Mechanisms of Effort Intolerance in Patients With Rheumatic Mitral Stenosis: Combined Echocardiography and Cardiopulmonary Stress Protocol.
This study sought to evaluate mechanisms of effort intolerance in patients with rheumatic mitral stenosis (MS).
Combined stress echocardiography and cardiopulmonary testing allows assessment of cardiac function, hemodynamics, and oxygen extraction (A-Vo2 difference).
Using semirecumbent bicycle exercise, 20 patients with rheumatic MS (valve area 1.36 ± 0.4 cm2) were compared to 20 control subjects at 4 pre-defined activity stages (rest, unloaded, anaerobic threshold, and peak). Various echocardiographic parameters (left ventricular volumes, ejection fraction, stroke volume, mitral valve gradient, mitral valve area, tissue s' and e') and ventilatory parameters (peak oxygen consumption [Vo2] and A-Vo2 difference) were measured during 8 to 12 min of graded exercise.
Comparing patients with MS to control subjects, significant differences (both between groups and for group by time interaction) were seen in multiple parameters (heart rate, stroke volume, end-diastolic volume, ejection fraction, s', e', Vo2, and tidal volume). Exercise responses were all attenuated compared to control subjects. Comparing patients with MS and poor exercise tolerance (<80% of expected) to other subjects with MS, we found attenuated increases in tidal volume (p = 0.0003), heart rate (p = 0.0009), and mitral area (p = 0.04) in the poor exercise tolerance group. These patients also displayed different end-diastolic volume behavior over time (group by time interaction p = 0.05). In multivariable analysis, peak heart rate response (p = 0.01), tidal volume response (p = 0.0001), and peak A-Vo2 difference (p = 0.03) were the only independent predictors of exercise capacity in patients with MS; systolic pulmonary pressure, mitral valve gradient, and mitral valve area were not.
In patients with rheumatic MS, exercise intolerance is predominantly the result of restrictive lung function, chronotropic incompetence, limited stroke volume reserve, and peripheral factors, and not simply impaired valvular function. Combined stress echocardiography and cardiopulmonary testing can be helpful in determining mechanisms of exercise intolerance in patients with MS.
Laufer-Perl M
，Gura Y
，Shimiaie J
，Sherez J
，Pressman GS
，Aviram G
，Maltais S
，Megidish R
，Halkin A
，Ingbir M
，Biner S
，Keren G
，Topilsky Y
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Accuracy of Echocardiography to Estimate Pulmonary Artery Pressures With Exercise: A Simultaneous Invasive-Noninvasive Comparison.
Exercise echocardiography is often applied as a noninvasive strategy to screen for abnormal pulmonary hemodynamic response, but it is technically challenging, and limited data exist regarding its accuracy to estimate pulmonary arterial pressure during exercise.
Among 65 patients with exertional intolerance undergoing upright invasive exercise testing, tricuspid regurgitation (TR) Doppler estimates and invasive measurement of pulmonary arterial pressure at rest and peak exercise were simultaneously obtained. TR Doppler envelopes were assessed for quality. Correlation, Bland-Altman, and receiver-operating characteristic curve analyses were performed to evaluate agreement and diagnostic accuracy. Mean age was 62±13 years, and 31% were male. High-quality (grade A) TR Doppler was present in 68% at rest and 34% at peak exercise. For grade A TR signals, echocardiographic measures of systolic pulmonary arterial pressure correlated reasonably well with invasive measurement at rest (r=0.72, P<0.001; bias, -2.9±8.0 mm Hg) and peak exercise (r=0.75, P<0.001; bias, -1.9±15.6 mm Hg). Lower quality TR signals (grade B and C) correlated poorly with invasive measurements overall. In patients with grade A TR signals, mean pulmonary arterial pressure-to-workload ratio at a threshold of 1.4 mm Hg/10 W was able to identify abnormal pulmonary hemodynamic response during exercise (>3.0 mm Hg/L per minute increase), with 91% sensitivity and 82% specificity (area under the curve, 0.90; 95% confidence interval, 0.77-1.0; P=0.001).
Agreement between echocardiographic and invasive measures of pulmonary pressures during upright exercise is good among the subset of patients with high-quality TR Doppler signal. While the limits of agreement are broad, our results suggest that in those patients, sensitivity is adequate to screen for abnormal pulmonary hemodynamic response during exercise.
van Riel AC
，Opotowsky AR
，Santos M
，Rivero JM
，Dhimitri A
，Mulder BJ
，Bouma BJ
，Landzberg MJ
，Waxman AB
，Systrom DM
，Shah AM
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