Detection of congenital heart defects
A recent study on epidemiological data of the potential impact of
technology on the diagnosis of congenital malformations demonstrated
that mainly the diagnosis of cardiac malformations that were not
preferentially present with overt symptoms increased in a 14-year
period. The authors suggested that these findings might at least
partially be explained by increased screening uptake (and intensity),
resulting in improved diagnosis of milder cases of selected common
malformations7. Although the detection rates of CHD
have reportedly increased in national or community-wide regional
programs in the last decade8-11, the sensitivity still
ranges somewhat between 22.5 % and 52.8 %12. Local
policies, parental sociodemographics, screening access, operator
expertise and the type of CHD most likely account for the wide
variability in the antenatal diagnosis of CHD13.
However, the most striking issue is that the vast majority of CHDs
actually occur in the population deemed to be at low risk, and only 10
% of fetal CHD cases occur in pregnancies with known risk factors, such
as increased nuchal translucency, family history, or fetal extracardiac
malformations14. The diagnosis of CHD in this
collective clearly shows operator dependency and is directly correlated
with the capability of recognizing that the appearance of the heart
deviates from normal15. This may be related to what
Sklansky & De Vore wrote in their 2016 commentary; i.e., future
prenatal cardiac examination and ameliorated detection of altered
cardiac anatomy should not only be based on the recommended views and
imaging modalities but also on the quality of the clips and the angles
at which they are acquired16.
A controversial debate exists on which set of cardiac scanning planes
should be obtained to screen for CHD. As very recently published, the
implementation of extended cardiac views beyond the four-chamber view
(4CV) (as shown in figure 1) recommended by the 2014 Consensus Report
guidelines for detailed anatomic ultrasound survey led to an increase in
examination time and the frequency of both incomplete scans and the rate
of repeat examinations17. Moreover, the authors stated
that detection of CHDs did not improve in their cohort. Similar findings
were reported by Sun et al., who could not register any significant
change in both referrals and prenatal diagnoses of critical outflow
tract anomalies despite revised obstetrical imaging
guidelines18.
According to a Dutch study addressing the reasons why congenital heart
defects are being missed during fetal life, the lack of adaptational
skills appears to play an important role in undetected
CHDs19. It may also require a logical approach to
understanding congenital heart disease rather than an approach in which
the various lesions are memorized20. A prerequisite
for this is a standardized display of all cardiac diagnostic planes to
capture crucial information on anatomical (spatial) arrangements that
will dictate later functional characteristics of the heart.