Aortic valve area: Difference between revisions
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==Overview== | ==Overview== | ||
Normal aortic valve offers little or no resistance to the blood flow across the valve despite the high [[Aortic stenosis pathophysiology#Flow Velocity|flow velocities]]. With progressive [[aortic stenosis]], the aortic valve orifice offers progressively greater resistance to the blood flow through the valve with subsequent reduction in the [[Intravascular pressure gradient|pressure gradient]] between the [[left ventricle]] and the [[aorta]]. Therefore, using both the pressure gradient across the valve and the surface area of the valve the severity of [[aortic stenosis]] can be estimated. The latter can be calculated using echocardiographic flow velocities while the trans-valvular pressure gradient can be calculated using the following equation: <blockquote>Pressure Gradient = 4 x (velocity of blood through the valve)<sup>2</sup> mmHg</blockquote> | |||
However, the absence of a [[Intravascular pressure gradient|large gradient]] across the [[aortic valve]] does not exclude the presence of [[critical aortic stenosis]] and the presence of a [[Intravascular pressure gradient|low gradient]], [[ejection fraction|low ejection]] may result in [[blood flow|low flow]] [[aortic stenosis]] which is associated with poor clinical outcomes. Therefore, it is for this reason that '''''the best measure of the severity of aortic stenosis is the [[aortic valve area]] and not the aortic valve gradient.''''' | |||
==Cardiac Catheterization== | ==Cardiac Catheterization== | ||
Revision as of 14:57, 12 April 2012
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Aortic Stenosis Microchapters |
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Diagnosis |
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Treatment |
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Percutaneous Aortic Balloon Valvotomy (PABV) or Aortic Valvuloplasty |
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Transcatheter Aortic Valve Replacement (TAVR) |
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Case Studies |
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Aortic valve area On the Web |
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American Roentgen Ray Society Images of Aortic valve area |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Lakshmi Gopalakrishnan, M.B.B.S. [2]
Overview
Normal aortic valve offers little or no resistance to the blood flow across the valve despite the high flow velocities. With progressive aortic stenosis, the aortic valve orifice offers progressively greater resistance to the blood flow through the valve with subsequent reduction in the pressure gradient between the left ventricle and the aorta. Therefore, using both the pressure gradient across the valve and the surface area of the valve the severity of aortic stenosis can be estimated. The latter can be calculated using echocardiographic flow velocities while the trans-valvular pressure gradient can be calculated using the following equation:
Pressure Gradient = 4 x (velocity of blood through the valve)2 mmHg
However, the absence of a large gradient across the aortic valve does not exclude the presence of critical aortic stenosis and the presence of a low gradient, low ejection may result in low flow aortic stenosis which is associated with poor clinical outcomes. Therefore, it is for this reason that the best measure of the severity of aortic stenosis is the aortic valve area and not the aortic valve gradient.
Cardiac Catheterization
Simultaneous measurement of left ventricular output (measures the flow through the aortic valve) and the pressure gradient across the aortic valve provides the essential variables that is required to calculate the aortic valve area and resistance.[1][2]
Gorlin Equation
References
- ↑ Hirshfeld JW, Kolansky DM. Valve function: Stenosis and regurgitation. In: Diagnostic and Therapeutic Cardiac Catheterization, 2nd ed, Pepine CJ, Hill JA, Lambert CR (Eds), Williams & Wilkins, Baltimore 1994. p.443
- ↑ Carabello BA, Grossman W. Calculation of stenotic valve orifice area. In: Cardiac Catheterization and Angiography, 3rd ed, Grossman W (Ed), Lea and Febiger, Philadelphia 1986. p.143.