1.Peak gradient across the aortic valve
Using the modified Bernoulli equation:
P= 4V2= 4(3)2 = 36mmHg
Peak gradient across aortic valve = 36mmHg
Mean Aortic gradient = 0.64 x peak gradient = 23 mmHg (2)
2.Stroke volume
LVOT cross sectional area == pr2 = 3.14 X (1.9/2)2 = 2.84 cm2
Stroke volume = LVOT VTI X LVOT cross sectional area
= 14 X 2.84 = 40 ml
Stroke volume index = stroke volume/ BSA = 40 ml/ 1.5 =26.7ml/m2
Cardiac output = Stroke volume x heart rate = 40x 55= 2200 ml/ min= 2.2L/ min
3.Aortic valve area (Continuity equation)
Aortic valve area= LVOT cross sectional area x LVOT VTI / aortic valve VTI
= 2.84 X 14 / 74
=0.54 cm2
4.Final summary: Mean gradient = 23 mmHg
Stroke volume index = 26.7 ml/m2
Cardiac output = 2.2 L/ min
Aortic valve area= 0.54 cm2
It is consistent with Low-flow, low-gradient severe aortic stenosis, as the ejection fraction is 45%.
References:
1.Baumgartner H, Hung J, Bermejo J, et al. Recommendations on the echocardiographic assessment of aortic valve stenosis: A focused update from the European Association of Cardiovascular Imaging and the American Society of Echocardiography. J Am Soc Echocardiogr 2017;30:372-92.
2.Teien D, Karp K, Eriksson P. Non-invasive estimation of the mean pressure difference in aortic stenosis by Doppler ultrasound. Br Heart J 1986;56:450-4.