I am very sorry I know how concerned you are, I suggest that you get some more information and do not rely on this doctor alone .The info above does quote Boston it may be a good idea to get in touch with them ..we also have a pediatric Cardiology forum on Med Help put this question there for some further help...good Luck
It sounds as if Boston children's hospital specialise in HLHS ....I have copied something may be of interest If a prenatal ultrasound has revealed that your baby will be born with hypoplastic left heart syndrome (HLHS)—or if your infant has been diagnosed with HLHS—an understanding of the condition will help you plan for, and cope with, this rare and complex congenital (present at birth) heart defect.
While this condition is very serious, children with HLHS can undergo therapy at Children’s Hospital Boston—shortly after birth or in some select situations, while your baby is in utero.