How will the heart function with tetralogy of Fallot?

Question

Hello doctor,

In tetralogy of Fallot, after a systemic-to-pulmonary artery shunt is created, mixed blood flows through the shunt into the pulmonary artery and then to the lungs to become oxygenated. The oxygenated blood returns to the heart through the pulmonary veins. Is the same mechanism occurring here? How does this procedure help increase the oxygen level in the blood?

Answer 1

Hello,

Welcome to icliniq.com.

I am a cardiologist, and I am happy to clarify your doubt.

In tetralogy of Fallot, the ventricular septal defect (VSD) is large and non-restrictive, allowing both ventricles to operate at the same pressure. Additionally, the aorta is positioned directly above the VSD. As a result, the distribution of blood between the pulmonary and systemic circulations depends on the severity of pulmonary stenosis.

If the pulmonary stenosis is severe, a significant amount of deoxygenated blood is pumped from the right ventricle into the aorta, leading to cyanosis (a bluish discoloration of the extremities). In contrast, if the pulmonary stenosis is mild, less blood is shunted to the systemic circulation, and the patient may not exhibit cyanosis at rest.

I hope this helps you.

Thank you.