Cardiac Magnetic Resonance to Predict Coronary Artery Compression in Transcatheter Pulmonary Valve Implantation Into Conduits.

OBJECTIVES: The aim of this study was to evaluate the accuracy of cardiac magnetic resonance (CMR) in predicting coronary artery (CA) compression during transcatheter pulmonary valve implantation (TPVi). BACKGROUND: TPVi is a widely available option to treat dysfunctional right ventricle (RV)-to-pulmonary artery (PA) conduits, but CA compression is an absolute contraindication. CMR can evaluate coronary anatomy, but its utility in predicting CA compression is not well established. METHODS: After Institutional Review Board approval was obtained, all patients at 9 centers with attempted TPVi in RV-PA conduits and recent CMR (≤12 months) were analyzed. A core laboratory reviewed all CMR studies for the shortest orthogonal distance from a CA to the conduit, the shortest distance from a CA to the most stenotic area of the conduit, and subjective assessment of CA compression risk. RESULTS: Among 231 patients, TPVi was successful in 198 (86%); in 24 (10%), balloon testing precluded implantation (documented CA compression or high risk). Distance to the RV-PA conduit ≤2.1 mm (area under the curve [AUC]: 0.70) and distance to most stenotic area ≤13.1 mm (AUC: 0.69) predicted CA compression. Subjective assessment had the highest AUC (0.78), with 96% negative predictive value. Both distances and qualitative assessment remained independently associated with CA compression when controlling for abnormal coronary anatomy or degree of conduit calcification. CONCLUSIONS: CMR can help predict the risk for CA compression during TPVi in RV-PA conduits but cannot completely exclude CA compression. CMR may assist in patient selection and counseling families prior to TPVi, although balloon testing remains essential.

Interruption of the Ascending Aorta-Biventricular Surgical Repair.

Interruption of the ascending aorta is an extremely rare anomaly defined by a point of interruption between the intrapericardial and extrapericardial aorta and can be explained by developmental errors proximal to the embryologic right aortic sac. Herein, we present a case of interruption of the ascending aorta and describe a successful biventricular surgical repair of this unique anomaly.

Neo-aortic Root Dilatation, Aortic Stiffness, and Ventricular interactions in Long-Term Follow-Up After the Ross Procedure in Childhood.

Patients after the Ross procedure are at risk for right (RV) and left ventricular (LV) dysfunction due to neo-aortic and pulmonary dysfunction. While neo-aortic root dilatation has been related to LV dysfunction, the potential contributions of aortic stiffness and ventricular interactions have not been evaluated. Patients status post Ross procedure up to age 18 years with cardiac magnetic resonance (CMR) exam from 2007 to 2018 were retrospectively reviewed. Aortic pulse wave velocity (PWV) was calculated from phase contrast and angiogram images. RV and LV peak global longitudinal (GLS) and circumferential strain (GCS) were measured using tissue tracking software. Multivariable regression was performed for variables associated with parameters of LV function. In 58 patients (median age 20.5 years at CMR exam), male gender, longer time since Ross procedure, aortic root dilatation, and lower RV ejection fraction (EF) were associated with decreased LV EF. There was no association with LV late gadolinium enhancement or neo-aortic or conduit regurgitation. LV GCS and GLS also correlated with RV GCS, RV GLS and PWV. In multivariable analysis, the relation of RV and LV systolic function, but not aortic measurements, remained significant. In conclusion, in long-term follow-up after pediatric Ross procedure, RV function rather than aortic root size or aortic stiffness most closely relates to LV function. Ventricular interactions may impact decision-making on timing of conduit intervention, which could differ from established criteria in populations with only aortic or pulmonary valve disease. Further study is warranted to evaluate possible association with clinical outcome.

Epidurals for Coarctation Repair in Children Are Associated with Decreased Postoperative Anti-Hypertensive Infusion Requirement as Measured by a Novel Parameter, the Anti-Hypertensive Dosing Index (ADI).

BACKGROUND: Sympathetically-associated hypertension after coarctation repair is a common problem often requiring anti-hypertensive infusions in an intensive care unit. Epidurals suppress sympathetic output and can reduce blood pressure but have not been studied following coarctation repair in children. We sought to determine whether epidurals for coarctation repair in children were associated with decreased requirement for postoperative anti-hypertensive infusions, if they were associated with changes in hospital course, or with complications. METHODS: In this observational retrospective cohort study, we evaluated all patients age 1-18 years undergoing coarctation repair at our institution during a 10-year period and compared the requirement for postoperative anti-hypertensive infusions in patients with and without epidurals using an anti-hypertensive dosing index (ADI) incorporating total dose-hours of all anti-hypertensive infusions (primary outcome). We also assessed intensive care unit (ICU) and hospital length of stay, discharge on oral anti-hypertensive medication, and complications potentially related to epidurals (secondary outcomes). RESULTS: Children undergoing coarctation repair with epidurals had decreased requirements for postoperative anti-hypertensive infusions compared to children without epidurals (cumulative ADI 65.0 [28.5-130.3] v. 157.0 [68.6-214.7], p = 0.021; mean ADI 49.0 [33.3-131.2] v. 163.0 [66.6-209.8], p = 0.01). After multivariable cumulative logit mixed-effects regression analysis, mean ADI was decreased in patients with epidurals throughout the postoperative period (p < 0.001). Patients with epidurals were 1.6 years older and weighed 10.6 kg more than patients without epidurals but were otherwise comparable. Epidural complications included pruritus (three patients), agitation (one patient), somnolence (one patient), and transient orthostatic hypotension (one patient). Duration of intensive care unit admission, duration of hospital stays, and requirement for anti-hypertensive medication at discharge were similar in patients with and without epidurals. CONCLUSIONS: This is the first study of children receiving an epidural for surgical repair of aortic coarctation via open thoracotomy. In this small, single-institution, observational retrospective cohort study, epidurals for coarctation repair in children were associated with decreased postoperative anti-hypertensive infusion requirements. Epidurals were not associated with length of ICU or hospital stay, or with discharge on anti-hypertensive medication. No significant epidural complications were noted. Prospective study of larger populations will be necessary to confirm these associations, address causality, verify safety, and assess other effects.

Bidirectional Inferior Cavopulmonary Anastomosis: Pre-Fontan Interim Palliation.

We report a novel method of constructing an extracardiac bidirectional inferior cavopulmonary anastomosis. Our patient was a 4-month-old girl with complex single-ventricle anatomy and a small-caliber superior vena cava. A direct anastomosis from the inferior vena cava to the main pulmonary artery was constructed by using all autologous tissue. The resulting pathway remained patent and exhibited growth with age. Furthermore, a pulmonary arteriovenous malformation did not develop. This case demonstrates how a bidirectional inferior cavopulmonary anastomosis is feasible in the human and can provide similar hemodynamic results as the bidirectional superior cavopulmonary anastomosis.

Synthetic hematocrit derived from the longitudinal relaxation of blood can lead to clinically significant errors in measurement of extracellular volume fraction in pediatric and young adult patients.

BACKGROUND: Extracellular volume fraction (ECV) is altered in pathological cardiac remodeling and predicts death and arrhythmia. ECV can be quantified using cardiovascular magnetic resonance (CMR) T1 mapping but calculation requires a measured hematocrit (Hct). The longitudinal relaxation of blood has been used in adults to generate a synthetic Hct (estimate of true Hct) but has not been validated in pediatric populations. METHODS: One hundred fourteen children and young adults underwent a total of 163 CMRs with T1 mapping. The majority of subjects had a measured Hct the same day (N = 146). Native and post-contrast T1 were determined in blood pool, septum, and free wall of mid-LV, avoiding areas of late gadolinium enhancement. Synthetic Hct and ECV were calculated and intraclass correlation coefficient (ICC) and linear regression were used to compare measured and synthetic values. RESULTS: The mean age was 16.4 ± 6.4 years and mean left ventricular ejection fraction was 59% ± 9%. The mean measured Hct was 41.8 ± 3.0% compared to the mean synthetic Hct of 43.2% ± 2.9% (p < 0.001, ICC 0.46 [0.27, 0.52]) with the previously published model and 41.8% ± 1.4% (p < 0.001, ICC 0.28 [0.13, 0. 42]) with the locally-derived model. Mean measured mid-free wall ECV was 30.5% ± 4.8% and mean synthetic mid-free wall ECV of local model was 29.7% ± 4.6% (p < 0.001, ICC 0.93 [0.91, 0.95]). Correlations were not affected by heart rate and did not significantly differ in subpopulation analysis. While the ICC was strong, differences between measured and synthetic ECV ranged from -8.4% to 4.3% in the septum and -12.6% to 15.8% in the free wall. Using our laboratory's normal cut-off of 28.5%, 59 patients (37%) were miscategorized (53 false negatives, 6 false positives) with published model ECV. The local model had 37 miscategorizations (20 false negatives, 17 false positives), significantly fewer but still a substantial number (23%). CONCLUSIONS: Our data suggest that use of synthetic Hct for the calculation of ECV results in miscategorization of individual patients. This difference may be less significant once synthetic ECV is calculated and averaged over a large research cohort, making it potentially useful as a research tool. However, we recommend formal measurement of Hct in children and young adults for clinical CMRs.

Relation of right ventricular mass and volume to functional health status in repaired tetralogy of Fallot.

After repair of tetralogy of Fallot, right ventricular (RV) mass and mass:volume ratio may reflect RV remodeling and adverse outcomes. This study aimed to evaluate the relation of RV mass to functional health status and subsequent adverse RV remodeling and to determine whether RV mass measurement in systole could improve reproducibility. In 53 patients with tetralogy of Fallot (median 29 years old) who previously underwent cardiovascular magnetic resonance and completed the Short Form 36, version 2 (Optum, Eden Prairie, MN), short-axis images were analyzed for RV end-diastolic volume and diastolic and systolic mass, indexed to body surface area. The most recent subsequent cardiovascular magnetic resonance study (before pulmonary valve or conduit replacement) was evaluated for change in RV end-diastolic volume and ejection fraction. Diastolic indexed mass ≥37.3 g/m(2) (odds ratio 7.6, p = 0.02) predicted decreased general health scores. In patients with normal RV ejection fraction, indexed mass correlated with Physical Component Summary and general health scores. RV diastolic mass:volume ratio >0.2 had a strong association with subsequent increase in RV end-diastolic volume (odds ratio 26.1, p = 0.002). Systolic RV mass measurement had excellent correlation with diastolic measurement (r = 0.97, p <0.0001), but did not improve intraobserver or interobserver variability. In conclusion, RV mass relates to functional health status and adverse RV remodeling and can be measured with good reproducibility. RV mass should be routinely evaluated in this population and is best measured in diastole; further study is necessary to evaluate longitudinal changes in functional health status and RV parameters.

Relation of aortic stiffness and strain by cardiovascular magnetic resonance imaging to age in repaired tetralogy of fallot.

Patients with tetralogy of Fallot (TOF) have abnormal aortic properties. It is not known if this increases the risk for aneurysm formation. We sought to identify clinical and cardiovascular magnetic resonance (CMR) imaging patient characteristics associated with worsened aortic pulse wave velocity (PWV) and aortic strain in patients with repaired TOF. In 124 patients with TOF undergoing CMR (median age 24.6 years, interquartile range 17.8 to 34.2), left and right ventricular volumetric data, aortic PWV, and aortic strain were evaluated. Increased PWV positively correlated with age at repair (r = 0.3, p = 0.001) and cross-sectional ascending aortic area (r = 0.34, p <0.001) and was associated with a history of shunt placement (p = 0.01). Decreased aortic strain also correlated with age at TOF repair (r = -0.5, p <0.001), cross-sectional ascending aortic area (r = -0.43, p <0.001), aortic regurgitation (r = -0.46, p ≤0.001), and history of shunt placement (p <0.001). In a multivariate regression model controlling for history of shunt placement, use of cardiac medication, and aortic regurgitation, age at CMR was significantly associated with PWV (p = 0.005), whereas age at repair trended toward significance (p = 0.06). In conclusion, patients with TOF have abnormal aortic properties correlated with greater age, which may be associated with later repair. Longitudinal data are necessary to assess the risk of aortic aneurysm and dissection as the TOF population grows older. Functional imaging of the aorta by CMR may be useful in predicting risk and assessing vascular health.