Cardiovascular and Bluish Skin Color

The most common cyanotic congenital heart defect in children is tetralogy of Fallot (ToF). This heart anomaly is known to be affiliated with other congenital problems that can affect development of other organs in the body.  While a baby is in the mother’s womb, ToF can start to develop when the right side of the heart deviates from the usual formation of it. Therefore, the sections of the heart affected are the right ventricle and the pulmonary valve along with the ventricular septum. The deformity on the right side may lead to ongoing problems with the heart since blood is obstructed from reaching the lungs. [147][148]

Four Defects (Tetralogy)

This defect comprises of four related defects that cause dysfunction not only to the heart, but also to the major blood vessels. [149]

Ventricular Septal Defect

Ventricular septal defect (VSD) is a hole between the two lower chambers of the heart (left and right ventricles) and is separating both of them.  Therefore, blood is pushed (shunted) from the left side to the right side, which may have difficulties with the extra load of blood and causes the heart to be overworked.  VSD can also cause profusion of pressure in the blood vessels that are connected to the lungs (pulmonary hypertension). Treatment for VSD is only a necessity if it is large.  [150] 

Pulmonary Stenosis

Pulmonary stenosis (PS) is a heart condition involving blood running from the right ventricle to the pulmonary artery being impeded.  The stenosis or narrowing at one or more area located somewhere from the right ventricle to the pulmonary artery causes the obstruction. [157] PS

includes obstruction from thickened muscle below the pulmonary valve, narrowing of the valve itself, or narrowing of the pulmonary artery above the valve. [157]

Aorta Shifting

Aorta shifting is the inability of the aorta to place itself over the left ventricle, which will let oxygen-rich blood to flow into the circulatory system.  In tetralogy of Fallot, the aorta is shifted to the right and lies directly over the ventricular septal defect. [147][158][159][160] The consequence of that shift is

oxygen-poor blood from the right ventricle flows directly into the aorta instead of into the pulmonary artery. [159]

Right Ventricular Hypertrophy

Right ventricular hypertrophy is the enlargement and thickened muscular (outer) wall of the right ventricle as the blood outflow to the lungs is hindered.  Augmented strenuous pumping action is exerted by the right ventricle due [160][161][162] to 

narrowing or blockage of the pulmonary valve coming out of the right ventricle.  [161]

The heart being overworked may lead to the organ becoming rigid, feeble and eventually heart failure. [160]