicalTrials.gov ID: 100358).

Pulmonary arterial hypertension associated with congenital heart disease in children: clinical characterisation, outcomes and changes in demographics over time

Background/Introduction

Pulmonary arterial hypertension (PAH) is a common complication of congenital heart disease (CHD) in children and is associated with significant morbidity and mortality. The impact of different phenotypes on management and survival remains unclear.

Purpose

To examine the clinical features, management and outcomes of paediatric PAH-CHD patients based on the 20-year experience of the UK National Paediatric Pulmonary Hypertension (PH) Service.

Methods

Consecutive PAH-CHD patients entering the service between January 2001 and January 2021 were included and classified into: Eisenmenger syndrome (ES, group A), PAH related to a significant systemic-pulmonary shunt (group B), PAH with small or co-incidental CHD (group C) and PAH following defect repair (group D). Incident patients (without pre-existing PAH) were included in survival analysis.

Results

Of the overall PH paediatric cohort of 1104 patients, 819 (74.2%) had co-existing CHD and 354 (32.1%) patients received a diagnosis of PAH-CHD: 57.1% female, median [IQR] 4.6 [1.7–10.9] years. Group D PAH-CHD was the commonest subgroup, accounting for 36%, while the least frequent subtype was group C (14%). Group A and group B PAH-CHD represented 26% and 24%, respectively. Down syndrome was present in over one third (122, 34.5%) of PAH-CHD patients and was more commonly associated with ES (p=0.02). PAH therapy was started in 79.9% of PAH-CHD patients. At the end of follow-up, patients with group C PAH-CHD were more likely to be on combination therapy than any other group (64.6% vs. 28.4%, p&lt;0.0001). Prostanoid therapy was used in a minority (11%) of patients.

The subgroup distribution of PAH-CHD at diagnosis changed from the early (2000–2005) to late (2015–2020) period (Figure 1). The proportion of ES patients decreased from 43.4% to 14.6% of PAH-CHD (p&lt;0.0001). The proportion of group B PAH-CHD patients increased (9.4% vs. 33.3%, p&lt;0.0001), with the majority (59.3%) deemed “operable” on specialist assessment. There was a trend for an increase in repaired PAH-CHD patients between the early and late era (31.1% vs. 43.8%, p=0.09).

Transplant-free survival in PAH-CHD was 90.9% (95% CI: 87.8–94%) at 1 year, 77.9% (95% CI: 73.1–83.1%) at 5 years, and 74.9% (95% CI: 69.6–80.7%) at 10 years (Figure 2). Group C PAH-CHD had a lower transplant-free survival than the other 3 groups (HR 2.54, 95% CI: 1.51–4.28, p=0.0005). There was no difference in outcome between group A and group D PAH-CHD (HR 1.19, 95% CI: 0.62–2.28, p=0.6).

Conclusions

Repaired PAH-CHD, not ES, was the most common subtype in this large paediatric cohort. Over time, there were fewer ES patients and more “operable” patients with left-right shunts, suggesting an improvement in early diagnosis and management. Despite widespread use of PAH therapy, PAH-CHD remains a life-limiting disease with the poorest outcomes in PAH with co-incidental CHD.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Dr Constantine received a personal PhD fellowship grant (CHAMPION PhD Fellowship) Figure 1Figure 2

Twenty-year experience and outcomes in a national paediatric pulmonary hypertension service

Background/Introduction

Paediatric pulmonary hypertension (PH) is an important cause of childhood morbidity and mortality, but there are limited data on the range of associated diseases (including several paediatric-specific aetiologies), contributions of different PH subtypes, therapeutic strategies and clinical outcomes in paediatric patients.

Purpose

In this study, we report the 20-year experience of a UK National Paediatric Pulmonary Hypertension Service focusing on the aetiology, management and outcomes of children with PH.

Methods

Consecutive patients presenting to the service between January 2001 and January 2021 were included in this retrospective study. Other inclusion criteria were: age ≤18 years at diagnosis and diagnosis of PH following specialist assessment. Only incident patients (without pre-existing PH) were entered in the survival analysis.

Results

A total of 1104 (81.5%) PH patients were included during the study period: 51% female, median age 2.6 [0.8–8.2] years. The most common PH diagnosis was group 1 (pulmonary arterial hypertension, PAH) in 532 (48.2%) patients, followed by group 3 PH (due to lung disease) in 358 (32.4%), group 2 (101, 9.1%), group 5 (93, 8.4%), and group 4 disease (20, 1.8%). The most common PAH subgroup was PAH associated with congenital heart disease (CHD, 63.3%), followed by idiopathic PAH (22.4%). One quarter of patients (23.6%) had multiple contributory factors for PH, fitting more than one diagnostic group.

Resolution of PH, defined as normalisation of pulmonary artery pressures following cessation of PAH therapy, occurred in 172 (15.6%) patients at a median age of 3.7 [2.1–5.7] years and was more common in group 3 than other PH groups (33.5% vs. 9.1% at 5 years post-diagnosis, p&lt;0.0001).

Overall, 909 (82.3%) patients received PAH therapy. Patients with group 3 PH were as likely to receive PAH therapy as an initial treatment strategy as group 1 patients (86.6% vs. 82.3%, p=0.11), but were more likely to receive sildenafil monotherapy (p=0.002) and less likely to be offered triple therapy (p&lt;0.0001). During follow-up, maintenance or escalation to triple therapy was required in 103 (9.3%) patients and was far more common in idiopathic compared to other PAH subgroups (37.7% vs. 7.8%, p&lt;0.0001).

Transplant-free survival was 86.7% (95% CI: 84.5–88.9%) at 1 year, 74.2% (95% CI: 71.1–77.5%) at 5 years, and 68.9% (95% CI: 65.1–73%) at 10 years (Figure 1). PAH related to CHD had the highest transplant-free survival (HR 0.62, 95% CI: 0.46–0.84, p=0.002). Group 2 had the lowest transplant-free survival (HR 2.09, 95% CI: 1.42–3.09, p=0.0002) whereas groups 3,4 and 5 did not differ significantly from PAH (Figure 2).

Conclusions

In this large, national cohort of paediatric PH patients, the most common type of PH was PAH, followed by group 3 PH. Multiple contributory causes for PH are common and PH resolution was not uncommon, especially in group 3 patients. Despite widespread use of PAH therapy, the prognosis remains guarded.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Dr Constantine has received a PhD grant from Janssen-Cilag Ltd. as the CHAMPION PhD Fellow. Figure 1Figure 2

Real-time deep artifact suppression using recurrent U-Nets for low-latency cardiac MRI

PURPOSE

Real-time low latency MRI is performed to guide various cardiac interventions. Real-time acquisitions often require iterative image reconstruction strategies, which lead to long reconstruction times. In this study, we aim to reconstruct highly undersampled radial real-time data with low latency using deep learning.

METHODS

A 2D U-Net with convolutional long short-term memory layers is proposed to exploit spatial and preceding temporal information to reconstruct highly accelerated tiny golden radial data with low latency. The network was trained using a dataset of breath-hold CINE data (including 770 time series from 7 different orientations). Synthetic paired data were created by retrospectively undersampling the magnitude images, and the network was trained to recover the target images. In the spirit of interventional imaging, the network was trained and tested for varying acceleration rates and orientations. Data were prospectively acquired and reconstructed in real time in 1 healthy subject interactively and in 3 patients who underwent catheterization. Images were visually compared to sliding window and compressed sensing reconstructions and a conventional Cartesian real-time sequence.

RESULTS

The proposed network generalized well to different acceleration rates and unseen orientations for all considered metrics in simulated data (less than 4% reduction in structural similarity index compared to similar acceleration and orientation-specific networks). The proposed reconstruction was demonstrated interactively, successfully depicting catheters in vivo with low latency (39 ms, including 19 ms for deep artifact suppression) and an image quality comparing favorably to other reconstructions.

CONCLUSION

Deep artifact suppression was successfully demonstrated in the time-critical application of non-Cartesian real-time interventional cardiac MR.

Deep artifact suppression for spiral real-time phase contrast cardiac magnetic resonance imaging in congenital heart disease

PURPOSE

Real-time spiral phase contrast MR (PCMR) enables rapid free-breathing assessment of flow. Target spatial and temporal resolutions require high acceleration rates often leading to long reconstruction times. Here we propose a deep artifact suppression framework for fast and accurate flow quantification.

METHODS

U-Nets were trained for deep artifact suppression using 520 breath-hold gated spiral PCMR aortic datasets collected in congenital heart disease patients. Two spiral trajectories (uniform and perturbed) and two losses (Mean Absolute Error -MAE- and average structural similarity index measurement -SSIM-) were compared in synthetic data in terms of MAE, peak SNR (PSNR) and SSIM. Perturbed spiral PCMR was prospectively acquired in 20 patients. Stroke Volume (SV), peak mean velocity and edge sharpness measurements were compared to Compressed Sensing (CS) and Cartesian reference.

RESULTS

In synthetic data, perturbed spiral consistently outperformed uniform spiral for the different image metrics. U-Net MAE showed better MAE and PSNR while U-Net SSIM showed higher SSIM based metrics. In-vivo, there were no significant differences in SV between any of the real-time reconstructions and the reference standard Cartesian data. However, U-Net SSIM had better image sharpness and lower biases for peak velocity when compared to U-Net MAE. Reconstruction of 96 frames took ~59 s for CS and 3.9 s for U-Nets.

CONCLUSION

Deep artifact suppression of complex valued images using an SSIM based loss was successfully demonstrated in a cohort of congenital heart disease patients for fast and accurate flow quantification.

Comprehensive mechanical & metabolic imaging of abdominal aortic aneurysm with 4D flow/ FDG PET on an integrated PETMRI: a feasibility study

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): NIHR Biomedical Research Centre, University College London Hospitals.

Background

A number of non-invasive imaging derived parameters have been implicated in the development and progression of abdominal aortic aneurysm, although the mechanism, and relationships of many of these are yet to be precisely determined.  Mechanical parameters can now be studied using 4D phase contrast magnetic resonance (PCMR), and inflammatory cellular activity can be detected with FDG PET.

Purpose

It may be postulated that inflammation of the aortic wall may be the intermediary at the tissue level linking mechanical wall shear stress (WSS) to aneurysm progression. It may be feasible to study 4D PCMR and FDG PET at the same patient visit on a PETMRI platform, with the potential to enhance temporal and spatial co-registration and improving the understanding of any relationship between these two parameters.  Our study aims to assess feasibility of studying these on an integrated PETMRI system.

Methods

7 patients with known aortic aneurysm were recruited in a vascular ultrasound screening follow up clinic.  During a single visit following 6 hours fasting, all patients underwent FDG injection and 60 minutes uptake period.  With quiet breathing, list mode PET acquisition and concurrent 4D PCMR was acquired using stacks of spiral acquisition, with ECG trace information for retrospective gating.  Images from the 4D PCMR and FDG PET were assessed qualitatively for image quality and visual matching.

Results

All 7 patients completed the study.  Overall image quality was adequate to good.  There is qualitatively a good concordance with impression of positive correlation between wall shear stress and inflammatory signal (see attached image).

Conclusion

We have demonstrated feasibility of combined assessment of mechanical and metabolic imaging parameters using an integrated PETMRI system.  Initial findings show there to be a broad concordance of wall shear stress and inflammatory signal in the abdominal aneurysm.

Experimental Validation of Enhanced Magnetic Resonance Imaging (EMRI) Using Particle Image Velocimetry (PIV)

Flow-sensitive four-dimensional Cardiovascular Magnetic Resonance Imaging (4D Flow CMR) has increasingly been utilised to characterise patients' blood flow, in association with patiens' state of health and disease, even though spatial and temporal resolutions still constitute a limit. Computational fluid dynamics (CFD) is a powerful tool that could expand these information and, if integrated with experimentally-obtained velocity fields, would enable to derive a large variety of the flow descriptors of interest. However, the accuracy of the flow parameters is highly influenced by the quality of the input data such as the anatomical model and boundary conditions typically derived from medical images including 4D Flow CMR. We previously proposed a novel approach in which 4D Flow CMR and CFD velocity fields are integrated to obtain an Enhanced 4D Flow CMR (EMRI), allowing to overcome the spatial-resolution limitation of 4D Flow CMR, and enable an accurate quantification of flow. In this paper, the proposed approach is validated in a U bend channel, an idealised model of the human aortic arch. The flow patterns were studied with 4D Flow CMR, CFD and EMRI, and compared with high resolution 2D PIV experiments obtained in pulsatile conditions. The main strengths and limitations of 4D Flow CMR and CFD were illustrated by exploiting the accuracy of PIV by comparing against PIV velocity fields. EMRI flow patterns showed a better qualitative and quantitative agreement with PIV results than the other techniques. EMRI enables to overcome the experimental limitations of MRI-based velocity measurements and the modelling simplifications of CFD, allowing an accurate prediction of complex flow patterns observed experimentally, while satisfying mass and momentum balance equations.

Intraoperative anti-A/B immunoadsorption is associated with significantly reduced blood product utilization with similar outcomes in pediatric ABO-incompatible heart transplantation

Background

Intraoperative anti-A/B immunoadsorption (ABO-IA) was recently introduced for ABO-incompatible heart transplantation. Here we report the first case series of patients transplanted with ABO-IA, and compare outcomes with those undergoing plasma exchange facilitated ABO-incompatible heart transplantation (ABO-PE).

Methods

Data were retrospectively analysed on all ABO-incompatible heart transplants undertaken at a single centre between January 1, 2000 and June 1, 2020. Data included all routine laboratory tests, demographics and pre-operative characteristics, intraoperative details and post-operative outcomes. Primary outcome measures were volume of blood product transfusions, maximum post-transplant isohaemagglutinin titres, occurrence of rejection and graft survival. Secondary outcome measures were length of intensive care and hospital stay. Demographic and survival data were also obtained for ABO-compatible transplants during the same time period for comparison.

Results

Thirty-seven patients underwent ABO-incompatible heart transplantation, with 27 (73%) using ABO-PE and 10 (27%) using ABO-IA. ABO-IA patients were significantly older than ABO-PE patients (p < 0.001) and the total volume of blood products transfused during the hospital admission was significantly lower (164 [126-212] ml/kg vs 323 [268-379] ml/kg, p < 0.001). No significant differences were noted between methods in either pre or post-transplant maximum isohaemagglutinin titres, incidence of rejection, length of intensive care or total hospital stay. Survival comparison showed no significant difference between antibody reduction methods, or indeed ABO-compatible transplants (p = 0.6).

Conclusions

This novel technique appears to allow a significantly older population than typical to undergo ABO-incompatible heart transplantation, as well as significantly reducing blood product utilization. Furthermore, intraoperative anti-A/B immunoadsorption does not demonstrate increased early post-transplant isohaemagglutinin accumulation or rates of rejection compared to ABO-PE. Early survival is equivalent between ABO-IA, ABO-PE and ABO-compatible heart transplantation.

The role of artificial intelligence in healthcare: a structured literature review

BACKGROUND/INTRODUCTION

Artificial intelligence (AI) in the healthcare sector is receiving attention from researchers and health professionals. Few previous studies have investigated this topic from a multi-disciplinary perspective, including accounting, business and management, decision sciences and health professions.

METHODS

The structured literature review with its reliable and replicable research protocol allowed the researchers to extract 288 peer-reviewed papers from Scopus. The authors used qualitative and quantitative variables to analyse authors, journals, keywords, and collaboration networks among researchers. Additionally, the paper benefited from the Bibliometrix R software package.

RESULTS

The investigation showed that the literature in this field is emerging. It focuses on health services management, predictive medicine, patient data and diagnostics, and clinical decision-making. The United States, China, and the United Kingdom contributed the highest number of studies. Keyword analysis revealed that AI can support physicians in making a diagnosis, predicting the spread of diseases and customising treatment paths.

CONCLUSIONS

The literature reveals several AI applications for health services and a stream of research that has not fully been covered. For instance, AI projects require skills and data quality awareness for data-intensive analysis and knowledge-based management. Insights can help researchers and health professionals understand and address future research on AI in the healthcare field.

A preoperative estimate of central venous pressure is associated with early Fontan failure

OBJECTIVE

Early Fontan failure is a serious complication after total cavopulmonary connection, characterized by high central venous pressure, low cardiac output, and resistance to medical therapy. This study aimed to estimate postoperative central venous pressure in patients with total cavopulmonary connection using data routinely collected during preoperative assessment. We sought to determine if this metric correlated with measured postoperative central venous pressure and if it was associated with early Fontan failure.

METHODS

In this retrospective study, central venous pressure in total cavopulmonary connection was estimated in 131 patients undergoing pre-total cavopulmonary connection assessment by cardiac magnetic resonance imaging and central venous pressure measurement under general anesthesia. Postoperative central venous pressure during the first 24 hours in the intensive care unit was collected from electronic patient records in a subset of patients. Early Fontan failure was defined as death, transplantation, total cavopulmonary connection takedown, or emergency fenestration within the first 30 days.

RESULTS

Estimated central venous pressure in total cavopulmonary connection correlated significantly with central venous pressure during the first 24 hours in the intensive care unit (r = 0.26, P = .03), particularly in patients without a fenestration (r = 0.45, P = .01). Central venous pressure in total cavopulmonary connection was significantly associated with early Fontan failure (odds ratio, 1.1; 95% confidence interval, 1.01-1.21; P = .03). A threshold of central venous pressure in total cavopulmonary connection 33 mm Hg or greater was found to have the highest specificity (90%) and sensitivity (58%) for identifying early Fontan failure (area under receiver operating curve = 0.73; odds ratio, 12.4; 95% confidence interval, 2.5-62.3; P = .002). This association was stronger in patients with single superior vena cava.

CONCLUSIONS

Estimated central venous pressure in total cavopulmonary connection is an easily calculated metric combining preoperative pressure and flow data. Higher central venous pressure in total cavopulmonary connection is associated with an increased risk of early Fontan failure and is correlated with directly measured post-total cavopulmonary connection pressure. Identification of patients at risk of early Fontan failure has the potential to guide risk-mitigation strategies.

Reducing Contrast Agent Dose in Cardiovascular MR Angiography with Deep Learning

Background

Contrast‐enhanced magnetic resonance angiography (MRA) is used to assess various cardiovascular conditions. However, gadolinium‐based contrast agents (GBCAs) carry a risk of dose‐related adverse effects.

Purpose

To develop a deep learning method to reduce GBCA dose by 80%.

Study Type

Retrospective and prospective.

Population

A total of 1157 retrospective and 40 prospective congenital heart disease patients for training/validation and testing, respectively.

Field Strength/Sequence

A 1.5 T, T1‐weighted three‐dimensional (3D) gradient echo.

Assessment

A neural network was trained to enhance low‐dose (LD) 3D MRA using retrospective synthetic data and tested with prospective LD data. Image quality for LD (LD‐MRA), enhanced LD (ELD‐MRA), and high‐dose (HD‐MRA) was assessed in terms of signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), and a quantitative measure of edge sharpness and scored for perceptual sharpness and contrast on a 1–5 scale. Diagnostic confidence was assessed on a 1–3 scale. LD‐ and ELD‐MRA were assessed against HD‐MRA for sensitivity/specificity and agreement of vessel diameter measurements (aorta and pulmonary arteries).

Statistical Tests

SNR, CNR, edge sharpness, and vessel diameters were compared between LD‐, ELD‐, and HD‐MRA using one‐way repeated measures analysis of variance with post‐hoc t‐tests. Perceptual quality and diagnostic confidence were compared using Friedman's test with post‐hoc Wilcoxon signed‐rank tests. Sensitivity/specificity was compared using McNemar's test. Agreement of vessel diameters was assessed using Bland–Altman analysis.

Results

SNR, CNR, edge sharpness, perceptual sharpness, and perceptual contrast were lower (P < 0.05) for LD‐MRA compared to ELD‐MRA and HD‐MRA. SNR, CNR, edge sharpness, and perceptual contrast were comparable between ELD and HD‐MRA, but perceptual sharpness was significantly lower. Sensitivity/specificity was 0.824/0.921 for LD‐MRA and 0.882/0.960 for ELD‐MRA. Diagnostic confidence was 2.72, 2.85, and 2.92 for LD, ELD, and HD‐MRA, respectively (P_LD‐ELD, P_LD‐HD < 0.05). Vessel diameter measurements were comparable, with biases of 0.238 (LD‐MRA) and 0.278 mm (ELD‐MRA).

Data Conclusion

Deep learning can improve contrast in LD cardiovascular MRA.

Level of Evidence Level

2

Technical Efficacy

Stage 2

Cardiovascular Magnetic Resonance in Congenital Heart Disease: Focus on Heart Failure

Over the past decade, cardiovascular magnetic resonance (CMR) has become a mainstream noninvasive imaging tool for assessment of adult and pediatric patients with congenital heart disease. It provides comprehensive anatomic and hemodynamic information that echocardiography and catheterization alone do not provide. Extracardiac anatomy can be delineated with high spatial resolution, intracardiac anatomy can be imaged in multiple planes, and functional assessment can be made accurately and with high reproducibility. In patients with heart failure, CMR provides not only reference standard evaluation of ventricular volumes and function but also information about the possible causes of dysfunction.

SCMR Position Paper (2020) on clinical indications for cardiovascular magnetic resonance

The Society for Cardiovascular Magnetic Resonance (SCMR) last published its comprehensive expert panel report of clinical indications for CMR in 2004. This new Consensus Panel report brings those indications up to date for 2020 and includes the very substantial increase in scanning techniques, clinical applicability and adoption of CMR worldwide. We have used a nearly identical grading system for indications as in 2004 to ensure comparability with the previous report but have added the presence of randomized controlled trials as evidence for level 1 indications. In addition to the text, tables of the consensus indication levels are included for rapid assimilation and illustrative figures of some key techniques are provided.

Comprehensive MRI assessment of the cardiovascular responses to food ingestion in Fontan physiology

In univentricular (Fontan) physiology, peripheral and splanchnic vascular tone may be raised to counteract reduced cardiac output (CO) and elevated central venous pressure and thus maintain vital organ perfusion. This could negatively affect the normal cardiovascular response to food ingestion, where mesenteric vasodilation and a concurrent rise in CO are central. We sought to elucidate this using rapid cardiovascular MRI. Thirty fasting subjects (50% controls, 40% women and 60% men) ingested a standardized meal. Responses over ~50 min in mean arterial pressure (MAP), CO, and blood flow in all major aortic branches were measured, and regional vascular impedance (Z0) was calculated. Differences from baseline and between groups were assessed by repeated-measures mixed models. Compared with the control group, the Fontan patient group had greater fasting Z0 of the legs and kidneys, resulting in greater systemic Z0 and similar MAP. They further had similar blood flow to the digestive organs at baseline, despite larger variation in mesenteric resistance. Postprandially, blood flow to the legs decreased in the control group but not in the Fontan patient group. Increases in CO and superior mesenteric blood flow were similar in both groups, but the celiac response was blunted in the Fontan patient group. No significant differences in MAP responses were observed. In conclusion, alterations in vascular tone to counteract adverse hemodynamics and raised hepatic afterload may blunt vasoreactivity in the legs and the celiac axis in Fontan physiology. Further study is needed to determine whether blunted celiac or mesenteric vasoreactivity is linked to deteriorating hemodynamics and poor prognosis in Fontan patients.NEW & NOTEWORTHY Novel data on cardiovascular physiology in response to a meal in Fontan patients are presented. Using a previously validated dynamic MRI protocol, we demonstrated that the usual increase in cardiac output and the dilation of the superior mesenteric artery are preserved in clinically well Fontan patients. In contrast, vasoconstriction of the legs may have prevented redistribution of blood flow from this region in response to the meal. This may also affect responses to other types of stress. Celiac vasodilation was also absent in Fontan patients. This may be due to abnormal hepatic circulation. The proposed protocol may be used to study Fontan complications secondary to abnormal regional hemodynamics.

Rapid whole-heart CMR with single volume super-resolution

BACKGROUND

Three-dimensional, whole heart, balanced steady state free precession (WH-bSSFP) sequences provide delineation of intra-cardiac and vascular anatomy. However, they have long acquisition times. Here, we propose significant speed-ups using a deep-learning single volume super-resolution reconstruction, to recover high-resolution features from rapidly acquired low-resolution WH-bSSFP images.

METHODS

A 3D residual U-Net was trained using synthetic data, created from a library of 500 high-resolution WH-bSSFP images by simulating 50% slice resolution and 50% phase resolution. The trained network was validated with 25 synthetic test data sets. Additionally, prospective low-resolution data and high-resolution data were acquired in 40 patients. In the prospective data, vessel diameters, quantitative and qualitative image quality, and diagnostic scoring was compared between the low-resolution, super-resolution and reference high-resolution WH-bSSFP data.

RESULTS

The synthetic test data showed a significant increase in image quality of the low-resolution images after super-resolution reconstruction. Prospectively acquired low-resolution data was acquired ~× 3 faster than the prospective high-resolution data (173 s vs 488 s). Super-resolution reconstruction of the low-resolution data took < 1 s per volume. Qualitative image scores showed super-resolved images had better edge sharpness, fewer residual artefacts and less image distortion than low-resolution images, with similar scores to high-resolution data. Quantitative image scores showed super-resolved images had significantly better edge sharpness than low-resolution or high-resolution images, with significantly better signal-to-noise ratio than high-resolution data. Vessel diameters measurements showed over-estimation in the low-resolution measurements, compared to the high-resolution data. No significant differences and no bias was found in the super-resolution measurements in any of the great vessels. However, a small but significant for the underestimation was found in the proximal left coronary artery diameter measurement from super-resolution data. Diagnostic scoring showed that although super-resolution did not improve accuracy of diagnosis, it did improve diagnostic confidence compared to low-resolution imaging.

CONCLUSION

This paper demonstrates the potential of using a residual U-Net for super-resolution reconstruction of rapidly acquired low-resolution whole heart bSSFP data within a clinical setting. We were able to train the network using synthetic training data from retrospective high-resolution whole heart data. The resulting network can be applied very quickly, making these techniques particularly appealing within busy clinical workflow. Thus, we believe that this technique may help speed up whole heart CMR in clinical practice.

Rapid 3D whole-heart cine imaging using golden ratio stack of spirals

Three-dimensional cine imaging provides a wealth of information about cardiac anatomy and function, but its use in the clinical environment is limited because data acquisition is very time consuming. In this work, a free-breathing 3D whole-heart cine imaging framework was developed using a time-efficient stack of spirals trajectory and accelerated reconstruction. Two suitable view ordering methods are considered with different spacing between k-space readouts in the partition dimension: uniform and tiny golden ratio based. A simulation study suggested the latter did not present any benefits in terms of similarity to the true image. The proposed method was subsequently tested on 10 prospective subjects and compared with conventional multi-slice breath-hold imaging. Image quality was evaluated using objective and subjective scores and ventricular measurements were compared to assess clinical accuracy. Image quality was lower in the proposed technique than in breath-hold images but good agreement was found in clinically relevant ventricular measurements. In addition, the proposed method was fast to acquire, required minimal planning and provided full anatomical coverage with isotropic resolution.