Update on the Role of Cardiac Magnetic Resonance Imaging in Congenital Heart Disease

Ambulatory sedation for children under 6 years with CHD in MRI and CT

INTRODUCTION

In infants and young children, good image quality in MRI and CT requires sedation or general anesthesia to prevent motion artefacts. This study aims to determine the safety of ambulatory sedation for children with CHD in an outpatient setting as a feasible alternative to in-hospital management.

METHODS

We recorded 91 consecutive MRI and CT examinations of patients with CHD younger than 6 years with ambulatory sedation. CHD diagnoses, vital signs, applied sedatives, and adverse events during or after ambulatory sedation were investigated.

RESULTS

We analysed 91 patients under 72 months (6 years) of age (median 26.0, range 1-70 months; 36% female). Sixty-eight per cent were classified as ASA IV, 25% as ASA III, and 7% as ASA II (American Society of Anesthesiologists Physical Status Classification). Ambulatory sedation was performed by using midazolam, propofol, and/or S-ketamine. The median sedation time for MRI was 90 minutes (range 35-235 minutes) and 65 minutes for CT (range 40-280 minutes). Two male patients (age 1.5 months, ASA II, and age 17 months, ASA IV) were admitted for in-hospital observation due to unexpected severe airway obstruction. The patients were discharged without sequelae after 1 and 3 days, respectively. All other patients were sent home on the day of examination.

CONCLUSION

In infants and young children with CHD, MRI or CT imaging can be performed under sedation in an outpatient setting by a well-experienced team. In-hospital backup should be available for unexpected events.

Cardiac Involvement in Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Disease): The role of cardiovascular magnetic resonance

Eosinophilic granulomatosis with polyangiitis (EGPA), previously known as Churg-Strauss disease, is a rare vasculitis that affects small- to medium-sized vessels and has a propensity to involve the heart. Patients with cardiac involvement have a poor prognosis and usually require immunosuppressive treatment along with corticosteroids. Cardiovascular magnetic resonance (CMR) is a non-invasive diagnostic tool for detecting cardiac involvement and guiding the management plan. We report a 39-year-old male patient with a known history of bronchial asthma who was referred to the chest clinic at a tertiary hospital in 2019 for further assessment of persistent lung parenchymal changes on chest computed tomography. Given the clinical context of the patient and the radiological findings, EGPA was suspected and confirmed with a lung biopsy. CMR was performed for further assessment, which confirmed cardiac involvement. The patient was started on prednisolone and azathioprine and showed significant radiological and clinical improvement.

1.5 vs 3 Tesla Magnetic Resonance Imaging: A Review of Favorite Clinical Applications for Both Field Strengths-Part 2

ABSTRACT

The second part of this review deals with experiences in neuroradiological and pediatric examinations using modern magnetic resonance imaging systems with 1.5 T and 3 T, with special attention paid to experiences in pediatric cardiac imaging. In addition, whole-body examinations, which are widely used for diagnostic purposes in systemic diseases, are compared with respect to the image quality obtained in different body parts at both field strengths. A systematic overview of the technical differences at 1.5 T and 3 T has been presented in part 1 of this review, as well as several organ-based magnetic resonance imaging applications including musculoskeletal imaging, abdominal imaging, and prostate diagnostics.

Supravalvular and Valvular Pulmonary Stenosis: Predictive Features and Responsiveness to Percutaneous Dilation

Supravalvular pulmonary stenosis (SVPS) is considered a rare form of pulmonary stenosis (PS) and represents both a diagnostic and therapeutic challenge. There currently exist no reliable echocardiographic criteria to accurately predict the supravalvular form. The aims of the study were to describe the response to treatment of the different PS presentations and to outline the diagnostic capacity of echocardiogram to differentiate the SVPS from valvular PS (VPS). This retrospective study included 106 patients who underwent percutaneous angioplasty between 2006 and 2017. Interventional outcomes of patients with SVPS were compared to those of patients with VPS. Diagnosis of VPS vs. SVPS by echocardiogram was compared to diagnosis obtained by angiogram. Echocardiogram yielded a sensitivity of 56%, a specificity of 82.5%, a positive predictive value of 50%, and a negative predictive value of 85.7%. Patients with SVPS had a significantly smaller pulmonary artery to pulmonary valve (PA:PV) ratio. At 6-12 months of follow-up, the VPS group had a mean right ventricular to pulmonary artery (RV-PA) gradient of 21.68 ± 19.85 mmHg compared to 45.27 ± 24.58 mmHg in the SVPS group. Patients with SVPS had a higher rate of reintervention than patients with VPS (32% vs. 6.2%, p < 0.001). There was no difference in major complications between groups, whereas VPS patients had a higher proportion of pulmonary insufficiency. Percutaneous angioplasty for PS is less effective in patients with a supravalvular component. A better understanding of the underlying histopathology of different PS subtypes could lead to development of different techniques to improve outcomes, with fewer reinterventions, in this population.

Right and left ventricle native T1 mapping in systolic phase in patients with congenital heart disease

BACKGROUND

T1 mapping is emerging as a powerful tool in cardiac magnetic resonance (CMR) to evaluate diffuse fibrosis. However, right ventricular (RV) T1 mapping proves difficult due to the limited wall thickness in diastolic phase. Several studies focused on systolic T1 mapping, albeit only on the left ventricle (LV).

PURPOSE

To estimate intra- and inter-observer variability of native T1 (nT1) mapping of the RV, and its correlations with biventricular and pulmonary function in patients with congenital heart disease (CHD).

MATERIAL AND METHODS

In this retrospective, observational, cross-sectional study we evaluated 36 patients with CHD, having undergone CMR on a 1.5-T scanner. LV and RV functional evaluations were performed. A native modified look-locker inversion recovery short-axis sequence was acquired in the systolic phase. Intra- and inter-reader reproducibility were reported as complement to 100% of the ratio between coefficient of reproducibility and mean. Spearman ρ and Mann-Whitney U-test were used to compare distributions.

RESULTS

Intra- and inter-reader reproducibility was 84% and 82%, respectively. Median nT1 was 1022 ms (interquartile range [IQR] 1108-972) for the RV and 947 ms (IQR 986-914) for the LV. Median RV-nT1 was 1016 ms (IQR 1090-1016) in patients with EDVI ≤100 mL/m² and 1100 ms (IQR 1113-1100) in patients with EDVI >100 mL/m² (P = 0.049). A significant negative correlation was found between RV ejection fraction and RV-nT1 (ρ = -0.284, P = 0.046).

CONCLUSION

Systolic RV-nT1 showed a high reproducibility and a negative correlation with RV ejection fraction, potentially reflecting an adaptation of the RV myocardium to pulmonary valve/conduit (dys)-function.

Three-dimensional printing for cardiovascular diseases: from anatomical modeling to dynamic functionality

Three-dimensional (3D) printing is widely used in medicine. Most research remains focused on forming rigid anatomical models, but moving from static models to dynamic functionality could greatly aid preoperative surgical planning. This work reviews literature on dynamic 3D heart models made of flexible materials for use with a mock circulatory system. Such models allow simulation of surgical procedures under mock physiological conditions, and are; therefore, potentially very useful to clinical practice. For example, anatomical models of mitral regurgitation could provide a better display of lesion area, while dynamic 3D models could further simulate in vitro hemodynamics. Dynamic 3D models could also be used in setting standards for certain parameters for function evaluation, such as flow reserve fraction in coronary heart disease. As a bridge between medical image and clinical aid, 3D printing is now gradually changing the traditional pattern of diagnosis and treatment.

3D Bioprinting of cardiac tissue and cardiac stem cell therapy

Cardiovascular tissue engineering endeavors to repair or regenerate damaged or ineffective blood vessels, heart valves, and cardiac muscle. Current strategies that aim to accomplish such a feat include the differentiation of multipotent or pluripotent stem cells on appropriately designed biomaterial scaffolds that promote the development of mature and functional cardiac tissue. The advent of additive manufacturing 3D bioprinting technology further advances the field by allowing heterogenous cell types, biomaterials, and signaling factors to be deposited in precisely organized geometries similar to those found in their native counterparts. Bioprinting techniques to fabricate cardiac tissue in vitro include extrusion, inkjet, laser-assisted, and stereolithography with bioinks that are either synthetic or naturally-derived. The article further discusses the current practices for postfabrication conditioning of 3D engineered constructs for effective tissue development and stability, then concludes with prospective points of interest for engineering cardiac tissues in vitro. Cardiovascular three-dimensional bioprinting has the potential to be translated into the clinical setting and can further serve to model and understand biological principles that are at the root of cardiovascular disease in the laboratory.

Noteworthy Literature published in 2017 for Congenital Cardiac Anesthesiologists

This review focuses on the literature published during the 13 months from December 2016 to December 2017 that is of interest to anesthesiologists taking care of children and adults with congenital heart disease. Five themes are addressed during this time period and 100 peer-reviewed articles are discussed.

Effects of contrast administration on cardiac MRI volumetric, flow and pulse wave velocity quantification using manual and software-based analysis

Objective:

The aim of the current study was to determine the effects of gadolinium contrast agent on right (RV) and left ventricular (LV) volumetric, aortic flow and pulse wave velocity (PWV) quantification using manual, semi-automatic and fully automatic analysis techniques.

Methods:

61 participants free from known cardiovascular disease were recruited. Cardiac MR was performed on a 3 T scanner. A balanced steady-state free precession stack was acquired of the ventricles with phase contrast imaging of the aorta performed pre- and post-administration of 10 ml 0.5 mmol ml⁻¹ gadoterate meglumine. The images were analysed manually, and using a semi-automated and a fully automated technique.

Results:

54 completed the study. Gadolinium-based contrast administration significantly increase the signal-to-noise ratio (pre: 830 ± 398 vs post: 1028 ± 540, p = 0.003) with no significant change in contrast-to-noise ratio (pre: 583 ± 302 vs post: 559 ± 346, p = 0.54). On LV analysis, post-contrast analysis yielded significantly higher end systolic volume (54 ± 20 vs 57 ± 18 ml, p = 0.04), and lower ejection fraction (59 ± 9 vs 57 ± 8%, p = 0.023). On RV analysis, gadolinium contrast resulted in no significant differences. Similar results were seen using the semi-automated and fully-automated techniques but with a larger magnitude of difference. Conversely, using both manual and software analysis aortic flow and PWV quantification proved robust to the effects of contrast agent producing only small non-significant differences.

Conclusion:

Gadolinium contrast administration significantly alters LV endocardial contour detection with this effect amplified when using semi-automated analysis techniques. In comparison, RV and PWV analysis is robust to these effects.

Advances in knowledge:

Contrast administration alters LV quantification but not flow analysis. However, these differences are small.