Antibiotic Prophylaxis for Infective Endocarditis: A Survey of Practice Among Pediatric Cardiology Providers.

The 2007 American Heart Association (AHA) guidelines limited antibiotic prophylaxis (AP) for infective endocarditis (IE) to fewer patients with predisposing cardiac conditions (PCC). We surveyed the American Academy of Pediatrics Section on Cardiology and Cardiac Surgery (AAP SOCCS) on their recommendations for AP for a number of PCC and procedures. We report on those 173 respondents who follow the 2007 AHA guidelines. AP rates for high-risk PCCs clearly meeting AHA criteria ranged from 70.5-89.8%. Conversely, for PCCs which did not meet AHA criteria, prescribing rates varied from <1% to 29.5%. PCC for which AP indication was unclear per guidelines, AP rates similarly varied from 9.9-39.8%. Similar variability is noted in AP for various procedures in setting of high-risk PCC. There is variability in AP prescribing practices among pediatric cardiologists based on both underlying PCC and noncardiac procedures in the setting of underlying cardiac disease.

Terbutaline-triggered fetal arrhythmia prior to neonatal diagnosis of Wolff-Parkinson-White syndrome: A case report.

INTRODUCTION: Short-term maternal administration of betamimetics is a common obstetric practice with uses including tocolysis during antenatal corticosteroid administration for fetal lung maturity, intrapartum tachysystole, and prior to external cephalic version. While previous research has demonstrated adverse effects of prolonged use of maternal betamimetics, no prior documentation exists of fetal tachyarrhythmias beyond sinus tachycardia after administration of terbutaline. CASE: This case documents a transient fetal tachyarrhythmia consistent with presumed atrial flutter after maternal administration of terbutaline for external cephalic version. On day of life 9, the neonate presented in supraventricular tachycardia with signs of heart failure and was subsequently diagnosed with Wolff-Parkinson-White syndrome. CONCLUSION: Maternal administration of terbutaline may be associated with transient fetal tachyarrhythmia. In some fetuses, this cardiac arrhythmia may predate diagnosis of an underlying cardiac disorder, warranting close follow-up after delivery.

A unique indication for the senning procedure: Atrioventricular discordance with ventriculoarterial concordance.

OBJECTIVE: We describe experience treating a patient with atrioventricular (AV) discordance with ventriculoarterial (VA) concordance, ventricular septal defect (VSD), and situs inversus. This is a rare congenital lesion in which closing the VSD would septate D-transposition physiology and performing an arterial switch and VSD closure would produce congenitally corrected transposition of the great arteries physiology. As such, it is the only lesion for which an isolated atrial switch (and VSD closure) remains the preferred correction. CASE: A term baby girl born with AV discordance/VA concordance, a large VSD, and situs inversus totalis was palliated with atrial septostomy on day of life 3 to allow for optimal mixing and pulmonary artery banding during the 6th week of life to control symptoms of pulmonary overcirculation and protect the pulmonary vasculature. At 8 months of age, she underwent complete repair with a Senning atrial switch procedure, VSD closure, and pulmonary artery debanding with pulmonary arterioplasty. RESULTS: The patient underwent corrective surgery with patch closure of the VSD, and the Senning atrial switch procedure resulting in a total anatomic correction. The patient was discharged on postoperative day 6 and is clinically doing well 12 months later. Follow-up transthoracic echocardiogram shows no pulmonary venous baffle obstruction, mild systemic venous baffle obstruction, and moderate pulmonary stenosis/pulmonary insufficiency. CONCLUSION: The isolated atrial switch is rarely employed as its outcomes are inferior to the arterial switch operation in the setting of the dextro-transposition of the great arteries. However, it remains the procedure of choice for AV discordance with VA concordance as it leads to physiologically corrected biventricular circulation.

In-utero idiopathic ductal constriction: a prenatal manifestation of Alagille and Williams syndrome arteriopathy.

OBJECTIVE: Williams and Alagille syndromes are genetic disorders associated with pathologic arterial narrowing. We hypothesized that fetal idiopathic ductus arteriosus (DA) constriction may represent a prenatal manifestation of the arteriopathy associated with these syndromes. METHODS: Multi-institutional case series review of the pre- and postnatal medical records, echocardiograms, and genetic test results of fetuses presenting with idiopathic DA constriction. RESULTS: We identified four cases of idiopathic fetal DA constriction at 21-36 weeks of gestation. All had right ventricular hypertension, dilation, hypertrophy, and dysfunction and either DA constriction or absence. All demonstrated progressive peripheral pulmonary artery stenosis after birth. Three met clinical diagnostic criteria for Alagille syndrome; two tested had confirmatory JAG1 mutations. One also developed supravalvar aortic stenosis after birth and was positive for 7q11.23 deletion (Williams syndrome). CONCLUSION: This is the first case series to suggest that idiopathic fetal DA constriction may be a prenatal manifestation of genetic arteriopathy.

Hemodynamic study of TCPC using in vivo and in vitro 4D Flow MRI and numerical simulation.

INTRODUCTION: Altered total cavopulmonary connection (TCPC) hemodynamics can cause long-term complications. Patient-specific anatomy hinders generalized solutions. 4D Flow MRI allows in vivo assessment, but not predictions under varying conditions and surgical approaches. Computational fluid dynamics (CFD) improves understanding and explores varying physiological conditions. This study investigated a combination of 4D Flow MRI and CFD to assess TCPC hemodynamics, accompanied with in vitro measurements as CFD validation. 4D Flow MRI was performed in extracardiac and atriopulmonary TCPC subjects. Data was processed for visualization and quantification of velocity and flow. Three-dimensional (3D) geometries were generated from angiography scans and used for CFD and a physical model construction through additive manufacturing. These models were connected to a perfusion system, circulating water through the vena cavae and exiting through the pulmonary arteries at two flow rates. Models underwent 4D Flow MRI and image processing. CFD simulated the in vitro system, applying two different inlet conditions from in vitro 4D Flow MRI measurements; no-slip was implemented at rigid walls. Velocity and flow were obtained and analyzed. The three approaches showed similar velocities, increasing proportionally with high inflow. Atriopulmonary TCPC presented higher vorticity compared to extracardiac at both inflow rates. Increased inflow balanced flow distribution in both TCPC cases. Atriopulmonary IVC flow participated in atrium recirculation, contributing to RPA outflow; at baseline, IVC flow preferentially traveled through the LPA. The combination of patient-specific in vitro and CFD allows hemodynamic parameter control, impossible in vivo. Physical models serve as CFD verification and fine-tuning tools.

Ventricular kinetic energy may provide a novel noninvasive way to assess ventricular performance in patients with repaired tetralogy of Fallot.

OBJECTIVE: Ventricular kinetic energy measurements may provide a novel imaging biomarker of declining ventricular efficiency in patients with repaired tetralogy of Fallot. Our purpose was to assess differences in ventricular kinetic energy with 4-dimensional flow magnetic resonance imaging between patients with repaired tetralogy of Fallot and healthy volunteers. METHODS: Cardiac magnetic resonance, including 4-dimensional flow magnetic resonance imaging, was performed at rest in 10 subjects with repaired tetralogy of Fallot and 9 healthy volunteers using clinical 1.5T and 3T magnetic resonance imaging scanners. Right and left ventricular kinetic energy (KERV and KELV), main pulmonary artery flow (QMPA), and aortic flow (QAO) were quantified using 4-dimensional flow magnetic resonance imaging data. Right and left ventricular size and function were measured using standard cardiac magnetic resonance techniques. Differences in peak systolic KERV and KELV in addition to the QMPA/KERV and QAO/KELV ratios between groups were assessed. Kinetic energy indices were compared with conventional cardiac magnetic resonance parameters. RESULTS: Peak systolic KERV and KELV were higher in patients with repaired tetralogy of Fallot (6.06 ± 2.27 mJ and 3.55 ± 2.12 mJ, respectively) than in healthy volunteers (5.47 ± 2.52 mJ and 2.48 ± 0.75 mJ, respectively), but were not statistically significant (P = .65 and P = .47, respectively). The QMPA/KERV and QAO/KELV ratios were lower in patients with repaired tetralogy of Fallot (7.53 ± 5.37 mL/[cycle mJ] and 9.65 ± 6.61 mL/[cycle mJ], respectively) than in healthy volunteers (19.33 ± 18.52 mL/[cycle mJ] and 35.98 ± 7.66 mL/[cycle mJ], respectively; P < .05). QMPA/KERV and QAO/KELV were weakly correlated to ventricular size and function. CONCLUSIONS: Greater ventricular kinetic energy is necessary to generate flow in the pulmonary and aortic circulations in repaired tetralogy of Fallot. Quantification of ventricular kinetic energy in patients with repaired tetralogy of Fallot is a new observation. Future studies are needed to determine whether changes in ventricular kinetic energy can provide earlier evidence of ventricular dysfunction and guide future medical and surgical interventions.

4D cardiovascular magnetic resonance velocity mapping of alterations of right heart flow patterns and main pulmonary artery hemodynamics in tetralogy of Fallot.

BACKGROUND: To assess changes in right heart flow and pulmonary artery hemodynamics in patients with repaired Tetralogy of Fallot (rTOF) we used whole heart, four dimensional (4D) velocity mapping (VM) cardiovascular magnetic resonance (CMR). METHODS: CMR studies were performed in 11 subjects with rTOF (5M/6F; 20.1 ± 12.4 years) and 10 normal volunteers (6M/4F; 34.2 ± 13.4 years) on clinical 1.5T and 3.0T MR scanners. 4D VM-CMR was performed using PC VIPR (Phase Contrast Vastly undersampled Isotropic Projection Reconstruction). Interactive streamline and particle trace visualizations of the superior and inferior vena cava (IVC and SVC, respectively), right atrium (RA), right ventricle (RV), and pulmonary artery (PA) were generated and reviewed by three experienced readers. Main PA net flow, retrograde flow, peak flow, time-to-peak flow, peak acceleration, resistance index and mean wall shear stress were quantified. Differences in flow patterns between the two groups were tested using Fisher's exact test. Differences in quantitative parameters were analyzed with the Kruskal-Wallis rank sum test. RESULTS: 4D VM-CMR was successfully performed in all volunteers and subjects with TOF. Right heart flow patterns in rTOF subjects were characterized by (a) greater SVC/IVC flow during diastole than systole, (b) increased vortical flow patterns in the RA and in the RV during diastole, and (c) increased helical or vortical flow features in the PA's. Differences in main PA retrograde flow, resistance index, peak flow, time-to-peak flow, peak acceleration and mean wall shear stress were statistically significant. CONCLUSIONS: Whole heart 4D VM-CMR with PC VIPR enables detection of both normal and abnormal right heart flow patterns, which may allow for comprehensive studies to evaluate interdependencies of post-surgically altered geometries and hemodynamics.

Assessment of left ventricular pre-ejection period in the fetus using simultaneous magnetocardiography and echocardiography.

INTRODUCTION: Fetal magnetocardiography (fMCG) is a promising new technique for assessing fetal rhythm; however, no prior studies have utilized fMCG to evaluate human fetal electromechanical physiology. Pre-ejection period (PEP) is an important measure of the electromechanical activation of the heart, and is altered by disease states and arrhythmias. MATERIALS AND METHODS: A novel technique was used to assess fetal PEP and its relationship to other fetal systolic time intervals, RR interval, and gestational age (GA). 25 normal human fetuses between 19 and 38 weeks' gestation were studied using simultaneous pulsed Doppler ultrasound and fMCG. Correlations among PEP, ejection time, QRS width and RR interval were assessed using linear regression. RESULTS: Across all subjects, PEP was found to correlate with GA (R = 0.57, p < 0.0001), QRS width (R = 0.35, p = 0.026), and RR interval (R = 0.37, p = 0.018). In individual sessions, PEP negatively correlated beat-to-beat with the preceding RR interval. CONCLUSION: PEP exhibits developmental trends that provide a better understanding of the normal development of the human fetal heart.

In utero premature closure of the ductus arteriosus presenting as isolated right ventricular hypertrophy.

BACKGROUND: The etiology of isolated right ventricular hypertrophy (RVH) is distinct from other forms of hypertrophic cardiomyopathy. RVH is typically seen in the setting of pulmonary valve stenosis or Tetralogy of Fallot. A rare cause of isolated RVH is premature closure of the patent ductus arteriosus (PDA) in utero that results in pulmonary hypertension. This can have a range of outcomes, from spontaneous resolution to fetal demise. METHODS: This case report describes a term infant who presented with respiratory distress and striking isolated RVH, pulmonary hypertension, and no PDA. She was treated conservatively with supplemental oxygen. RESULTS: The patient was gradually weaned off oxygen over the course of two weeks and follow-up echocardiography showed resolution of her RVH and pulmonary hypertension by 14 weeks of age. CONCLUSIONS: The presentation and course of this patient with severe isolated RVH is consistent with spontaneous premature closure of the ductus arteriosus in utero.

Overview of fetal arrhythmias.

PURPOSE OF REVIEW: Though fetal arrhythmias account for a small proportion of referrals to a fetal cardiologist, they may be associated with significant morbidity and mortality. The present review outlines the current literature with regard to the diagnosis and, in brief, some management strategies in fetal arrhythmias. RECENT FINDINGS: Advances in echocardiography have resulted in significant improvements in our ability to elucidate the mechanism of arrhythmia at the bedside. At the same time, magnetocardiography is broadening our understanding of mechanisms of arrhythmia especially as it pertains to ventricular arrhythmias and congenital heart block. It provides a unique window to study electrical properties of the fetal heart, unlike what has been available to date. Recent reports of bedside use of fetal ECG make it a promising new technology. Fetal magnetocardiography is also developing. The underlying mechanisms resulting in immune-mediated complete heart block in a small subset of 'at-risk' fetuses is under investigation. SUMMARY: There have been great strides in noninvasive diagnosis of fetal arrhythmias. However, we still need to improve our knowledge of the electromechanical properties of the fetal heart as well as the mechanisms of arrhythmia to further improve outcomes. Multiinstitutional collaborative studies are needed to help answer some of the questions regarding patient, drug selection and management algorithms.