Edward Marcus

Magnetic Resonance Imaging Predictors of Coarctation Severity

Background—MRI is increasingly used for anatomic assessment of aortic coarctation (CoA), but its ability to predict the transcatheter pressure gradient, considered the reference standard for hemodynamic severity, has not been studied in detail. This study evaluated the ability of MRI to distinguish between mild versus moderate and severe CoA as determined by cardiac catheterization. Methods and Results—The clinical, MRI, and catheterization data of 31 subjects referred for assessment of native or recurrent CoA were reviewed retrospectively. Patients were divided into 2 groups on the basis of peak coarctation gradient by catheterization: <20 mm Hg (n=12) and ≥20 mm Hg (n=19). Patients with cardiac index <2.2 L · min−1 · m−2 by catheterization were excluded. By logistic regression analysis, the following variables simultaneously predicted coarctation gradient ≥20 mm Hg: (1) smallest aortic cross-sectional area (adjusted for body surface area) measured by planimetry from gadolinium-enhanced 3D magnetic resonance angiography (OR 1.71 for 10 mm2/m2 decrease, P=0.005) and (2) heart rate–corrected mean flow deceleration in the descending aorta measured by phase-velocity cine MRI (OR 1.68 for 100 mL/s1.5 increase, P=0.018). For the combination of these variables, a predicted probability >0.38 had 95% sensitivity, 82% specificity, 90% positive and negative predictive values, and an area under the receiver-operator characteristics curve of 0.938. In a subsequent validation study, the prediction model correctly classified 9 of 10 patients, with no false-negatives. Conclusions—The combination of anatomic and flow data obtained by MRI provides a sensitive and specific test for predicting catheterization gradient ≥20 mm Hg.

Comparison of Echocardiographic and Cardiac Magnetic Resonance Imaging Measurements of Functional Single Ventricular Volumes, Mass, and Ejection Fraction (from the Pediatric Heart Network Fontan Cross-Sectional Study)

Assessment of the size and function of a functional single ventricle (FSV) is a key element in the management of patients after the Fontan procedure. Measurement variability of ventricular mass, volume, and ejection fraction (EF) among observers by echocardiography and cardiac magnetic resonance imaging (CMR) and their reproducibility among readers in these patients have not been described. From the 546 patients enrolled in the Pediatric Heart Network Fontan Cross-Sectional Study (mean age 11.9 +/- 3.4 years), 100 echocardiograms and 50 CMR studies were assessed for measurement reproducibility; 124 subjects with paired studies were selected for comparison between modalities. Interobserver agreement for qualitative grading of ventricular function by echocardiography was modest for left ventricular (LV) morphology (kappa = 0.42) and weak for right ventricular (RV) morphology (kappa = 0.12). For quantitative assessment, high intraclass correlation coefficients were found for echocardiographic interobserver agreement (LV 0.87 to 0.92, RV 0.82 to 0.85) of systolic and diastolic volumes, respectively. In contrast, intraclass correlation coefficients for LV and RV mass were moderate (LV 0.78, RV 0.72). The corresponding intraclass correlation coefficients by CMR were high (LV 0.96, RV 0.85). Volumes by echocardiography averaged 70% of CMR values. Interobserver reproducibility for the EF was similar for the 2 modalities. Although the absolute mean difference between modalities for the EF was small (<2%), 95% limits of agreement were wide. In conclusion, agreement between observers of qualitative FSV function by echocardiography is modest. Measurements of FSV volume by 2-dimensional echocardiography underestimate CMR measurements, but their reproducibility is high. Echocardiographic and CMR measurements of FSV EF demonstrate similar interobserver reproducibility, whereas measurements of FSV mass and LV diastolic volume are more reproducible by CMR.

Changes in left heart hemodynamics after technically successful in-utero aortic valvuloplasty.

Severe aortic stenosis in the mid‐gestation fetus can progress to hypoplastic left heart syndrome (HLHS). @ In‐utero aortic valvuloplasty is an innovative therapy to promote left ventricular growth and function and potentially to prevent HLHS. This study evaluated the effects of mid‐gestation fetal balloon aortic valvuloplasty on subsequent fetal left ventricular function and left heart Doppler characteristics.

Significance and outcome of left heart hypoplasia in fetal congenital diaphragmatic hernia.

In patients with a left‐sided congenital diaphragmatic hernia (CDH), the left ventricle (LV) is often compressed and smaller than normal. The objective of this study was to investigate whether small left heart dimensions prenatally normalize after birth in patients with CDH, or whether prenatal indices of left heart size and flow predict postnatal outcome.

Circumferential and longitudinal ventricular strain in the normal human fetus.

BACKGROUND Echocardiography with speckle tracking is a novel, angle-independent technique for assessing global and regional cardiac function. Normal data on longitudinal strain have been reported for human fetuses. The aim of this study was to define circumferential left ventricular (LV) strain in a normal fetal population. METHODS Singleton fetuses between 17 and 42 weeks in gestational age with no adverse maternal health issues or fetal abnormalities were studied. Regional and averaged cardiac strain were measured using syngo Velocity Vector Imaging software. RESULTS Data from 81 fetuses were analyzed (mean gestational age, 29.2 ± 5.7 weeks). Overall, average midventricular circumferential strain was 18.7 ± 3.3%, LV longitudinal strain was 15.2 ± 2.7%, and right ventricular longitudinal strain was 16.0 ± 3.3%, with no correlation with gestational age. CONCLUSION This is the first study to report normal fetal LV circumferential strain. These data may be useful as a reference for assessing fetal cardiac function. The retrospective study design and relatively low frame rates used in this study were important limitations.

Impaired cardiac reserve and severely diminished skeletal muscle O2 utilization mediate exercise intolerance in Barth syndrome

Barth syndrome (BTHS) is a mitochondrial myopathy characterized by reports of exercise intolerance. We sought to determine if 1) BTHS leads to abnormalities of skeletal muscle O(2) extraction/utilization and 2) exercise intolerance in BTHS is related to impaired O(2) extraction/utilization, impaired cardiac function, or both. Participants with BTHS (age: 17 ± 5 yr, n = 15) and control participants (age: 13 ± 4 yr, n = 9) underwent graded exercise testing on a cycle ergometer with continuous ECG and metabolic measurements. Echocardiography was performed at rest and at peak exercise. Near-infrared spectroscopy of the vastus lateralis muscle was continuously recorded for measurements of skeletal muscle O(2) extraction. Adjusting for age, peak O(2) consumption (16.5 ± 4.0 vs. 39.5 ± 12.3 ml·kg(-1)·min(-1), P < 0.001) and peak work rate (58 ± 19 vs. 166 ± 60 W, P < 0.001) were significantly lower in BTHS than control participants. The percent increase from rest to peak exercise in ejection fraction (BTHS: 3 ± 10 vs. control: 19 ± 4%, P < 0.01) was blunted in BTHS compared with control participants. The muscle tissue O(2) saturation change from rest to peak exercise was paradoxically opposite (BTHS: 8 ± 16 vs. control: -5 ± 9, P < 0.01), and the deoxyhemoglobin change was blunted (BTHS: 0 ± 12 vs. control: 10 ± 8, P < 0.09) in BTHS compared with control participants, indicating impaired skeletal muscle extraction in BTHS. In conclusion, severe exercise intolerance in BTHS is due to both cardiac and skeletal muscle impairments that are consistent with cardiac and skeletal mitochondrial myopathy. These findings provide further insight to the pathophysiology of BTHS.

Echocardiographic Methods, Quality Review, and Measurement Accuracy in a Randomized Multicenter Clinical Trial of Marfan Syndrome

BACKGROUND The Pediatric Heart Network is conducting a large international randomized trial to compare aortic root growth and other cardiovascular outcomes in 608 subjects with Marfan syndrome randomized to receive atenolol or losartan for 3 years. The authors report here the echocardiographic methods and baseline echocardiographic characteristics of the randomized subjects, describe the interobserver agreement of aortic measurements, and identify factors influencing agreement. METHODS Individuals aged 6 months to 25 years who met the original Ghent criteria and had body surface area-adjusted maximum aortic root diameter (ROOTmax) Z scores > 3 were eligible for inclusion. The primary outcome measure for the trial is the change over time in ROOTmaxZ score. A detailed echocardiographic protocol was established and implemented across 22 centers, with an extensive training and quality review process. RESULTS Interobserver agreement for the aortic measurements was excellent, with intraclass correlation coefficients ranging from 0.921 to 0.989. Lower interobserver percentage error in ROOTmax measurements was independently associated (model R(2) = 0.15) with better image quality (P = .002) and later study reading date (P < .001). Echocardiographic characteristics of the randomized subjects did not differ by treatment arm. Subjects with ROOTmaxZ scores ≥ 4.5 (36%) were more likely to have mitral valve prolapse and dilation of the main pulmonary artery and left ventricle, but there were no differences in aortic regurgitation, aortic stiffness indices, mitral regurgitation, or left ventricular function compared with subjects with ROOTmaxZ scores < 4.5. CONCLUSIONS The echocardiographic methodology, training, and quality review process resulted in a robust evaluation of aortic root dimensions, with excellent reproducibility.

Left ventricular function and geometry in fetuses with severe tricuspid regurgitation

Neonatal congenital tricuspid valve (TV) dysplasia and/or displacement (Ebsteins malformation) with severe tricuspid regurgitation (TR) is a challenging condition in which outcomes are frequently poor. Little is known about left ventricular (LV) function during the perinatal period in patients with congenital TV disease. The objective of this study was to evaluate LV function in fetuses with congenital TV anomalies associated with significant TR.

Impact of Transcatheter Pulmonary Valve Replacement on Biventricular Strain and Synchrony Assessed by Cardiac Magnetic Resonance Feature Tracking

Background—Transcatheter pulmonary valve (TPV) replacement is an emerging therapy intended to restore pulmonary valve function in patients with right ventricular outflow tract conduit dysfunction; the impact of this technique on ventricular strain and synchrony is not known. Methods and Results—Cardiac magnetic resonance and ECG data acquired at 1 center as part of the US Melody TPV trial were analyzed. Biventricular strain and mechanical synchrony measurements were made based on short-axis and 4-chamber steady-state free precession images using feature tracking software. Post- versus pre-TPV replacement findings were compared for all patients (n=31) and subgroups with predominant pulmonary regurgitation (n=13) or stenosis (n=18). Most patients had tetralogy of Fallot (18/31). After TPV replacement, left ventricular (LV) circumferential strain increased for the whole cohort (P<0.001) and both subgroups (pulmonary regurgitation P=0.01; pulmonary stenosis P=0.02). LV longitudinal strain increased for the whole cohort (P=0.02) and pulmonary regurgitation subgroup (P=0.05); circumferential right ventricular strain increased for the pulmonary stenosis group only (P=0.05). LV longitudinal synchrony improved significantly in the pulmonary regurgitation group (maximum wall delay P=0.03; cross-correlation delay P=0.01). Electric measures of synchrony did not improve. Conclusions—In patients with right ventricular outflow tract conduit dysfunction, TPV replacement is associated with improved global LV strain, as well as improved right ventricular strain and LV synchrony in subgroups. Given the associations between strain and synchrony and clinical outcomes, these findings support potential long-term benefits of TPV replacement.

Faster flow quantification using sensitivity encoding for velocity-encoded cine magnetic resonance imaging: In vitro and in vivo validation

To test the agreement between conventional and sensitivity‐encoded (SENSE) velocity encoded cine (VEC) MRI in a flow phantom and in subjects with congenital and acquired heart disease.