Right to left cardiac shunt is a congenital heart defect. It is present since birth and leads to low oxygen level in blood. A cardiac shunt is an abnormal flow of blood between the chambers of heart. This abnormality occurs due to a structural defect in the wall that separates the four chambers of heart, the right side consists of right atrium and right ventricle and left side consists of left atrium and left ventricle.
Cardiac shunt is one of the most common congenital heart defects. Fetal heart starts to develop from 20 days after conception.The tube gradually takes the shape of heart with all its structures and chambers in place within 50 days of conception. Normally the wall or septa between the right side and left side of heart closes by the time fetus is born. However, in some fetuses a shunt or a hole remains between the two sides.
Cardiac shunts can be of two types; right to left and left to right. In right to left shunt the blood from right atrium and ventricle mixes with the blood in left side of heart. Let us know the condition in detail.
Left To Right Shunt Congenital Heart Disease
Human heart is made up of four chambers; the two upper atrium and the two lower ventricles. The right side of heart is comprised of right atrium and right ventricles and left side with left atrium and left ventricle. Both right atrium and ventricle handle impure blood that comes from body (deoxygenated blood) while left side handles the oxygenated blood that comes from the lungs.
In a normal heart there is a wall called septum between the right and left side of heart. This wall prevents mixing of oxygenated pure blood with deoxygenated impure blood. However, in right to left cardiac shunt the deoxygenated blood mixes with the pure oxygenated blood in the left side, surpassing the pulmonary circulation.
This means the oxygenated blood in the left side dilutes with the impure blood. As a result the entire body receives less amount of oxygenated blood. Thus bluish discoloration (cyanosis) of the skin is classical feature of this cardiac anomaly besides other symptoms. Right to left cardiac shunt is hence referred as cyanotic congenital heart disease.
Causes Of Right To Left Cardiac Shunt
Right to left cardiac shunt is congenital heart malformation which is present since birth. It occurs due to abnormality in the embryonic development. The exact cause of cardiac shunts is not known, but there are several factors that have been implicated in its development. The anomaly occurs when the heart gets affected during the first few weeks of its development in the womb.
- Genetic aberration is noted in large number of cases. This means defective genes inherited from one or both the parents may be the cause. Cardiac shunt is thus seen in genetic conditions such as Down’s syndrome, Turner’s syndrome, trisomy 13, marfan syndrome etc.
- Exposure of a pregnant woman to environmental chemicals and organic solvents can become a cause for congenital heart defect in babies.
- Viral infection such as rubella during pregnancy.
- Certain medications can be the cause of congenital heart disease if they are taken during pregnancy. Thus a pregnant woman should always take prescribed drug by her doctor instead of taking them without consulting.
- Poor control of diabetes in pregnancy.
- Smoking and drinking alcohol during pregnancy.
Symptoms Of Right To Left Cardiac Shunt
There are several types of congenital heart defects that may have right to left shunt. Among them the most common are fallot tetralogy, persistent truncus arteriosus, tricuspid atresia, total anomalous pulmonary venous return. Irrespective of different type of cardiac defects that may cause right to left shunt, the symptoms of these condition remain common. Patient presents with following symptoms.
- Blue discoloration of skin, lips and tongue. This occurs due to more amount of deoxygenated blood circulating in the body. It becomes more obvious when the child cries or coughs.
- Clubbing of fingers. It can be recognized easily as the nail is wider and round. The nail becomes soft and turns more downwards. The finger tip is swollen.
- The baby fails to thrive after birth.
- Difficulty in breathing. Slightest exertion causes severe breathlessness.
- Fainting and syncope attacks.
- Murmur can be heard by the doctor while examining with a stethoscope.
Treatment For Right To Left Cardiac Shunt
Most of the patients suffering from different types of conditions having right to left cardiac shunts need treatment. In some the treatment may become essential as soon as the child is born, while some patients may need treatment few years later when the symptoms become apparent. Both medication and surgery are essential part of treatment. These procedures have enhanced the survival of the patients.
Today it is possible to detect congenital cyanotic heart disease when the fetus is still in the womb. A fetal echocardiographic study is able to detect such anomalies. Early detection will help to plan a better treatment option for the sick infant.