What are the effects of having a hole in the heart?

Hole in heart. Not enough room here, short inadequate answer is atrial or ventricular septal defects(holes)cause left to right shunting till bad things happen. For atrial the right heart gets overloaded and eventually pulmonary hypertension and right heart failure happen. For ventricular septal defect, left heart is overloaded and left heart failure and sometimes both sided failure occurs eventually. Oversimple.