Abstract 12185: In vitro Assessment of Proximal Isovelocity Surface Area (PISA) Method on Double Orifice Mitral Regurgitation: Implication for Mitral Clipping

• Published in: Circulation (New York, N.Y.) N.Y.), 2019-11, Vol.140 (Suppl_1 Suppl 1), p.A12185-A12185
• Main Authors: Lee, Jeesoo, El Hangouche, Nadia, Van Assche, Lowie M, O’Brien, Ellie, Barker, Alexander J, Markl, Michael, Thomas, James D
• Format: Article
• Language: English
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/circ.140.suppl_1.12185

IntroductionTranscatheter edge-to-edge mitral regurgitation repair techniques such as MitraClip and Pascal typically transform a regurgitant orifice into a double orifice. However, quantifying effective regurgitant orifice area (EROA) of double orifices with the established Proximal Isovelocity Surface Area (PISA) method is challenging due to the confluence of flow convergence (FC) zones. We sought to systematically evaluate the PISA method under well controlled in vitro flow conditions for double orifices with different area ratio (AR).MethodsFlow through two circular orifices with the AR of 1:1, 2:1 and 3:1 were evaluated using an in vitro gravity-driven flow phantom that generated linearly decreasing velocity through orifices with a predetermined discharge flow volume. Aliasing velocity (va) was adjusted to segregate or merge aliased FC zone of each orifice, and EROA was quantified with PISA in 10 randomly selected frames in each AR measurement. EROA by PISA was compared with EROA measured with the discharge flow volume divided by a Doppler velocity time integral (VTI). Additionally, proximal flow field was simulated with inviscid flow theory to identify the 3D morphology of FC zones.Results and DiscussionWhen applied to separate FC zones (va>10% orifice velocity), PISA predicted EROA within 7% of the true summed EROA regardless of relative area difference between orifices (4.4±12.2%, –6.6±11.8% and –3.4±14.4% for AR 1:1, 2:1 and 3:1, respectively). On the contrary, when applied to a merged flow convergence zone (low va) PISA significantly underestimated for the two symmetrical orifices but improved with increasing AR (–33.1±15.2%, –26.0±9.8% and –2.3±10.7% for AR 1:1, 2:1 and 3:1, respectively). This can be explained by the reduced contribution from the smaller orifice to a merged FC zone resulting in more hemispheric shape as shown in Figure. These findings may suggest of using high va for roughly balanced jets and low va for a clearly dominant jet.