Prevalence and clinical significance of cardiac murmurs in neonates

Congenital heart disease in maternal phenylketonuria: report from the Maternal PKU Collaborative Study

The frequency and types of congenital heart disease in offspring from pregnancies in women with hyperphenylalaninemia were examined in the international prospective Maternal Phenylketonuria Collaborative Study. Relationships of congenital heart disease in offspring to the basal blood phenylalanine level in the mother, metabolic control through diet during pregnancy, and phenylalanine hydroxylase mutations in mother and offspring were determined. The 416 offspring from 412 maternal phenylketonuria pregnancies that produced live births and 100 offspring from the 99 control pregnancies were included in this examination. Thirty-four of the 235 offspring (14%; 95% CI, 10.2 to 19.6%) from pregnancies in phenylketonuric women with a basal phenylalanine level > or = 900 microM (15 mg/dL) [normal blood phenylalanine < 120 microM (2 mg/dL)] and not in metabolic control [phenylalanine level < or = 600 microM (10 mg/dL)] by the eighth gestational week had congenital heart disease compared with one control offspring (1%) with congenital heart disease. One offspring among the 50 (2%) from mothers with non-phenylketonuria mild hyperphenylalaninemia also had congenital heart disease. Coarctation of the aorta and hypoplastic left heart syndrome were overrepresented compared with expected percentages among those with congenital heart disease in the general population. A basal maternal phenylalanine level > 1800 microM (30 mg/dL) significantly increased the risk for bearing a child with congenital heart disease (p = 0.003). Phenylalanine hydroxylase mutations in the mothers and offspring did not have an independent relationship to congenital heart disease but were related through the basal maternal phenylalanine levels. The data in this study indicate that a basal maternal phenylalanine level of 900 microM may be a threshold for congenital heart disease, that women with the most severe degree of phenylketonuria are at highest risk for bearing such a child, and that prevention of the congenital heart disease requires initiation of the low phenylalanine diet before conception or early in pregnancy with metabolic control no later than the eighth gestational week.

Undiagnosed cardiomyopathy in a neonate: significance of low oxygen saturation during anaesthesia

A case study is described of a 7-day-old full term baby with bilateral congenital cataracts who underwent surgical removal of both cataracts 2 days apart. Problems with oxygen saturation during and after the first anaesthetic prompted further investigation that revealed a non-obstructive hypertrophic cardiomyopathy. The significance and possible causes of low oxygen saturation in a previously healthy neonate during anaesthesia are discussed. The likely diagnosis of Sengers syndrome, and the evaluation of asymptomatic babies with cardiac pathology are discussed.

Early diagnosis of congenital heart disease

Routine examination of apparently healthy newborn babies detects less than half of those with congenital cardiac malformations because they are asymptomatic and without signs. More severe cardiac malformations are not detected more easily. A normal clinical examination does not exclude serious congenital cardiac malformation. Left heart obstruction is easily overlooked but often causes serious deterioration in less than 3 weeks. It is important to arrange early echocardiography of babies with signs and to consider cardiac malformation in a sick baby even if a previous routine examination was normal. All babies with Down syndrome should have early expert cardiological assessment.

Limitations of using first-trimester nuchal translucency measurement in routine screening for major congenital heart defects

OBJECTIVE

To evaluate the effectiveness of nuchal translucency (NT) measurement in screening for major congenital heart disease (CHD) in chromosomally normal fetuses.

DESIGN

A population based cohort study of all women having fetal NT measurement at 10-14 weeks of gestation in an unselected population over a 3-year period. The outcome measure was the identification of major CHD in chromosomally normal pregnancies either antenatally or postnatally.

RESULTS

Major defects of the heart and great arteries were identified in 26 out of 7339 pregnancies (prevalence 3.5 per 1000 pregnancies). Out of 26 cases, only four (sensitivity 15.4%, 95% CI 4-35) were in the group of 258 pregnancies (3.5%) with increased NT of > or = 2.5 mm. The prevalence of major CHD increased from 3.1 per 1000 for NT < 2.5 mm to 50 per 1000 for NT > or = 3.5 mm (likelihood ratio of 14.1, 95% CI 4.2-47.9). The positive and negative predictive values for NT > or = 2.5 mm were 1.6% and 99.7%, respectively.

CONCLUSIONS

The prevalence of major CHD in this study was 3.5 per 1000, suggesting that ascertainment of CHD in our study population was thorough. Fetuses with NT measurements > or = 3.5 mm have a significantly increased risk of major CHD, and this identifies a subgroup of high-risk patients in whom early fetal echocardiography would be advocated. The low sensitivity of NT for major CHD in the general population, however, indicates that NT cannot be relied on as the sole or major screening tool for this condition as previously reported.

The natural history of ventricular septal defects

AIMS

To correlate the size and position of isolated ventricular septal defects with closure rate in a cohort of children with mean follow up of more than six years.

DESIGN

A birth cohort was identified using the northern region cardiac database. The following were noted from case notes: defect size, position, means of closure, and age at closure.

RESULTS

68 children were identified. 49 defects were small, 14 were moderate, and 5 were large. 13 cases required surgical closure, including 12 perimembranous defects. 35 defects closed spontaneously. Nine of the small muscular defects remained open and five of the small perimembranous defects remained open. The spontaneous closure rate for muscular defects was significantly greater than for perimembranous defects. Mean age of follow up for patients who still have defects is 76 months.

CONCLUSIONS

The position of a ventricular septal defect is extremely relevant to its natural history. Perimembranous defects accounted for most of the moderate and large defects that required surgical intervention. After more than six years almost a third of all perimembranous and just over two thirds of all muscular defects closed spontaneously.

Presentation of congenital heart disease in infancy: implications for routine examination

AIM

To investigate the performance of routine neonatal and 6 week examinations for detecting congenital heart disease.

METHODS

A retrospective review of findings on clinical examination was conducted of a cohort of live born infants with congenital heart disease in one health region in 1987-94.

RESULTS

Of 1590 babies with congenital heart disease, 523 (33%) presented before neonatal examination because of symptoms or non-cardiac abnormalities. 1061 underwent routine neonatal examination which was abnormal in 476 (45%), but only 170 were referred directly for diagnosis. Of 876 discharged with no diagnosis, 306 presented or died undiagnosed before 6 weeks. At 6 weeks 252 of 569 babies underwent a second routine examination which was abnormal in 164 (65%).

CONCLUSIONS

Routine neonatal examination fails to detect more than half of babies with heart disease; examination at 6 weeks misses one third. A normal examination does not exclude heart disease. Babies with murmurs at neonatal or 6 week examinations should be referred for early paediatric cardiological evaluation which will result either in a definitive diagnosis of congenital heart disease or in authoritative reassurance of normal cardiac anatomy and function.