Key result
PISA consistently estimates geometric orifice area across LVOT velocities, avoiding continuity equation overestimation.
Why the study?
High flow velocity at the LVOT potentially causes overestimation of effective orifice area by the continuity equation in aortic stenosis.
Does the PISA method provide a more accurate estimation of effective orifice area compared to the continuity equation in patients with aortic stenosis and high LVOT velocity?
Observational (n=114)
Blinded analysis
No
Does the PISA method provide a more accurate estimation of effective orifice area compared to the continuity equation in patients with aortic stenosis and high LVOT velocity?
Answers are grounded in this paper and cite their sources.
The PISA method provides a more consistent estimation of effective orifice area in aortic stenosis compared to the continuity equation, particularly in patients with high LVOT velocity where the continuity equation tends to overestimate the area.
Purpose: Because existence of high flow velocity at the left ventricular outflow tract (LVOT) potentially causes an overestimation of effective orifice area (EOA) by continuity equation in aortic stenosis (AS), we tested the proximal isovelocity surface area (PISA) method as an alternative tool for AS. Methods: EOA was calculated using the continuity equation (EOA Cont ) and PISA method (EOA PISA ), respectively, in 114 patients with at least moderate AS. The geometric orifice area (GOA) was also measured in 51 patients who also underwent three-dimensional transesophageal echocardiography (TEE). Patients were divided into two groups according to the median LVOT flow velocity. Results: Feasibility of EOA PISA was 95% in the 114 patients. While there was a strong correlation between EOA Cont and EOA PISA , EOA Cont was greater than EOA PISA especially in patients with high LVOT velocity. In TOE cohort, both EOA Cont and EOA PISA similarly correlated with GOA. However, a fixed bias, which is supposed to exist in AS, was observed only between EOA PISA and GOA with smaller EOA PISA than GOA. The difference between EOA Cont and GOA was significantly greater with a larger EOA Cont relative to GOA in patients with high LVOT velocity than in those without (0.16±0.25 vs -0.07±0.10 cm 2 , P <0.001). In contrast, the difference between EOA PISA and GOA was consistent in both groups (-0.07±0.12 vs -0.07±0.15 cm 2 , P = 0.936). Conclusion: The PISA method was applied to estimate EOA of AS. EOA PISA could be an alternative parameter for AS severity grading in patients with high LVOT velocity in whom EOA Cont would overestimate the orifice area.
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Nakabachi et al. (2021) conducted an observational in Aortic stenosis (n=114). Proximal isovelocity surface area (PISA) method vs. Continuity equation was evaluated on Difference between EOAPISA and geometric orifice area (GOA) in patients with high vs low LVOT velocity (p=0.936). The PISA method provided consistent estimation of the geometric orifice area regardless of LVOT flow velocity, avoiding the significant overestimation seen with the continuity equation in patients with high LVOT velocity.
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