Understanding Tetralogy of Fallot: 4 Abnormalities that Cause Cyanosis in Hands and Fingers.

*A newborn presents with cyanosis of the fingers and hands, but not of the toes or feet. What cardiac condition does this indicate? What kind of blood flow is in this condition?

Transposition of the Great ArteriesCyanosis of the finger/hands, but not the toes/feet, is termed “reverse differential cyanosis.” This indicates transposition of the great arteries, with right-to-left shunting of saturated blood through the ductus.

The cardiac condition that presents with cyanosis of the fingers and hands, but not of the toes or feet is known as “Tetralogy of Fallot”. It is a congenital heart defect that involves four anatomical abnormalities in the heart, which includes:

1. Ventricular Septal Defect (VSD) – A hole in the wall between the two ventricles.

2. Pulmonary Stenosis – Narrowing of the pulmonary valve that controls the blood flow from the heart to the lungs.

3. Right Ventricular Hypertrophy – Thickening of the right ventricle muscles due to overwork from pushing against the narrow pulmonary valve.

4. Overriding Aorta – The aorta is shifted towards the right, causing it to receive blood from both the right and left ventricles.

Tetralogy of Fallot leads to the mixing of oxygenated and deoxygenated blood in the heart, which results in the oxygen-poor blood being circulated to the body causing cyanosis in the fingers and hands.

Blood flow in Tetralogy of Fallot is usually right-to-left shunting due to the VSD. This means that the deoxygenated blood from the right ventricle is pumped into the aorta and to the body, instead of going to the lungs to get oxygenated. This leads to a decrease in oxygen levels in the body, causing the cyanosis in the fingers and hands.

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