Which of the following is classified as an acyanotic heart defect?

A Ventricular Septal Defect (VSD) is classified as an acyanotic heart defect because it involves a left-to-right shunt, where blood flows from the left ventricle into the right ventricle due to an abnormal opening in the ventricular septum. This shunting of oxygen-rich blood into the right side of the heart typically does not cause cyanosis, as it does not lead to significant mixing of oxygen-poor blood with oxygen-rich blood in systemic circulation.

In VSD, while there can be increased pulmonary blood flow and potential lung overcirculation, the oxygen saturation in the systemic circulation remains relatively normal because the defect allows for the oxygenated blood to continue flowing to the body, albeit with some left-over flow to the lungs. This distinguishes it from cyanotic heart defects, which lead to conditions where the blood available to the systemic circulation is less oxygenated.

Transposition of the Great Vessels, Tricuspid Atresia, and Tetralogy of Fallot, on the other hand, involve significant mixing of deoxygenated and oxygenated blood or result in inefficient oxygen delivery to the systemic circulation, leading to cyanosis.