Clinical Investigations
Echocardiography in Mitral Valve Disease
A Novel Approach for Semiautomated Three-Dimensional Quantification of Mitral Regurgitant Volume Reflects a More Physiologic Approach to Mitral Regurgitation

https://doi.org/10.1016/j.echo.2022.05.005Get rights and content

Highlights

  • Conventional 2D quantification for MR uses assumptions of MR jet characteristics.

  • Use of a semiautomated 3D approach integrates flow dynamics for MR quantification.

  • 3D RVol values were lower than 2D-derived values across a spectrum of MR pathology.

  • Automated dynamic MR flow curves expressed temporal variation of MR by mechanism.

Background

Quantification of mitral regurgitation (MR) by echocardiography is integral to assessing lesion severity and entails the integration of multiple Doppler-based parameters. These methods are founded primarily upon the principle of proximal isovelocity surface area (PISA), a two-dimensional (2D) method known to involve several assumptions regarding MR jet characteristics. The authors analyzed the results of a semiautomated method of three-dimensional (3D)–based regurgitant volume (RVol) estimation that accounts for jet behavior throughout the cardiac cycle and compared it with conventional 2D PISA methods for MR quantification.

Methods

A total of 50 patients referred for transesophageal echocardiography for evaluation of primary (n = 25) and secondary (n = 25) MR were included for analysis. Three-dimensional full-volume color data sets were acquired, along with standard 2D methods for PISA calculation. A 3D semiautomated MR flow quantification algorithm was applied offline to calculate 3D RVol, with simultaneous temporal curves generated from the 3D data set. Three-dimensional RVol was compared with 2D RVol. Three-dimensional vena contracta area was also performed in all cases.

Results

There was a modest correlation between 2D RVol and 3D RVol (r = 0.60). The semiautomated 3D approach resulted in significantly lower values of RVol compared with 2D PISA. Real-time and dynamic flow curve patterns were used for integral estimates of 3D RVol over the cardiac cycle, with a distinct bimodal pattern in functional MR and a brief and solitary peak in primary MR.

Conclusions

Using a semiautomated 3D software for the quantification of MR allows the simultaneous calculation of 3D RVol with an automated generation of dynamic flow curves characteristic of the underlying MR mechanism. The present flow curve pattern results highlight well-known differences between MR flow dynamics in degenerative MR compared with functional MR.

Section snippets

Study Design

We conducted a single-center study in which we prospectively enrolled subjects referred to our echocardiography laboratory at the University of Chicago for clinically indicated TEE for evaluation of valvular heart disease between 2018 and 2020. Patients were categorized by etiology of MR (primary or degenerative vs secondary or functional). Inclusion criteria required patients to have acceptable 3D image quality and at least mild MR, with complete integrative 2D measurements for MR estimation

Results

A total of 50 patients were included in this study, with baseline demographics as shown in Table 1. The mean age of subjects was 71 ± 13 years, with a balanced sex distribution (50% women). The mean 3D ejection fraction was mildly reduced (48 ± 16%) and significantly lower in the functional MR group with larger LV volumes (40 ± 13% vs 61 ± 6%, P < .001). Eccentric MR jets were present in 52% of cases. A spectrum of MR severity was represented, with 14% mild, 46% moderate, and 40% severe (using

Discussion

Our results emphasize the role of temporal flow pattern variations in MR that occur in accordance with underlying mechanism and how this variability exerts an associated impact upon physiologic parameters of MR severity. We demonstrate that dynamic MR flow patterns can be reproducibly captured using a novel semiautomated 3D software program that simultaneously quantifies flow-modeled RVol and transmitral dynamic flow curves that are more reflective of jet alterations occurring throughout the

Conclusion

Although the importance of a time-integrated 3D PISA has been introduced, and consideration of dynamic flow changes over time is an important component of MR assessment, this concept has been difficult to incorporate into clinical practice. We demonstrate the feasibility of a 3D semiautomated program for the assessment of MR using color Doppler as the primary data set, which results in the expression of quantitative parameters that capture the dynamic behavior of MR and impart incremental

References (18)

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Drs Lang and Singh were provided software support by Philips, Netherlands. Dr Su, Dr Bonnefous, Dr Allaire, Dr Rouet, Dr This, and Ms Laghi are employed by Philips.

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