What is the criteria for differentiating mild, moderate and severe defects?

What is the criteria for differentiating mild, moderate and severe defects?

In this video, Dr. Radha Krishnan, Director, Pediatric Cardiologist at Fortis Escorts Heart Institute, New Delhi, will explain the criteria for differentiating mild, moderate and severe defects. It is generally a echocardiography findings and the measurements of the defects. Pulmonary artery pressure is predicted after the findings. If it is a large PDA or VSD, it will always cause pulmonary hypertension which damages the heart and lungs. After a certain period, pulmonary hypertension is irreversible. So it is always an emergency to close large PDA or VSD before six months of age.