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139


Ductal arteriosus aneurysm, right aortic arch, and isolated left subclavian artery in a neonate [Case Report]

Scott, Claudeen K F; Meyer, David; Phoon, Colin K L; Srichai, Monvadi B
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
PMID: 19489948
ISSN: 1747-0803
CID: 99247

Is it ventricular diverticulum or closed muscular ventricular septal defect? - Reply [Letter]

Srichai, MB; Phoon, CKL; Jacobs, JE
ISI:000256064700059
ISSN: 0361-803x
CID: 86982

Utility of cardiac monitoring in fetuses at risk for congenital heart block: the PR Interval and Dexamethasone Evaluation (PRIDE) prospective study

Friedman, Deborah M; Kim, Mimi Y; Copel, Joshua A; Davis, Claudine; Phoon, Colin K L; Glickstein, Julie S; Buyon, Jill P
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
PMID: 18195175
ISSN: 1524-4539
CID: 77788

Jean S. Kan, MD: A conversation with Colin K.L. Phoon, MPH, MD [Biography]

Phoon, CKL; Kan, JS
ISI:000252136400025
ISSN: 0002-9149
CID: 75636

Delayed enhancement cardiac magnetic resonance imaging in a patient with Duchenne muscular dystrophy [Case Report]

Guillaume, Melissa D; Phoon, Colin K L; Chun, Anne J L; Srichai, Monvadi B
PMCID:2565516
PMID: 18941638
ISSN: 0730-2347
CID: 97023

Expression of a sorcin missense mutation in the heart modulates excitation-contraction coupling

Collis, Leon P; Meyers, Marian B; Zhang, Jie; Phoon, Colin K L; Sobie, Eric A; Coetzee, William A; Fishman, Glenn I
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.
PMID: 17130302
ISSN: 1530-6860
CID: 72805

Imaging tools for the developmental biologist: ultrasound biomicroscopy of mouse embryonic development

Phoon, Colin Kit Lun
Progress has been rapid in the elucidation of genes responsible for cardiac development. Strategies to ascertain phenotypes, however, have lagged behind advances in genomics, particularly in the in vivo mouse embryo, considered a model organism for mammalian development, and for human development and disease. Over the past several years, our laboratory and others have pioneered a variety of ultrasound biomicroscopy (UBM)-Doppler approaches to study in vivo development in both normal and mutant mouse embryos. This state-of-the-art review will discuss the development and potential of ultrasound biomicroscopy as a tool for the in vivo imaging and phenotyping of both cardiac and non-cardiac organ systems in the early developing mouse. Broad, long-term research objectives are to define living structure-function relationships during critical periods of mammalian morphogenesis
PMID: 16690959
ISSN: 0031-3998
CID: 68628

Finding balance

Phoon, Colin K L
PMID: 16544464
ISSN: 0031-7179
CID: 64203

Noninvasive localization of nuclear factor of activated T cells c1-/- mouse embryos by ultrasound biomicroscopy-Doppler allows genotype-phenotype correlation

Ji, Rui Ping; Phoon, Colin K L
Ultrasound biomicroscopy (UBM)-Doppler allows study of cardiovascular physiology in the in utero mouse embryo from embryonic day (E)8.25 onward. We determined the accuracy of localization of embryos by transabdominal, noninvasive 40-MHz UBM-Doppler imaging. Nuclear factor of activated T cells c1-/- mice lack semilunar valves, exhibit outflow tract regurgitation, and die in utero. In timed pregnant mice generated from heterozygote crosses, an UBM-derived map of the in situ litter was compared with a definitive laparotomy map, and UBM-Doppler cardiac screen attempted for each embryo. All 109 living and dead (nonresorbed) E10.5 to 17.5 embryos were imaged and accurately localized. All 10 embryos with reversed diastolic aortic flow and 7 of 9 dead embryos genotyped were nuclear factor of activated T cells c1-/-. In 30 embryos followed up serially over 1 to 2 days from E12.5 to E16.5, we again achieved 100% accuracy in localizing at follow-up. Noninvasive localization and UBM-Doppler analysis of in situ mouse embryos can provide accurate genotype-phenotype correlation, along with nontraumatic serial imaging of embryos
PMID: 16376776
ISSN: 0894-7317
CID: 63803

Management of anomalous coronary arteries from the contralateral sinus [Case Report]

Mirchandani, Sunil; Phoon, Colin K L
Anomalous origin of the coronary artery from the contralateral sinus of Valsalva, coursing between the aorta and pulmonary artery, has garnered much attention because of its association with sudden death. Current medical opinion is heavily skewed toward 'successful' intervention. However, two key issues have not been critically analyzed: what is the true risk of sudden death from an anomalous coronary artery, and how does this risk balance against the risk of surgical intervention? Common misconceptions about risk derive from citations of autopsy data. In fact, the scant available data suggest a far lower absolute risk than commonly cited. The risks of surgical intervention, while likely quite low, remain real, and include aortic valve damage and neurological sequelae. The lack of long-term outcomes data precludes any definite recommendations in most patients. The decision to intervene is thus not straightforward, and should be approached cautiously and only after appropriate counseling of the patient
PMID: 16004881
ISSN: 0167-5273
CID: 61363