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 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.

Improved Lung Perfusion After Left Pulmonary Artery Patch Enlargement During the Norwood Operation.

BACKGROUND: Optimal pulmonary perfusion is crucial for a well-functioning Fontan circulation in patients with hypoplastic left heart syndrome (HLHS). To obtain an adequate size of the left pulmonary artery (LPA), patch enlargement is a routine part of the hemi-Fontan procedure in our center. However, LPA patch enlargement at the time of the modified Norwood procedure may have surgical advantages. Therefore, the aim of this study was to evaluate whether anatomic and functional effects of the new approach are superior. METHODS: A total of 51 consecutive HLHS patients underwent a cardiovascular magnetic resonance imaging study including assessment of LPA anatomy and lung perfusion. The LPA of 20 patients was enlarged during the modified Norwood procedure (group N) and of 31 patients during the hemi-Fontan procedure (group HF). RESULTS: The median indexed cross-sectional area of the LPA in group N was significantly higher than in group HF (49.5 versus 27.9 mm2/m2, p < 0.0001). The regional pulmonary perfusion as measured by first-pass, contrast-enhanced signal intensity upslope was significantly improved in group N (left side 0.67 s-1 versus 0.40 s-1, p = 0.002; right side 0.84 s-1 versus 0.52 s-1, p = 0.01). The total hemi-Fontan bypass and procedure times were significantly shorter in group N (both p < 0.001). CONCLUSIONS: These first magnetic resonance imaging data show that HLHS patients after LPA patch enlargement during the modified Norwood procedure have significantly higher LPA cross-sectional areas and show improved lung perfusion and shorter overall procedure time as compared with LPA patching during second stage (hemi-Fontan). Therefore, this promising surgical technique may improve blood flow dynamics of the Fontan circulation in the long run.

Neuro-developmental outcome in single-ventricle patients: is the Norwood procedure a risk factor?

OBJECTIVES: Complex neonatal surgery is considered a risk factor for neuro-developmental impairment in single-ventricle patients. Neuro-developmental outcome was compared between preschool-aged Fontan patients who underwent a Norwood procedure and single-ventricle patients not requiring neonatal surgery with cardiopulmonary bypass. METHODS: Verbal, performance and full-scale intelligence quotient (IQ) were evaluated with the Wechsler Preschool and Primary Scale of Intelligence. Cognitive functions were assessed with the German 'Kognitiver Entwicklungstest für das Kindergartenalter' (KET-KID). Risk factors for impaired neuro-development were evaluated. RESULTS: Neuro-developmental assessment was completed in 95 patients (Norwood: n = 69; non-Norwood: n = 26). Median (interquartile range) IQ and KET-KID scores were in the normal range. Except for verbal KET-KID, scores did not differ between Norwood and non-Norwood patients (verbal IQ: 98 (86-105) vs 93 (85-102), P = 0.312; performance IQ: 91 (86-100) vs 96 (86-100), P = 0.932; full-scale IQ: 93 (86-101) vs 89 (84-98), P = 0.314; KET-KID verbal: 48 (17-72) vs 25 (2-54), P = 0.020; KET-KID non-verbal: 33 (18-62) vs 45 (15-54), P = 0.771; KET-KID global: 42 (14-65) vs 28 (6-63), P = 0.208). Full-scale IQ was below average (<85 points) in 14 (20%) Norwood and 9 (35%) non-Norwood cases (P = 0.181). Global KET-KID was below average (<16th percentile) in 19 (28%) and 10 (38%) patients (P = 0.326). Smaller head circumference z-score and complications before neonatal surgery were independently associated with lower scores. CONCLUSIONS: Neuro-developmental outcome of preschool-aged Fontan patients was in the normal range. The Norwood procedure was not a risk factor for neuro-developmental impairment. Preoperative condition and patient-related factors were more important determinants than variables related to surgical palliation.

Restrictive enlargement of the pulmonary annulus at repair of tetralogy of Fallot: a comparative 10-year follow-up study.

OBJECTIVES: Since 1996, our centre performs restrictive enlargement of the pulmonary annulus at surgical repair of tetralogy of Fallot. A transannular patch is only used if the z-score of the pulmonary annulus is smaller than -2. We sought to determine whether this strategy reduces pulmonary insufficiency (PI) and reoperation rate compared to a nationwide contemporary cohort that has not been operated using a uniform strategy. METHODS: Eighty-seven tetralogy of Fallot patients were included in the study (Group 1). One hundred sixty-seven tetralogy of Fallot patients from the Competence Network for Congenital Heart Disease served as controls (Group 2). Clinical, echocardiographic, electrocardiogram, cardiovascular magnetic resonance and outcome data were analysed. RESULTS: Follow-up time since repair was not different between groups [12.9 (7.8-18.8) vs 13.1 (5.2-16.9) years, P = 0.96] while transannular patch rate was significantly lower in Group 1 (32.2% vs 64.7%, P < 0.001). Ten-year freedom from reoperation for PI was significantly higher in our cohort (98% vs 92%, P = 0.01). Multivariable analysis identified restrictive enlargement as the only predictor for no need of reoperation [hazard ratio 0.4 (95% confidence interval 0.24-0.84), P < 0.01]. In Group 1, cardiovascular magnetic resonance-derived volumes were smaller (indexed end-diastolic volume: 103 ± 24 vs 123 ± 31 ml/m2, P < 0.001; indexed end-systolic volume: 53 ± 19 vs 59 ± 20 ml/m2, P = 0.04) and regurgitation fraction was lower (21 ± 14 vs 31 ± 17%, P < 0.001). CONCLUSIONS: Restrictive enlargement of the pulmonary annulus reduces PI and limits the amount of right ventricular dilatation at intermediate-term follow-up. The need for reoperation to alleviate PI is significantly lower compared to a contemporary cohort. Restrictive enlargement strategy has a stronger influence on freedom from reoperation than the use of a transannular patch. CLINICAL TRIAL REGISTRATION: WHO Main ID: DRKS00010087. URL: http://apps.who.int/trialsearch/Trial2.aspx?TrialID=DRKS00010087.

Is the Lecompte technique the last word on transposition of the great arteries repair for all patients? A magnetic resonance imaging study including a spiral technique two decades postoperatively.

OBJECTIVES: To compare the Lecompte technique and the spiral anastomosis (complete anatomic correction) two decades after arterial switch operation (ASO). METHODS: Nine patients after primary ASO with Lecompte and 6 selected patients after spiral anastomosis were evaluated 20.8 ± 2.1 years after ASO versus matched controls. Blood flow dynamics and flow profiles (e.g. vorticity, helicity) in the great arteries were quantified from time-resolved 3D magnetic resonance imaging (MRI) phase contrast flow measurements (4D flow MR) in addition to a comprehensive anatomical and functional cardiovascular MRI analysis. RESULTS: Compared with spiral reconstruction, patients with Lecompte showed more vortex formation, supranatural helical blood flow (relative helicity in aorta: 0.036 vs 0.089; P < 0.01), a reduced indexed cross-sectional area of the left pulmonary artery (155 vs 85 mm²/m²; P < 0.001) and more semilunar valve dysfunctions (n = 5 vs 1). There was no difference in elastic aortic wall properties, ventricular function, myocardial perfusion and myocardial fibrosis between the two groups. Cross-sectional area of the aortic sinus was larger in patients than in controls (669 vs 411 mm²/m²; P < 0.01). In the spiral group, the pulmonary root was rotated after ASO more towards the normal left position (P < 0.01). CONCLUSIONS: In this study, selected patients with spiral anastomoses showed, two decades after ASO, better physiologically adapted blood flow dynamics, and attained a closer to normal anatomical position of their great arteries, as well as less valve dysfunction. Considering the limitations related to the small number of patients and the novel MRI imaging techniques, these data may provoke reconsidering the optimal surgical approaches to transposition of the great arteries repair.

Frequent Dilatation of the Descending Aorta in Children With Hypoplastic Left Heart Syndrome Relates to Decreased Aortic Arch Elasticity.

BACKGROUND: Patients with hypoplastic left heart syndrome after a Norwood operation show dilatation and reduced distensibility of the reconstructed proximal aorta. Cardiac magnetic resonance imaging (CMR) and angiographic examinations indicate that the native descending aorta (DAo) is also dilated, but this has not been studied in detail. METHODS AND RESULTS: Seventy-nine children with hypoplastic left heart syndrome in Fontan circulation (aged 6.3±3.2 years) and 18 control participants (aged 6.8±2.4 years) underwent 3.0-tesla CMR. Gradient-echo cine and phase-contrast imaging was applied to measure cross-sectional areas (CSAs), distensibility, pulse wave velocity, and the incremental elastic modulus of the thoracic aorta. CSA of the DAo in patients was also compared with published percentiles for aortic CSA. Patients had significantly larger CSA of the DAo at the level of pulmonary artery bifurcation (229.1±97.2 versus 175.7±24.3 mm/m(2), P=0.04) and the diaphragm (196.2±66.0 versus 142.6±16.7 mm/m(2), P<0.01). In 41 patients (52%), CSA of the DAo was >95th percentile level for control participants, and the incremental elastic modulus of the aortic arch and the DAo was higher than in patients with normal CSAs (arch: 90.1±64.3 versus 45.6±38.9 m/s; DAo: 86.3±53.7 versus 47.1±47.6 m/s; P<0.01). Incremental elastic modulus of the aortic arch and the DAo correlated with the CSA of the DAo (arch: r=0.5; DAo: r=0.49; P<0.01). CONCLUSIONS: Children with hypoplastic left heart syndrome frequently show dilatation of their DAo associated with increased stiffness of the aortic arch. Higher aortic impedance increases the afterload of the systemic circulation and likely contributes to the burden of the systemic right ventricle.