Aortic regurgitation shortens Doppler pressure half-time in mitral stenosis: clinical evidence, in vitro simulation and theoretic analysis

Transthoracic two-dimensional and three-dimensional echocardiography for the measurement of mitral valve area planimetry in English Bull Terriers with and without heart disease

INTRODUCTION

Mitral valve area (MVA) planimetry is used to diagnose and classify mitral stenosis (MS) in humans using two-dimensional and three-dimensional echocardiography (MVA_2D and MVA_3D). This study aimed to evaluate agreement, feasibility, and observer variability between MVA_2D and MVA_3D in English Bull Terriers (BT). Our hypotheses were (1) that the MVA of BT is generally smaller than that of breeds with similar body weight and (2) that these techniques could be used to diagnose MS in BTs.

ANIMALS

Twenty healthy BTs, 15 healthy Boxers, and 49 BTs with heart disease.

MATERIALS AND METHODS

A prospective diagnostic agreement study was conducted. All dogs underwent a thorough clinical examination, conventional transthoracic echocardiography, and three-dimensional echocardiography.

RESULTS

Bland-Altman plots (limits of agreement: 0.12-1.5) showed consistent bias and poor agreement between MVA_2D and MVA_3D. For the 69 BTs, MVA_3D (2.1 ± 0.50 cm²) measurements were significantly lower than MVA_2D measurements (2.9 ± 0.60 cm²), and healthy BTs had significantly lower MVA parameters than healthy Boxers (p < 0.001). Intraobserver and interobserver variability were excellent for both MVA_2D and MVA_3D (intraclass correlation coefficient >0.9). Six BTs were diagnosed with MS, with MVA_3D less than 1.8 cm² and a mean transmitral gradient (MTG) of more than 5 mmHg.

CONCLUSIONS

Both MVA_2D and MVA_3D are feasible, have low observer variability and can be used to diagnose MS in BTs. For assessing the narrowest orifice area, the preferred method is MVA_3D. The smaller MVA in BTs compared to Boxers may indicate some degree of MS.

Echocardiographic Assessment of Mitral Stenosis Orifice Area: A Comparison of a Novel Three-Dimensional Method Versus Conventional Techniques

BACKGROUND

A comprehensive evaluation of mitral stenosis (MS) severity commonly utilizes two-dimensional (2D) echocardiography techniques. However, the complex three-dimensional (3D) structure of the mitral valve (MV) poses challenges to accurate measurements of its orifice area by 2D imaging modalities. We aimed to assess MS severity by comparing measurements of the MV orifice area using conventional echocardiography methods to 3D orifice area (3DOA), a novel echocardiographic technique which minimizes geometric assumptions.

METHODS

Routine 2D and 3D intraoperative transesophageal echocardiographic images from 26 adult cardiac surgery patients with at least moderate rheumatic MS were retrospectively reviewed. Measurements of the MV orifice area obtained by pressure half-time (PHT), proximal isovelocity surface area (PISA), continuity equation, and 3D planimetry were compared to those acquired using 3DOA.

RESULTS

MV areas derived by PHT, PISA, continuity equation, 3D planimetry, and 3DOA (mean value ± standard deviation) were 1.12 ± 0.27, 1.03 ± 0.27, 1.16 ± 0.35, 0.97 ± 0.25, and 0.76 ± 0.21 cm, respectively. Areas obtained from the 3DOA method were significantly smaller than areas derived from PHT (mean difference 0.35 cm, P < .0001), PISA (mean difference: 0.28 cm, P = .0002), continuity equation (mean difference: 0.43 cm, P = .0015), and 3D planimetry (mean difference: 0.19 cm, P < .0001). MV 3DOAs also identified a significantly greater percentage of patients with severe MS (88%) compared to PHT (31%, P = .006), PISA (42%, P = .01), and continuity equation (39%, P = .017) but not in comparison to 3D planimetry (62%, P = .165).

CONCLUSIONS

Novel measures of the stenotic MV 3DOA in patients with rheumatic heart disease are significantly smaller than calculated values obtained by conventional methods and may be consistent with a higher incidence of severe MS compared to 2D techniques. Further investigation is warranted to determine the clinical relevance of 3D echocardiographic techniques used to measure MV area.

The impact of cardiac rhythm on the mitral valve area and gradient in patients with mitral stenosis

OBJECTIVE

The aim of this study was to evaluate the effect of cardiac rhythm on the echocardiographic mitral valve area (MVA) and transmitral gradient calculation in relation to net atrioventricular compliance (Cn).

METHODS

Patients (n=22) with mild or moderate pure rheumatic mitral stenosis (MS) (MVA <2 cm2 and MVA >1 cm2) and atrial fibrillation (AF) were evaluated. All patients underwent transthoracic electrical DC cardioversion under amiodarone treatment. Nineteen of the 22 patients were successfully converted to sinus rhythm (SR). The patients were evaluated with transthoracic echocardiography before and two to three days after DC cardioversion. In order to deal with variable R-R intervals, the measurements were averaged on five to eight consecutive beats in AF. Cn was calculated with a previously validated equation [Cn (mL/mm Hg)=1.270 x MVA/E-wave downslope]. The Cn difference between AF and SR was calculated as follows: [(AF Cn-SR Cn)/AF Cn] x 100. The percentage gradient (mean or maximal) difference between AF and SR was calculated as follows: [AF gradient (mean or maximal) - SR gradient (mean or maximal)]/[AF gradient (mean or maximal)] x 100.

RESULTS

The MVA was lower (MVA planimetric; 1.62±0.29 vs. 1.54±0.27; p=.003, MVA PHT; 1.66±0.30 vs. 1.59±0.26; p=0.01) but transmitral gradient (mean gradient; 6.49±2.51 vs. 8.89±3.52; p=0.001, maximal gradient: 16.94±5.11 vs. 18.57±4.54; p=0.01) and Cn values (5.37±0.77 vs. 6.26±0.64; p<0.001) were higher in the AF than SR. There was a significant correlation between Cn difference and transmitral gradient difference (mean and maximal) (Cn difference-mean gradient difference; r=0.46; p=0.05; Cn difference-maximal gradient difference; r=0.72; p=0.001).

CONCLUSION

Cardiac rhythm has a significant impact on echocardiographic evaluation of MVA, transmitral gradient, and Cn in patients with MS.

Pathophysiology and management of multivalvular disease

Multivalvular disease (MVD) is common among patients with valvular disease, and has a complex pathophysiology dependent on the specific combination of valve lesions. Diagnosis is challenging because several echocardiographic methods commonly used for the assessment of stenosis or regurgitation have been validated only in patients with single-valve disease. Decisions about the timing and type of treatment should be made by a multidisciplinary heart valve team, on a case-by-case basis. Several factors should be considered, including the severity and consequences of the MVD, the patient's life expectancy and comorbidities, the surgical risk associated with combined valve procedures, the long-term risk of morbidity and mortality associated with multiple valve prostheses, and the likelihood and risk of reoperation. The introduction of transcatheter valve therapies into clinical practice has provided new treatment options for patients with MVD, and decision-making algorithms on how to combine surgical and percutaneous treatment options are evolving rapidly. In this Review, we discuss the pathophysiology, diagnosis, and treatment of MVD, focusing on the combinations of valve pathologies that are most often encountered in clinical practice.

Radius of proximal isovelocity surface area in the assessment of rheumatic mitral stenosis: Connecting flow to anatomy and hemodynamics

Background

Echocardiographic assessment of left atrial pressure (LAP) in mitral stenosis (MS) is controversial. We sought to examine the role of the radius of the proximal isovelocity surface area (PISA-r) in the assessment of the hemodynamic status of MS after fixing the aliasing velocity (Val).

Methods and results

We studied 42 candidates of balloon mitral valvuloplasty (BMV), for whom pre-BMV echocardiography was done and LAP invasively measured before dilatation. PISA-r was calculated after fixing aliasing velocity to 33 cm/s. In addition, the ratio IVRT/Te’–E was also measured, where IVRT was isovolumic relaxation time, and Te’–E was the time difference between the onset of mitral flow E-wave and mitral annular early diastolic velocity. IVRT/Te’–E and PISA-r showed a strong correlation with LAP (r = −0.715 and −0.637, all p < 0.001) and with right-sided pressures. In addition, PISA-r correlated with mitral valve area by planimetry method (MVA) and with left ventricular outflow tract stroke volume (r = 0.66 and 0.71, all p < 0.001). Receiver operator characteristic curve (ROC-curve) showed that PISA-r was not inferior to IVRT/Te’–E in differentiating LAP ⩾25 from <25 mmHg.

Conclusion

Provided that Val is set to a constant of 33 cm/s, PISA-r can assess the hemodynamic status of MS, and seems a simple alternative to the tedious IVRT/Te’–E for estimation of LAP.

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).

Calculation of pressure half-time

Doppler echocardiography is useful in assessing the severity of obstructive cardiac lesions, such as mitral valve stenosis. The Doppler study can be used to calculate pressure half-time (PHT), which is defined as the time required for the pressure gradient across an obstruction to decrease to half of its maximal value. Thus, PHT increases as the severity of stenosis increases. In this report, we describe the methodology involved in measuring PHT in a dog with mitral valve stenosis before and after balloon valvuloplasty.

New quantitative three-dimensional echocardiographic indices of mitral valve stenosis

BACKGROUND

We studied the value of quantitative three-dimensional echocardiography (3DE) in the evaluation of mitral valve stenosis using the measurement of the mitral valve area (MVA) with two new indices: the doming volume and mitral valve volume.

METHODS AND RESULTS

A total of 45 consecutive patients with mitral valve stenosis were studied. MVA was measured using Doppler with the pressure half-time (PHT) method. Following a diagnostic multiplane transesophageal (TEE) examination, data for 3DE were acquired with a rotational mode of acquisition. MVA was assessed by anyplane echocardiography (APE) and from surface rendered images. Moreover, the doming volume, i.e., the volume subtended by the anterior and posterior mitral valve and annular cut plane was measured by APE. Comparing PHT-derived with 3DE-derived MVA's, using both APE and surface rendered images, only moderate correlations were observed: PHT-derived MVA versus APE-derived MVA: r = 0.74, P < 0.0001; PHT-derived area versus 3DE-surface rendered MVA: r = 0.70, P < 0.0001. Multiple linear regression analysis showed a relation of atrial fibrillation to the doming volume (P = 0.04), but not to PHT-derived MVA (P = 0.28), APE-derived area (P = 0.33) and mitral valve volume (P = 0.08). Comparison of patients with MVA < 1 cm(2) and MVA > 1 cm(2) revealed significant difference in mitral valve volume: mean mitral valve volume in critical stenosis was 3.7 ml versus 1.4 ml in non-critical stenosis (P = 0.04).

CONCLUSIONS

Only moderate correlations between 3DE and Doppler-derived MVA's were observed. Measurement of the doming volume allows quantification of the 3DE geometry of the mitral apparatus. Patients with conical or funnel-like geometry are more likely to have sinus rhythm, whereas, patients with flat geometry are likely to have atrial fibrillation. Mitral valve volume can be used for the evaluation of mitral stenosis severity. These new 3DE indices might be used for selection of patients for balloon valvuloplasty.

Does chronic mitral regurgitation influence Doppler pressure half-time-derived calculation of the mitral valve area in patients with mitral stenosis?

BACKGROUND

In patients with mitral stenosis (MS), Doppler pressure half-time (PHT) may be influenced by hemodynamic variables other than the anatomic mitral valve orifice narrowing. This study was undertaken to assess whether the presence of concomitant mitral regurgitation (MR) affects mitral valve area (MVA) estimation by PHT.

METHODS

Consecutive patients (n = 166) with noncalcific MS, in sinus rhythm, were studied. Group 1 (n = 106) had no or mild MR, and group 2 (n = 60) had moderate or severe MR. MVA was assessed by using the PHT method and planimetry.

RESULTS

There was a strong correlation between planimetry and PHT MVA in both groups (group 1: r = 0.86, P <.001; group 2: r = 0.73, P <.001). However, compared with planimetry MVA, PHT underestimated MVA by > or =20% in 18 patients (17%) in group 1 and 21 patients (35%) in group 2 (P <.01). Overestimation by > or =20% occurred in 12 patients (11%) in group 1 and in 7 (12%) in group 2. Group 2 subanalysis (group 2A: moderate MR, n = 16; group 2B: severe MR, n = 44) revealed that linear regression weakened with increasing severity of MR (group 2A: r = 0.824, P <.001, group 2B: r = 0.70, P <.001). PHT underestimation of MVA occurred in 31% and 36% of patients in Groups IIA and IIB, respectively (P = NS).

CONCLUSIONS

PHT appears to be reliable for estimating MVA in most patients with MS, even in the presence of MR. However, the presence of significant MR reduces the reliability of PHT-derived MVA, with underestimation of MVA in a significant number of subjects. The severity of MR has a direct impact on PHT-derived MVA.

The Use of Stress Echocardiography in the Assessment of Mitral Valvular Disease

Stress echocardiography plays an important role in evaluating asymptomatic patients with significant mitral stenosis and symptomatic patients with only mild disease at rest, as it correlates the exercise-induced symptoms with changes in transmitral gradients, pulmonary pressures, and mitral valve area. In patients with mitral regurgitation (MR), exercise or dobutamine protocols assess for the change in the degree of regurgitation and the pulmonary artery pressure (PAP) in response to high flow states, and detect underlying left ventricular (LV) dysfunction prior to valvular surgery. Exercise echocardiography also helps in the prognostic assessment of patients with mitral valve prolapse as new MR, or latent LV dysfunction may be provoked to identify a group of high risk individuals with normal resting echocardiographic parameters. Finally, it evaluates the proper functioning of prosthetic mitral valves and helps on the monitoring of transmitral gradients and PAPs after mitral valve surgery.

Real-time three-dimensional echocardiography for rheumatic mitral valve stenosis evaluation

OBJECTIVES

Our aim was to assess which echo-Doppler method has the best agreement with the mitral valve area (MVA) invasively evaluated by the Gorlin's formula. We also evaluated the feasibility and reproducibility of real-time three-dimensional echocardiography (RT3D) for the estimation of MVA and the Wilkins score in patients with rheumatic mitral stenosis (RMVS).

BACKGROUND

Real-time three-dimensional echocardiography is a novel technique that allows us to visualize the mitral valvular anatomy in any desired plane orientation. The usefulness and accuracy of this technique for evaluating RMVS has not been established.

METHODS

We studied a series of consecutive patients with RMVS from two tertiary care hospitals. Mitral valvular area was determined by conventional echo-Doppler methods and by RT3D, and their results were compared with those obtained invasively. Real-time three-dimensional echocardiography planimetry and mitral score were measured by two independent observers and then repeated by one of them.

RESULTS

Eighty patients with RMVS comprised our study group (76 women; 50.6 +/- 13.9 years). Compared with all other echo-Doppler methods, RT3D had the best agreement with the invasively determined MVA (average difference between both methods and limits of agreement: 0.08 cm(2) [-0.48 to 0.6]). Interobserver variability was as good for RT3D (intraclass correlation coefficient [ICC] = 0.90) as for pressure half-time (PHT) (ICC = 0.95). For PHT and RT3D, the intraobserver variability was similar (ICC 0.92 and 0.96, respectively). Real-time three-dimensional echocardiography valvular score evaluation showed a better interobserver agreement with RT3D than with 2D echocardiography.

CONCLUSIONS

Real-time three-dimensional echocardiography is a feasible, accurate, and highly reproducible technique for assessing MVA in patients with RMVS. Real-time three-dimensional echocardiography has the best agreement with invasive methods.

Clinical Applicability for the Assessment of the Valvular Mitral Stenosis Severity with Doppler Echocardiography and the Proximal Isovelocity Surface Area (PISA) Method

Evaluation of the severity of valvular mitral stenosis and measurements of the effective rheumatic mitral valve area by noninvasive echocardiography has been well accepted. The area is measured by the two-dimensional planimetry (PLM) method and the Doppler pressure half-time (PHT) method. Recently, the proximal isovelocity surface area (PISA) by color Doppler technique has been used as a quantitative measurement for valvular heart disease. However, this method needs more validation. The aim of this study was therefore to investigate the clinical applicability of the PISA method in the measurements of effective mitral valve area in patients with rheumatic valvular heart disease. Forty-seven patients aged from 23 to 71 years, with a mean age of 53 +/- 13 (25 male and 22 female, 15 with sinus rhythm, mean heart rate of 83 +/- 14 beats per minute, with rheumatic valvular mitral stenosis without hemodynamically significant mitral regurgitation) were included in the study. Effective mitral valve area (MVA) derived by the PISA method was calculated as follows: 2 x Pi x (proximal aliasing color zone radius)2x aliasing velocity/peak velocity across mitral orifice. Effective mitral valve areas measured by three different methods (PLM, PHT, and PISA) were compared and correlated with those calculated by the "gold standard" invasive Gorlin's formula. The MVA derived from PHT, PLM, PISA and Gorlin's formula were 1.00 +/- 0.31cm2, 0.99 +/- 0.30 cm2, 0.95 +/- 0.30 cm2 and 0.91 +/- 0.29 cm2, respectively. The correlation coefficients (r value) between PHT, PLM, PISA, and Gorlin's formula, respectively, were 0.66 (P = 0.032, SEE = 0.64), 0.67 (P = 0.25, SEE = 0.72) and 0.80 (P = 0.002, SEE = 0.53). In conclusion, the PISA method is useful clinically in the measurement of effective mitral valve area in patients with rheumatic mitral valve stenosis. The technique is relatively simple, highly feasible and accurate when compared with the PHT, PLM, and Gorlin's formula. Therefore, this method could be a promising supplement to methods already in use.

Accuracy of mitral valve area measurements using transthoracic rapid freehand 3-dimensional scanning: comparison with noninvasive and invasive methods

OBJECTIVE

The feasibility and accuracy of direct transthoracic 3-dimensional (3D) mitral valve area (MVA) measurements obtained using freehand scanning was investigated in patients with mitral stenosis.

METHODS

A total of 30 patients (26 women, 4 men; aged 55 +/- 13 years) underwent a 2-dimensional (2D) and Doppler study 1 hour before percutaneous balloon mitral valvuloplasty. Transthoracic freehand data were acquired using a magnetic receiver attached to a broadband transducer, gated to electrocardiography and respiration. Volumetric MVA measurements from the left ventricle and left atrium were obtained and compared with MVA measurements derived from 2D planimetry, pressure half-time, and proximal isovelocity surface area. Invasive Gorlin MVA measurements were the gold standard for comparison.

RESULTS

In all, 29 patients (97%) had 3D data allowing MVA measurements. Direct 3D measurements from the left ventricle had the least bias (0.06 +/- 0.19 cm(2)) and tightest limits of agreement (-0.44 to 0.32) compared with left atrium measurements (0.17 +/- 0.25 cm(2) and -0.67 to 0.33, respectively). The proximal isovelocity surface area method (bias: 0.09 +/- 0.34 cm(2)) was the most accurate of all 2D methods followed by pressure half-time (0.17 +/- 0.36 cm(2)) and planimetry (0.21 +/- 0.29 cm(2)).

CONCLUSION

Direct 3D MVA measurements from the left ventricle using transthoracic freehand scanning are more accurate than traditional 2D methods.

Live Three-Dimensional Echocardiographic Assessment of Mitral Stenosis

In the present study, we describe our experience in using live three-dimensional transthoracic echocardiography in the assessment of mitral stenosis.

Additional value of three-dimensional transesophageal echocardiography for patients with mitral valve stenosis undergoing balloon valvuloplasty

The objective of this study was to validate the additional value of 3-dimensional (3D) transesophageal echocardiography (TEE) for patients with mitral valve stenosis undergoing percutaneous mitral balloon valvotomy (PTMV). Therefore, in a series of 21 patients with severe mitral valve stenosis selected for PTMV, 3D TEE was performed before and after PTMV. The mitral valve area was assessed by planimetry pre- and post-PTMV; the mitral valve volume was assessed and attention was paid to the amount of fusion of the commissures. These results were compared with findings by 2-dimensional transthoracic echocardiography using pressure half-time method for assessment of mitral valve area, and were analyzed for the prediction of successful outcome. Pre-PTMV the mitral valve area assessed by 3D TEE was 1.0 +/- 0.3 cm(2) vs 1.2 +/- 0.4 cm(2) assessed by 2-dimensional transthoracic echocardiography (P =.03) and post-PTMV it was 1.8 +/- 0.5 cm(2) vs 1.9 +/- 0.6 cm(2) (not significant), respectively. The mitral valve volume could be assessed by 3D TEE (mean 2.4 +/- 2.5 cm(3)) and was inversely correlated to a successful PTMV procedure (P <.001). The 3D TEE method enabled a better description of the mitral valvular anatomy, especially post-PTMV. We conclude that 3D TEE will have additional value over 2-dimensional echocardiography in this group of patients, for selection of patients pre-PTMV, and for analyzing pathology of the mitral valve afterward.

Clinical application in routine practice of the proximal flow convergence method to calculate the mitral surface area in mitral valve stenosis

BACKGROUND

Two-dimensional (2D) echocardiography planimetry, the Doppler pression half-time (PHT), and the continuity equation methods were used to estimate mitral valve area (MVA) in patients with mitral stenosis (MS). Recently, the proximal isovelocity surface area (PISA) method has been shown to be accurate for calculating MVA. The purpose of this study is (1) to compare in a large non-selected population the accuracy of the PISA and planimetry methods for echocardiographic estimation of MVA; (2) to determine the effect of atrial fibrillation (AF), Wilkins score, associated mitral regurgitation (MR), aortic regurgitation (AR), and of commissural calcifications on the accuracy of the PISA method.

METHODS

One hundred and eight consecutive patients with rheumatic MS were studied (76 females and 32 males; mean age: 36 +/- 12 years); 64 were in sinus rhythm; 51 had associated MR and 46 had AR. By the PISA method. MVA was calculated assuming a uniform radius flow convergence region along a hemispherical surface.

RESULTS

The mean value of 2D MVA was 1.32 +/- 0.59 cm2 (0.4-3.1 cm2) and that of PISA MVA 1.33 +/- 0.62 cm2 (0.38-3 cm2). MVA calculated using the PISA method correlated well with 2D MVA (r = 0.93, y = 0.97x + 0.04, p < 0.0001, SEE = 0.21 cm2). The correlation was also good in patients with AF (r = 0.93, y = 0.99x + 0.03, p < 0.0001, SEE = 0.21 cm2), with MR (r = 0.94, y = 1.0 14x + 0.003, p < 0.0001, SEE = 0.19 cm2), with AR (r = 0.93, y = 0.90x + 0.11, p < 0.0001, SEE = 0.2 cm2), when Wilkins score was >8 (r = 0.92, = 0.96x + 0.06, p < 0.0001, SEE = 0.19 cm2), and in patients with commissural calcifications (r = 0.90, y = 0.88x + 0.009, p < 0.0001, SEE = 0.20 cm2).

CONCLUSION

Our study shows that in routine practice, MVA calculated by the PISA method correlated well with the area obtained by planimetry even in the presence of commissural calcifications, associated MR, AR, AF and of high Wilkins score. Therefore, the PISA method provides a reliable measurement of the MVA in MS under different anatomic and clinical conditions and may be a useful alternative method for calculating MVA.

The use of echocardiography in the critical care setting

Echocardiography has become an invaluable tool in the management of critically ill patients. Its safety and portability allow for use at the bedside to provide rapid, detailed information regarding the cardiovascular system. Echocardiography can elucidate cardiac structure and mechanical function. Recently, the power of clinical echocardiography has been augmented by the use of Doppler techniques to evaluate cardiovascular hemodynamics. An in-depth understanding of the proper use of echocardiography is a prerequisite for the intensivist.

Improved assessment of mitral valve stenosis by volumetric real-time three-dimensional echocardiography

OBJECTIVES

This study was performed to determine the feasibility, accuracy and reproducibility of real-time volumetric three-dimensional echocardiography (3-D echo) for the estimation of mitral valve area in patients with mitral valve stenosis.

BACKGROUND

Planimetry of the mitral valve area (MVA) by two-dimensional echocardiography (2-D echo) requires a favorable parasternal acoustic window and depends on operator skill. Transthoracic volumetric 3-D echo allows reconstruction of multiple 2-D planes in any desired orientation and is not limited to parasternal acquisition, and could thus enhance the accuracy and feasibility of calculating MVA.

METHODS

In 48 patients with mitral stenosis (40 women; mean age 61 +/- 13 years) MVA was determined by planimetry using volumetric 3-D echo and compared with measurements obtained by 2-D echo and Doppler pressure half-time (PHT). All measurements were performed by two independent observers. Volumetric data were acquired from an apical view.

RESULTS

Although 2-D echo allowed planimetry of the mitral valve in 43 of 48 patients (89%), calculation of the MVA was possible in all patients when 3-D echo was used. Mitral valve area by 3-D echo correlated well with MVA by 2-D echo (r = 0.93, mean difference, 0.09 +/- 0.14 cm2) and by PHT (r = 0.87, mean difference, 0.16 +/- 0.19 cm2). Interobserver variability was significantly less for 3-D echo than for 2-D echo (SD 0.08cm2 versus SD 0.23cm2, p < 0.001). Furthermore, it was much easier and faster to define the image plane with the smallest orifice area when 3-D echo was used.

CONCLUSIONS

Transthoracic real-time volumetric 3-D echo provides accurate and highly reproducible measurements of mitral valve area and can easily be performed from an apical approach.

[The effect of the duration of the cardiac cycles on determining mitral valve area by means of pressure half-time]

INTRODUCTION AND AIMS

To analyze the influence of variations in the length of cardiac cycle length of calculating mitral valve area by means of the pressure half time in patients with mitral valve stenosis and atrial fibrillation.

METHODS

Fifty-nine patients with pure mitral valve stenosis and atrial fibrillation were subjected to transmitral flow measurements by continuous Doppler monitoring from the apical window. In each patient the pressure half time was quantified, corresponding to a minimum of 30 consecutive cycles.

RESULTS

Considering all the measurements made in each patient, the correlation between pressure half time and cardiac cycle was significant in 20 cases (34%). The pressure half time variation coefficients were significantly greater when including the values corresponding to the shortest cycles. Thus, for cycle duration of > or = 800, 700, 600, 500 and 400 ms, the mean values were 0.096 +/- 0.041, 0.106 +/- 0.042 (NS), 0.128 +/- 0.032 (p < 0.05), 0.167 +/- 0.048 (p < 0.001) and 0.231 +/- 0.057 (p < 0.0001), respectively. Upon analyzing the relation between pressure half time and cardiac cycle with progressive exclusion of the longer cycles > or = 800, 700 and 600 ms the number of patients with significant correlation coefficients increased to 19/37 (51%), 12/23 (52%) and 4/6 (67%) on respectively excluding.

CONCLUSIONS

Patients with mitral valve stenosis and atrial fibrillation show a variation in pressure half time that may complicate calculation of the mitral valve area. Variability is inherent to the measurement method, and is furthermore dependent upon cardiac cycle duration. This may be resolved by limiting determinations to cycles longer than 800 ms.

Application of proximal isovelocity surface area method to determine prosthetic mitral valve area

BACKGROUND

In this study, we investigated the accuracy of orifice area determination of the prosthetic valve (Biocor) by using proximal isovelocity surface area method (PISA). Thirty-two patients (26 women, 6 men; mean age 44 +/- 8.1 years) were studied. Eleven patients were in normal sinus rhythm and the rest were in atrial fibrillation. Associated valvular lesions were mild aortic regurgitation in 12 patients and moderate tricuspid regurgitation in 19 patients. Sizes of prosthetic valves were 27 to 31, and implantation duration was 4 to 8 years.

METHODS AND RESULTS

We analyzed the flow convergence zone proximal to the valve orifice with the concept of a hemispheric model. Mitral valve area (MVA) calculation was formulated by MVA = 2pi r2 x Va/Vm x (Vm/Vm-Va), where Vm is the maximal mitral velocity and Vm/Vm - Va is a correction factor to account for flattening of isotachs near the prosthetic orifice. MVA calculations by PISA were compared with pressure half-time (PHT), continuity equation (CONT), and color flow area (CFA) methods. Mitral valve areas were 2.17 +/- 0.17 cm2, 2.22 +/- 0.21 cm2, 2.19 +/- 0.22 cm2, and 2.16 +/- 0.17 cm2 in PISA, CFA, PHT, and CONT methods, respectively. Values in the comparison of MVA measurements by different methods were PISA vs PHT, r =.86; PISA vs CFA, r =.77; and PISA vs CONT, r =.89.

CONCLUSIONS

The PISA method gives reliable estimates of large orifices such as prosthetic valves. Although the best correlation was seen with the CONT method, results of this study also confirmed that the PISA method can be applied with reasonable accuracy.

Doppler pressure half-time method of assessing mitral valve area: aortic insufficiency does not adversely affect validity

OBJECTIVES

This study evaluated the effect of aortic insufficiency on the correlation of pressure half-time-derived mitral valve area with each of 2 standards for mitral valve area (planimetry and cardiac catheterization) in a prospectively assembled cohort of patients scheduled for percutaneous balloon mitral commissurotomy.

BACKGROUND

Although Doppler pressure half-time has been validated as a method for assessing mitral valve area, most previous studies have suggested that this noninvasive technique overestimates mitral valve area in the setting of coexistent aortic insufficiency.

METHODS AND RESULTS

Echocardiography and cardiac catheterization were performed on 212 consecutive patients scheduled for percutaneous balloon mitral commissurotomy. After excluding 35 patients who did not have aortography, the rest were divided into a "no aortic insufficiency [AI] group" (n = 146) including those with trivial or no aortic insufficiency at catheterization and an "AI group" (n = 31 ) including those with mild or moderate aortic insufficiency. The pressure half-time mitral valve area tended to slightly underestimate invasive valve area by 0.04 cm2 in the AI group and to slightly overestimate invasive valve area by 0.06 cm2 in the no AI group. This difference between the groups was not statistically significant (P = .13). The pressure half-time mitral valve area tended to underestimate planimetered valve area by 0.11 cm2 in the AI group and by 0.10 cm2 in the no AI group. There was no difference between the 2 groups (P = .94). Potential confounders that could theoretically mask the effect of aortic insufficiency on the pressure half-time (including age, heart rate, blood pressure, left ventricular diastolic pressure, ejection fraction, mitral regurgitation, and atrial fibrillation) were excluded by multivariable analyses.

CONCLUSIONS

The pressure half-time method of determining mitral valve area is not adversely affected by mild to moderate aortic insufficiency. This finding has implications for the utility of this technique in the rheumatic valvular disease population, in which mitral and aortic valve disease frequently coexist.

Evaluation of mitral valve disease using transesophageal echocardiography

In the past 10 years, clinical application of transesophageal echocardiography (TE) has grown explosively. Intraoperative TE offers a powerful diagnostic and monitoring tool for the physicians in the cardiac operating room. The use of TE revolutionizes the assessment of patients with mitral valve disease. Surgical decisions are often altered based on the information obtained from TE. This review describes the basic features of TE as well as its uses in the intraoperative setting for evaluation of the mitral valve.

Clinical assessment and management of mitral stenosis

There have been significant advances in the diagnosis and treatment of the patient with mitral stenosis over the past two decades. Two-dimensional and Doppler echocardiography have supplanted the cardiac catheterization laboratory in the diagnosis and determination of the hemodynamic severity of the stenotic mitral valve. The development of a catheter-based approach for splitting fused commissures has led to earlier indications for intervention. It is likely that with the resurgence of rheumatic fever as well as influx of immigrant populations, the incidence of mitral stenosis may increase in the twenty-first century. It is thus important for the clinician to have a complete understanding of the evaluation and treatment options for the patient with mitral stenosis in the modern-day era.

Validation of flow convergence region method in assessing mitral valve area in the course of transthoracic and transesophageal echocardiographic studies

The purpose of this study was to determine the diagnostic value of flow convergence region method (FCR) to complement well-accepted techniques in assessing mitral valve area (MVA). Fifty-three patients (39 women, 14 men) were enrolled in the study. Transesophageal echocardiography (TEE) was performed after transthoracic echocardiographic (TTE) evaluation, and all measurements were performed for each patient. Mean MVA values determined by different methods both in TEE and TTE studies did not differ (p = not significant). In 51 (96%) patients, TEE and TTE were feasible and measurements of MVA with FCR correlated well with the conventional methods (r = 0.87, standard error of the estimate = 0.13 cm2). In TEE, MVA determined by FCR also correlated well with that obtained by the "pressure half time" method (r = 0.90, standard error of the estimate = 0.11 cm2). Results of our study confirmed the feasibility and accuracy of FCR. Because TEE provides reliable estimation of MVA by FCR, intraoperative monitoring by TEE should be considered as a comparative alternative method.

Valve Resistance in Mitral Stenosis: Its Determinants and its Role in the Evaluation of the Disease

To evaluate the value and the determinants of valve resistance in mitral stenosis, 95 patients with pure mitral stenosis were examined by Doppler echocardiography during their clinical follow-up, measuring cavity dimensions, left ventricular function, mitral area (by planimetry and pressure half time), mean transmitral pressure gradient, aortic flow, and pulmonary artery systolic pressure. The mitral resistance was calculated as mean transmitral pressure gradient/aortic flow ratio. To graduate the severity of the morphological abnormalities in valvular structure, we used a point score system with evaluation of leaflet and subvalvular thickness, calcification, and valvular mobility. The functional class was determined according to NYHA classification. In this study, both mitral area (r = -0.79, P < 0.001 and r(p) = -0.60, P < 0.001) and mitral score (r = 0.68, P < 0.001 and r(p) = 0.25, P = 0.013) were independent determinants of mitral resistance. In multivariate analysis, mitral resistance and female gender were selected by multiple linear regression analysis as determinants of pulmonary artery systolic pressure, and mitral area and pulmonary artery systolic pressure were selected by logistic linear regression analysis as determinants of NYHA functional class. In patients with moderate or severe mitral stenosis, the estimated probability for III and IV NYHA functional class considering mitral area 1 cm(2) or below went from 51.1-86.4% when mitral resistance below or above 130 dynes.sec.cm(-5), respectively, was considered together. Thus, mitral valve resistance should be used as a complement to the mitral area method in assessment of mitral stenosis, adding the effects of the reduction in mitral area and the damage in mitral valve apparatus.

Quantification of mitral valve stenosis by three-dimensional transesophageal echocardiography

The aim of this study was the evaluation of the diagnostic potentials of transesophageal 3D- echocardiography in the determination of mitral valve stenosis. 54 patients were investigated by transthoracic and multiplane transesophageal echocardiography. In 41 patients cardiac catheterization was performed. 3D- echocardiographic data acquisition was performed by automatic transducer rotation at 2 degree increments over a span of 180 degrees. The transesophageal probe was linked to an ultrasound unit and to a 3D- workstation capable of ECG- and respiration gated data acquisition, postprocessing and 2D/3D image reconstruction. The mitral valve was visualized in sequential cross-sectional planes out of the 3D data set. The spatial position of the planes was indicated in a reference image. In the cross-sectional plane with the narrowest part of the leaflets the orifice area was measured by planimetry. For topographic information a 3D view down from the top of the left atrium was reconstructed. Measurements were compared to conventional transthoracic planimetry, to Doppler-echocardiographic pressure half time and to invasive data. The mean difference to transthoracic planimetry, pressure half time and to invasive measurements were 0.3 +/- 0.1 cm2, 0.2 +/- 0.1 cm2 and 0.1 +/- 0.1 cm2, respectively. Remarkable differences between the 3D- echocardiographic and the 2D- or Doppler- echocardiographic methods were observed in patients with severe calcification or aortic regurgitation. In 22% of the patients the 3D data set was not of diagnostic quality. New diagnostic information from a 3D view of the mitral valve could be obtained in 69% of the patients. Thus, although image quality is limited, 3D- echocardiography provides new topographic information in mitral valve stenosis. It allows the use of a new quantitative method, by which image plane positioning errors and flow-dependent calculation is avoided.

Measurement of mitral valve area in mitral stenosis: four echocardiographic methods compared with direct measurement of anatomic orifices

OBJECTIVES

This study sought to compare the mitral valve areas of patients with rheumatic mitral valve stenoses as determined by means of four echocardiographic and Doppler methods with those obtained by direct anatomic measurements.

BACKGROUND

There has been no systemic comparison between Doppler-determined valve areas and the true anatomic orifice in a single cohort.

METHODS

In 30 patients with mitral stenosis, the mitral valve areas determined by two-dimensional echocardiographic planimetry, pressure half-time, flow convergence region and flow area were compared with the values directly measured on the corresponding excised specimen by means of a custom-built sizer.

RESULTS

The correlation coefficient was r = 0.95 (SE 0.06, p < 0.0001) for two-dimensional planimetry; r = 0.80 (SE 0.09, p < 0.0001) for pressure half-time; r = 0.87 (SE 0.09, p < 0.0001) for flow convergence region; and r = 0.54 (SD 0.1, p < 0.002) for flow area. Two-dimensional echocardiographic planimetry, pressure half-time, flow convergence region and flow area overestimated the actual anatomic orifice by > 0.3 cm2 in 2, 1, 6 and 0 patients, respectively, and underestimated it by > 0.3 cm2 in 0, 4, 1 and 8 patients, respectively.

CONCLUSIONS

Mitral valve areas determined by two-dimensional planimetry, pressure half-time and proximal flow convergence region reliably correlated with size of the anatomic orifice. The flow area method provided a less reliable correlation.

Doppler echocardiographic assessment of long-term progression of mitral stenosis in 103 patients: valve area and right heart disease

OBJECTIVES

The purpose of this study was to determine, in a large referral population, the rate of echocardiographic change in mitral valve area (MVA) without interim intervention, to determine which factors influence progression of narrowing and to examine associated changes in the right side of the heart.

BACKGROUND

Little information is currently available on the echocardiographic progression of mitral stenosis, particularly on progressive changes in the right side of the heart and the ability of a previously proposed algorithm to predict progression.

METHODS

We studied 103 patients (mean age 61 years; 74% female) with serial two-dimensional and Doppler echocardiography. The average interval between entry and most recent follow-up study was 3.3 +/- 2 years (range 1 to 11).

RESULTS

During the follow-up period, MVA decreased at a mean rate of 0.09 cm2/year. In 28 patients there was no decrease, in 40 there was only relatively little change (< 0.1 cm2/year) and in 35 the rate of progression of mitral valve narrowing was more rapid (> or = 0.1 cm2/year). The rate of progression was significantly greater among patients with a larger initial MVA and milder mitral stenosis (0.12 vs. 0.06 vs. 0.03 cm2/year for mild, moderate and severe stenosis, p < 0.01). Although the rate of mitral valve narrowing was a weak function of initial MVA and echocardiographic score by multivariate analysis, no set of individual values or cutoff points of these variables or pressure gradients could predict this rate in individual patients. There was a significant increase in right ventricular diastolic area (17 to 18.7 cm2) and tricuspid regurgitation grade (2 + to 3 +; p < 0.0001 between entry and follow-up studies). Progression in right heart disease occurred even in patients with minimal or no change in MVA. Patients with associated aortic regurgitation had a higher rate of decrease in MVA than did those with trace or no aortic regurgitation (0.19 vs. 0.086 cm2/year, p < 0.05).

CONCLUSIONS

The rate of mitral valve narrowing in individual patients is variable and cannot be predicted by initial MVA, mitral valve score or transmitral gradient, alone or in combination. Right heart disease can progress independent of mitral valve narrowing.

Stenotic lesions

Images

Transesophageal echocardiographic evaluation of native valvular disease and repair

Surgery for valvular heart disease corrects systolic or diastolic dysfunction of the mitral, aortic, or tricuspid valves. The intraoperative echocardiographic assessment of the native heart valve is aimed at defining the pathology of valve disease, determining the mechanism of valve dysfunction, and quantitating the degree (grade) of valvular stenosis or insufficiency.

Comparison of proximal isovelocity surface area method with pressure half-time and planimetry in evaluation of mitral stenosis

OBJECTIVES

This study sought to 1) compare the accuracy of the proximal isovelocity surface area (PISA) and Doppler pressure half-time methods and planimetry for echocardiographic estimation of mitral valve area; 2) evaluate the effect of atrial fibrillation on the accuracy of the PISA method; and 3) assess factors used to correct PISA area estimates for leaflet angulation.

BACKGROUND

Despite recognized limitations of traditional echocardiographic methods for estimating mitral valve area, there has been no systematic comparison with the PISA method in a single cohort.

METHODS

Area estimates were obtained in patients with mitral stenosis by the Gorlin hydraulic formula, PISA and pressure half-time method in 48 patients and by planimetry in 36. Two different factors were used to correct PISA estimates for leaflet angle (theta): 1) plane-angle factor (theta/180 [theta in degrees]); and 2) solid-angle factor [1-cos(theta/2)].

RESULTS

After exclusion of patients with significant mitral regurgitation, the correlation between Gorlin and PISA areas (0.88) was significantly greater (p < 0.04) than that between Gorlin and pressure half-time (0.78) or Gorlin and planimetry (0.72). The correlation between Gorlin and PISA area estimates was lower in atrial fibrillation than sinus rhythm (0.69 vs. 0.93), but the standard error of the estimate was only slightly greater (0.24 vs. 0.19 cm2). The average ratio of the solid- to the plane-angle correction factors was approximately equal to previously reported values of the orifice contraction coefficient for tapering stenosis.

CONCLUSIONS

1) The accuracy of PISA area estimates in mitral stenosis is at least comparable to those of planimetry and pressure half-time. 2) Reasonable accuracy of the PISA method is possible in irregular rhythms. 3) A simple leaflet angle correction factor, theta/180 (theta in degrees), yields the physical orifice area because it overestimates the vena contracta area by a factor approximately equal to the contraction coefficient for a tapering stenosis.

Color flow Doppler determination of transmitral flow and orifice area in mitral stenosis: experimental evaluation of the proximal flow-convergence method

To evaluate the in vivo accuracy of color Doppler flow-convergence methods for determining transmitral flow volumes and effective orifice areas in mitral stenosis, we studied two models for flow-convergence surface geometry, a hemispheric (HS) model and an oblate hemispheroid (OH) model in a chronic animal model with quantifiable mitral flows. Color Doppler flow mapping of the proximal flow-convergence region has been reported to be useful for evaluation of intracardiac flows. Flow-convergence methods in patients with mitral stenosis that use HS assumption for the isovelocity surface have resulted in underestimation of actual flows. Chronic mitral stenosis was created surgically in six sheep with annuloplasty rings (group 1) and 11 sheep with bioprosthetic porcine valves (group 2). Hemodynamic and echocardiographic/Doppler studies (n = 18 in group 1; n = 21 in group 2) were performed 20 to 34 weeks later. Left ventricular inflow obstruction was of varied severity, with mean transmitral valve gradients in group 1 ranging from 1.3 to 18 mm Hg and in group 2 ranging from 6.3 to 25.6 mm Hg. Although transmitral flows derived by both geometric flow convergence models showed significant correlations with reference cardiac outputs, the correlations for the OH model were better than those for the HS model (group 1, r = 0.86 for the OH model vs r = 0.72 for the HS model; group 2; r = 0.84 for the OH model vs r = 0.62 for the HS model). The OH model was also superior to the HS model in determining effective orifice areas compared to reference orifice areas determined by postmortem planimetry of anatomic orifices (group 1 only, r = 0.64 for OH vs 0.58 for HS), by the Gorlin and Gorlin formula (group 1, r = 0.63 for OH vs 0.72 for HS; group 2, r = 0.82 for OH vs 0.76 for HS), and by the Doppler pressure half-time method (group 1, r = 0.76 for OH vs 0.69 for HS; group 2, r = 0.84 for OH vs 0.62 for HS).(ABSTRACT TRUNCATED AT 400 WORDS)