Main Points in Doppler Assessment of Valve Regurgitation

Main points in doppler assessment of valve regurgitation (1)

1. Colour doppler 

• The ideal Nyquist limit is 50 - 60cm
• Reducing the Nyquist limit can increase the size of the jet, and can result in overestimation of the severity of the regurgitation
• Due to this reason, the color flow area of the regurgitant jet is not recommended to assess and quantify how severe valve regurgitation is.

2. Vena Contracta

• This is the narrowest part of the regurgitant jet below the level of the regurgitant valve orifice (2)
• It is essential to focus on jet alone, so the size of the color jet and the imaging depth must be reduced. 
• It is difficult to accurately assess vena contracta in the presence of multiple jets and an irregular orifice

Nevertheless, it still remains a very useful method to assess the severity of valve regurgitation

3. Proximal Isovelocity Surface Area (PISA)

• Also called flow convergence
• The main principle here is that as blood flows across a regurgitant valve, convergence at this level results in the formation of ‘concentric isovelocity shells’, which can be visualized with color flow doppler at an optimal aliasing velocity
• The product of the the size of this shell and the aliasing velocity provides the flow rate. 
• The regurgitant orifice area can then be calculated by dividing this value by peak velocity of the regurgitant jet obtained on continuous wave doppler.

Advantages

• Reproducible
• Can be used for eccentric jets as well (3)
• Unaffected by the cause of regurgitation

References

1. Patrizio Lancellotti, Christophe Tribouilloy, Andreas Hagendorff, Luis Moura,Bogdan A. Popescu, Eustachio Agricola, Jean-Luc Monin, Luc A. Pierard, Luigi Badano,Jose L. Zamorano, Rosa Sicari, Alec Vahanian, and Jos R.T.C. Roelandt. European Association of Echocardiography recommendations for the assessment of valvular regurgitation. Part 1: aortic and pulmonary regurgitation (native valve disease)Eur J Echocardiogr (2010) 11(3): 223-244
2. Roberts BJ, Grayburn PA. Color flow imaging of the vena contracta in mitral regurgitation: technical considerations. J Am Soc Echocardiogr 2003;16:1002-6.
3. Enriquez-Sarano M, Tajik AJ, Bailey KR, Seward JB. Color flow imaging compared with quantitative Doppler assessment of severity of mitral regurgitation: influence of eccentricity of jet and mechanism of regurgitation. J Am Coll Cardiol 1993;21:1211-9.