CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 6, November/December 2011
308
AFRICA
distribution of CHD among DS patients is not clear, although
some consistency is observed between certain global areas. This
variation in geographical distribution may be caused by numer-
ous factors, one of which could be the genetic make up of each
nation or global region; or it could be due to specific embryo-
logical mechanisms.
Types of CHD can also be determined by cell characteristics
in each nation or population.
23
The embryology and anatomy of
VSD, ASD and PDA are quite different from that of AVSD.
24-26
Some publications have suggested that ethnicity and different
geographic factors, such as high altitude with lower partial
pressures of oxygen may contribute to a higher frequency of
PDA.
17,27,28
However, these hypotheses need to be tested by
further large-scale multinational collaborative studies.
The most common mode of presentation of CHD in DS was
the routine referral to cardiology clinics, but only 44% of the
cases were presented in this manner. There were 62 patients
(12%) who presented with heart failure; this was probably due
to the fact that these patients were missed or not referred at an
earlier age for cardiac screening. This stresses the importance of
early referral to cardiac clinics.
1,29
The mother’s age is an important risk factor for DS, with the
risk of giving birth to a child with DS increasing from 1 in 1 250
at age 25, to 1 in 1 000 at age 30, to 1 in 400 at age 35, to 1 in 100
at age 40, to 1 in 30 at age over 45 years.
30
Nevertheless, about
80% of infants with DS are born to mothers who are under 35
years of age.
28
In our series, CHD was more common in children
whose mothers were in the age range of 31 to 45 years (71%),
which is comparable with international figures. In addition, the
single and multiple cardiac lesions were nearly doubled in those
of older mothers.
On the other hand, there was no specific association between
ASD and mothers’ ages. Interestingly, we found tetrology of
Fallot in 13 children of mothers who were over 30 years of age,
and not in younger mothers. Coarctation of the aorta is unusual
in patients with DS; however, we found this to occur in 1% of
the cases, which is similar to a previous report from the USA.
15
There are a number of limitations in our study, such as the fact
that the figures reported herein are not population based, and any
patients with DS who died at home or at other hospitals and had
never been diagnosed with CHD were not included. Moreover,
cytogenetic studies were not routinely performed on all patients
because diagnosis was mainly based on clinical grounds. Due
to poor organisation and infrastructure at our cardiac centre in
previous years, we were unable to accompany the presented
figures with any surgical results. Irrespective of these limita-
tions, we believe that we have made some progress in document-
ing the distribution of CHD in Libyan children with DS.
Conclusion
This is the first study to document the types, distribution and
frequency of CHDs in Libyan children with DS. ASD was the
most common single cardiac lesion in DS. The distribution of
CHDs in Libyan children with DS was similar to what has been
reported internationally but the frequency was not compared
with international rates. We stress the importance of early refer-
ral and screening for CHDs in this group of patients.
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TABLE 3. COMPARISON OF CONGENITAL HEART
DISEASES IN LIBYAN TRISOMY 21 PATIENTS
(
n
=
537) WITH OTHER NATIONS
Cardiopathy
ASD
%
AVSD
%
VSD
%
PDA
%
TOF
%
CoA
%
Others
%
Libya
24 19 12
4
2 1
39
Mexico
17
38
9 30 21
1 0
1
Guatemala
22
13 10 28 29
0 0
22
Saudi Arabia
18
21 23 33 14
5 0
4
India
21
12
3 26
5 16 0
39
China
20
13 15 44 12 13 0
2
Italy
14
5 55 25
5
6 0
4
USA
16
8 45 35
7
4 1
1
Sudan
15
5 48 23
7
6 0
11
ASD, atrial septal defect; AVSD, atrioventricular septal defect; VSD,
ventricular septal defect; PDA, patent ductus arteriosus; TOF, tetral-
ogy of Fallot; CoA, coarctation of aorta.
