Aortic prosthetic valve design and size: Relation to Doppler echocardiographic findings and pressure recovery - An in vitro study

The extent to which Doppler echocardiography information can be used in the assessment of prosthesis hemodynamic performance is still controversial. T he goals of our study were to assess the importance of valve design and siz e both on Doppler echocardiography findings and on pressure recovery in a f luid mechanics model. We performed Doppler and catheter measurements in the different orifices of the bileaflet St Jude (central and side orifices), t he monoleaflet Omnicarbon (major and minor orifices), and the stented Bioco r porcine prosthesis. Net pressure gradients were predicted from Doppler fl ow velocities, assuming either independence or dependence of valve size. Th e peak Doppler estimated gradients (mean +/- SD for sizes 21 to 27) were 21 +/- 10.3 rum Hg for St Jude, 18 +/- 9.3 mm Hg for Omnicarbon, and 37 +/- 1 4.5 mm Hg for Biocor (P <.05 for St Jude and Omnicarbon vs Biocor). The pre ssure recovery (proportion of peak catheter pressure) was 53% +/- 8.6% for central-St Jude, 29% +/- 8.9% for side-St Jude, 20% +/- 5.6% for major-Omni carbon, 23% +/- 7.4% for minor-Omnicarbon, and 18% +/- 3.6% for Biocor (P < .05 for central-St Jude and side-St Jude vs Omnicarbon and Biocor). Valve s izes (2) significantly influenced pressure recovery (y in percentage) (cent ral-St Jude: y = 3.7x - 35.9, r = 0.88, P =.0001; major-Omnicarbon: y = 2.1 x - 30.3, r = 0.85, P =.0001). By assuming dependence of valve size, Dopple r was able to predict net pressure gradients in St Jude with a mean differe nce between net catheter and Doppler-predicted gradient of - 3.8 +/- 2.5 mm Hg. In conclusion, prosthetic value design and size influence the degree o f pressure recovery, making Doppler gradients potentially misleading in bot h the assessment of hemodynamic performance and the comparison of one desig n with another. The preliminary results indicate that net gradient can be p redicted from Doppler gradients,