Echocardiographic Evaluation of the Mitral Valve Area Before and After Percutaneous Mitral Commissurotomy: The Pressure Half-time Method Revisited

Recommendations for the Use of Echocardiography in the Evaluation of Rheumatic Heart Disease: A Report from the American Society of Echocardiography

Acute rheumatic fever and its chronic sequela, rheumatic heart disease (RHD), pose major health problems globally, and remain the most common cardiovascular disease in children and young people worldwide. Echocardiography is the most important diagnostic tool in recognizing this preventable and treatable disease and plays an invaluable role in detecting the presence of subclinical disease needing prompt therapy or follow-up assessment. This document provides recommendations for the comprehensive use of echocardiography in the diagnosis and therapeutic intervention of RHD. Echocardiographic diagnosis of RHD is made when typical findings of valvular and subvalvular abnormalities are seen, including commissural fusion, leaflet thickening, and restricted leaflet mobility, with varying degrees of calcification. The mitral valve is predominantly affected, most often leading to mitral stenosis. Mixed valve disease and associated cardiopulmonary pathology are common. The severity of valvular lesions and hemodynamic effects on the cardiac chambers and pulmonary artery pressures should be rigorously examined. It is essential to take advantage of all available modalities of echocardiography to obtain accurate anatomic and hemodynamic details of the affected valve lesion(s) for diagnostic and strategic pre-treatment planning. Intraprocedural echocardiographic guidance is critical during catheter-based or surgical treatment of RHD, as is echocardiographic surveillance for post-intervention complications or disease progression. The role of echocardiography is indispensable in the entire spectrum of RHD management.

Advances in Rheumatic Mitral Stenosis: Echocardiographic, Pathophysiologic, and Hemodynamic Considerations

Echocardiography is the primary imaging modality used in patients with mitral stenosis. Doppler-derived measurements of mitral pressure half-time are commonly used to calculate mitral valve area, but a number of hemodynamic confounders associated with advanced age limit its utility. Planimetry remains the gold standard for determining mitral valve area and may be performed using two- or three-dimensional imaging. Although the Wilkins score has been used for >30 years to predict balloon mitral valvuloplasty outcomes, newer scoring systems have been proposed to improve predictive accuracy. Some patients undergoing technically successful balloon mitral valvuloplasty may not have satisfactory clinical outcomes. These individuals may be identified by the presence of reduced net atrioventricular compliance, which can be measured echocardiographically. Exercise testing may be useful in patients with mitral stenosis whose symptomatic status is incongruous their mitral valve area. Last, reduced left atrial systolic strain, an indicator of poor left atrial compliance, has been shown to reliably predict adverse outcomes in patients with mitral stenosis. The author discusses the hemodynamics and path ophysiology of mitral stenosis and reviews current and emerging roles of echocardiography in its evaluation.

Additive value of 3D-echo in prediction of immediate outcome after percutaneous balloon mitral valvuloplasty

Background

Results of percutaneous balloon mitral valvuloplasty (BMV) are basically dependent on suitable patient selection. Currently used two-dimensional (2D) echocardiography (2DE) scores have many limitations. Three-dimensional (3D) echocardiography (3DE)-based scores were developed for better patient selection and outcome prediction. We aimed to compare between 3D-Anwar and 2D-Wilkins scores in mitral assessment for BMV, and investigate the additive value of 3DE in prediction of immediate post-procedural outcome. Fifty patients with rheumatic mitral stenosis and candidates for BMV were included. Patients were subjected to 2D- and real-time 3D-transthoracic echocardiography (TTE) before and immediately after BMV for assessing MV area (MVA), 2D-Wilkins and 3D-Anwar score, commissural splitting, and mitral regurgitation (MR). Transesophageal echocardiography (TEE) was also undertaken immediately before and intra-procedural. Percutaneous BMV was performed by either multi-track or Inoue balloon technique.

Results

The 2DE underestimated post-procedural MVA than 3DE (p = 0.008). Patients with post-procedural suboptimal MVA or significant MR had higher 3D-Anwar score compared to 2D-Wilkins score (p = 0.008 and p = 0.03 respectively). The 3D-Anwar score showed a negative correlation with post-procedural MVA (r = − 0.48, p = 0.001). Receiver operating characteristic (ROC) curve analysis for both scores revealed superior prediction of suboptimal results by 3D-Anwar score (p < 0.0001). The 3DE showed better post-procedural posterior-commissural splitting than 2DE (p = 0.004). Results of both multi-track and Inoue balloon were comparable except for favorable posterior-commissural splitting by multi-track balloon (p = 0.04).

Conclusion

The 3DE gave valuable additive data before BMV that may predict immediate post-procedural outcome and suboptimal results.

Electronic supplementary material

The online version of this article (10.1186/s43044-019-0019-x) contains supplementary material, which is available to authorized users.

Quadruple valve replacement in a patient with severe rheumatic heart disease

We present a patient with rheumatic heart disease involving all the heart valves. An intraoperative transoesophageal echocardiography confirmed severe mitral stenosis, severe aortic regurgitation, severe tricuspid regurgitation and stenosis, and severe pulmonary stenosis. The patient underwent successful quadruple valve replacement during a single operation at the Groote Schuur Hospital, Cape Town, South Africa.

Degenerative Mitral Stenosis: From Pathophysiology to Challenging Interventional Treatment

Mitral stenosis (MS) is characterized by obstruction of left ventricular inflow as a result of narrowing of the mitral valve orifice. Although its prevalence has declined over the last decade, especially in developed countries, it remains an important cause of morbidity and mortality.  The most often cause of MS worldwide is still postrheumatic mitral valve disease. However, in developed countries, degenerative or calcific changes cause MS in a siginificant proportion of patients. Although the range of treatment for mitral valve disease has grown over the years in parallel with transcatheter therapies for aortic valve disease, these improvements in mitral valve disease therapy have experienced slower development. This is mainly due to the more complex anatomy of the mitral valve and entire mitral apparatus, and the interplay of the mitral valve with the left ventricle which hinders the development of effective implantable mitral valve devices. This is especially the case with degenerative MS where percutaneous or surgical comissurotomy is rarely employed due to the presence of extensive annular calcification and at the base of leaflets, without associated commissural fusion. However, the last few years have witnessed innovations in transcatheter interventional procedures for degenerative MS which consequently hinted that in the future, transcatheter mitral valve replacement could be the treatment of choice for these patients.

Mitral leaflet separation to evaluate the severity of mitral stenosis: Validation of the index by transesophageal three-dimensional echocardiography

BACKGROUND

Determining severity of mitral stenosis (MS) by planimetry of mitral valve orifice area (MVA) has been a challenging issue in clinical practice, especially for less experienced cardiologists. Mitral leaflet separation (MLS) has shown a good correlation with MVA measurements. However, it has never been validated against multiplane 3DTEE planimetry (MVA_3D ). We aimed to evaluate the accuracy of MLS index (MLSI_2D ) in predicting MS severity.

METHODS

We prospectively enrolled 144 patients with MS who underwent clinically indicated 2DTTE and 3DTEE. MLSI_2D was yield by averaging the maximal leaflet tip distance in diastole, in parasternal long-axis and apical four-chamber views. MVA_3D was used as the reference method.

RESULTS

MLSI_2D showed an excellent discriminatory ability between different grades of MS (P < .001). There was a significant positive correlation between MLSI_2D and MVA_3D (r = .93, P < .001) irrespective of concurrent mitral regurgitation (r = .94, P < .001) and/or atrial fibrillation (r = .92, P < .001). By receiver operating characteristic (ROC) curves, MLSI_2D  ≤ 8.6 mm showed 100% sensitivity and 76% specificity for very severe MS. MLSI_2D  ≥ 11.2 mm determined progressive MS with 100% sensitivity and 82% specificity. The study population was then divided into a derivation group and a validation group. A regression equation for MVA by MLSI_2D was derived in first group. Then, the MVA was calculated by this equation in validation group and was not significantly different from MVA_3D .

CONCLUSION

MLSI_2D showed an excellent ability to assess MS severity and correlates well with planimetered MVA measured by 3DTEE.

Effect of Percutaneous Edge-to-Edge Repair on Mitral Valve Area and Its Association With Pulmonary Hypertension and Outcomes

Percutaneous edge-to-edge repair using the MitraClip system causes reduction in mitral valve area (MVA). However, its clinical impact is not fully elucidated. This study assessed the impact of postprocedural MVA reduction on pulmonary hypertension and outcomes. A total of 92 patients with grades 3 to 4 + mitral regurgitation (MR) who underwent MitraClip therapy were retrospectively reviewed. Using intraprocedural, 3-dimensional transesophageal echocardiography, postprocedural MVA was obtained by 2 optimized planes through the medial and lateral orifices of the repaired valve. MVA was reduced by 60.1% immediately after MitraClip procedure (p <0.001). Postprocedural MVA correlated moderately with mean transmitral pressure gradient (TMPG) in the majority of patients (r = -0.56, p <0.001), but discordance of MVA and TMPG was observed in 40% of patients. In multivariable linear regression analysis, postprocedural MVA ≤1.94 cm² was independently associated with a blunted decrease in systolic pulmonary artery pressure at 1-month follow-up (β-estimate -4.63, 95% confidence interval -9.71 to -0.15, p = 0.042). Postprocedural MVA ≤1.94 cm² was an independent predictor of all-cause mortality and heart failure hospitalization after MitraClip (hazard ratio 4.28, 95% confidence interval 1.56 to 11.7, p = 0.005) even after adjustment for age, gender, atrial fibrillation, cause of MR, left ventricular systolic function, pre-existing pulmonary hypertension, and residual MR. After further adjustment for TMPG ≥5 mm Hg, postprocedural MVA ≤1.94 cm² remained predictive for adverse outcomes (p = 0.048). In conclusion, the intraprocedural assessment of MVA by 3-dimensional transesophageal echocardiography can predict hemodynamic response and postprocedural prognosis after MitraClip therapy.

Current diagnostic and treatment strategies for Lutembacher syndrome: the pivotal role of echocardiography

Lutembacher syndrome (LS) is a rare cardiac abnormality characterized by any combination of a congenital or iatrogenic atrial septal defect (ASD) and a congenital or acquired mitral stenosis (MS). Clinical features and hemodynamic effects of LS depend on the balance of effects of the MS and the ASD. Prognosis is influenced by several factors [pulmonary vascular resistance, right ventricle (RV) compliance, size of ASD and MS severity] but the occurrence of secondary pulmonary hypertension and congestive heart failure is commonly associated with poor outcome. Echocardiography remains the gold standard for diagnosis and evaluation of LS. Timely diagnosis is critical for modifying the natural course, by allowing patients to benefit from currently available percutaneous trans-catheter therapies with favorable effects on the outcomes. This article is a review of published literature on the current diagnostic and therapeutic modalities for LS, focusing on the pivotal role of echocardiography as the key diagnostic tool. Clinical suspicion of LS should prompt extensive investigation with non-invasive and where possible, invasive technics. Multicenter registers have a potential to assist the evaluation of long term outcomes of percutaneous trans-catheter therapies in patients with LS.

Simplifying proximal isovelocity surface area as an assessment method of mitral valve area in patients with rheumatic mitral stenosis by fixing aliasing velocity and mitral valve angle

We aimed to test the ability of a simple equation using proximal isovelocity surface area method (PISA), created by fixing the angle to 100° and the aliasing velocity to 33 cm/s, to calculate mitral valve area (MVA) and assess severity in patients with rheumatic mitral stenosis (MS).

METHODS AND RESULTS

In a series of 51 consecutive patients with rheumatic MS, MVA was assessed by four methods, conventional PISA equation (PISAconventional), simple PISA equation (PISAsimple), pressure half time (PHT), and planimetry (PLN) which was taken as the reference method. All methods correlated significantly with PLN with the highest correlation found in case of PISAconventional and PISAsimple (r = 0.97, 0.96, p < 0.001), while the correlation in case PHT was relatively weaker (r = 0.69, p < 0.001). Bland-Altman analysis revealed that the level of agreement with PLN was better in case of both PISA methods than PHT and, moreover, were close to each other. The number of cases that showed agreement of severity grade with planinetry was better in case of PISAconventional (42 cases) and PISAsimple (44 cases) than that in case of PHT (34 cases, p = 0.037). Finally, the measure of agreement with Cohen's Kappa test was better in case of PISAconventional and PISAsimple than that in case of PHT.

CONCLUSION

Provided that aliasing velocity is fixed at 33 cm/s, PISA can effectively predict mitral valve area and severity of MS by a simple equation, with the advantage of easy and accurate calculation over other methods.

Real-time 3D transoesophageal measurement of the mitral valve area in patients with mitral stenosis

AIMS

Planimetry measured by two-dimensional transthoracic echocardiography (TTE, MVA2D) is the reference method for the evaluation of the severity of mitral stenosis (MS) but requires experienced operators and good echocardiographic windows. Real-time three-dimensional transoesophageal echocardiography (3D-TEE, MVA3D) may overcome these limitations but its accuracy has never been evaluated.

METHODS AND RESULTS

We prospectively enrolled 80 patients (58±15 years, 86% female) referred for MS evaluation who underwent, within 1 week, a clinically indicated TTE and TEE. MVA2D was measured by experienced operators (Level III), MVA3D by one experienced and one non-experienced (Level I) operators blinded of any clinical or TTE information. MVA3D measured by the experienced operator [1.11±0.32 cm2; median, 1.1 cm2; range (0.45-2.20)] did not differ from and correlated well with MVA2D [1.10±0.34 cm2; median, 1.05 cm2; range (0.45-2.30)], P=0.87; r=0.79, P<0.0001; ICC=0.79) and mean difference between methods was small (+0.004±0.21 cm2). MVA3D measured by the non-experienced operator [1.08±0.34 cm2; median 1.02 cm2; range (0.45-2.23)] also did not differ from and correlated well with MVA2D measured by experienced operators (P=0.25; r=0.86, P<0.0001; mean difference -0.02±0.18 cm2; ICC=0.86). Intra and interobserver variability were 0.02±0.25 and 0.01±0.33 cm2.

CONCLUSION

3D-TEE provides accurate and reproducible MVA measurements similar to 2D planimetry performed by experienced operators. Thus, 3D-TEE could be considered as a second-line alternative tool for the evaluation of MS severity in patients with poor echocardiographic windows or for team less accustomed to evaluate MS patients.

Comparison of mitral valve area by pressure half-time and proximal isovelocity surface area method in patients with mitral stenosis: effect of net atrioventricular compliance

AIMS

The aim of this study was to test the hypothesis that, unlike calculation of the mitral valve area (MVA) with the pressure half-time method (PHT), the proximal isovelocity surface area method (PISA) is not affected by changes in net atrioventricular compliance (C(n)).

METHODS AND RESULTS

We studied 51 patients with mitral stenosis (MS) from two centres. MVA was assessed with the PISA (MVA(PISA)), PHT (MVA(PHT)), and planimetry (MVA(PLN), serving as the gold standard) method. C(n) was calculated with a previously validated equation using 2D echocardiography. MVA(PISA) closely correlated with MVA(PLN) (r = 0.96, P < 0.0001), while MVA(PHT) and MVA(PLN) showed a weaker but still good correlation (r = 0.69, P < 0.0001). The correlation between MVA(PHT) and MVA(PLN) for patients with C(n) between 4 and 6 mL/mmHg (considered to be normal) was excellent (r = 0.93, P < 0.0001), but that for patients with C(n) of less than 4 or more than 6 mL/mmHg was not as good (r = 0.64, P < 0.0001). Importantly, a significant inverse correlation was detected between the percentage difference among MVA(PHT), MVA(PLN), and C(n) (r = -0.77, P < 0.0001), but the line of fit was nearly flat for the percentage difference among MVA(PISA), MVA(PLN), and C(n) (r = 0.1, P = 0.388).

CONCLUSION

MVA calculated with both the PISA and PHT methods correlated well with MVA calculated with the planimetry method. However, the PISA rather than PHT is recommended for patients with MS and extreme C(n) values because PISA, unlike PHT, is not affected by changes in C(n).

Evaluation of mitral stenosis in 2008

Percutaneous mitral valve commissurotomy (PMC) is the treatment of choice for patients with mitral stenosis (MS) and favorable anatomy. Evaluation of MS should answer two questions: is MS severe? And is the valve suitable for PMC? Evaluation of MS severity relies on accurate echocardiographic assessment of the mitral valve area (MVA). Several methods can be used, often in combination. The planimetry is the reference method but must be precisely performed at the tips of the leaflets in a well-oriented plane and thus requires experienced operators. New imaging technologies, such as 3D-echocardiography, MRI or computed tomography may reduce planimetry's operator dependence. The pressure half-time method (PHT) has the merit of simplicity but should be used cautiously in elderly patients or those in atrial fibrillation. It is invalid immediately after PMC but can still be used as a semi-quantitative method: a PHT less than 130 msec is associated with a good valve opening with an excellent specificity and positive predictive value whereas a PHT 130 msec does not allow any conclusion. The continuity equation, easy to perform, may be invalidated by the commonly associated aortic or mitral regurgitation or in case of atrial fibrillation. The PISA method, is reputed technically challenging and requires a direct measurement of angle between the mitral leaflets, although the use of a fixed value of 100 degrees provides an accurate MVA estimation. The main indication of transesophageal echocardiography is the exclusion of left atrial thrombus, which is a contra-indication to PMC as well as a 2/4 or greater mitral regurgitation grade. Two-dimensional-echocardiography allows detailed evaluation of valve morphology, including leaflet thickness and mobility, degree and localization of calcifications, extent of the subvalvular involvement. Unfavorable valve anatomy is associated with a lower rate of PMC success and lower event-free survival. However, given the low predictive value of all anatomic scores, the decision to perform or not the procedure should be based on a global approach taking into account not only the valve anatomy but also individual patients characteristics such as age, rhythm, NYHA class, MVA and the predicted operative mortality based on associated comorbidities.

A nomogram for measurement of mitral valve area by proximal isovelocity surface area method

INTRODUCTION

Although its accuracy has been documented in many studies, the proximal isovelocity surface area (PISA) method is not used widely for mitral valve area (MVA) measurement. In this study, we prepared a new nomogram and tested its use in MVA assessment.

MATERIAL AND METHODS

The study included 23 patients (age: 27 +/- 5 years) with mitral stenosis, of whom 7 were in atrial fibrillation. The MVA was measured by four methods: planimetry (PL) (reference method), pressure-half time (PHT), conventional PISA (CP), and nomogram (Nomo) methods. The nomogram included two unknowns: (1) r; the radius of the first PISA section; (2) a; the length of the border opposite to the PISA angle in the triangle with both adjacent borders of 1 cm. The nomogram was also tested for its popularity potential by eight echocardiographers, none of whom were included in the author list.

RESULTS

Mean MVA(PL) was 1.85 +/- 0.53 cm(2) (range: 0.72-2.99), mean MVA(PHT) was 1.72 +/- 0.56 cm(2) (range: 0.91-3.30), mean MVA(CP) was 1.69 +/- 0.45 cm(2) (range: 0.97-2.54), and MVA(Nomo) was 1.70 +/- 0.44 cm(2) (0.96-2.49). The nomogram correlated with planimetry (r = 0.87; P < 0.001), pressure half-time (r = 0.71; P < 0.001) and conventional PISA (r = 0.99; P = 0.000) methods. The nomogram method also correlated with planimetry in patients with atrial fibrillation (r = 0.81; P = 0.026). The echocardiographers found that the nomogram is superior to the planimetry and conventional PISA methods but inferior to the pressure half-time method in terms of simplicity.

CONCLUSION

The new nomogram is potentially helpful in measurement of MVA. It may be used as an additional method in assessing severity of mitral stenosis.

Mitral Valve Resistance as a Determinant of Resting and Stress Pulmonary Artery Pressure in Patients with Mitral Stenosis: A Dobutamine Stress Study

BACKGROUND

Severity of mitral stenosis (MS) is assessed by means of mitral valve area and mean transmitral gradient. However, these conventional stenosis indexes poorly reflect the major hemodynamic consequence of MS, which is increase in pulmonary artery pressure (PAP). Valve resistance (VR) is a physiologic expression of stenosis because it incorporates both the pressure gradient and flow data. Previously, in patients with aortic stenosis, hemodynamic burden on the left ventricle has been shown to be closely related to aortic VR but not to aortic valve area. Accordingly, we hypothesized that mitral VR may also better reflect the hemodynamic burden of MS and, hence, be an important determinant of PAP in patients with MS. This study sought to evaluate the relation between several echocardiographic parameters of MS severity, in particular mitral VR and the resting and stress PAP in patients with MS. Determinants of exercise capacity were also assessed.

METHODS

Twenty patients with pure MS were studied by Doppler echocardiography. Mitral valve area, mean transmitral gradient, mitral VR, net atrioventricular compliance, and left atrial diameter were derived from resting Doppler echocardiographic examination as possible determinants of resting and stress PAP. PAP was measured by Doppler echocardiography at rest and during dobutamine-induced stress. Patients completed a symptom-limited exercise test to determine exercise capacity. Determinants of resting and stress PAP and exercise capacity were analyzed.

RESULTS

Systolic PAP increased significantly from 39.2 +/- 9.4 mm Hg at rest to 59.5 +/- 18.4 mm Hg during dobutamine-induced stress. Mitral VR was the most closely correlated stenosis index with the resting and stress PAP (r = 0.80, P < .001 and r = 0.93, P < .001, respectively) and it was an independent predictor for both with multivariate analysis. Exercise capacity was mostly and equally correlated with stress PAP (r = -0.62, P = .004) and mitral VR (r = -0.62, P = .004). Multivariate analysis revealed stress PAP as the only significant independent predictor of exercise capacity.

CONCLUSION

Mitral VR is the strongest and the independent predictor of both resting and stress PAP in patients with MS and by this aspect it is superior to mitral valve area and mean transmitral gradient in the expression of stenosis severity. These results underline the importance of mitral VR as a severity index in patients with MS.

Mitral Leaflet Separation Index: A New Method for the Evaluation of the Severity of Mitral Stenosis? Usefulness Before and After Percutaneous Mitral Commissurotomy

BACKGROUND

Two-dimensional planimetry (MVA(2D)) is the reference method for the evaluation of the severity of mitral stenosis (MS) but requires experienced operators. The mitral leaflet separation (MLS) index (distance between mitral leaflets) was recently presented as a reliable measure of MS severity. This method has the advantage of simplicity but has not been evaluated in a nonselected series of consecutive patients before and after percutaneous mitral commissurotomy (PMC).

METHODS

Patients referred for MS evaluation in our institution between February and September 2006 were prospectively enrolled in the present study. The only exclusion criterion was nonfeasible planimetry. MLS index was obtained by averaging the maximal leaflet separation distance at the tips in diastole in parasternal long-axis and apical four-chamber views. Planimetry was used as reference.

RESULTS

Ninety consecutive patients were enrolled, and 116 examinations were performed: 55 before PMC and 61 after PMC. Overall mean MVA(2D) was 1.48 +/- 0.52 cm(2), MLS index was 1.01 +/- 0.24 cm, and a good correlation between both measurements was observed (r = 0.77, P < .00001). MLS index was significantly different between patients with severe (MVA(2D) >or= 1,5 cm(2)) and nonsevere MS (0.87 +/- 0.17 vs. 1.17 +/- 0.21 cm, P < .0001), but there was an important overlap. No threshold value could predict a nonsevere MS with both a sensitivity and a specificity greater than 80%. A threshold value of 0.97 cm provided the best combination of sensitivity and specificity (86% and 75%, respectively). However, an MLS index of 1.2 cm or more provided a good specificity and positive predictive values for the diagnosis of nonsevere MS (85% and 89%, respectively) and an MLS index of less than 0.8 cm an excellent specificity and positive predictive value for severe MS (98% and 96%, respectively).

CONCLUSION

The MLS index cannot be considered as a substitute for MVA, but it can be used as a semiquantitative and complementary method for the integrative assessment of MS severity.