Aortic Valve Stenosis

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Aortic stenosis quantification

Slight Moderate Severe
PG max 15-40 mmHg 40-70 mmHg 70-100 mmHg (> 100 mmHg severe AoS)
PG mean <20mmHg 20-40mmHg> 40mmHg
AVA> 1.5cm2 1.5-1cm2 <1cm2
Dimensionless index> 0.50 0.25 to 0.50 <0.25
Vmax <3m/s 3-4m/s >4m/s
AVA BSAindex >0.85cm2/m2 0.85-0.60cm2/m2 <0.60cm2/m2
 
Serious AoS: PG max 101mmHg, PG mean 69mmHg[1] PHT moderate Aol [1]
Click here to calculate AGM

Aortic valve area (AVA)

For the calculation of the aortic valve surface, the continuity equation can be applied.

Continuity equation:

A1.v1 = A2.v2

  Where: A=area (∏r2) cm2

v=velocity, cm/s (can be used as maximum speed or TVI)

so :

Aortic valve area (AVA)=( D LVOT/2 )2 x 3:14 x Vmax LVOT/Vmax peak in AoS jet

Where: D LVOT=diameter LVOT in cm

Dimensionless index (DI)

If you are unable to get a good measurement of the LVOT can also the ratio of the velocity in the LVOT and the speed of the aortic valve to give a good impression about the severity of aortic stenosis .

DI = V LVOT/V aorta In a DI = 25, there is almost always a severe aortic valve stenosis .

Low- gradient aortic stenosis vs . pseudo stenosis

In an aortic valve stenosis with a low gradient (<30 mmHg ), and poor left ventricular function is to be a valve surface calculated . If an AVA <1 cm ² is calculated can be a severe aortic valve stenosis are present despite the low gradient . However, it could also be that the valve does not open properly due to low cardiac output ( pseudo stenosis ) . To gain more insight into the aortic valve or a "true " or stenosis has a "pseudo stenosis " seems dobutamine stress worthwhile . If during dobutamine infusion up to 20 micrograms / kg there is an increase of more than 20 % in the LVOT VTI (ie cardiac output ) and the calculated valve area remains below 1 cm ² then there is a true aortic stenosis . If not , and there appears to be a contractile reserve (which is predictive of a better prognosis after aortic valve replacement ) it is called a pseudo stenosis.

References

  1. Baumgartner H, Hung J, Bermejo J, Chambers JB, Evangelista A, Griffin BP, Iung B, Otto CM, Pellikka PA, Quiñones M, and EAE/ASE. Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. Eur J Echocardiogr. 2009 Jan;10(1):1-25. DOI:10.1093/ejechocard/jen303 | PubMed ID:19065003 | HubMed [1]