Author
Information
Shilotri M*, More
V**, Satia MN***
(** Second
year resident, **Assistant Professor, *** Professor, Department of Obstetrics
and Gynecology, Seth G. S. Medical College and KEM Hospital , Mumbai , India
Abstract
Congenital complete
atrioventricular block may result from a congenital cardiac anomaly or the
presence of anti-Ro and/or anti-La antibodies in women who have systemic lupus
erythematosus, Sjogren’s syndrome, undifferentiated autoimmune disorder, or are
asymptomatic. The prognosis of the baby depends on the time of diagnosis and
presence of a cardiac anomaly. Down syndrome has a high incidence of congenital cardiac anomalies,
however, complete atrioventricular block is rarely seen. We present a case of a 23
year old gravida 2, para 1, living 1 who was asymptomatic and was diagnosed to have autoimmune
antibodies on evaluation for fetal bradycardia which was later diagnosed as
complete heart block on fetal echocardiography. The neonate was later
incidentally diagnosed to have Down syndrome with atrial septal defect.
Introduction
Congenital
complete atrioventricular block is a rare disorder with an incidence of 1 in
22,000 live births.[1] Congenital cardiac anomalies are seen in 44% of Down syndrome cases.[2]
Amongst cases of Down syndrome, varying degrees of heart block are seen with
atrioventricular septal defects while atrial septal defect is only associated
with PR interval prolongation on ECG.[3] Congenital complete atrioventricular block may be
diagnosed antenatally as early as 16 weeks gestation. It has a high perinatal
morbidity and mortality. Women with positive anti-Ro and/or anti-La antibodies
should be monitored with serial fetal echocardiography to detect early any
congenital conduction defects. Although there are no guidelines for antenatal
treatment of fetal heart block, there are many promising therapies being
studied.
Case
Report
A 23 year old gravida 2 para 1, living 1 registered
antenatally at our clinic at 23.5 weeks gestation. She had no history of any
significant medical or surgical illness. She had a previous full term normal
delivery and the child was well. At 28.5 weeks gestation the fetal heart sounds
were found to be irregular ranging from 60 beats/ minute to 120 beats/ minute,
as heard on a stethoscope and confirmed on a hand-held Doppler device during a
routine antenatal examination. She was advised admission for evaluation of
possible fetal cardiac anomaly. However she was not willing for the same. An
obstetric ultrasonography for fetal anomalies and a fetal echocardiography was
advised. At her next antenatal visit at 31.5 weeks, the baseline fetal heart
rate was 50 beats/ minute. Ultrasonography for fetal malformations at 29 weeks
showed evidence of fetal bradycardia (53 beats per minute) most probably due to
conduction defect with a complete heart block, mild pericardial effusion and
reverse flow in ductus venosus suggestive of early fetal hydrops. No other
anomalies were evident. As she was not willing for admission, she was advised
to do blood investigations such as anti-nuclear (ANA) antibodies, anti-double
stranded DNA (dsDNA) antibodies, anti-Ro (SSA), anti-La (SSB) antibodies and
blood sugars. She was advised to follow up with the reports in the outdoor
patient department. Patient later returned to the hospital in active labor at
37.1 weeks and delivered uneventfully. She delivered a female child of 1.672 kg
with an Apgar score of 8/10. On examination of the neonate, Mongoloid features
were observed (slanting eyes, low set ears and depressed nasal bridge) with
clinodactyly and bradycardia. Baby was immediately shifted to the neonatal
intensive care unit for further evaluation. ECG of the neonate was suggestive
of complete heart block with atrial rate of 160 beats/ minute and ventricular
rate of 60 beats/ minute. Echocardiography showed a 3 mm atrial septal defect
of ostium secundum type. No other cardiac anomalies were detected. Cardiology
opinion was taken who advised monthly follow up of the baby. The neonate’s
blood counts, hepatic and renal function tests were within normal limits.
Karyotype and thyroid function tests of the baby were sent in view of the
Mongoloid features. The baby was
discharged on full feeds and advised to follow up with the above reports and
was diagnosed to have Down syndrome on karyotyping. On maternal evaluation, the patient tested positive for ANA , anti-Ro
and anti-La antibodies and was negative for anti-dsDNA antibodies. Rheumatology
opinion was sought and was advised urine routine examination and complement
levels (C3, C4) which were normal. CRP levels
were raised and thyroid function tests were suggestive of
hypothyroidism. Her complete blood counts, renal and liver function tests and
blood sugars were normal. She had no complaints of rash, photosensitivity,
arthritis or long standing fever. She was asked to follow up in the
rheumatology outpatient department for further evaluation of type of autoimmune
disorder. Thus, the patient was diagnosed to have an autoimmune disorder on
evaluation for the fetal heart block.
Discussion
Congenital
complete atrioventricular heart block may manifest any time from 16 weeks
gestation to young adulthood. In the antenatal period it may first be detected
as bradycardia on auscultation during an obstetric examination, as in our case,
or on a routine obstetric ultrasonography. Fetal congenital heart block may be
a result of an underlying cardiac structural anomaly as seen in 30 – 53% of cases.[1]
The most common cardiac anomaly associated with heart block is left atrial
isomerism with or without atrioventricular septal defect and levo-transposition
of great arteries.[4] In a structurally normal heart, congenital heart block in
the form of neonatal lupus is a result of maternal autoantibodies to
intracellular ribonucleoprotiens {anti-Ro (SS-A) and/ or anti-La (SS-B)}, detected on enzyme linked
immunosorbent assay. Women that test positive for anti-Ro antibodies have a 3%
risk of bearing a child with neonatal lupus.[2] At the time of diagnosis of the
fetal heart block the mother may be a known case of systemic lupus
erythematosus (26%), Sjogren’s disease (14%), an undifferentiated autoimmune
disorder (19%) or may be completely asymptomatic (40%).[3] It is postulated
that these autoantibodies are passively transferred through placental
circulation which in turn injure a formerly normal fetal heart. The heart block
varies from first to third degree and the antibody mediated injury may result
in a late cardiomyopathy as seen in 5-11% of cases.[4] Neonatal lupus has other
manifestations such as an annular, photosensitive rash on the face, low counts
of red blood cells, white blood cells, platelets and deranged liver function
tests. These manifestations usually resolve spontaneously, however, the cardiac
changes are permanent.
Down syndrome
is associated with atrioventricular septal defects (30%), atrial septal defect
(25%), ventricular septal defect (22%), patent ductus arteriosus (5%),
coarctation of aorta (5%) and tetralogy of Fallot (3%).[2] The type of
conduction disorder seen in Down syndrome depends upon the cardiac anomaly.
Varying degrees of heart block are seen with atrioventricular septal defects
while atrial septal defect is only associated with PR interval prolongation on
ECG. Isolated complete congenital heart block in a case of Down syndrome is
rare.[7] Thus, in our case, the fetal complete heart block was most likely
caused by the maternal autoimmune antibodies.
On diagnosis
of congenital heart block, the fetus is monitored by serial echocardiograms.
Several antenatal therapies for neonatal lupus have been attempted such as
dexamethasone therapy, plasmapheresis, beta stimulation by salbutamol,
hydroxychloroquine, intravenous immunoglobulins etc.[8] However, no therapy has
been approved as standard protocol for antenatal management of neonatal lupus.
In neonates and children cardiac pacing may be required if they are
symptomatic, have congestive cardiac failure or in asymptomatic neonates with
awake baseline heart rate of less than 55/min.[1] As the neonate in our case
had a baseline heart rate of 60/minute and was asymptomatic, pacing was not
done.
Complete heart
block predisposes the baby to cardiac failure, hydrops fetalis, fetal or neonatal
death. Prognosis depends on the presence of an underlying cardiac structural
abnormality with a survival beyond the neonatal period of only 14% as compared
to 85% in autoimmune congenital heart block.[1] Prognosis is also determined by
the time of diagnosis of the disease, with those diagnosed in the newborn
period having a better fate than those that are detected in-utero as it is
thought that those with severe disease perish in-utero and those with a milder
disease survive for a longer time. Although women who test positive for anti-Ro
and/or anti-La antibodies may be asymptomatic at the time of diagnosis, there
are reports of them becoming symptomatic a few years after the affected
delivery, the median time being 1.5 years.[3] Thus it is worthwhile to advise
these patients to follow up with a rheumatologist.
References
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- Stoll C, Dott B, Alembik Y, Roth MP. Associated congenital anomalies among cases with Down syndrome. Eur J Med Genet. 2015 Dec;58(12):674-80.
- Clark EB, Kugler JD. Preoperative secundum atrial septal defect with coexisting sinus node and atrioventricular node dysfunction. Circulation. 1982;65(5):976-80. PubMed PMID: 7074763
- Friedman DM, Duncanson LJ, Glickstein J, Buyon JP. A review of congenital heart block. Images Paediatr Cardiol. 2003;5(3):36-48.
- Waltuck J, Buyon JP. Autoantibody-associated congenital heart block: outcome in mothers and children. Ann Intern Med 1994;120:544-51.
- Moak JP, Barron KS, Hougen TJ, Wiles HB, Balaji S, Sreeram N, et al. Congenital heart block: development of late-onset cardiomyopathy, a previously underappreciated sequela. J Am Coll Cardiol. 2001;37(1): 238–242. [PubMed: 11153745]
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Shilotri M, More V, Satia
MN. Maternal
Autoimmune Disorder diagnosed by Fetal Heart Block. JPGO
2016. Volume 3 No. 3. Available from: http://www.jpgo.org/2016/03/maternal-autoimmune-disorder-diagnosed.html