Answer
If the blood from the left ventricle is mixed with blood from the right ventricle, then the blood pumped to the rest of the body through the systemic circuit will be lower in oxygen content than normal.
Work Step by Step
With a hole between the left and right ventricles, the blood between these two ventricles will mix. Blood from the right ventricle is low in oxygen content, ready to be pumped to the lungs to pick up oxygen; on the other hand, blood from the left ventricle is rich in oxygen, ready to be pumped to the rest of the body. If the blood from the left ventricle is mixed with blood from the right ventricle, then the blood pumped to the rest of the body through the systemic circuit will be lower in oxygen content than normal.
