What happens if you have poor blood circulation in the body caused by congenital heart disease?

All organs need O2. There are many types of congenital heart disease, so it is not possible to answer your specific question. Poor heart muscle function may cause back up of fluid in the lungs or congestive heart failure. Heart disease causing low oxygen will affect brain and kidney functioning, low exercise tolerance, and peripherally, poor circulation in extremities makes wounds heal slowly and loss of sensation.