Baby echocardiography. The accuracy.

I am mother to 7month old baby... My paedritician suggested echocardiography for my baby ... It showed an asd of 5 to 6 mm.. my hubby got so much worried he went to repeat the echo at another diagnostic center... It showed same asd of 5 to 6 mm ... Though doc's here said it is normal and there are 90% chance to heal up by itself... But he is extra worried that he wants to move to Delhi to recheck at 2 3 places there ...i am concerned that if we will go to 2 3 doc's they will perform echo at their own clinic ... to check the accuracy.. Is too many echo bad for baby ...probably if 2 3 are  done within a week....this thing is making me mad...but my hubby dsnt understand this....please reply doc's is it safe to do too many echocardiography.....