Jet eccentricity: A misleading source of agreement between Doppler/catheter pressure gradients in aortic stenosis

Abstract

In regard to a recent article in the Journal of the American Society of Echocardiography by VanAuker et al,1VanAuker MD Chandra M Shirani J Strom JA Jet eccentricity: a misleading source of agreement between Doppler/Catheter pressure gradients in aortic stenosis.J Am Soc Echocardiogr. 2001; 14: 853-862Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar we commend the authors for their efforts in investigating pressure recovery and valve area in eccentric jets. However, we have a few issues with the report. Although this is numerical experimentation reported in a clinical journal, several important computational parameters were left out that needed to be included. Such parameters are essential for others to be able to have confidence in and duplicate the reports findings. First, there was no mention of the size of the numerical grids used and no mention of grid validation. Grid validation2Migliavacca F de Leval M Dubini G Pietrabissa R. A computational pulsatile model of the bidrectional cavopulmonary anastomosis.J Biomech Eng. 1996; 118: 520-528Crossref PubMed Scopus (48) Google Scholar is the process of comparing the results of flow simulations while sequentially refining the computational grid (ie, creating more grid points in the computational model). The grid (and thus the numerical model) is assumed to be valid only after further grid refinements create no significant change in “critical” flow parameters. Second, even though changes in valve area with eccentric jets were secondary findings in this study, the authors did not address how changes in the cross-sectional velocity profile at the vena contracta effect valve area calculations. We have addressed this problem in noneccentric jets3DeGroff CG Shandas R Valdes-Cruz LM Analysis of the effect of flow rate on the Doppler continuity equation for stenotic orifice area calculations: A numerical study.Circulation. 1998; 97: 1597-1605Crossref PubMed Scopus (65) Google Scholar and it would be interesting to see how cross-sectional velocity profiles vary in these eccentric jets. Such changes in the cross-sectional velocity profiles influence the results of valve area calculations and these changes have a significant dependence on flow rate. Thus, it would have been valuable for the authors to cite flow rates directly in this study.