How long would it take to repair an asd (hole in the heart) in a newborn?

No need to repair : There is no need to repair an ASD in neonates. In fact most asds in neonates and infants are rather small and will close by themselves. If asds are large and lead to a volhme load of the right ventricle they will be repaired after the 2nd year of life. We do that mostly as catheter procedures with less tan 30 minutes procedure time and less than 2 minutes of x ray under echocardiographic guidance.

As long as it takes.: 4 types of asd. Primum asd, secundum asd, sinus venosus type asd, pfo. Also rare unroofed coronary sinus. Once cardioplegic arrest and atriotomy done, about 15-20 mins. Once the ASD closed you have to close the atrium, re-start the heart, come off cardiopulmonary bypass, dry up and close up the chest. These may take as long as necessary to get them done.

No need for therapy: Again. No need to do anything for isolated ASD in a newborn!