If someone has had open heart surgery as a child, would he usually have a shorter lifespan?

It depends: Some problems can be essentially cured with open heart surgery, with little effect on the lifespan or activity. Other serious problems result in a notably shorter life expectancy.

What surgery?: It depends on what defect was treated. Some defects can be cured with surgery but others can only be palliated. Either way surveillance is important so follow up with the cardiologist is necessary. Some heart defect do lead to a shorter life span.