Valve absence

I recently found out that my (not very close) friend has a heart defect - a missing valve. He lives a normal life, although he's not recommended to do sports or some hard chores. I'm very worried about him, since I don't know anything about heart diseases, so I decided to ask you for any information about this kind of disease and what could be the major problems it can cause. Will he need an obligatory operation after some time? How dangerous it is?
Thank you very much for your answers.

[kenkeith]

With this condition the valve between the left ventricle (pumping chamber) and the aorta (main artery to the body) is blocked or missing and therefore blood cannot pump from the ventricle to the body, so the route the blood takes is through the ductus arteriosus (which bypasses the baby's lungs in the womb).

Depending on the other defects found, treatment may include giving drugs to keep the ductus arteriosus from closing (as it normally does shortly after birth). The baby will require an operation to re-route the blood flow, so that the right ventricle can pump the blood to the body.

Apparently, medication keeps open the ductus arteriosus and provides a bypass.  Or there has been an operation when your friend was a baby.

Congenital cardiovascular defects, most of which involve deformed or missing heart valves, are detected in almost three to four percent of all live births.

IF DEFORMED surgical correction of valve defects carries significant challenges in children, and it is not atypical for an adolescent with congenital valve defects to have undergone several major surgical procedures in their lifetime. These numerous surgeries are required because children, unlike adults, outgrow their replacement valves