AS: Aortic Valve Area (Gorlin)

The Gorlin Equation relies on the ratio of peak-to-peak instantaneous gradients. In mild-moderate stenosis the peak-to-peak gradient, does not reflect mean gradient however it is often close to mean gradient for severe stenosis. In low-flow states (CO < 2.5 L/min) as the Gorlin equation tends to overestimate the degree of stenosis.

The normal aortic valve area is 3-4 cm². Symptoms tend to not be apparent until the AS is severe (<1cm²). If a patient presents with symptoms and the AVA is measured in the mild-moderate range alternative causes should be explored before attributing them to AS alone.