Congenital heart defects describe malformations of the heart that are existing at birth. Defects may involve the interior walls of the heart,

the valves inside the heart or the arteries and veins that carry blood to the heart or the body, that did not develop normally before birth.

The cause of congenital heart defects is not clearly defined. However, heredity as well as smoking during pregnancy may play a role. In general, congenital heart defects change the normal blood flow through the heart. Defects range in severity from simple problems, e.g. “holes” between chambers of the heart to complex malformations with severe, life-threatening symptoms, such as the complete absence of one or more chambers or valves.

In some cases, the patent ductus arteriosus (PDA), the blood vessel that connects the aorta and the pulmonary artery before birth which is supposed to closed after birth, remains open. As a consequence, oxygen-rich blood from the aorta can mix with oxygen-poor blood from the pulmonary artery, which will put strain to the heart. The PDA may shrink and disappear with time or needs closure through treatment.

Having congenital heart defects may increase the risk of developing other medical conditions, for instance pulmonary hypertension, arrhythmias, infective endocarditis, anticoagulation or congestive heart failure. Some heart defects do not cause any symptoms, but severe defects in new-borns may show signs like rapid breathing, Cyanosis (bluish discoloration of the skin, lips and fingernails), fatigue and poor blood circulation. Simple conditions can usually be fixed easily, whereas complex defects will require special medical care soon after birth, such as catheter or surgical procedures, or the necessity to take medicines for years.

Source: National Heart, Lung and Blood Institute, American heart association