My 2 year old has vsd. He gets realy bad chest infections and has asthma. And gets sick easily. Should he get the flu injection? Is their risk for him

Yes. Influenza can lead to serious illness in children with congenital heart disease. If he does not have an allergy or adverse reaction to components of the vaccine, aap recommendations are that he should receive the vaccine. Discuss all the risks and benefits with his doctor before deciding, but in general, the benefits of preventing serious flu infections outweigh the risks.
He should. There's no risk of the flu vaccine on the vsd, and it is recommended for all kids >6m old. . But discuss it with your pediatrician to make sure that your kid can receive it. As for the vsd, there is no contraindication for the flu vac. (i.e.. It is ok for him to get the vaccine).