Congenital heart disease (hole in the heart). Angiogram of a ventricular septal defect, seen at centre left as a narrow, short horizontal tubule to the left of the catheter (dark tube). It is a hole in the ventricular septum causing blood to flow from the left ventricle (right of image) to the right one and from here to the lungs. The catheter at centre is used to obtain the angiogram. The aorta is at upper centre and below it is the pulmonary artery. Septal defects cause enlargement of the heart and pulmonary artery. They also cause the passage of deoxygenated blood to the body instead of to the lungs and oxygenated blood to the lungs instead of to the body.