Fetal complete heart block
No survivors of fetal pacing
Anti-Ro SSA 100%
Anti-la SSB 70%
Maternal auto immune disease is ‘the’ reason for fetal arrhythmia screening. Fetuses with structural heart disease as well as a positive family history calls for fetal arrhythmia screening.
M-mode echo can be used to assess AV relation and so can Doppler. VA interval can be picked up from the Doppler (E – A relation).
Those with CHD have heart block earlier than those with maternal auto immune disease. Overall prognosis is very poor with an associated structural heart disease.
Some studies suggest steroids for all cases of complete heart block to maternal autoimmune disease. Dexamethasone is used because it causes placental barrier while prednisolone may not. Steroid toxicity to the mother may not be a concern because steroids may be indicated for the mother for her autoimmune disease. Dexamethasone 4 mg is started and reduced to 2 mg towards term. Oligohydramnios can occur with steroid treatment.
Treatment of fetal tachyarrhythmias
75% of them have SVT while 25% have atrial flutter. Digoxin is a good drug, but not useful in hydrops. Amiodarone is a good drug and so is sotalol. Sotalol can be proarrhythmic. Baseline RFT and thyroid function of the mother has to be checked. Higher doses may be required and frequent monitoring is necssary. Delivery should be as close to term as possible as it is easier to take care of a bigger infant. After delivery, the first line is usually digoxin and second line could be beta blockers or amiodarone. Direct current cardioversion may also be resorted.