Abstract 11516: Quantification of Regurgitation Through Dual Orifices: Pulsatile in Vitro Analysis with Echocardiography and MRI Assessment

• Published in: Circulation (New York, N.Y.) Vol. 144; no. Suppl_1; p. A11516
• Main Authors: Wu, Erik, Lee, Jeesoo, Mason, Oneil R, Markl, Michael, Thomas, James D
• Format: Journal Article
• Language: English
• Published: Lippincott Williams & Wilkins 16.11.2021
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/circ.144.suppl_1.11516

IntroductionProximal Isovelocity Surface Area (PISA) measurement is widely accepted to quantify mitral regurgitant volume (RVol), but flow convergence (FC) zones are complicated with dual orifices, seen with mitral clipping. This study seeks to investigate how flow through one orifice affects PISA measurement across the other to better quantify RVol in dual orifice conditions. Methods3D-printed dual circular orifice models with varying relative areas were integrated into a pulsatile flow phantom simulating left heart flow. One orifice (A) was standardized at 19.6 mm2 while the other (B) was 1X, 2X, and 3X the area of A in three models. Inter-orifice distance was 5 mm to emulate mitral clipping. Continuous wave doppler echocardiography measured peak velocity and velocity time integral. PISA was performed at four aliasing velocities normalized to peak velocity (Va/Vpeak) (10%, 8%, 4%, 2%) to compute RVol with 2D phase contrast MRI as reference. In each model, PISA RVol and percent error was calculated to see how varying the area of B impacts PISA accuracy of A. 4D flow MRI FC data was also collected to visualize the 3D formation of FC zones. ResultsUsing a high Va/Vpeak to create distinct FC zones provides a better RVol estimation with PISA, as low Va/Vpeak will merge the FC zones, overestimating flow across individual orifices. Single factor analysis of variance (ANOVA) of percent error of A across the three models showed no significant difference at high Va/Vpeak (8%p=0.80, 10%p=0.23), but significant difference at low Va/Vpeak (2%p=0.010, 4%p=0.005). High Va/Vpeak FC zones of orifices are independent from each other; PISA can be measured with standard practices and added together for an accurate total RVol. At low Va/Vpeak, FC orifice zones overlap with overestimation error increasing with larger B area. This finding suggests that resolving two separate FC zones to minimize flow interference is important for accurate RVol estimate in a dual orifice setting.