FAS babies have a high chance of being born with a heart defect.
Heart Murmurs
Many babies end up being born with abnormal heart murmurs, an extra beat in their heart beat. This is caused by a lose valve in one of the chambers. The most common type in FAS babies is ventricular septal defect which is a lose valve between the two lower ventricles. When the heart muscle contracts blood gets pushed through this valve as well, creating an extra beat. This causes oxygen-poor and oxygen-rich blood from mixing so when blood is pumped out of the left ventricle through the aorta to the body it often contains oxygen-poor blood. In the same way, when the right ventricle pumps blood through the pulmonary vein to the lungs to be oxygenated not as much oxygen is obtained as some of the blood already had oxygen while going to the lungs. The lack of oxygen in the body is fatal as we need oxygen to live. This will also result in the child being very lethargic as he or she will have less oxygen for degrading glucose and produce energy.
Coarctation of the Aorta and Heart Failure
Children who are born with Fetal Alcohol Syndrome can be born with the birth defect, the coartctation of the aorta. In this condition, the aorta, the artery that takes blood from the heart to the body, is narrower than it should be. Since the aorta is the main pathway of oxygenated blood to the body, if it is narrow, less oxygen reaches all the cells. This causes the heart to beat harder and faster to send out more oxygen which leads to congestive heart failure.
(Medicine Net)