My daughter 19wf was diagnosed with vsd as a child. we were told the hole was small but it never closed. she is a competitive tennis player. should we worry? how often should we follow up with cardiologist? we were told no more than once in 3-4 yrs?

Yes: If it is truly still open in a 19 yo I would want to have it closed.A small one might not stress the heart, but any such communication between the right/left side circulation can be a problem at some point in life. Closure with an an umbrella like device through a catheter may be a simple solution. The only way to know if it is still open would be thru proper testing.