Q. What is Low Gradient Aortic Stenosis?

One may come across patients who have severe left ventricular dysfunction and modest gradients across aortic valve. This situation may be due to afterload mismatch in a patient with severe valvular aortic stenosis and left ventricular dysfunction or this situation can also be due to moderate aortic stenosis in a patient with intrinsically severe left ventricular muscle dysfunction. Valve area calculation or valve resistance calculations are not particularly useful in this situation with low cardiac output. Dobutamine stress echo cardiography is helpful in this situation. In a patient with intrinsic myocardial dysfunction, cardiac output, trans aortic gradient and calculated valve area - all increase. In a patient with severe aortic stenosis with afterload mismatch also dobutamine infusion would increase calculated valve area but it will still be in the range severe aortic stenosis. The latter patient may benefit from aortic replacement while the former would not.