Now, of course, this situation can be surgically fixed. Now, let's move on to the other type of abnormality that can arise as a result of the non closure of the forayman O'Valley. So, normally, under normal conditions, what happens is as a result of the reversal in pressure, because we reverse the pressure at birth and the left side increases in pressure, it becomes greater than the right side of the heart. That one way valve essentially closes, but in some cases, it does not actually close. And what that means is we can still have a movement of blood between the two atrium of the heart. So, once again, during fetal development, there is a valve like structure that exists between the right and the left atrium.