Faculty Bibliography

OBJECTIVE: The recurrence rate of anti-SSA/Ro-associated congenital heart block (CHB) is 17%. Sustained reversal of third-degree block has never been achieved. Based on potential reduction of maternal autoantibody titers as well as fetal inflammatory responses, intravenous immunoglobulin (IVIG) was evaluated as preventive therapy for CHB. METHODS: A multicenter, prospective, open-label study based on Simon's 2-stage optimal design was initiated. Enrollment criteria included the presence of anti-SSA/Ro antibodies in the mother, birth of a previous child with CHB/neonatal lupus rash, current treatment with < or = 20 mg/day of prednisone, and <12 weeks pregnant. IVIG (400 mg/kg) was given every 3 weeks from week 12 to week 24 of gestation. The primary outcome was the development of second-degree or third-degree CHB. RESULTS: Twenty mothers completed the IVIG protocol before the predetermined stopping rule of 3 cases of advanced CHB in the study was reached. CHB was detected at 19, 20, and 25 weeks; none of the cases occurred following the finding of an abnormal PR interval on fetal Doppler monitoring. One of these mothers had 2 previous children with CHB. One child without CHB developed a transient rash consistent with neonatal lupus. Sixteen children had no manifestations of neonatal lupus at birth. No significant changes in maternal titers of antibody to SSA/Ro, SSB/La, or Ro 52 kd were detected over the course of therapy or at delivery. There were no safety issues. CONCLUSION: This study establishes the safety of IVIG and the feasibility of recruiting pregnant women who have previously had a child with CHB. However, IVIG at low doses consistent with replacement does not prevent the recurrence of CHB or reduce maternal antibody titers

Neural crest-specific ablation of BMP type IA receptor (BMPRIA) causes embryonic lethality by embryonic day (E) 12.5, and this was previously postulated to arise from a myocardial defect related to signaling by a small population of cardiac neural crest cells (cNCC) in the epicardium. However, as BMP signaling via cNCC is also required for proper development of the outflow tract cushions, precursors to the semilunar valves, a plausible alternate or additional hypothesis is that heart failure may result from an outflow tract cushion defect. To investigate whether the outflow tract cushions may serve as dynamic valves in regulating hemodynamic function in the early embryo, in this study we used noninvasive ultrasound biomicroscopy-Doppler imaging to quantitatively assess hemodynamic function in mouse embryos with P0-Cre transgene mediated neural crest ablation of Bmpr1a (P0 mutants). Similar to previous studies, the neural crest-deleted Bmpr1a P0 mutants died at approximately E12.5, exhibiting persistent truncus arteriosus, thinned myocardium, and congestive heart failure. Surprisingly, our ultrasound analyses showed normal contractile indices, heart rate, and atrioventricular conduction in the P0 mutants. However, reversed diastolic arterial blood flow was detected as early as E11.5, with cardiovascular insufficiency and death rapidly ensuing by E12.5. Quantitative computed tomography showed thinning of the outflow cushions, and this was associated with a marked reduction in cell proliferation. These results suggest BMP signaling to cNCC is required for growth of the outflow tract cushions. This study provides definitive evidence that the outflow cushions perform a valve-like function critical for survival of the early mouse embryo.

An excellent imaging tool in the prenatal diagnosis and ongoing evaluation of congenital heart defects, fetal echocardiography is indicated in a selected population at increased risk compared with the general population. For certain 'soft markers' of fetal congenital heart defects, ambiguity in the indications for fetal echo may result in a high referral rate, but low yield of congenital heart disease. Here, we critically examine 4 conditions, 2 maternal and 2 fetal: maternal gestational diabetes, advanced maternal age, isolated echogenic focus, and single umbilical artery. This critical review reveals that more prospective population-based studies with higher power and minimal bias need to be performed to establish the absolute risk of congenital heart defects in a selected population compared with that of the general population. Nonetheless, our analysis indicates that the absolute risk of congenital heart defects associated with each of these markers is low. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians LEARNING OBJECTIVES: After completion of this article, the reader should be able to define which patients should be referred for fetal echocardiography based on known risks, distinguish between relative and absolute risks for fetal congenital heart disease, and summarize fetal anomaly risks for women with altered glucose metabolism

Ductal arteriosus aneurysm (DAA) is a well-recognized condition, especially in infancy, and is usually asymptomatic. We report the first case of a newborn who presented with significant inspiratory stridor and, using multiple imaging investigations, was subsequently diagnosed with the rare constellation of a congenital DAA, a right aortic arch and an isolated left subclavian artery with normal intra-cardiac anatomy. The patient underwent surgical resection of the DAA with significant improvement in symptoms

BACKGROUND: Anti-SSA/Ro-associated third-degree congenital heart block is irreversible, prompting a search for early markers and effective therapy. METHODS AND RESULTS: One hundred twenty-seven pregnant women with anti-SSA/Ro antibodies were enrolled; 95 completed an evaluable course in 98 pregnancies. The protocol included fetal echocardiograms performed weekly from 16 to 26 weeks' gestation and biweekly from 26 to 34 weeks. PR intervals >150 ms were considered prolonged, consistent with first-degree block. Ninety-two fetuses had normal PR intervals. Neonatal lupus developed in 10 cases; 4 were neonatal lupus rash only. Three fetuses had third-degree block; none had a preceding abnormal PR interval, although in 2 fetuses >1 week elapsed between echocardiographic evaluations. Tricuspid regurgitation preceded third-degree block in 1 fetus, and an atrial echodensity preceded block in a second. Two fetuses had PR intervals >150 ms. Both were detected at or before 22 weeks, and each reversed within 1 week with 4 mg dexamethasone. The ECG of 1 additional newborn revealed a prolonged PR interval persistent at 3 years despite normal intervals throughout gestation. No first-degree block developed after a normal ECG at birth. Heart block occurred in 3 of 16 pregnancies (19%) in mothers with a previous child with congenital heart block and in 3 of 74 pregnancies (4%) in mothers without a previous child with congenital heart block or rash (P=0.067). CONCLUSIONS: Prolongation of the PR interval was uncommon and did not precede more advanced block. There was a trend toward more congenital heart block in fetuses of women with previously affected offspring than those without previously affected offspring. Advanced block and cardiomyopathy can occur within 1 week of a normal echocardiogram without initial first-degree block. Echodensities and moderate/severe tricuspid regurgitation merit attention as early signs of injury

Sorcin is a Ca2+ binding protein implicated in the regulation of intracellular Ca2+ cycling and cardiac excitation-contraction coupling. Structural and human genetic studies suggest that a naturally occurring sequence variant encoding L112-sorcin disrupts an E-F hand Ca2+ binding domain and may be responsible for a heritable form of hypertension and hypertrophic heart disease. We generated transgenic mice overexpressing L112-sorcin in the heart and characterized the effects on Ca2+ regulation and cardiac function both in vivo and in dissociated cardiomyocytes. Hearts of sorcin(F112L) transgenic mice were mildly dilated but ventricular function was preserved and systemic blood pressure was normal. Sorcin(F112L) myocytes were smaller than control cells and displayed complex alterations in Ca2+ regulation and contractility, including a slowed inactivation of L-type Ca2+ current, enhanced Ca2+ spark width, duration, and frequency, and increased Na+-Ca2+ exchange activity. In contrast, mice with cardiac-specific overexpression of wild-type sorcin displayed directionally opposite effects on L-type Ca2+ channel function and Ca2+ spark behavior. These data further define the role of sorcin in cardiac excitation-contraction coupling and highlight its negative regulation of SR calcium release. Our results also suggest that additional factors may be responsible for the development of cardiac hypertrophy and hypertension in humans expressing the L112-sorcin sequence variant.