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Validation of the proximal isovelocity surface area method for assessing mitral regurgitation in children
H Aotsuka1, K Tobita, H Hamada
1Department of Cardiology, Chiba Children's Hospital, 579-1 Hetacho, Midoriku, Chiba 266, Japan.
Insights
The proximal isovelocity surface area (PISA) method accurately quantifies mitral regurgitation severity in children. This Doppler echocardiography technique provides reliable measurements of regurgitant flow and fraction, crucial for pediatric cardiac assessments.
Area of Science:
- Pediatric Cardiology
- Echocardiography
- Cardiovascular Physiology
Background:
- The proximal isovelocity surface area (PISA) method is widely used for assessing regurgitant flow, with established accuracy in adults.
- Application in children presents challenges due to small regurgitation volumes and wide body size variations.
- Accurate quantitative assessment of mitral regurgitation (MR) severity in pediatric patients is clinically significant.
Purpose of the Study:
- To investigate the accuracy of the PISA method for quantitative assessment of mitral regurgitation severity in children.
- To evaluate the reliability of PISA-derived parameters in a pediatric cohort with varying cardiac conditions.
Main Methods:
- Twenty children (7 months to 12 years) with mitral regurgitation underwent Doppler echocardiography.
- PISA radius and regurgitation duration were measured; maximal regurgitant flow rate (MFR) and regurgitant stroke volume (RSVpisa) were calculated assuming a hemispherical PISA.
- Validation was performed by comparing PISA-derived values with stroke volumes and regurgitant fractions calculated using standard echocardiographic methods (area-length volumetry and pulsed Doppler).
Main Results:
- Strong linear correlations were observed between PISA-derived maximal regurgitant flow rate (MFR) and regurgitant stroke volume (RSVpisa) and validated regurgitant stroke volume (RSVD) (r=0.84 and r=0.90, respectively).
- Regurgitant stroke volume indexed to body surface area (RSVpisa/BSA) and MFR indexed to BSA showed significant nonlinear correlations with regurgitant fraction (r=0.85 and r=0.79, respectively).
Conclusions:
- The PISA method, utilizing Doppler echocardiography, accurately predicts maximal regurgitant flow rate, regurgitant stroke volume, and regurgitant fraction in children.
- This validated approach offers a reliable tool for assessing mitral regurgitation severity in pediatric populations.
Abstract:
The proximal isovelocity surface area (PISA) method for calculating volume flow through the regurgitant orifice has attracted significant attention. A number of in vitro studies and clinical studies in adults suggest that the method is accurate. However, when applying the method to children it must be noted that the absolute regurgitation volume is small, and the range of body sizes is wide. This study investigated the accuracy of the PISA method for quantitative assessment of the severity of mitral regurgitation in children. Twenty children aged 7 months to 12 years (average 4.7 years) with mitral regurgitation but without interventricular shunt or aortic stenosis were selected for this study. Underlying cardiac diseases included atrioventricular septal defects in nine, isolated mitral regurgitation in five, and association with other heart defects in six. The PISA radius (r) and the duration of regurgitation (T) were measured on color M-mode recordings, with the M line passing through the center of the PISA. Assuming that the PISA is a hemisphere, maximal regurgitant flow rate (MFR: ml/s) was calculated as MFR = 2pi x r2 x V (r = maximal radius, V = aliasing velocity), and regurgitant stroke volume (RSVpisa) as RSVpisa = 2pi x MSR x V x T (MSR = mean square of the PISA radius during regurgitation). As a validating standard, total stroke volume (TSV) using two-dimensional echocardiography determined by the area-length volumetry method and forward stroke volume (FSV) by the pulsed Doppler method were measured, and regurgitant stroke volume (RSVD: RSVD = TSV - FSV) and regurgitant fraction (RF: RF = RSVD/TSV) were calculated. A linear correlation was found between MFR, RSVpisa, and RSVD (X) (MFR = 4.2X + 54.0, r = 0.84. RSVpisa = 1. 0X + 9.8, r = 0.90), and both RSVpisa and MFR divided by body surface area (BSA: m2) revealed a significant correlation with regurgitant fraction (X) by nonlinear regression analysis (RSVpisa/BSA = 26.2 x X/(1 - X) + 16.8, r = 0.85. MFR/BSA = 121.8 x X/(1 - X) + 92.2, r = 0.79). It is concluded that maximal regurgitant flow rate, regurgitant stroke volume, and regurgitant fraction can be accurately predicted in children using the PISA method by Doppler echocardiography.