Proximal Flow Convergence Region as Assessed by Real-time 3-Dimensional Echocardiography: Challenging the Hemispheric Assumption

doi:10.1016/j.echo.2006.09.006

Journal of the American Society of Echocardiography

Volume 20, Issue 4, April 2007, Pages 389-396

https://doi.org/10.1016/j.echo.2006.09.006 Get rights and content

Objective

Traditionally, a hemispheric assumption for the proximal flow convergence region (PFCR) is used when calculating mitral regurgitant (MR) effective orifice area (EROA). However, 2-dimensional (2D) echocardiography limits evaluation of the complete PFCR contour. Real-time 3-dimensional (3D) echocardiography (RT3D) allows direct assessment of the true PFCR contour. We hypothesized that the PFCR contour is not necessarily hemispheric, but rather hemielliptic, and aimed to apply a hemielliptic calculation, based on the 3D contour of the PFCR for more accurate MR quantification.

Methods

In all, 50 patients with MR underwent RT3D to characterize PFCR contour as hemispheric or hemielliptic. MR EROA by RT3D-derived PFCR was calculated using a hemielliptic formula using 3D data. The 2D EROA was computed using standard hemispheric assumption. EROAs calculated from 2D and RT3D data were compared with quantitative Doppler EROA (mitral inflow − aortic outflow/MR time-velocity integral), used as an independent comparison.

Results

Only 1 of 50 patients (2%) had a hemispheric PFCR contour by RT3D. The remaining had hemielliptic PFCR contours. Compared with Doppler method, 2D echocardiography significantly underestimated EROA (0.34 ± 0.14 vs 0.48 ± 0.25 cm², P < .001). RT3D EROA was not significantly different from Doppler EROA (0.52 ± 0.17 vs 0.48 ± 0.25, P = not significant). Of 33 patients with Doppler EROA greater than 0.3 cm² (≥moderate-severe MR), 45% (15 of 33) were underestimated as having mild to moderate MR by 2D EROA.

Conclusions

The true PFCR contour as shown by RT3D is generally not hemispheric but hemielliptic, tracking the orifice contour. Based on this 3D shape, a hemielliptic approach can be used for practical clinical application with improved MR quantification.

Section snippets

Methods

Fifty patients with at least mild MR underwent 2D echocardiography and RT3D in a prospective and consecutive manner. Patients with technically poor acoustic windows or irregular heart rhythm were excluded. Quantitative pulsed Doppler assessment of EROA was performed in 40 patients with technically adequate images, as an independent method for comparison of 2D and 3D PFCR approaches, to compute the pulsed Doppler flow EROA. Patients with significant aortic stenosis, aortic insufficiency (≥mild)

Results

Fifty patients (mean age 65 ± 13 years; 22 women, 28 men) underwent 2D echocardiography and RT3D to assess PFCR contour. MR quantification was obtained in 40 patients, with the remaining 10 having exclusion factors (see above) or inadequate images for accurate pulsed Doppler MR quantification. The cause of MR was functional and/or ischemic in 60%, prolapse in 20%, and rheumatic in 20%. Of the jets, 40% were eccentric.

The PFCR contour was hemispheric by RT3D in only one patient with mild to

Discussion

This study demonstrates that the hemispheric assumption for the PFCR is frequently not valid. Indeed, only 1 of 50 patients in this study had a hemispheric contour demonstrated by RT3D. The remainder of the contours was hemielliptic, tracking the elliptic orifice of the mitral valve. These contours retained their nonhemispheric shape even at low Nyquist limits. This study highlights the limitations of a hemispheric assumption for the PFCR, frequently resulting in significant underestimation of

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Spatiotemporal complexity of the color Doppler vena contracta challenging the assumption of a circular and constant orifice may lead to mitral regurgitation (MR) grading inconsistencies. Using 3D transesophageal echocardiography, we characterized spatiotemporal vena contracta complexity and its impact on MR severity grading.
In 192 patients with suspected moderate or severe MR (100 primary MR [PMR]; 92 secondary MR [SMR]), we performed three-dimensional vena contracta area (VCA) quantification using single-frame (midsystolic or VCAmid, maximum or VCAmax) and multiframe (VCAmean) methods, as well as measures of orifice shape (shape index) and systolic variation of VCA. Vena contracta complexity and intermethod discrepancies were analyzed and correlated with functional class and pulmonary vein flow (PVF) patterns and with cardiac magnetic resonance (CMR) in a subset of cases (n = 20).
The vena contracta was noncircular (shape index > 1.5) in 90% of patients. Severe noncircularity (shape index > 3) was more prevalent in SMR than in PMR (32.4% vs 14.6%). Variations of the VCA were more prominent in SMR than in PMR. VCAmid showed a low grading agreement with VCAmax (62%) and high grading agreement with VCAmean (83.3%). Pulmonary vein flow systolic reversal was associated with MR severity by VCA in SMR but not in PMR. VCAmid and VCAmean showed a stronger association with systolic flow reversal than VCAmax (area under the curve, 0.88, 0.86, and 0.79, respectively). In the subset of patients with CMR quantification, severe MR by VCAmax was graded as nonsevere by CMR more frequently compared with VCAmid and VCAmean.
Highly prevalent spatiotemporal vena contracta complexity features in MR challenge the assumption of a circular and constant orifice. VCAmid seems the best single-frame approximation to multiframe quantification, and VCAmax may lead to severity overestimation.
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Transesophageal echocardiography is crucial to evaluate patients with mitral regurgitation undergoing mitral valve surgery. Characterization of the anatomy of the valve, mechanism and severity of the regurgitation are the first steps to plan the type of intervention. Two-dimensional echocardiography has been widely available and a prerequisite before referring the patient to mitral valve surgery. However, the advent of 3-dimensional echocardiography has allowed visualization of the mitral valve resembling the view the surgeons have at the operating theater and has provided more accurate quantification of the severity of the mitral regurgitation. Accordingly, 3-dimensional echocardiography has become a must in the evaluation of patients with severe mitral regurgitation. In this review article, the role of 2- and 3-dimensional echocardiography in the evaluation of mitral regurgitation and the key aspects needed before mitral valve surgery are described.
La ecocardiografía transesofágica es fundamental para evaluar a los pacientes con insuficiencia mitral sometidos a cirugía de la válvula mitral. La caracterización de la anatomía de la válvula, el mecanismo y la gravedad de la regurgitación son los primeros pasos para planificar el tipo de intervención. La ecocardiografía bidimensional ha estado ampliamente disponible y es un requisito previo antes de derivar al paciente a cirugía de la válvula mitral; sin embargo, el desarrollo de la ecocardiografía tridimensional ha permitido una visualización de la válvula mitral similar a la visualizacion de los cirujanos en el quirófano y ha proporcionado una cuantificación más precisa de la gravedad de la insuficiencia mitral. En consecuencia, la ecocardiografía tridimensional es esencial en la evaluación de pacientes con insuficiencia mitral grave. En este artículo de revisión se describe el papel de la ecocardiografía bidimensional y tridimensional en la evaluación de la insuficiencia mitral y los aspectos que deben ser evaluados antes de la cirugía de la válvula mitral.
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Citation Excerpt :
A meta-analysis of both studies reported that application of phenylephrine led to a clinically significant overestimation in about a fifth of the patients, which also makes this method not really feasible or reliable.7 Superiority of 3D-VCA to 2D methods in evaluation of MR is well-known.9 Considering that 3D-VCA represents a direct measurement and not a calculation of the regurgitant orifice, the authors assumed that it would be less susceptible to the hemodynamic changes induced by GA.
To evaluate the effect of general anesthesia (GA) on severity of mitral regurgitation (MR) in patients undergoing transcatheter mitral valve repair (TMVR).
Retrospective cohort study.
Tertiary care university hospital.
Fifty consecutive patients with symptomatic severe MR and extremely high surgical risk.
TMVR under GA.
Transesophageal echocardiography was performed during the preprocedural workup under conscious sedation and during TMVR under GA. After the parameters of MR were assessed, color-flow jet area (CJA), vena contracta (VC), effective regurgitant orifice area (EROA), regurgitant volume (RVOL), three-dimensional (3D) vena contracta area (VCA), and severity of MR were compared between the two examinations.
In patients with primary MR (n = 11), there were no significant differences in CJA, VC, EROA, RVOL, or 3D-VCA between pre- and intraprocedural transesophageal echocardiography. In patients with secondary MR (n = 39), GA led to significant decreases of CJA (10 ± 7 v 7 ± 3 cm², p < 0.001), VC (5.5 ± 1.6 v 4.7 ± 1.5 mm, p = 0.002), EROA (30 ± 11 v 24 ± 10 mm², p < 0.001), and RVOL (47 ± 17 v 34 ± 13 mL/beat, p < 0.001). Consequently, GA led to a downgrade of regurgitation severity classification in 44% of patients when assessed by two-dimensional analysis. When evaluated by 3D analysis, GA also led to a significant but less extensive decrease of MR (3D-VCA: 66 ± 27 v 60 ± 29 mm², p = 0.002), and subsequent downgrade of MR classification in 20% of patients.
GA underestimates regurgitation severity in patients with secondary, but not primary MR, undergoing TMVR. This effect must be considered when evaluating the immediate result of the procedure.
Functional Mitral Regurgitation Outcome and Grading in Heart Failure With Reduced Ejection Fraction
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This study aims to define excess-mortality linked to functional mitral regurgitation (FMR) quantified in routine-practice.
Appraisal of FMR in heart failure with reduced ejection fraction (HFrEF) is challenging because risks of excess mortality remain uncertain and guidelines diverge.
Cases of HFrEF (ejection-fraction <50%) Stage B-C that were diagnosed between 2003 and 2011 and had routine-practice FMR quantitation (FMR cohort, n = 6,381) were analyzed for excess mortality thresholds/rates within the cohort and in comparison to the general population. These were also compared to those of a degenerative mitral regurgitation (DMR) simultaneous cohort (DMR cohort, n = 2,416).
In the FMR cohort (age: 70 ± 11 years, ejection fraction: 36 ± 10%, effective regurgitant orifice area [EROA]: 0.09 ± 0.13 cm²), EROA distribution was skewed towards low-values (≥0.40 cm² in only 8% vs 38% for the DMR cohort; P < 0.0001). One-year mortality was high (15.6%), increasing steeply from 13.3% without FMR to 28.5% with EROA ≥0.30 cm² (adjusted odds ratio: 1.57 [95% CI: 1.19-2.97]; P = 0.001). In the long term, 3,538 FMR cohort patients died with excess mortality threshold ∼0.10 cm² (vs ∼0.20 cm² in the DMR cohort), with 0.10 cm² EROA increments independently associated with considerable mortality increment (adjusted HR: 1.11 [95% CI: 1.08-1.15]; P < 0.0001) and with no detectable interaction. Compared to the general population, FMR excess mortality increased exponentially with higher EROA (risk ratio point estimates 2.8, 3.8, and 5.1 at EROA 0.20, 0.30, and 0.40 cm², respectively), and was much steeper than that of the DMR cohort (P < 0.0001). In nested models, individualized EROA was the strongest FMR survival marker, and a new expanded FMR grading scale based on 0.10 cm² EROA increments provided incremental power over current American Heart Association–American College of Cardiology/European Society of Cardiology guidelines (all P < 0.03).
In HFrEF, FMR is skewed towards smaller EROA. Nevertheless, when measured in routine practice, EROA is the strongest independent FMR determinant of survival after diagnosis. Excess mortality increases exponentially above the threshold of 0.10 cm², with a much steeper slope than in DMR, for any EROA increment. An expanded EROA-based stratification, superior to existing grading schemes in determining survival, should allow guideline harmonization.

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: Supported by National Institutes of Health grants K23 HL04504 (Dr Hung), and RO1 HL38176 and K24 HL67434 (Dr Levine).

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Original articleProximal Flow Convergence Region as Assessed by Real-time 3-Dimensional Echocardiography: Challenging the Hemispheric Assumption

Objective

Methods

Results

Conclusions

Section snippets

Methods

Results

Discussion

J Thorac Cardiovasc Surg

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

J Am Soc Echocardiogr

J Am Coll Cardiol

Int J Cardiol

J Am Coll Cardiol

J Am Soc Echocardiogr

J Am Coll Cardiol

J Am Soc Echocardiogr

Ultrasound Med Biol

J Am Soc Echocardiogr

J Am Soc Echocardiogr

J Am Soc Echocardiogr

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

J Am Soc Echocardiogr

J Am Soc Echocardiogr

J Am Coll Cardiol

Clinical significance of mitral regurgitation after acute myocardial infarction

Circulation

Original article
Proximal Flow Convergence Region as Assessed by Real-time 3-Dimensional Echocardiography: Challenging the Hemispheric Assumption