Mitral Valve Resistance Research Articles

Pulmonary vascular resistance and proper timing of percutaneous balloon mitral valvotomy

It is frequent to see pulmonary hypertension (PH) in patients with mitral stenosis (MS) secondary to increased pulmonary vascular resistance (PVR), data about the effect of PVR on the results of percutaneous balloon mitral valvotomy (PBMV) are insufficient. To detect the role of PVR in predicting residual PH immediately after PBMV. This prospective study comprised 49 consecutive patients with moderate to severe MS who were investigated pre and within 48h post a successful PBMV for the first time. Echocardiography was used to assess the mitral valve area (MVA), mean transmitral pressure gradient (MPG), mitral valve resistance (MVR), right ventricular systolic pressure (RVSP) and PVR. Patients were classified into two groups according to the pre PVR (≥ 1.6 WU as group I and < 1.6 as group II). At baseline compared to group II (32 patients), Group I (17 patients) had higher MPG (13.6 ± 5.2 vs. 11.7 ± 3.7mmHg, P < 0.05), RVSP (45.6 vs. 37.9mmHg, P < 0.001) and PVR (2.2 ± 0.1 vs. 1.2 ± 0.1WU, P < 0.001) with no significant difference regarding age, gender, MVS, MVA and MVR. Patients of group I had comparatively lower improvement immediate post procedural of RVSP and PVR with no significant difference in immediate post procedural improvement in NYHA classification, MVA, MPG and MVR. Basal PVR > 1.8WU was proved to be a highly specific (91%), a good predictor (AUC 0.78) of persistent elevation of RVSP > 50mmHg post PMV. Pathological rise of PVR that associates MS had provided a strong and an independent predictor of persistent pulmonary hypertension post PBMV and by this aspect it could be used as a valuable tool as MVA and MPG to send patients earlier for PBMV even with less severe MS. PVR > 1.81 WU could be used as a noninvasive parameter for predicting regression of PH immediately after PBMV.

Effect of balloon mitral valvuloplasty on mitral valve resistance and its correlation with clinical outcome

Effect of balloon mitral valvuloplasty on mitral valve resistance and its correlation with clinical outcome

Mitral valve resistance determines hemodynamic consequences of severe rheumatic mitral stenosis and immediate outcomes of percutaneous valvuloplasty.

The mitral valve area (MVA) poorly reflects the hemodynamic status of (MS). In this study, we compared the MVA with mitral valve resistance (MVR) with regard to the determination of hemodynamic consequences of MS and the immediate outcomes of percutaneous balloon mitral valvuloplasty (PBMV). In a prospective study, 36 patients with severe rheumatic MS with left ventricular ejection fraction (LVEF) >50% were evaluated. They underwent transthoracic echocardiography (TTE) and catheterization. The MVA was measured by two-dimensional planimetry and pressure half-time (PHT), and the MVR was calculated using the equation: 1333×transmitral pressure gradient mean transmitral diastolic flow rate. The patients' mean age was 47.8±10.5years. MVR ≥140.6 dynes·s/cm5 detected systolic pulmonary arterial pressure (sPAP) >55mm Hg with a sensitivity of 100% and a specificity of 74%. The sensitivity and specificity of MVA<0.75cm2 to discriminate elevated sPAP were 81% and 89%, respectively. PHT ≥323.5mseconds had a sensitivity of 78% and a specificity of 96% to detect an elevated sPAP. To predict a successful PBMV, preprocedural MVR≥106.1 dynes·s/cm5 had a sensitivity of 100% and a specificity of 67% (area under the curve [AUC]=0.763; 95% confidence interval [CI]=0.520-1.006; P=.034); preprocedural MVA <0.95cm2 had a sensitivity of 78% and a specificity of 73% (AUC=0.730; 95% CI=0.503-0.956; P=.065); and preprocedural PHT ≥210.5mseconds had a sensitivity of 73% and a specificity of 78% (AUC=0.707; 95% CI=0.474-0.941; P=.095). MVR seems to be more accurate than MVA in determining the hemodynamic consequences of severe MS as determined by sPAP. In addition, preprocedural MVR detected successful PBMVs.

Match and mismatch between opening area and resistance in mild and moderate rheumatic mitral stenosis.

Mitral valve resistance (MVR) is a hemodynamic consequence of mitral stenosis (MS), but it has no clear threshold with a shortage of data to be reliable. We aimed to investigate match and mismatch between opening area and resistance especially in patients with moderate and mild MS. This study comprised 88 patients with moderate and mild rheumatic MS. Transthoracic echocardiographic study estimated the following: mitral valve area (MVA) by both planimetry (2D) and pressure half-time (PHT), mitral valve score (MVS), mean transmitral pressure gradient (MPG), diastolic filling time (DFT), left ventricular out flow tract diameter (LVOTd) and velocity-time integral (LVOTvti), and MVR = MPG/aortic flow ratio [(LVOTd) (LVOTvti)/DFT] in dynes·s/cm5 . Patients were classified into two groups: group 1 (51 patients) with matched MVR and group 2 (37 patients) with mismatched higher MVR. In the matched group, moderate MS showed MVR <105 dynes·s/cm5 and <76dynes·s/cm5 with mild MS. Group 2 compared to group 1 had higher NYHA class (1.4±0.6 vs 1.2±0.4, P<.05) and higher MVS (8.1±1.8 vs 7±0.9, P<.05). MVR showed positive correlation with MVS (r=.5, P<.05), and logistic regression analysis showed that MVS is the only independent predictor of the MVR severity in the mismatched group (i.e., with higher MVR compared to the ROC analysis results) (B±SE=6.997±2.826, t=2.476, 95% CI 1.241±12.752 with an odds ratio=0.412, P<.05). On investigating match and mismatch between opening area and resistance, the only independent predictor of mismatch is the mitral valve score.

Role of the Mitral Valve Resistance in Evaluation of Mitral Stenosis Severity

Background: Mitral valve resistance (MVR) is an important hemodynamic consequence of mitral stenosis (MS). We aimed to determine whether the mitral valve resistance could be used as a clinically reliable method for estimation of MS severity. Materials and Methods: Transthorathic echocardiographic study of 128 patients with rheumatic MS to estimate; mitral valve area (MVA); planimerty (2D) and pressure half time (PHT), mitral valve score (MVS), right ventricular systolic pressure (RVSP), mean transmitral pressure gradient (MPG), diastolic filling time (DFT), left ventricular out flow tract diameter (LVOTd) and velocity time integral (LVOT vti), MVR calculated as: MPG/aortic flow ratio [(LVOTd) (LVOTvti)/DFT] in dynes.sec.cm-5. Results: MVR at cut off values of: ≥105.26 dynes.sec.cm-5, had a sensitivity of 86.7% and a specificity of 74.5% for severe MS, between 76.02 and 105.26 dynes.sec/cm5 it had a sensitivity of 85.2% and a specificity of 72% for moderate MS, at ≤76.02 dynes.sec/cm5 it had a sensitivity of 81% and a specificity of 91% for mild MS. MVR in moderate MS; can detect symptomatic patients at a cut off value ≥85.65 dynes.sec/cm5 with a sensitivity of 87% and a specificity of 100%. MVR had positive correlations with MVS and RVSP (r=0.618 and 0.401), -ve correlations with MVA-2D and PHT (r=-0.559 and -0.284), P<0.01. MVR was an independent predictor of the NYHA functional class (B ± SE0.003 ± 0.001, odds ratio 0.3, P<0.01). NYHA functional class showed the best correlation with MVR (r=0.630, P<0.01). Conclusion: MVR can be used as a parameter for expression of stenosis severity, and could be used for evaluation of symptomatic moderate MS.

Control system design for the mock ventricle with aortic and mitral valve resistance uncertainty

Reproducing the native left ventricle’s contractile behavior is the key ingredient for the mock cardiovascular circulatory system. It can be achieved by controlling either mock ventricle’s pressure or volume so that it could follow the reference signal calculated by the Elastance waveform. However, due to inherent uncertainties of the parameter values of the mock ventricle, such as check valve resistance, it is difficult to achieve high quality control performance. In this paper, we present an adaptive control scheme to overcome this parameter value uncertainty and to achieve high quality control performance. To the best knowledge of the author, it is the first report that reproduces the mock ventricle pumping dynamics precisely considering the resistance of the aortic/mitral check valves and overcoming the uncertainty of them. In the paper, along with the detailed design of the controller, rigorous proof of the stability and the convergence is presented as well. Computer simulation was performed using an electrical-analog cardiovascular circulatory system model and a piston pump mock ventricle model. Results confirmed that adaptive control achieved almost perfect tracking performance in spite of large parameter uncertainty and high bandwidth dynamic characteristics of the mock ventricle. Performance comparison verified the superiority of the adaptive controller over PID controllers.

Value of the Mitral Valve Resistance in Evaluation of Symptomatic Patients with Mild and Moderate Mitral Stenosis – A Dobutamine Stress Echocardiographic Study

Conventional stenosis indexes poorly reflect the major hemodynamic consequence of mitral stenosis (MS). Valve resistance (VR) is a physiologic expression of stenosis. This study aimed to demonstrate whether the mitral valve resistance (MVR) and its changes, relate to restricted exercise capacity in patients with mild and moderate mitral stenosis. Twenty-four patients with rheumatic mild-to-moderate MS underwent transthoracic echocardiographic study (resting and dobutamine stress echocardiography [DSE]), divided into two groups; group I: symptomatic (12 patients) and group II: asymptomatic (12 patients). Mitral valve area (MVA), mean transmitral diastolic pressure gradient (TMPG), cardiac output (CO), and MVR were measured in all patients at rest and at peak DSE. Changes (∆) in MVA, TMPG, CO, and MVR were calculated. Data underwent statistical analysis. From resting to peak dobutamine infusion, the MVR significantly decreased from 111.4 ± 28.2 to 83.6 ± 27.0 dynes sec/cm(5) in group II (P < 0.001). The increase in MVR in group I (13.8 ± 10.3 dynes sec/cm(5)) compared with its reduction (-27.8 ± 15.6 dynes sec/cm(5)) in group II were highly significant different (P < 0.001). A reduction in MVR by less than 21.5 dynes sec/cm(5) at peak dobutamine infusion reflect a cutoff value considered to detect the hemodynamic significance of mild-to-moderate MS with a sensitivity of 92% and a specificity of 73%. The changes in the MVR can be used as a DSE parameter for expression of stenosis severity and to describe discrepancy in symptom status in patients with mild-to-moderate mitral stenosis.

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

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. 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. 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. 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.

The use of mitral valve resistance in the evaluation of native mitral valve stenosis Carey L. O'Bryan, IV, Daniel S. White, Steven Guidera, Robert M. Shad. Wilford Hall U.S. Air Force Medical Center, San Antonio, TX

The use of mitral valve resistance in the evaluation of native mitral valve stenosis Carey L. O'Bryan, IV, Daniel S. White, Steven Guidera, Robert M. Shad. Wilford Hall U.S. Air Force Medical Center, San Antonio, TX

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.

Evaluation of the Mitral Valve Resistance as a Hemodynamic Parameter in Mitral Stenosis

Evaluation of the Mitral Valve Resistance as a Hemodynamic Parameter in Mitral Stenosis

Mitral valve resistance as a hemodynamic indicator in mitral stenosis

Variability of the valve area calculated by the Gorlin formula has been noted in bioprosthetic and aortic valves, but few data are available for native stenotic mitral valves. Valve resistance has been proposed as an alternative hemodynamic indicator; however, its value in mitral stenosis has not been assessed. Thirty-four patients had simultaneous recordings of left atrial and ventricular pressures, 26 after percutaneous balloon mitral dilatation (PBMD). Patients with shunt or mitral regurgitation were excluded. Mitral valve resistance correlated exponentially with Gorlin mitral area (y = 133 ∗[area] −1.5; p < 0.0001). Both Gorlin mitral area and mitral resistance improved after PBMD (0.89 ± 0.07 cm 2 to 2.22 ± 0.15 cm 2; p < 0.001; and 166 ± 20 to 40 ± 8 dynes · s · cm −5; p < 0.001). Gorlin area and mitral resistance correlated with New York Heart Association functional class. After infusion of isoproterenol in 17 patients, there was an increase in Gorlin area (baseline 1.77 ± 0.22 cm 2, change 0.23 ± 0.10; p < 0.03), whereas mitral resistance did not change (baseline 96 ± 16 dynes · s · cm −5, change 2 ± 5; p = not significant). Mitral resistance is valuable in the assessment of mitral stenosis. It varies less than Gorlin mitral area under changing hemodynamic conditions.