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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.

Sudden cardiac death (SCD) is the most common cause of late mortality in tetralogy of Fallot (TOF). Pulmonary regurgitation (PR) was previously found to be the most common hemodynamic abnormality associated with ventricular arrhythmias (VA), but cardiovascular magnetic resonance (CMR)-based studies did not show this association. The aim of this study is to investigate the risk factors for VA in TOF using CMR. Electronic records of TOF patients and their CMR studies between July 2006 and October 2018 in one center were retrospectively reviewed. Demographic, clinical and CMR data of patients were collected. Outcome was defined as sustained ventricular tachycardia (VT), aborted SCD and SCD. From a total of 434 TOF patients with complete CMR studies, 19 (4.4%) patients developed a positive outcome (12 sustained VT, 4 aborted SCD, 3 SCD) at a median age of 24 years. The number of surgical interventions was significantly greater in patients who developed VA. Right ventricular volumes were significantly larger in patients who suffered a positive outcome. Odds ratio for developing VA was 6.905 for RVEDVI ≥ 160 ml/m 2 and 6.141 for RVESVI ≥ 80 ml/m 2 (P = 0.0014 and 0.0012, respectively). Event-free survival was longer in patients with smaller right ventricular volumes. In conclusion, right ventricular dimensions are the most significant factors associated with the development of VA in TOF. The number of surgical interventions is also related to an increased risk.

Percutaneous pulmonary valve replacement (PPVI) in native or patched right ventricular outflow tract (RVOT) has proven to be feasible. The procedure is highly dependent on the size of the RVOT. Several methods exist to evaluate the size of the RVOT by cardiovascular magnetic resonance (CMR). We evaluated different CMR modalities for measuring RVOT diameters. Thirty-one consecutive patients with native or patched RVOT were retrospectively evaluated. CMR was part of follow-up of patients with corrected Tetralogy of Fallot or pulmonary stenosis with significant pulmonary regurgitation (PR). CMR included 3D-SSFP whole-heart in systole, diastole, and contrast-enhanced MR angiography (ceMRA). Diameters of the RVOT were assessed by the three sequences. Additionally, in patients who underwent cardiac catheterization (n = 11) for PPVI, vessel diameters assessed by cine-angiography were compared to CMR. Systolic diameters of RVOT were significantly larger compared to the diameters taken in diastole and ceMRA (median difference 5.0 mm and 3.8 mm). Diastolic and ceMRA diameters did not differ significantly. CMR diameters taken in systole showed no statistical difference to systolic diameters taken by cine-angiography, while diastolic and ceMRA diameters were significantly smaller. PPVI was feasible to a maximal CMR diameter of 31 mm measured by SSFP whole-heart sequence in systole. Absolute diameters of native RVOT differ depending on the CMR sequence and timing of acquisition (systolic vs diastolic gating). Diameters taken during heart catheterization by cine-angiography best correlate to systolic CMR values. Data may help to select RVOTs suitable for PPVI.

Background: Alterations in wall shear stress (WSS) assessed using 4D flow MRI have been shown to play a role in various vascular pathologies, such as bicuspid aortic valve aortopathy. Most studies have focused on systolic WSS, whereas altered diastolic hemodynamics in regurgitant semilunar valvular lesions have not so far been well characterized., Purpose: To investigate diastolic WSS in aortic and pulmonary regurgitation., Study Type: Retrospective data analysis., Population: Thirty tetralogy of Fallot patients, 19 bicuspid aortic valve patients, 11 healthy volunteers., Field Strength/sequence: 5 T, 3D time-resolved phase-contrast MRI with 3D velocity encoding., Assessment: Estimation of WSS and its axial and circumferential vector components along cardiac cycle timeframes in the proximal main pulmonary artery in pulmonary regurgitation (PR) and in the proximal ascending aorta in aortic regurgitation (AR) as well as in healthy volunteers., Statistical Tests: Wilcoxon matched pairs test was used for intra-group comparisons and Mann-Whitney test for intergroup comparisons. Correlations were assessed using Spearman correlation., Results: WSS along the entire cardiac cycle was higher in PR and AR in comparison with controls (mean WSS 0.381 ± 0.070 vs. 0.220 ± 0.018, P < 0.0001; 0.361 ± 0.099 vs. 0.212 ± 0.030, P < 0.0001; respectively). Peak diastolic WSS was significantly higher than the mean WSS in AR and PR (P < 0.0001-0.005). The severity of PR correlated with the peak diastolic axial WSS (Spearman's r s  = 0.454, P = 0.018), whereas the severity of AR correlated with both peak systolic and diastolic tangential WSS (Spearman's r s  = 0.458, P = 0.049; r s  = 0.539, P = 0.017, respectively)., Data Conclusion: Elevated diastolic WSS is a component of the altered flow hemodynamics in AR and PR. This may give more insight into the pathophysiologic role of WSS in vascular remodeling in AR and PR., Level of Evidence: 4 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:763-770., (© 2019 International Society for Magnetic Resonance in Medicine.)