What Is Aortic Stenosis (AS)?

The aorta is the main artery that delivers the oxygenated blood from the left ventricle to the body.  The blood passes through the aortic valve as it leaves the ventricle.

The valve has three cusps that meet in the middle like a Mercedes Benz symbol.  When the left ventricle contracts the blood passes through the valve, opening the three leaflets out of the way, so there is no resistance to blood flow.  When the ventricle relaxes the pressure in the aorta exceeds that in the ventricle and so the blood passes backwards and closes the valve.

Over time, the aortic valve leaflets may thicken and become stiff.  This can lead to the valve not opening properly so that there is resistance to the blood flow through the valve.  This narrowing of the aortic valve is called aortic stenosis.  Alternately, the valve leaflets may not close properly so the blood leaks back into the left ventricle.  This leakiness is known as aortic regurgitation or aortic incompetence.

When the aortic valve function is severely compromised it needs to be mechanically replaced.  This is performed either from the leg by a Transcatheter Aortic Valve Implantation (TAVI), or through an open chest operation by surgical aortic valve replacement (SAVR).