Estimating the birth prevalence and pregnancy outcomes of congenital malformations worldwide

Congenital anomaly registries have two main surveillance aims: firstly to define baseline epidemiology of important congenital anomalies to facilitate programme, policy and resource planning, and secondly to identify clusters of cases and any other epidemiological changes that could give early warning of environmental or infectious hazards. However, setting up a sustainable registry and surveillance system is resource-intensive requiring national infrastructure for recording all cases and diagnostic facilities to identify those malformations that that are not externally visible. Consequently, not all countries have yet established robust surveillance systems. For these countries, methods are needed to generate estimates of prevalence of these disorders which can act as a starting point for assessing disease burden and service implications. Here, we describe how registry data from high-income settings can be used for generating reference rates that can be used as provisional estimates for countries with little or no observational data on non-syndromic congenital malformations.

Twenty-year trends in diagnosis of life-threatening neonatal cardiovascular malformations

BACKGROUND

Infants with cardiovascular malformations are usually asymptomatic at birth. Earlier diagnosis is likely to improve outcome.

OBJECTIVE

To examine trends in the diagnosis of potentially life-threatening cardiovascular malformations.

METHODS

Ascertainment of all cardiovascular malformations diagnosed in infancy in the resident population of one English health region between 1985 and 2004. Infants with life-threatening cardiovascular malformations were all with hypoplastic left heart, pulmonary atresia with intact ventricular septum, transposition of the great arteries or interruption of the aortic arch; and those dying or undergoing operation within 28 days with coarctation of the aorta, aortic stenosis, pulmonary stenosis, tetralogy of Fallot, pulmonary atresia with ventricular septal defect or total anomalous pulmonary venous connection.

RESULTS

Cardiovascular malformations were diagnosed in infancy in 4444 of 690,215 live births (6.4 per 1000) and were potentially life threatening in 669 (15%). Overall, 55 (8%) were recognised prenatally, 416 (62%) postnatally before discharge from hospital, 168 (25%) in living infants after discharge and 30 (5%) after death. Antenatal diagnoses increased from 0 to around 20% and no case was first diagnosed after death in the past 6 years. However, the proportion going home without a diagnosis remains around 25%. Malformations most likely to remain undiagnosed at discharge were coarctation of the aorta (54%), interruption of the aortic arch (44%), aortic valve stenosis (40%) and total anomalous pulmonary venous connection (37%).

CONCLUSIONS

One in three infants with a potentially life-threatening cardiovascular malformation left hospital undiagnosed. Better early diagnosis is likely to be achieved by further improvements in antenatal diagnosis and more widespread use of routine pulse oximetry.

Guidelines and adenosine dosing in supraventricular tachycardia

This retrospective review of present practice of administration of adenosine by paediatricians shows that current guidelines recommend starting doses that are effective in only 9% of infants and children.

Newborn screening for congenital heart defects: a systematic review and cost-effectiveness analysis

OBJECTIVES

To provide evidence to inform policy decisions about the most appropriate newborn screening strategy for congenital heart defects, identifying priorities for future research that might reduce important uncertainties in the evidence base for such decisions.

DATA SOURCES

Electronic databases. Groups of parents and health professionals.

REVIEW METHODS

A systematic review of the published medical literature concerning outcomes for children with congenital heart defects was carried out. A decision analytic model was developed to assess the cost-effectiveness of alternative screening strategies for congenital heart defects relevant to the UK. A further study was then carried out using a self-administered anonymous questionnaire to explore the perspectives of parents and health professionals towards the quality of life of children with congenital heart defects. The findings from a structured review of the medical literature regarding parental experiences were linked with those from a focus group of parents of children with congenital heart defects.

RESULTS

Current newborn screening policy comprises a clinical examination at birth and 6 weeks, with specific cardiac investigations for specified high-risk children. Routine data are lacking, but under half of affected babies, not previously identified antenatally or because of symptoms, are identified by current newborn screening. There is evidence that screen-positive infants do not receive timely management. Pulse oximetry and echocardiography, in addition to clinical examination, are alternative newborn screening strategies but their cost-effectiveness has not been adequately evaluated in a UK setting. In a population of 100,000 live-born infants, the model predicts 121 infants with life-threatening congenital heart defects undiagnosed at screening, of whom 82 (68%) and 83 (69%) are detected by pulse oximetry and screening echocardiography, respectively, but only 39 (32%) by clinical examination alone. Of these, 71, 71 and 34, respectively, receive a timely diagnosis. The model predicts 46 (0.5%) false-positive screening diagnoses per 100,000 infants with clinical examination, 1168 (1.3%) with pulse oximetry and 4857 (5.4%) with screening echocardiography. The latter includes infants with clinically non-significant defects. Total programme costs are predicted of pound 300,000 for clinical examination, pound 480,000 for pulse oximetry and pound 3.54 million for screening echocardiography. The additional cost per additional timely diagnosis of life-threatening congenital heart defects ranges from pound 4900 for pulse oximetry to pound 4.5 million for screening echocardiography. Including clinically significant congenital heart defects gives an additional cost per additional diagnosis of pound 1500 for pulse oximetry and pound 36,000 for screening echocardiography. Key determinants for cost-effectiveness are detection rates for pulse oximetry and screening echocardiography. Parents and health professionals place similar values on the quality of life outcomes of children with congenital heart defects and both are more averse to neurological than to cardiac disability. Adverse psychosocial effects for parents are focused around poor management and/or false test results.

CONCLUSIONS

Early detection through newborn screening potentially can improve the outcome of congenital heart defects; however the current programme performs poorly, and lacks monitoring of quality assurance, performance management and longer term outcomes. Pulse oximetry is a promising alternative newborn screening strategy but further evaluation is needed to obtain more precise estimates of test performance and to inform optimal timing, diagnostic and management strategies. Although screening echocardiography is associated with the highest detection rate, it is the most costly strategy and has a 5% false-positive rate. Improving antenatal detection of congenital heart defects increases the cost per timely postnatal diagnosis afforded by any newborn screening strategy but does not alter the relative effects of the strategies. An improvement of timely management of screen positive infants is essential. Further research is required to refine the detection rate and other aspects of pulse oximetry, to evaluate antenatal screening strategies more directly, and to investigate the psychosocial effects of newborn screening for congenital heart defects.

A case control study to examine the pharmacological factors underlying ventricular septal defects in the North of England

BACKGROUND

Amphetamine exposure is associated with congenital cardiac abnormalities in animals. We previously reported an association between recreational use of 2,4-methylenedioxymethamphetamine (ecstasy, MDMA) and ventricular septal defect in babies born to users. We have carried out a case control study to investigate risks in the occurrence of ventricular septal defect in a cohort of babies born in the North East of England.

METHODS

Cases were identified from paediatric cardiology units in Newcastle upon Tyne and Leeds, and controls were recruited from the mothers of babies born in the same hospital as the index case. Research nurses carried out interviews using a structured questionnaire.

RESULTS

A total of 296 case control pairs were studied. There was insufficient exposure to ecstasy to test the primary hypothesis. Increased risk of ventricular septal defect was found to be associated with consumption of cough and cold remedies [pre-conception OR 2.2, 95% CI 1.41, 3.51; pregnancy OR 5.1, 95% CI 2.56, 11.27; exposure in either OR 2.83, 95% CI 1.85, 4.45; P<0.005] and in the case of non-steroidals for exposures in pregnancy (OR 4.2, 95% CI 1.54, 14.26; P<0.005).

CONCLUSIONS

These findings suggest that ventricular septal defect is associated with consuming the medications identified. They are also compatible with the hypothesis that sympathomimetics (pseudoephedrine, phenylephrine and phenylpropanolamine) present in cough mixtures cause the increased risk, and with our original hypothesis that sympathomimetics and amphetamines are potentially cardiotoxic in utero.

Variability of four limb blood pressure in normal neonates

AIMS

To assess the variation in blood pressure (BP) between limbs in normal neonates. To assess whether comparison of arm and leg BP in neonates is reproducible enough to allow the difference to raise suspicion of coarctation of the aorta.

METHODS

Infants recruited from the postnatal wards and the postnatal murmur clinic underwent echocardiography and BP measurement in each limb using a Dinamap Compact T 482210. The method of BP measurement was guided by a telephone survey of 40 UK neonatal units.

RESULTS

Forty healthy neonates underwent echocardiography and all had a normal aortic arch. BP was measured in 39. In three, BP in the arms was 20 mm Hg higher than in the legs. This gave a specificity of comparison of the upper and lower limb BPs of 92 (36/39) or a false positive rate of 8% (3/39). The standard deviation in BPs was 15.7 mm Hg between arms, 14.5 mm Hg between legs, and 11 mm Hg when the nearest arm and leg were compared.

CONCLUSIONS

With current measurement techniques, normal neonates may have a wide variation in BP between limbs. A difference of 20 mm Hg in isolation is more likely to be due to random variability in measurement than to coarctation of the aorta. If coarctation of the aorta is suspected, it can only be excluded or confirmed by echocardiography.

Cardiovascular malformations in infants of diabetic mothers

OBJECTIVE

To compare the prevalence at live birth and the spectrum of cardiovascular malformations in infants born to diabetic mothers with pre-existing diabetes with that in infants of non-diabetic mothers.

DESIGN

Prospective study of all live births in the resident population of one health region, with recording of details of the outcome of all pregnancies of women with pre-existing diabetes and of all live born babies with cardiovascular malformations.

RESULTS

In the six years 1995-2000 there were 192 618 live births in the study population. Cardiovascular malformations were confirmed in 22 of 609 (3.6%) babies with diabetic mothers and in 1417 of 192 009 (0.74%) babies with non-diabetic mothers. The odds ratio for a cardiovascular malformation with maternal diabetes was 5.0 (95% confidence interval 3.3 to 7.8). Combination of these results with previous reports and comparison with the spectrum of cardiovascular malformations in infants of non-diabetic mothers shows a greater than threefold excess of transposition of the great arteries, truncus arteriosus, and tricuspid atresia.

CONCLUSIONS

Pre-existing maternal diabetes is associated with a fivefold increase in risk of cardiovascular malformations. Transposition of the great arteries, truncus arteriosus, and tricuspid atresia are overrepresented to produce a substantial excess of these malformations.

The influence of congenital heart disease on survival of infants with oesophageal atresia

OBJECTIVE

To examine the prevalence of congenital heart disease in babies with oesophageal atresia and its influence on outcome.

DESIGN

Retrospective analysis.

SETTING

The resident population of one health region.

RESULTS

A total of 153 babies with oesophageal atresia were identified from 509 975 live births (0.30 per 1000); 26 (17%) had cardiac defects. Survival of babies with normal hearts was 97%, 97%, and 95% at one week, one month, and one year. Survival of babies with congenital heart disease was 85%, 85%, and 67% at one week, one month, and one year, but only one of ten deaths was the result of the congenital heart disease. The remaining deaths were due to other congenital malformations, respiratory disease, or chromosome abnormalities.

CONCLUSIONS

There is a high prevalence of congenital heart disease in babies with oesophageal atresia. Congenital heart disease is associated with a higher mortality in oesophageal atresia but it is not the cause of it.

Survival with congenital heart disease and need for follow up in adult life

OBJECTIVE

To predict the growth in demand for long term follow up of adults with congenital heart disease.

DESIGN

Observed diagnoses of congenital heart disease in infancy and childhood were adjusted for observed infant survival, predicted further survival to age 16 years, underascertainment in older childhood, and predicted need for long term follow up.

SETTING

The resident population of one health region in the UK.

PATIENTS

All confirmed cardiovascular malformations diagnosed in 1985 to 1999 in children born in 1985 to 1994.

RESULTS

1942 cases of congenital heart disease were diagnosed in infancy in a population of 377 310 live births (5.2/1000). 1588 (82%) survived to 1 year and 1514 were predicted to survive to age 16. 605 further diagnoses were made in childhood-678 when adjusted for underascertainment. Thus, 2192 children were predicted to reach age 16, of whom 784 would require long term follow up in adult life. The adult population would comprise 28% complex, 54% significant, and 18% minor congenital heart disease. These figures predict the need for adult follow up of congenital heart disease of over 200 extra cases per 100 000 live births each year or over 1600 extra cases a year every year in the UK.

CONCLUSIONS

The need for follow up of congenital heart disease in adult life is likely to grow linearly, with increasing complexity and increasing need for reinvestigation and reintervention with time. Appropriate provision should be made for adequate manpower, resources, and facilities for care of these patients.

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.

Recommendations of the British Paediatric Cardiac Association for therapeutic cardiac catheterisation in congenital cardiac disease

The aims of these recommendations are to improve the outcome for patients after, and to provide acceptable standards of practice of therapeutic cardiac catheterisation performed to treat congenital cardiac disease. The scope of the recommendations includes all interventional procedures, recognising that for some congenital malformations, surgical treatment is equally as effective as, or occasionally preferable to, interventional treatment. The limitations of the recommendations are that, at present, no data are available which compare the results of interventional treatment with surgery, and certainly none which evaluate the numbers and types of procedures that need to be performed for the maintenance of skills. Thus, there is a recognised need to collect comprehensive data with which these recommendations could be reviewed in the future, and re-written as evidence-based guidelines. Such a review will have to take into account the methods of collection of data, their effectiveness, and the latest developments in technology. The present recommendations should, therefore, be considered as consensus statements, and as describing accepted practice, which could be used as a basis for ensuring and improving the quality of future care.

Natural and unnatural history of pulmonary atresia

OBJECTIVE

To investigate mortality, cause of death, survival, and quality of life in all types of cardiac malformation with congenital pulmonary atresia.

DESIGN

Retrospective analysis.

SETTING

The resident population of one health region with a single tertiary referral centre.

PATIENTS

All babies with pulmonary atresia live born in 1980 to 1995.

MAIN OUTCOME MEASURES

Anatomical classification, total mortality, cause of death, duration of survival, exercise ability. All cases were classified as pulmonary atresia with intact septum (PA-IVS), pulmonary atresia with ventricular septal defect (PA-VSD), or pulmonary atresia with complex cardiac malformation (complex pulmonary atresia).

RESULTS

129 cardiac malformations with congenital pulmonary atresia were identified from 601 635 live births (21.4/100 000): 29 had PA-IVS, 60 had PA-VSD, and 40 had complex pulmonary atresia. Total mortality was 72/129 (56%), with 15 deaths in the first week and 49 in the first year. There were 23 surgical deaths, 33 hospital deaths (not related to surgery), and 16 sudden deaths, 12 of which remained unexplained. The sudden death rate was 29/1000 patient years of follow up. Of the 57 survivors, 39% have exercise ability I or II and 61% III or IV. Definitive surgical repair produced better exercise ability.

CONCLUSIONS

Early mortality is high in all types of pulmonary atresia, although survival has improved in recent years. Most children who have not undergone definitive repair have significant exercise limitation.

Temporal variability in birth prevalence of cardiovascular malformations

OBJECTIVE

To investigate changes over time in the prevalence at live birth of cardiovascular malformations and to compare "anatomical" and "physiological" diagnostic hierarchies within a population.

DESIGN

Retrospective and prospective ascertainment of all congenital cardiovascular malformations diagnosed in infancy.

SETTING

The resident population of one health region.

PATIENTS

All infants live born from 1985 to 1997 with cardiovascular malformations confirmed by echocardiography, cardiac catheterisation, surgery or autopsy.

MAIN OUTCOME MEASURES

Year to year variation in prevalence of individual malformations and of "complex", "significant", and "minor" groups.

RESULTS

2671 babies with cardiovascular malformations were confirmed in a denominator population of 477 960 live births (5.6 per 1000). There was no change over 13 years in the birth prevalence of "complex" or "significant" defects, but a highly significant increase in "minor" defects (p < 0.0001), mainly small ventricular septal defects. Termination of pregnancy increased from no cases in 1985 to 16 in 1997 with no demonstrable effect on live born babies with heart defects. A one dimensional "anatomical" diagnostic hierarchy led to under ascertainment of pulmonary atresia by 27%, coarctation of the aorta by 39%, and interruption of the aorta by 100%.

CONCLUSIONS

The apparent increase in live born cardiovascular malformations results mainly from improved diagnosis of minor defects. There has been no change over time in birth prevalence of more serious defects. Spontaneous year to year variation in numbers will make it difficult to ascribe any short term changes to any particular intervention. A two dimensional diagnostic hierarchy is offered as a standard.

Sudden death in children and adolescents

OBJECTIVE

To identify the incidence, causes, and characteristics of sudden death at age 1-20 years.

DESIGN

A review of all deaths at age 1-20 years. Death certificates were obtained from the Office for National Statistics, and further information, where appropriate, from coroners, paediatricians, physicians, and pathologists.

SETTING

The resident population of one English health region in 1985-1994.

RESULTS

In a population of 806 500 children and adolescents aged 1-20 years there were 2523 deaths in 10 years. Medical causes accounted for 1017 deaths (40%); 1236 (49%) were unnatural, and 270 (11%) were sudden. These sudden deaths comprised 142 with a previous diagnosis, the commonest being epilepsy 49 (34%), cardiovascular disease 33 (23%), and asthma 30 (21%); 87 attributed to a cause discovered at necropsy, which was respiratory infection in 32 (37%), other infections in 17 (20%), and unsuspected cardiovascular abnormalities in 26 (30%); 41 remained unexplained.

CONCLUSIONS

Half of all sudden deaths in children or adolescents were attributed to an already diagnosed condition. Abnormalities identified at necropsy accounted for one third of sudden deaths. Undiagnosed hypertrophic cardiomyopathy caused less than one death per million person years in the population aged 1-20 years. Unexplained sudden death, which may be caused by primary cardiac arrhythmia, is probably about 10 times more common.

Ambulatory blood pressure in schoolchildren

OBJECTIVE

To define the range and variability of ambulatory blood pressure in normal schoolchildren.

DESIGN

Prospective study.

METHODS

Resting blood pressure of 1121 schoolchildren from Newcastle upon Tyne was recorded. An ambulatory blood pressure device, which uses both auscultatory (Korotkoff) and oscillometric methods of blood pressure measurement, was then put in place for 24 hours.

RESULTS

The day was divided into three time periods: school, home, and night time. Normal centiles for blood pressure for each of these time periods were obtained and many daytime readings were outside reported normal resting levels. The normal variation of blood pressure was quantified by comparing each of these time periods with the resting readings. Resting systolic blood pressure did not predict 24 hour mean systolic blood pressure.

CONCLUSIONS

The availability of normal ambulatory blood pressure data on the level and variation of blood pressure in children may facilitate the early identification of hypertension in this age group.

Fate of the stented arterial duct

BACKGROUND

The technical aspects of ductal stenting have been reported, but little is known of the fate of the duct after stent implantation.

METHODS AND RESULTS

Nineteen patients underwent stent implantation to maintain ductal patency. Eight had hypoplastic left heart (HLH) syndrome, 10 had pulmonary atresia, and 1 had tricuspid atresia. Median survival with HLH was 57 (12 to 907) days. Stent implantation was successful in all cases of HLH, but there were no long-term survivors. Two well-palliated infants died at transplantation. Median survival with duct-dependent pulmonary flow was 183 (0 to 1687) days, with 3 patients well at latest follow-up (56, 55, and 9 months, respectively). There were 2 operative deaths due to ductal spasm and 4 late deaths, 1 due to duct thrombosis, 1 due to chronic lung disease, and 2 of unknown cause. Stent implantation failed in 4 of the 11 cases. Assessment of endothelialization was possible in 13 cases; the stent was partially covered in 3 and fully endothelialized in all 10 cases assessed >8 weeks after implantation. In patients stented for inadequate pulmonary flow, ductal intimal hyperplasia occurred by 9 months in all 3 survivors but responded to repeated dilation.

CONCLUSIONS

Ductal stenting cannot be recommended. In patients with HLH, it provides only short-term palliation even when combined with pulmonary artery banding. With duct-dependent pulmonary blood flow, the procedure carries high risk, and duration of palliation is poor. In patients with bilateral ducts and absent central pulmonary arteries, good palliation may be achieved, but repeated angioplasty is necessary to counteract intimal hyperplasia.

Prevalence and clinical significance of cardiac murmurs in neonates

AIM

To determine the prevalence and clinical significance of murmurs detected during routine neonatal examination.

METHODS

In a two year prospective study, 7204 newborn babies underwent routine examination by senior house officers. All those with murmurs underwent echocardiographic examination. All babies presenting later in infancy were also identified, to ascertain the total prevalence of congenital heart disease in infancy.

RESULTS

Murmurs were detected in 46 babies (0.6%) of whom 25 had a cardiac malformation. The most common diagnosis was a ventricular septal defect, although four babies had asymptomatic left heart outflow obstruction. A further 32 infants from the same birth cohort had a normal neonatal examination but were found to have a cardiac malformation before 12 months of age.

CONCLUSIONS

The neonatal examination detects only 44% of cardiac malformations which present in infancy. If a murmur is heard there is a 54% chance of there being an underlying cardiac malformation. Parents and professionals should be aware that a normal neonatal examination does not preclude a clinically significant cardiac malformation. The detection of a murmur should prompt early referral to a paediatric cardiologist for diagnosis or appropriate reassurance.

Examination for cardiac malformations at six weeks of age

AIM

To attempt to define the prevalence and significance of murmurs detected on routine clinical examination at six to eight weeks.

METHODS

A retrospective review of the results of routine clinical examination of a cohort of 6 to 8 week old babies resident in Newcastle upon Tyne, was carried out in two 12 month periods. All cardiac defects diagnosed in infancy in the same cohort were ascertained.

RESULTS

7132 babies were eligible for routine examination; 83% of these were examined. Murmurs were heard in 47 of 5395 babies and in 11 of 25 referred for evaluation congenital heart disease was found. The six to eight week examination led to diagnosis of 11 of 35 cases (31%) of congenital heart disease in the study population.

CONCLUSIONS

Nearly one baby in 100 had a murmur on routine examination at six to eight weeks. Nearly half of those with murmurs who were referred had a structural cardiovascular malformation.

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.

Atrial fibrillation with neonatal pulmonary lymphangiectasia

A female infant born at 28 weeks' gestation was found to have mild hydrops foetalis. Initial echocardiography showed a structurally normal heart. During the first week of life, episodic atrial tachycardia with 1:1 or 2:1 conduction was seen, requiring therapy with digoxin. The infant remained ventilator dependent, with a persistent, chylous pleural effusion which contained a preponderance of lymphocytes. Congenital pulmonary lymphangiectasia (CPL) was confirmed histologically. Worsening episodes of atrial tachycardia, including episodes of atrial fibrillation, were further investigated and a repeat echocardiogram revealed thickening of the entire right atrial wall. The cardiac findings of a thickened right atrial wall with the histological signs of myocarditis were thought to be the cause of paroxysms of atrial fibrillation, an extremely rare arrhythmia in the neonatal period. To the authors' knowledge there have been no previous reports of CPL in association with the cardiac abnormalities described herein.

A population study of chromosome 22q11 deletions in infancy

AIMS

To determine the prevalence of submicroscopic deletions within chromosome band 22q11 in infants with significant heart disease and compare this with the prevalence of other chromosomal abnormalities causing significant heart disease. To determine a minimum prevalence of deletions within chromosome band 22q11 in infants in the general population.

METHODS

Chromosome analysis was performed on samples from infants born in the former UK Northern Health Region in 1994 and 1995 who either had significant heart disease or who were suspected to have a chromosome band 22q11 deletion following referral to the Northern Genetics Service. Significant heart disease was defined as major structural malformation or cases where invasive investigation or intervention was required in infancy.

RESULTS

Chromosome band 22q11 deletions were identified in nine infants in a population of 69,129 livebirths, giving a minimum prevalence of 13 per 100,000 (95% confidence interval 4.5 to 21.5). Six cases had significant heart disease, one of whom died before diagnosis. In the same population there were 53 cases of trisomy 21, 15 of whom had significant heart disease.

CONCLUSION

The most common chromosomal cause of significant congenital heart disease remains trisomy 21, while the second most common chromosomal cause is deletion in chromosome band 22q11.

Validation of the Takeda 2421 ambulatory blood pressure monitor in children

The purpose of this study was to assess the accuracy of an ambulatory monitor (Takeda 2421; A&D company) which measures blood pressure using oscillometric and Korotkoff methods, in children. Blood pressure was measured simultaneously by the device and two observers in 529 children aged 7-15 years. The Korotkoff method received BHS grade A for sitting and standing readings in all age groups except for age 13-15 years (grade C). The diastolic readings (phase V) received grade B for sitting and C when standing. The oscillometric method received grade C or worse for systolic and diastolic blood pressure in both sitting and standing positions except for systolic readings in those aged 13-15 years (grade B). During the ambulatory phase 30% of the Korotkoff readings and 4% of the oscillometric readings gave an error code. The Takeda 2421 ambulatory monitor achieved generally satisfactory grades using the Korotkoff system but the oscillometric readings were generally unacceptable. Ambulatory devices should be specifically validated in children before being accepted into clinical paediatric practice.

Incessant tachycardias

Incessant tachycardias are some of the rarer forms of normal QRS tachycardias. They are usually diagnosed in infancy or childhood and often present with heart failure secondary to left ventricular dysfunction. Permanent junctional reciprocating tachycardia is a rare type of orthodromic atrioventricular re-entry. Control with drugs is possible but best long-term results are achieved with radio-frequency ablation. Congenital His bundle tachycardia is an automatic arrhythmia characterized by ventriculo-atrial dissociation on the electrocardiogram. The risk of atrio-ventricular block with radiofrequency ablation is high and long-term drug treatment is often effective. Atrial ectopic tachycardia is also automatic and may originate in the left or right atrium. Drug suppression is possible but radiofrequency ablation offers the prospect of cure. All three arrhythmias are likely to persist long term. Drug treatment with class IC or class III drugs is most likely to be effective. Rate control or arrhythmia suppression are likely to lead to improvement or normalization of left ventricular function.

IsK and KvLQT1: mutation in either of the two subunits of the slow component of the delayed rectifier potassium channel can cause Jervell and Lange-Nielsen syndrome

The Jervell and Lange-Nielsen syndrome (JLNS) comprises profound congenital sensorineural deafness associated with syncopal episodes. These are caused by ventricular arrhythmias secondary to abnormal repolarisation, manifested by a prolonged QT interval on the electrocardiogram. Recently, in families with JLNS, Neyroud et al. reported homozygosity for a single mutation in KVLQT1 , a gene which has previously been shown to be mutated in families with dominantly inherited isolated long QT syndrome [Neyroud et al . (1997) Nature Genet ., 15, 186-189]. We have analysed a group of families with JLNS and shown that the majority are consistent with mutation at this locus: five families of differing ethnic backgrounds were homozygous by descent for markers close to the KVLQT1 gene and a further three families from the same geographical region were shown to be homozygous for a common haplotype and to have the same homozygous mutation of the KVLQT1 gene. However, analysis of a single small consanguineous family excluded linkage to the KVLQT1 gene, establishing genetic heterogeneity in JLNS. The affected children in this family were homozygous by descent for markers on chromosome 21, in a region containing the gene IsK . This codes for a transmembrane protein known to associate with KVLQT1 to form the slow component of the delayed rectifier potassium channel. Sequencing of the affected boys showed a homozygous mutation, demonstrating that mutation in the IsK gene may be a rare cause of JLNS and that an indistinguishable phenotype can arise from mutations in either of the two interacting molecules.

Strategies for antenatal detection of Down's syndrome

AIM

To predict the effect of maternal serum screening and fetal echocardiography on the birth prevalence of Down's syndrome.

METHODS

The outcome of all Down's syndrome pregnancies in the Northern Health Region between 1985 and 1991 was retrospectively ascertained. The number and outcome of all Down's syndrome pregnancies were used to define a theoretical population which would exist in the absence of screening. Published reports were used to predict the effects of screening strategies.

RESULTS

Down's syndrome was identified in 412 pregnancies of which 315 (76%) resulted in live birth. A theoretical population with no antenatal screening would be expected to produce 31 stillbirths and 381 (92%) live births affected by Down's syndrome. In the same population a programme of maternal serum screening and fetal echocardiography would lead to 155 and 14 terminations, respectively, and when combined, would reduce affected live births to 229 (56%).

CONCLUSIONS

Even if maternal serum screening and fetal echocardiography achieve their predicted potential, around half of all pregnancies affected by Down's syndrome will result in live born babies.

Digoxin or flecainide for prophylaxis of supraventricular tachycardia in infants?

OBJECTIVES

This study compared the safety and efficacy of digoxin and flecainide in the prophylaxis of supraventricular tachycardia in infants.

BACKGROUND

Recurrence of supraventricular tachycardia in infants is common. Digoxin is the conventional drug of first choice for prophylaxis, but its efficacy has not been tested in a controlled clinical trial, and there is no consensus on the drug of choice when digoxin is ineffective.

METHODS

We reviewed retrospectively the records of all infants with supraventricular tachycardia due to atrioventricular (AV) reentry admitted to our hospital between January 1986 and December 1993.

RESULTS

Thirty-nine infants presented with sustained AV reentrant tachycardia at age 1 to 330 days (median 12). Intravenous flecainide was required to maintain immediate control in six patients who were then treated with oral flecainide. The other 33 patients were treated with oral digoxin. There was no recurrence of tachycardia in 14 (42%) of the 33 patients (95% confidence interval [CI] 25% to 61%). In the other 19 patients (58%) (95% CI 39% to 75%), digoxin was replaced by oral flecainide because of multiple recurrence of tachycardia. Full control was achieved in all 19 of these patients (100%) (95% CI 82% to 100%) and in 5 of the 6 patients treated with both intravenous and oral flecainide. Thus, overall, flecainide was effective in 24 (96%) of 25 patients (95% CI 80% to 100%).

CONCLUSIONS

Comparison with previous natural history studies suggests that digoxin is ineffective in the prophylaxis of supraventricular tachycardia. Oral flecainide was effective in a small number of infants, with no adverse effects (95% CI 0% to 12%), and may now be preferred as the primary prophylactic agent.

Antenatal diagnosis of congenital heart disease and Down's syndrome: the potential effect on the practice of paediatric cardiology

OBJECTIVE

To predict the effect of antenatal ultrasound screening for congenital heart disease and maternal serum screening of Down's syndrome on the practice of paediatric cardiology and paediatric cardiac surgery.

DESIGN

A retrospective and prospective ascertainment of all congenital heart disease diagnosed in infancy in 1985-1991.

SETTING

One English health region.

PATIENTS

All congenital heart disease diagnosed in infancy by echocardiography, cardiac catheterisation, surgery, or necropsy was classified as "complex", "significant", or "minor" and as "detectable" or "not detectable" on a routine antenatal ultrasound scan.

RESULTS

1347 infants had congenital heart disease which was "complex" in 13%, "significant" in 55%, and "minor" in 32%. 15% of cases were "detectable" on routine antenatal ultrasound. Assuming 20% detection and termination of 67% of affected pregnancies, liveborn congenital heart disease would be reduced by 2%, infant mortality from congenital heart disease by 5%, and paediatric cardiac surgical activity by 3%. Maternal screening for Down's syndrome, assuming 75% uptake, 60% detection, and termination of all affected pregnancies, would reduce liveborn cases of Down's syndrome by 45%, liveborn cases of congenital heart disease by 3.5%, and cardiac surgery by 2.6%.

CONCLUSIONS

Screening for congenital heart disease using the four chamber view in routine obstetric examinations and maternal serum screening for Down's syndrome is likely to have only a small effect on the requirements for paediatric cardiology services and paediatric cardiac surgery.

Differences in amiodarone, digoxin, flecainide and sotalol concentrations between antemortem serum and femoral postmortem blood

1. The concentrations of amiodarone/desethylamiodarone, digoxin, flecainide and sotalol were measured in serum collected immediately prior to death and in postmortem blood collected from the femoral vein and artery of an 18-year-old male with congenital heart disease who developed a fatal arrhythmia. 2. The concentrations of all four drugs in the sample collected during life were consistent with the dosage given and in the range accepted for normal therapy. 3. There were no differences in amiodarone/desethylamiodarone, flecainide and sotalol concentrations in arterial or venous postmortem blood. 4. The concentrations of desethylamiodarone, digoxin, flecainide and sotalol but not amiodarone, were higher in postmortem blood than in antemortem serum. The flecainide concentration was significantly greater than the upper limit associated with toxicity in life. Without knowledge of the true concentration measured in life, this apparently high, toxic concentration would have suggested that death could have resulted from arrhythmogenic/proarrhythmic effects of the drug in excess. 5. These results further demonstrate the hazards in interpreting postmortem blood concentrations following suspected drug intoxication.

Presentation of obstructive left heart malformations in infancy

This study documents the presentation of acutely life threatening congenital heart disease in infancy in order to assess the performance of screening examinations soon after birth and at 6 weeks of age. All cases of obstructive left heart malformations presenting in infancy in one health region from 1987-91 were analysed retrospectively. Altogether, 120 infants presented with either hypoplastic left heart syndrome, interruption of the aortic arch, coarctation of the aorta, or aortic valve stenosis. Twelve became symptomatic or died within 24 hours. Thirty four had an abnormal neonatal examination, eight of whom were referred. Six more became symptomatic before discharge. Ninety four babies went home, 51 developed heart failure before 6 weeks, and another seven died without diagnosis. Twenty five of 36 (69%) reaching 6 weeks without diagnosis had a second examination which was abnormal in 17. Two babies died undiagnosed after 6 weeks and the other 18 presented at up to 11 months of age. The neonatal and 6 week examinations perform poorly as screening tests for congenital heart disease. A normal neonatal examination does not exclude life threatening congenital heart disease.

Internal splints for prevention of first web contracture following severe disruption of the first web space

Different internal spring-splint configurations were examined to determine the most effective in preventing adduction contracture after severe injuries disrupting the first web space.

Death in infancy from unrecognised congenital heart disease

This study was undertaken to identify all congenital heart disease in infancy, including deaths before diagnosis, to provide a truer picture of the spectrum of congenital heart disease and to assess the 'treatability' of those dying before diagnosis. All births, infant deaths, and surviving babies with congenital heart disease in one health region in 1985-90 were identified and were classified as 'complex', 'significant', or 'minor'. Of the 1074 infants diagnosed in infancy, 185 died and 56 of these (30%) died undiagnosed. Severe non-cardiac malformations were present in 29 of the 56 while 27 were otherwise normal. Cardiovascular abnormalities in the latter group were complex in 13/27 and significant in 14/27. Identification of undiagnosed cardiovascular anomalies will improve epidemiological evaluation of congenital heart disease and, more importantly, earlier recognition of treatable abnormalities may reduce mortality.

Screening for fetal cardiac malformations

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End-on aortogram: improved identification of important coronary artery anomalies in tetralogy of Fallot

OBJECTIVE

To identify coronary artery anomalies in patients with tetralogy of Fallot with an aortogram taken with steep caudal and left oblique angulation ("end-on" aortogram).

DESIGN

Prospective evaluation of end-on aortogram in the preoperative angiographic assessment of consecutive patients with tetralogy of Fallot.

SETTING

Regional paediatric cardiology centre.

PATIENTS

34 patients, aged 3 months to 12 years (median age 9 months).

METHODS

An aortogram was performed with steep caudal (38 degrees-45 degrees) and left oblique (0 degrees-30 degrees) angulation under general anaesthetic as part of routine preoperative angiographic assessment.

RESULTS

The origins and courses of the coronary arteries were visualised in all patients and important coronary artery anomalies were identified in four patients: single left coronary artery; single right coronary artery (two patients); separate high origin of left anterior descending. These anomalous coronary vessels crossed the right ventricular outflow tract.

CONCLUSIONS

It is important to identify preoperatively coronary arteries that may interfere with right ventricular outflow tract reconstruction. An aortogram with steep caudal and left oblique angulation is useful in identifying anomalous coronary arteries and more importantly it defines the relation of these vessels to the right ventricular outflow tract.

Ambulatory blood pressure monitoring

Ambulatory blood pressure monitoring (ABPM) in adults is proving to be useful. The aim of this study was to determine if ABPM is accurate in the lower blood pressure range encountered in children and, equally important, whether it is acceptable to children. Thirty one children, between the ages of 6 and 18 years, were assessed using an ambulatory blood pressure monitor that uses an auscultatory method. Blood pressure was measured in the contralateral arm with a mercury sphygmomanometer and an oscillometric device at the beginning and end of the study for comparison. Over a blood pressure range of 90-130 mm Hg systolic and 40-80 mm Hg diastolic, a close agreement was found with the sphygmomanometer; the limits of agreement (+/- 2 SD) were 11.6 mm Hg for systolic blood pressure and 13.6 mm Hg for diastolic blood pressure. The bias was less than 1.0 mm Hg. The ambulatory device was worn by all patients for at least 16 hours with an average of 52 recordings per patient. The majority found the device comfortable to wear and were not woken from sleep.

Ondine's curse and neurally mediated syncope--a new and important association

A 6-year-old boy with congenital central hypoventilation syndrome (Ondine's curse) presented with presyncope. Investigation revealed a diagnosis of neurally mediated syncope. This previously unreported association provides strong evidence that autonomic dysfunction is implicated in both these conditions.