AS: Aortic Valve Area (Cont)
Estimate aortic valve area
Derivation of valve area is based the continuity equation which states that the flow passing through the LVOT has to equal the flow through the AV. Echocardiographic derived measurements are based on maximal instantaneous gradient which provide a more accurate assessment then non-physiologic peak-to-peak gradients observed on invasive studies. In general, the VTI (cm) is felt provide a more accurate assessment of valve area however peak velocity (m/sec) can also be used.
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.
Robert O Bonow, Blase A Carabello et al.
ACC/AHA 2006 Guidelines for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease): Developed in Collaboration With the Society for Cardiovascular Angiography and Interventions: Endorsed by the Society of Cardiovascular Anesthesiologists and the Society of Thoracic Surgeons.
Circulation 2006 August 1, 114 (5): e84-231
Oh J, Seward JB, Tajik AJ.
The Echo Manual 3rd edition. Lippincott, Williams, Wilkins. 2007
The Cardiac Catheterization Handbook 4th Edition. Mosby 2003
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