Author
Information
Khadkikar Rashmi*,
Prasad Madhva**, Jain Neha**, Chauhan AR
(* Assistant
Professor, ** Resident,
***, Additional Professor. Department of Obstetrics and Gynecology, Seth G.S. Medical College
and K.E.M Hospital ,
Mumbai , India
Abstract
Congenital
heart block (CHB) is associated with maternal antibodies to Ro (SSA) and La
(SSB) that cross the placenta and damage the AV node of fetus. An asymptomatic
27-year-old primigravida, diagnosed with second degree fetal heart block was
investigated and found positive for antinuclear antibodies (ANA), anti-Ro and
anti-La antibodies. Fetal
echocardiography (2D-echo) showed no structural defect but bradycardia. The patient
was started on dexamethasone 8mg/day. She had preterm premature rupture of
membranes (PPROM) at 34 weeks and underwent emergency cesarean section (LSCS).
The baby was born with complete heart block but was managed conservatively in
view of low birth weight. The infant is now 5 months old and permanent
pacemaker implantation is planned.
Introduction
The occurrence rate of CHB is approximately 2 to 3% of all pregnancies
born to women with autoantibodies. The recurrence rate with a previous affected
child is 18 to 20%.[1] CHB is most commonly diagnosed between
18 and 24 weeks of gestation, and may be first, second or third degree
(complete). In pregnant women with
autoimmune conditions, maternal autoantibodies cross the placenta and cause
inflammation and fibrosis of AV node, causing block in signal conduction
leading to congenital heart block. However, though the fetus is affected due to
maternal anti-Ro/SSA and anti-La/SSB antibodies, the mother herself may be
asymptomatic.
Case report
A 27 year
old primigravida was referred at 28 weeks’ gestation in view of fetal
bradycardia (fetal heart rate [FHR] of 78 beats/ min) and 2D-echo showing second degree heart block (intermittent type
II) with early diastolic dysfunction, without evidence of hydrops fetalis.
Detailed malformation scan was normal, liquor was adequate and there was no
placental abnormality. She had no clinical features of autoimmune disorder or
any known medical or surgical illness, except hypothyroidism for which she was
on thyroid hormone supplementation.
In view of
these findings, she was investigated: ANA, Anti-Ro, anti-La antibody tests were
positive, anti-dsDNA was negative. Consultations
with a rheumatologist, a neonatologist and a cardiologist were obtained. Maternal
therapy was started with tablet Dexamethasone 4 mg and tablet Hydoxychloroquine
twice daily which was continued till delivery.
The patient
was followed up weekly (FHR on auscultation varied between 60 -70/min) with USG
for fetal viability and growth, and fetal 2D-Echo every 15 days. Degree of heart
block progressed despite medications, and at 33 weeks there was complete heart
block (FHR 50/min). She was counseled regarding need of pacemaker
post-delivery.
Patient
had premature rupture of membranes at 34 weeks of gestation. In view of
impossibility of fetal heart monitoring during labor, emergency LSCS was
performed. Male child of 1820 g was born with Apgar of 9/10 and was managed
conservatively in neonatal ICU. Post delivery, ECG was suggestive of complete
heart block with narrow QRS escape rhythm. Conservative management was
continued in view of prematurity and low birth weight. Four months
post-delivery, the infant was started on diuretics and was advised permanent
pacemaker implantation as ECG showed complete heart block with ventricular rate
of 43/min.
Figure 1: Fetal 2D
Echocardiography
Figure 2: Postnatal ECG
Discussion
Neonatal lupus is diagnosed by
the presence of bradycardia in a fetus or newborn without structural cardiac
abnormalities. Other manifestations of neonatal lupus are skin rashes, liver
function abnormalities and cytopenias. These non-cardiac manifestations
resolve after maternal antibodies are cleared from circulation (6 to 8 months
after birth) but the conduction system disease is irreversible. The mother may
have SLE or Sjogren's syndrome or may be asymptomatic, as in our case.[2]
CHB associated with
neonatal lupus is a form of passively acquired autoimmune disease in which
maternal autoantibodies cross the placenta and injure the previously normal
fetal heart. Anti-Ro
and anti-La antibodies have direct arrhythmogenic activity; the onset of bradycardia is
between 16 and 24 weeks of gestation, corresponding to placental transfer of
maternal IgG antibodies. These antibodies bind to fetal cardiocytes and inhibit
the normal physiological removal of apoptotic cells, resulting in inflammatory
reaction and fibrosis of the conduction system. Though these antibodies are
directly involved in the pathogenesis of CHB, environmental, fetal, maternal,
and genetic factors also predispose to this condition.[3]
Most patients are diagnosed antenatally with first and second degree
heart block which should be managed with steroids and monitored for improvement
or worsening to irreversible complete heart block, where steroids may not be
effective. Fetal heart rate is a prognostic indicator of the disease; a
critical level of less than 55/min, along with myocardial dysfunction and presence of
hydrops fetalis (due to increase in ventricular size as an adaptation to persistent bradycardia), are risk factors for high mortality
(85%) in neonatal period.[4]
Fetal 2D echo is recommended in second trimester in mothers affected
with autoimmune disorders and those with previous child affected with neonatal
lupus. Conversely, presence of autoantibodies in mother should be suspected
with fetal congenital heart block in the absence of any cardiac structural
abnormality.
No guidelines for treatment of CHB exist though various therapeutic
regimens are proposed: β-sympathomimetic drugs to increase the FHR; plasmapheresis
and steroids to target the antibody-mediated inflammation; and digoxin or frusemide
to prevent hydrops. The use of glucocorticoids in fetal second degree heart
block may increase the chances of reverting to first degree heart block
rather than progressing to third degree heart block.
Dexamethasone may also improve fetal survival in complete heart block. After
birth, therapy includes medical management, along with pacing in those
infants who do not respond to medical treatment alone.[4]
In conclusion, multidisciplinary team approach by level III sonologist,
obstetrician, neonatologist and pediatric cardiologist is valuable in
management of this rare condition.
References
1.
Buyon JP, Heibert R, Copel J, et al.
Autoimmune-associated congenital heart block: Mortality, morbidity, and
recurrence rates obtained from a national neonatal lupus registry. J Am Coll
Cardiol.1998; 31:165.
2.
Tincani A, Rebaioli CB, Taglietti M and
Shoenfeld Y. Heart involvement in systemic lupus erythematosus,
anti-phospholipid syndrome and neonatal lupus. Rheumatology 2006; 45(suppl 4):
iv8-iv13.
3.
Friedman DM, Duncanson LJ, Glickstein J
and Buyon JP. A review of congenital heart block. Images Paediatr Cardiol. 2003
Jul- Sep; 5(3): 36-48.
4.
Friedman DM, Rupel A, Glickstein J and
Buyon JP. Congenital heart block in neonatal lupus: the pediatric
cardiologist's perspective. Indian J Pediatr 2002 Jun; 69(6): 517-22.
Citation
Khadkikar
R, Prasad M, Jain N, Chauhan AR. Congenital
Heart Block Due To Maternal Autoantibodies. JPGO 2014 Volume 1
Number 5 Available from: http://www.jpgo.org/2014/05/congenital-heart-block-due-to-maternal.html