James C. Nielsen

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.

3D Printing to Guide Ventricular Assist Device Placement in Adults With Congenital Heart Disease and Heart Failure

As the population of adults with congenital heart disease continues to grow, so does the number of these patients with heart failure. Ventricular assist devices are underutilized in adults with congenital heart disease due to their complex anatomic arrangements and physiology. Advanced imaging techniques that may increase the utilization of mechanical circulatory support in this population must be explored. Three-dimensional printing offers individualized structural models that would enable pre-surgical planning of cannula and device placement in adults with congenital cardiac disease and heart failure who are candidates for such therapies. We present a review of relevant cardiac anomalies, cases in which such models could be utilized, and some background on the cost and procedure associated with this process.

Use of 3-Dimensional Printing to Demonstrate Complex Intracardiac Relationships in Double-Outlet Right Ventricle for Surgical Planning

Double-outlet right ventricle falls under the category of congenital heart disease known as conotruncal defects, which possess abnormal ventriculoarterial relationships.1 For complex cases, the surgeon must determine whether the left ventricle and one of the great arteries can be aligned using the ventricular septal defect to construct an unobstructed pathway or baffle, resulting in a 2-ventricle repair.2 Creation of the baffle can be complicated by anatomic obstructions because of prominent conal septum, straddling atrioventricular valve attachments, or location of the ventricular septal defect in the inlet septum, remote from any great artery. Three-dimensional (3D) printing has been applied in the management of many different congenital heart diseases.3 In this specific patient population, in whom communicating the complex intracardiac anatomy to the surgeon is so critical, the use of 3D modeling and printing is invaluable. We used this approach in a patient with dextrocardia, complex double-outlet right ventricle (S,L,A)1 and supratricuspid ring. She underwent pulmonary artery banding in infancy and had been doing relatively well clinically; so that any further surgical intervention was deferred until she was 8 years old. Although she was growing well and required no medication, …

Imaging of congenital coronary artery anomalies

Imaging of the coronary arteries is an important part of the evaluation of children with congenital heart disease and isolated congenital coronary artery anomalies. Echocardiography remains the main imaging modality and is complemented by MRI and CT angiography in the older or difficult-to-image child. We review echocardiography, MRI, and CT angiography for coronary artery imaging, with emphasis on techniques. The clinical implications of isolated congenital coronary artery anomalies are also addressed, along with a discussion about the current consensus on optimal management of these anomalies.

Prediction of Hemodynamic Severity of Coarctation by Magnetic Resonance Imaging

A published formula containing minimal aortic cross-sectional area and the flow deceleration pattern in the descending aorta obtained by cardiovascular magnetic resonance predicts significant coarctation of the aorta (CoA). However, the existing formula is complicated to use in clinical practice and has not been externally validated. Consequently, its clinical utility has been limited. The aim of this study was to derive a simple and clinically practical algorithm to predict severe CoA from data obtained by cardiovascular magnetic resonance. Seventy-nine consecutive patients who underwent cardiovascular magnetic resonance and cardiac catheterization for the evaluation of native or recurrent CoA at Childrens Hospital Boston (n = 30) and the University of California, San Francisco (n = 49), were retrospectively reviewed. The published formula derived from data obtained at Childrens Hospital Boston was first validated from data obtained at the University of California, San Francisco. Next, pooled data from the 2 institutions were analyzed, and a refined model was created using logistic regression methods. Finally, recursive partitioning was used to develop a clinically practical prediction tree to predict transcatheter systolic pressure gradient ≥ 20 mm Hg. Severe CoA was present in 48 patients (61%). Indexed minimal aortic cross-sectional area and heart rate-corrected flow deceleration time in the descending aorta were independent predictors of CoA gradient ≥ 20 mm Hg (p <0.01 for both). A prediction tree combining these variables reached a sensitivity and specificity of 90% and 76%, respectively. In conclusion, the presented prediction tree on the basis of cutoff values is easy to use and may help guide the management of patients investigated for CoA.

Congenital Heart DiseaseFrequency of Aortic Dilation in Noonan Syndrome

Noonan syndrome (NS) is a genetic disorder caused by mutations altering proteins relevant to RAS/mitogen-activated protein kinase signal transduction. Cardiac involvement is common, most prevalently pulmonary valve stenosis and hypertrophic cardiomyopathy. Because abnormal mitogen-activated protein kinase signaling contributes to the aortopathy in Marfan syndrome and with rare reports of aortic aneurysm in NS, we undertook a retrospective study of ascending aortic anatomy in 37 patients with NS and without confounding medical conditions. Age ranged from 0.6 to 32 years. Based on the most recent echocardiogram, the aortic annulus and root were dilated in the cohort (mean z scores of 1.14 and 0.98, respectively, p <0.005) but the sinotubular junction and ascending aorta were not (mean z scores of 0.05 and 0.19, respectively). The aortic root was aneurysmal (>2 z scores) in 8 subjects (21.6%). PTPN11 mutations were present in 14 subjects, whose aortic status was similar to the cohort overall. Comparison of age and z scores revealed a modest tendency for the aortic annulus and root to dilate over time. Among 13 subjects with multiple imaging studies over an average of 6.8 years, the average z score increased to 0.78 and 0.39 for the aortic annulus and root, respectively. Multivariate analysis revealed that age accounted for 7.0% and 11.0% of the variance in the aortic annular and root diameters, respectively. In conclusion, we found that aortic annular dilation and aortic root aneurysm are prevalent in NS, often presenting during childhood and progressing over time. Further study is needed to identify potential risks associated with these abnormalities.

Extracorporeal membrane oxygenation for pneumonitis after a Glenn palliation

A five-month old male with a single ventricle palliated with a bidirectional cavopulmonary anastomosis developed severe respiratory insufficiency from respiratory syncytial virus (RSV) pneumonitis. He was successfully rescued with extra-corporeal membrane oxygenation (ECMO) therapy and recovered with minimal morbidity.

Transcatheter closure of recurrent postmyocardial infarction ventricular septal defect facilitated by percutaneous left ventricle access.

We report a case of a 68-year-old woman with a basal postmyocardial infarction ventricular septal defect that recurred 4 months after initial surgical repair. Successful transcatheter closure using an Amplatzer Muscular VSD Occluder was facilitated by direct percutaneous left ventricular access.

Comparison between proximal thoracic vascular measurements obtained by contrast enhanced MRA and transthoracic echocardiography in infants with congenital heart disease

Background Accurate assessment of the proximal thoracic vasculature in infants with congenital heart disease (CHD) is vital in deciding the appropriate surgical or interventional procedure and predicting outcomes. In most infants this information is obtained by transthoracic echocardiography (TTE). When the image quality is limited by TTE, Contrast Enhanced MRA (CE-MRA) is frequently utilized. Calculating Z-scores for measurements obtained by CE-MRA in this population is currently not possible due to the lack of normative data. Demonstrating reasonable agreement between vessel dimensions by CE-MRA and TTE will allow the use of TTE based Zscores on measurements from CE-MRA. This study examines the accuracy and agreement of proximal thoracic vascular measurements obtained by CE-MRA compared to TTE. Methods