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Survival of a preterm child depends on a lot many factors like gestational age
birth wt congenital anomalies and antenatal and postnatal complications.
But the chances of survival are more if fetus has passed the period of viability that is 28 wks inside the uterus
and preferably has no anomalies.
A hole in the heart is a layman term used for all congenital heart disorders but treatment and prognosis is very different for different disorders.so in your query the specific treatment and survival can't be answered.but yes with the latest scientific advancement in a good hospital many such babies can be survived depending on their severity of disease.