Tiffanie R. Johnson

A Prospective Analysis of the Incidence and Risk Factors Associated with Junctional Ectopic Tachycardia Following Surgery for Congenital Heart Disease

This study was designed to evaluate the incidence and risk factors associated with the occurrence of junctional ectopic tachycardia (JET) in patients after congenital heart surgery. We prospectively analyzed cardiac rhythm status in 336 consecutive patients undergoing surgery for congenital heart disease at our institution during a 1-year period. The incidence of JET was 8% (27/336). Repairs with the highest incidence of JET were arterial switch operation (3/13, 23%), atrioventricular (AV) canal repair (4/19, 21%), and Norwood repair (2/10, 20%). Compared to patients with no arrhythmias, patients with JET were more likely to be younger (2.75 ± 2.44 vs 5.38 ± 7.25 years, p < 0.01), have had longer cardiopulmonary bypass times (126 ± 50 vs 85 ± 73, p < 0.01), and have a higher inotrope score (6.26 ± 7.55 vs 2.41 ± 8.11, p < 0.01). By multivariate analysis, ischemic time was the only factor associated with JET [odds ratio, 1.01 (confidence interval, 1.005–1.02); p = 0.0014). The presence of JET did not correlate with electrolyte abnormalities. JET is not necessarily related to surgery near the His bundle or hypomagnesemia. Longer ischemic time is the best predictor of JET. Patients undergoing arterial switch operation, AV canal repair, and Norwood repair are at highest risk of postoperative JET and should be considered for prophylactic therapy.

Characterization of cardiac tumors in children by cardiovascular magnetic resonance imaging: a multicenter experience.

OBJECTIVES The aim of this study was to report the results of an international multicenter experience of cardiac magnetic resonance imaging (MRI) evaluation of cardiac tumors in children, each with histology correlation or a diagnosis of tuberous sclerosis, and to determine which characteristics are predictive of tumor type. BACKGROUND Individual centers have relatively little experience with diagnostic imaging of cardiac tumors in children, because of their low prevalence. The accuracy of cardiac MRI diagnosis on the basis of a pre-defined set of criteria has not been tested. METHODS An international group of pediatric cardiac imaging centers was solicited for case contribution. Inclusion criteria comprised: 1) age at diagnosis ≤18 years; 2) cardiac MRI evaluation of cardiac tumor; and 3) histologic diagnosis or diagnosis of tuberous sclerosis. Data from the cardiac MRI images were analyzed for mass characteristics. On the basis of pre-defined cardiac MRI criteria derived from published data, 3 blinded investigators determined tumor type, and their consensus diagnoses were compared with histologic diagnoses. RESULTS Cases (n = 78) submitted from 15 centers in 4 countries had the following diagnoses: fibroma (n = 30), rhabdomyoma (n = 14), malignant tumor (n = 12), hemangioma (n = 9), thrombus (n = 4), myxoma (n = 3), teratoma (n = 2), and paraganglioma, pericardial cyst, Purkinje cell tumor, and papillary fibroelastoma (n = 1, each). Reviewers who were blinded to the histologic diagnoses correctly diagnosed 97% of the cases but included a differential diagnosis in 42%. Better image quality grade and more complete examination were associated with higher diagnostic accuracy. CONCLUSIONS Cardiac MRI can predict the likely tumor type in the majority of children with a cardiac mass. A comprehensive imaging protocol is essential for accurate diagnosis. However, histologic diagnosis remains the gold standard, and in some cases malignancy cannot be definitively excluded on the basis of cardiac MRI images alone.

The Fontan Procedure: Anatomy, Complications, and Manifestations of Failure

The Fontan procedure refers to any operation that results in the flow of systemic venous blood to the lungs without passing through a ventricle. It is performed to treat several complex congenital heart abnormalities including tricuspid atresia, pulmonary atresia with intact ventricular septum, hypoplastic left heart syndrome, and double-inlet ventricle. The original Fontan procedure included direct anastomosis of the right atrium to the main pulmonary artery; however, multiple modifications have been employed. Creation of Fontan circulation is palliative in nature, with good results in patients with ideal hemodynamics and substantial morbidity and mortality in those with poor hemodynamics. Complications of Fontan circulation include exercise intolerance, ventricular failure, right atrium dilatation and arrhythmia, systemic and hepatic venous hypertension, portal hypertension, coagulopathy, pulmonary arteriovenous malformation, venovenous shunts, and lymphatic dysfunction (eg, ascites, edema, effusion, protein-losing enteropathy, and plastic bronchitis). Magnetic resonance imaging is best for postoperative evaluation of patients who underwent the Fontan procedure, and cardiac transplantation remains the only definitive treatment for those with failing Fontan circulation.

MRI of Surgical Repair of Transposition of the Great Vessels

OBJECTIVE Our objectives are to review the surgical procedures that have been performed for the treatment of transposition of the great vessels. Using MRI, we illustrate the normal postoperative findings and many of the long-term complications for each of the surgical procedures. CONCLUSION MRI is an extremely useful imaging method for evaluation of normal and abnormal findings after surgical repair of transposition of the aorta and pulmonary artery.

Conotruncal Cardiac Defects: A Clinical Imaging Perspective

Conotruncal cardiac defects make up a significant portion of congenital heart disease. For proper diagnosis and subsequent care of patients with these defects, different and sometimes multiple imaging modalities are needed at various stages of care. This article reviews the characteristics of some of the most common conotruncal defects and the imaging options available along with the advantages and disadvantages of each. Intricate knowledge of the capabilities of each modality will aid the practitioner in making optimal clinical decisions.

After Repair, Atrioventricular Valve Regurgitation During Cardiac Extracorporeal Membrane Oxygenation Predicts Survival

BACKGROUND When echocardiography is used to follow up cardiac patients on extracorporeal membrane oxygenation (ECMO), ejection fraction as a measure of ventricular function has been used to determine likelihood of survival after decannulation. We hypothesized that systemic atrioventricular (AV) valve regurgitation while on ECMO may be a better predictor of survival. METHODS From February 1995 to March 2001, 64 patients required ECMO postoperatively. Three were removed from ECMO owing to brain death, so 61 patients formed our study group. Retrospective chart review was performed with systemic AV valve regurgitation and ejection fraction while on ECMO recorded from echocardiography reports. Patients alive 1 month after decannulation were considered survivors. RESULTS There were 29 survivors (47.5%). Ejection fraction in survivors (mean 41% +/- 0.13%) was not significantly different from that of nonsurvivors (41% +/- 0.18%; p < or = 0.839) but severity of systemic AV valve regurgitation was significantly different. Only 2 survivors (6.8%) had at least moderate AV valve regurgitation compared with 17 of the 32 nonsurvivors (53%). Patients with moderate to severe regurgitation while on ECMO were less likely to survive for 1 month after decannulation, with an odds ratio of 16.63 (95% confidence interval 3.08, 89.70; p = 0.001). Also female sex increased the odds of death by a factor of 5.43 (95% confidence interval 1.45, 20.36; p = 0.012). CONCLUSIONS Severity of systemic AV valve regurgitation on ECMO is a more reliable predictor than ejection fraction for survival at 1 month after decannulation. Patients with less than moderate AV valve regurgitation have a significantly better chance of survival.

Resolution of Acquired Pulmonary Arteriovenous Malformations in a Patient with Total Anomalous Systemic Venous Return

An 11-year-old male with total anomalous systemic venous return had surgical repair except for the hepatic venous return, which drained to the left atrium. He developed progressive cyanosis and fatigue and was diagnosed with large pulmonary arteriovenous malformations (PAVMs) during cardiac catheterization with the use of bubble contrast echocardiography. After surgical redirection of hepatic venous flow to the right heart and pulmonary arterial system, resolution of these PAVMs was demonstrated clinically and by contrast echocardiography. This unique case report demonstrates the development of PAVMs with exclusion of hepatic venous return through the pulmonary vascular bed while pulsatile pulmonary blood flow remains intact. It reinforces the likelihood of the absence of an as yet unidentified hepatic vasoactive substance as the source for development of PAVMs.

Relationship of Echocardiographic Z Scores Adjusted for Body Surface Area to Age, Sex, Race, and EthnicityCLINICAL PERSPECTIVE: The Pediatric Heart Network Normal Echocardiogram Database

Background— Published nomograms of pediatric echocardiographic measurements are limited by insufficient sample size to assess the effects of age, sex, race, and ethnicity. Variable methodologies have resulted in a wide range of Z scores for a single measurement. This multicenter study sought to determine Z scores for common measurements adjusted for body surface area (BSA) and stratified by age, sex, race, and ethnicity. Methods and Results— Data collected from healthy nonobese children ⩽18 years of age at 19 centers with a normal echocardiogram included age, sex, race, ethnicity, height, weight, echocardiographic images, and measurements performed at the Core Laboratory. Z score models involved indexed parameters (X/BSA&agr;) that were normally distributed without residual dependence on BSA. The models were tested for the effects of age, sex, race, and ethnicity. Raw measurements from models with and without these effects were compared, and <5% difference was considered clinically insignificant because interobserver variability for echocardiographic measurements are reported as ≥5% difference. Of the 3566 subjects, 90% had measurable images. Appropriate BSA transformations (BSA&agr;) were selected for each measurement. Multivariable regression revealed statistically significant effects by age, sex, race, and ethnicity for all outcomes, but all effects were clinically insignificant based on comparisons of models with and without the effects, resulting in Z scores independent of age, sex, race, and ethnicity for each measurement. Conclusions— Echocardiographic Z scores based on BSA were derived from a large, diverse, and healthy North American population. Age, sex, race, and ethnicity have small effects on the Z scores that are statistically significant but not clinically important.

Use of Cardiac Magnetic Resonance Imaging to Determine Myocardial Viability in an Infant with In Utero Septal Myocardial Infarction and Ventricular Noncompaction

We describe the use of cardiac magnetic resonance imaging (CMRI) to determine myocardial viability and subsequently clinical prognosis in a patient with in utero septal myocardial infarction (MI) and dilated cardiomyopathy. MI is most commonly associated with congenital heart disease. These lesions include aortic atresia and stenosis, interrupted aortic arch, hypoplastic left ventricle (LV), and total anomalous pulmonary venous return (TAPVR) [3]. Within the last decade, it has been clearly established that systolic dysfunction is not always a definitive status after MI [10]. In the presence of residual viable myocardium and an adequate myocardial perfusion, contractility might normalize—this process being related to a remarkable prognostic benefit [10]. Until the use of CMRI, myocardial viability has been poorly characterized by other imaging modalities, thus making prognosis difficult to predict. Using myocardial delayed-enhancement CMRI, this patient was shown to have a dilated left ventricle with noncompaction, longitudinal midwall hyperenhancement consistent with nonviable tissue, and severely diminished left ventricular function. In conclusion, CMRI is the only imaging modality that can define anatomy, function, and tissue characterization simultaneously. In the future, CMRI could circumvent the need for more invasive diagnostic procedures in determining the cause and prognosis of patients with dilated cardiomyopathy and myocardial infarction.

CMR techniques and findings in children with myocarditis: a multicenter retrospective study

Background CMR is increasingly used to diagnose myocarditis in adults but its use in pediatric-age pts is not well estab- lished. We sought to describe the clinical presentation, CMR imaging protocols, CMR findings, and outcomes in a multicenter cohort of children with myocarditis. Methods 71 studies (66%) and was abnormal in 49 (69%). First pass contrast perfusion (FPP) imaging was performed in 42 studies (45%) and was abnormal in 4 (10%). T1- weighted imaging for early gadolinium enhancement (EGE) was performed in 35 studies (37%) and was abnor- mal in 19 (51%). Late gadolinium enhancement (LGE) imaging was performed in all studies, and was abnormal in 93 (83%) with the following reported distributions: 89% subepicardial or midwall, 6% patchy, 3% sub-endo- cardial, 1% transmural, and 1% diffuse. The CMR study was interpreted as positive for myocarditis in 96 pts (87%), negative in 11 (10%), and equivocal in 4 (4%), yielding a sensitivity of 86% for an ultimate clinical diag- nosis of myocarditis. There was significant practice varia- tion in the use of T2W, FPP, and EGE imaging among the participating institutions (Figure 1). At a median fol- low-up time from CMR of 6 mo (0.2-217), all patients were alive and 3 had undergone cardiac transplantation, all of whom had CMR studies positive for myocarditis. Conclusions This is the largest study to date describing the CMR findings in children with myocarditis. The CMR techni- ques used, from most to least common, were LGE, T2W, FPP, and EGE. Abnormalities were most often seen with LGE followed by T2W, EGE, and FPP. There was significant practice variation in the CMR protocol between institutions. The information from this study should be useful in planning a prospective study to eval- uate the diagnostic and predictive performance of CMR in children with suspected myocarditis. Funding None.