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Twenty-year trends in diagnosis of life-threatening neonatal cardiovascular malformations
  1. C Wren,
  2. Z Reinhardt,
  3. K Khawaja
  1. Freeman Hospital, Newcastle upon Tyne, UK
  1. Dr C Wren, Department of Paediatric Cardiology, Freeman Hospital, Newcastle upon Tyne NE7 7DN, UK; christopher.wren{at}nuth.nhs.uk

Abstract

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.

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Cardiovascular malformations are the commonest type of congenital malformation, accounting for 6–10% of all infant deaths and 20–40% of all infant deaths from malformation.1 2 Most babies with serious cardiovascular malformations are asymptomatic at birth.3 Some of them deteriorate or die before the diagnosis is recognised.2 Earlier diagnosis, before clinical deterioration, ought to lead to an improvement in outcome.4

All babies are examined after birth before discharge from hospital. Although this examination is commonly regarded as a screening test, it is known to perform poorly in babies with life-threatening cardiovascular malformations, as there may be no abnormal physical signs before the development of symptoms.5 6 The opportunity for presymptomatic diagnosis may also be reduced by earlier discharge from hospital after delivery.

This study examines trends in the time of diagnosis of potentially life-threatening cardiovascular malformations over a 20-year period.

PATIENTS AND METHODS

Study population

We based this study on the former Northern Health Region of England. The resident population is approximately 3.1 million with a recent average of 35 000 live births per year. All babies with suspected congenital heart disease are referred to a single paediatric cardiology centre. We identified all live born babies with a cardiovascular malformation from the regional paediatric cardiology database.7 We identified all those dying before diagnosis by the Northern Congenital Abnormality Survey.8 This survey also provided data on terminations of pregnancy for antenatally diagnosed heart defects and on total live births.

Case definition

We included all live born infants with potentially life-threatening cardiovascular malformations born in 1985–2004. We considered as having a potentially life-threatening abnormality all infants with a diagnosis of hypoplastic left heart, pulmonary atresia with intact ventricular septum, simple transposition of the great arteries, or interruption of the aortic arch and all infants dying or undergoing an operation within the first 28 days of life with the following diagnoses: coarctation of the aorta, aortic valve stenosis, pulmonary valve stenosis, tetralogy of Fallot, pulmonary atresia with ventricular septal defect, or total anomalous pulmonary venous connection. In infants with two life-threatening malformations the first presenting was coded (eg, an infant with transposition of the great arteries and coarctation of the aorta was coded as transposition). We used the 28-day limit for pragmatic reasons, although we recognise that the risk of death from undiagnosed cardiovascular malformations may be present after that age. In a previous report we documented sudden death from critical aortic valve stenosis in two babies at the age of 2 months.2

The Newcastle and North Tyneside Local Research Ethics Committee approved the study.

RESULTS

In 1985–2004 there were 690 215 live births in the study population. A diagnosis of a cardiovascular malformation was made in 4444 (6.4 per 1000) and 669 (15%) of these met our criteria for life-threatening congenital cardiovascular malformation defined above. There was a 20% fall in the live birth rate from nearly 39 000 to around 30 000 per year, but there was no change in the prevalence at live birth of life-threatening cardiovascular malformations over the 20 years of the study, with a mean of 0.97 per 1000 live births.

Of 669 infants with life-threatening cardiovascular malformations, 55 (8%) had an antenatal diagnosis, 416 (62%) had a postnatal diagnosis before discharge from hospital, 168 (25%) were diagnosed in living infants after discharge from hospital and 30 (5%) were diagnosed only at autopsy. Figure 1 shows that over 20 years the proportion with an antenatal diagnosis increased to about 20% and overall there was a decrease in the proportion of cases diagnosed before discharge from hospital.

Figure 1 Time of diagnosis by year of birth 1985–2004.

What is already known on this topic

  • Early diagnosis of asymptomatic cardiovascular malformations is difficult as clinical examination performs poorly as a screening test.

  • Earlier diagnosis improves outcome.

Cardiovascular malformations were undiagnosed at the time of discharge from hospital in 198 infants (30%) and in 30 of these the diagnosis was made only after death. Table 1 shows the timing of diagnosis of individual malformations. Figure 2 shows that the diagnoses most likely to be unrecognised at the time of discharge included coarctation of the aorta (54%), interruption of the aortic arch (44%), aortic valve stenosis and total anomalous pulmonary venous connection (37%).

Figure 2 Time of diagnosis for individual malformations (ranked according to probability of predischarge diagnosis). For abbreviations see table 1.
Table 1 Timing of diagnosis for individual malformations

What this study adds

  • Life-threatening cardiovascular malformations are present at live birth in 1 baby in 1000, but 25% of these are discharged without being diagnosed.

  • Coarctation of the aorta, interruption of the aortic arch, total anomalous pulmonary venous connection and aortic valve stenosis are the diagnoses most likely to be overlooked.

Over 20 years the all-causes 12-month mortality for live born infants with life-threatening cardiovascular malformations fell from around 50% to around 20%.

There were 139 terminations of pregnancy in fetuses with a cardiovascular malformation. The majority had associated major chromosomal or other non-cardiac abnormalities, but 60 had isolated cardiovascular malformations which would meet our criteria for being potentially life-threatening in postnatal life. The rate of termination increased, with 14 in the first 10 years and 46 in the second 10 years.

We have no regional data on the length of hospital stay after birth.

DISCUSSION

Our study has found that around 30% of infants with potentially life-threatening cardiovascular malformations were undiagnosed at the time of discharge from hospital. This proportion fell to around 25% in recent years. Terminations of pregnancy increased, but there was no change in the prevalence at live birth of life-threatening cardiovascular malformations, which remained at around 1 in 1000 live births. Despite this, the total infant mortality for such babies has reduced substantially.

Earlier postnatal recognition of potentially serious cardiovascular malformations should contribute to reduction in morbidity and mortality.4 9 There is also evidence that prenatal diagnosis improves postnatal outcome for a number of malformations, including transposition of the great arteries,10 hypoplastic left heart11 and coarctation of the aorta.12

There have been few other studies of the timing of diagnosis of potentially life-threatening cardiovascular malformations. In a recent report Mellander and Sunnegårdh investigated postdischarge diagnosis in neonates and young infants with critical heart disease.13 They included all infants requiring surgery or catheter intervention in the first 2 months of life and thus had a wider range of diagnoses over a longer time period than our study. Mellander and Sunnegårdh found that 50% of their patients had duct-dependent systemic circulation, 41% had duct-dependent pulmonary circulation and 9% were not duct dependent. The proportion of their patients diagnosed after discharge from hospital averaged 20% but doubled over 9 years. Their study did not include patients not referred for surgery or dying before diagnosis and could not take account of changes in prenatal diagnosis or termination of pregnancy.

In a much smaller study from a hospital with only 2300 births a year Meberg et al reported a lower rate of late diagnosis.14 They also found that coarctation of the aorta and aortic valve stenosis were the potentially dangerous malformations most likely to be overlooked before discharge.

Influences on the speed of recognition of life-threatening cardiovascular malformations include antenatal diagnosis, the speed of referral of babies with a clinical suspicion of congenital heart disease and the length of stay in the maternity hospital after birth. We are unaware of any published data from the United Kingdom on age at discharge, but reports from Sweden, the United States and Canada show a reduction from 4 or 5 days in the 1980s to 1–3 days in the 1990s.1519 It is likely that the trend towards earlier discharge in our population mirrors that in the UK nationally, with an increasing proportion of babies being sent home 6–12 hours after delivery.

In a previous study we found that the diagnosis of cardiovascular malformations is often delayed despite the detection of a murmur at the first neonatal examination.5 It is impractical to refer all neonates with murmurs for urgent paediatric cardiology assessment, but if a significant murmur is detected and echocardiography skills are available in the neonatal unit, earlier diagnosis of potentially serious cardiovascular malformation ought to lead to a better outcome.20 21

Given the failure of clinical examination to increase the number of babies with serious heart disease detected before discharge, any improvement is likely to come from a different strategy. This will include further improvements in antenatal diagnosis,22 more widespread adoption of routine pulse oximetry in the newborn,2325 and better education of midwives and other primary healthcare professionals that the absence of physical signs at birth does not mean that there is no life-threatening problem.3 The trend towards a shorter postnatal length of stay is likely to continue.

Acknowledgments

We are indebted to Valerie Sutherland for helping with data extraction, to the Children’s Heart Unit Fund for financial support of the paediatric cardiology database and to the Northern Congenital Abnormality Survey for providing additional data.

REFERENCES

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Footnotes

  • Competing interests: None.

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