It isn't a good idea to use any stimulants when you have a heart problem. MDMA can be (it isn't always) significantly stimulating. Since VSD can cause hypertension, I would be very cautious with drugs such as MDMA or avoid them altogether.
Only a doctor can tell you whether or not it would be dangerous to take MDMA with your condition. None of us are qualified to give you an answer. There are also varying levels of severity of the condition.
MDMA is generally a safe drug but not with pre-existing heart conditions. I wouldn't recommend it.