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Valvular Aortic Stenosis

Disease Severity and Timing of Intervention

Division of Cardiology, Department of Medicine, University of Washington, Seattle, Washington.

View larger version (150K): [in a new window]   Figure 1 Standard evaluation of aortic stenosis (AS) severity is based on measurement of left ventricular outflow tract (LVOT) diameter (D) in a parasternal long-axis view for calculation of a circular cross-sectional area (CSA), outflow tract velocity (V) from an apical approach using pulsed Doppler, and the maximum aortic jet (AS-Jet, Vmax) from the continuous-wave Doppler recording. Either velocity-time integrals (VTIs) or maximum velocities can be used in the continuity equation for aortic valve area (AVA).

View larger version (19K): [in a new window]   Figure 2 Schematic representation of the flow and static pressure across the left ventricular (LV) outflow tract, aortic valve, and ascending aorta during systole. AA = aortic cross-sectional area; AVA = effective aortic valve area (i.e., the cross-sectional area of the vena contracta); LVSP = left ventricular systolic pressure; MGnet = transvalvular pressure gradient after pressure recovery (i.e., net MG); MGvc = transvalvular pressure gradient at the vena contracta; SAP = systolic aortic pressure; SAPvc = systolic aortic pressure at the vena contracta; SV = stroke volume; SVi = stroke volume index; ZVA = valvulo-arterial impedance. From Briand et al. (12), with permission.

View larger version (17K): [in a new window]   Figure 3 Hemodynamic data in a model of aortic stenosis were obtained using a dual micromanometer catheter and a transit time flow probe. (A) The simultaneous instantaneous electrocardiogram, aortic and left ventricular (LV) pressures, transaortic volume flow (Q), and aortic pressure gradient (P) are shown. During late ejection P is negative. (B) The phase diagram of P-Q for this cardiac cycle demonstrates the nonlinearity and time dependence of the P-Q relationship. EKG = electrocardiogram. From Bermejo et al. (15), with permission.

View larger version (28K): [in a new window]   Figure 4 Suggested approach to evaluation of adults with severe aortic stenosis. Additional considerations include comorbidities and patient preferences. AVA = aortic valve area; AVR = aortic valve replacement; BNP = brain natriuretic peptide; BP = blood pressure; CRF = cardiac risk factors; f/u = follow-up; LV = left ventricular; Vmax = maximum velocity.

View larger version (23K): [in a new window]   Figure 5 Suggested approach to evaluation of adults with moderate aortic stenosis (AS). *Additional evaluation of AS severity may include measurement of newer parameters discussed in the text, evaluation of the extent of leaflet calcification, cardiac catheterization, and/or dobutamine stress echocardiography. Dx = diagnosis; Rx = therapy; other abbreviations as in Figure 4.

View larger version (101K): [in a new window]   Figure 6 Example of decision making with moderate aortic stenosis (AS) and aortic regurgitation (AR). This 59-year-old man has a markedly calcified aortic valve, but aortic velocity is only 3.7 m/s, mean gradient 34 mm Hg, and valve area is 1.3 cm2. Moderate regurgitation also is present with a vena contract of 5 mm, and holodiastolic flow reversal in the descending aorta. However, significant left ventricular dilation and systolic dysfunction are present, so that aortic valve replacement is appropriate. EF = ejection fraction; ESD = end-systolic dimension.

View larger version (114K): [in a new window]   Figure 7 This 82-year-old woman underwent echocardiography for evaluation of a systolic murmur. The valve was heavily calcified as seen the short-axis view (top) with reduced systolic opening in the long-axis view (bottom), with Doppler data consistent with severe stenosis. At cardiac catheterization several days later, a lower pressure gradient and lower stroke volume were recorded. The apparent discrepancy in the catheterization data most likely is related to pressure recovery and severe hypertension (blood pressure [BP] 194 systolic during catheterization). AoV = aortic valve; AVA = aortic valve area; Grad = gradient; Mn = mean; Pk = peak; SV = stroke volume; Vmax = maximum velocity; VTI = velocity time integral.

View larger version (129K): [in a new window]   Figure 8 Dobutamine stress echocardiography was requested in this 52-year-old man with a history of radiation therapy with heart failure symptoms, left ventricular dysfunction, and a calcified aortic valve. With dobutamine, ejection fraction (EF) and stroke volume (SV) increased, indicating contractile reserve. Outflow tract peak velocity increased from 0.9 to 1.0 cm/s (left ventricular outflow tract [LVOT] diameter 2.2 cm), so calculated aortic valve area was unchanged at 1.0 cm2 at rest and at peak dose dobutamine consistent with stiff inflexible leaflets. AS-Jet = aortic jet.