I am a cardiologist and will try to answer your question with the information supplied:e
The Diagnostic Possibilities and what to do I will list as follows:
a.) In view of auscultated murmur I would keep one serious possibility that is Cyanotic Spells in a child with congenital heart disease
called Tetralogy of Fallot: I will quickly exclude because you have not mentioned any blue discoloration of your child either otherwise or during the episode of loss of consciousness
. Moreover, the doctor who auscultated murmur would have arranged an urgent echo which would have confirmed or excluded the diagnosis in 5 minutes flat.
b.) Most Benign possibility that is breath holding spells without any relation to murmur. Nothing to worry child will outgrow this
c.). Sleep Apnea syndrome
, will need sleep studies a consult with child neurologist
and of course echo Doppler study to ascertain the cause of murmur: which has nothing to do with b or c
d.) Some form of seizures, would need consult with pediatric neurologist. Shall need prescription medicines.
So apparently, till some specialist perform an echo and other specialist seethe patient we are doing only guesswork. Child has been seen by a doctor who did not think any serious illness and with no history suggestive of significant heart or neurological illness(no neurological deficit remaining after the episode), I personally will go with benign condition like breath holding spells. Let the parents have the joy of seeing your child grow meanwhile treating doctors make up their mind.
Dr Anil Grover