To study the change in respiratory muscle strength in patients with Rheumatic mitral stenosis (MS) before and after Percutaneous Balloon Mitral Valvotomy (PBMV).
A prospective study was done with 20 patients, mean age 31 years, with moderate to severe MS who underwent successful PBMV. Patients with known lung disease, neuromuscular disease, electrolyte imbalance and non-ambulatory patients were excluded. The following parameters were evaluated in all study subjects before PBMV and repeated 1 week after the procedure: 1.Transthoracic Echocardiogram 2.Spirometric measurements including Vital Capacity, Forced Vital Capacity, Forced Expiratory Volume in 1 second, and Peak Expiratory Flow Rate 3. Assessment of respiratory muscle strength by Maximal Static Inspiratory mouth pressure (MIP) and Maximal Static Expiratory mouth pressure (MEP) 4.Assessment of severity of dyspnea by the Six Minute Walk Test and Visual Analog scale. Student's t tests were used to analyze continuous variables. Chi-Square tests were used to analyze dichotomous variables.
After PBMV, a significant increase in mitral area (0.86 ± 0.20 to 1.88 ± 0.25; p < 0.001) and a reduction in mitral mean diastolic gradient (19.99 ± 8.79 to 4.97 ± 1.36 mmHg; p < 0.001) and end diastolic gradients (12.28 ± 6.79 to 2.69 ± 1.21 mmHg; p < 0.001) were observed. Significant differences were observed in the six minute walking distance (219 ± 30.15 to 237.55 ± 32.25 meters; p < 0.001) and visual analog scale as a measure of dyspnea (60.95 ± 12.16 to 44.4 ± 13.71 mm; p < 0.001). Significant improvements were noted in MIP (51.9 ± 10.28 to 60.36 ± 3.57 mmHg; p < 0.001) and MEP (62.15 ± 19.68 to 67.20 ± 21.91 mmHg; p < 0.001), the indices of inspiratory and expiratory muscle strength respectively.
Improvement in dyspnea in MS after PBMV is associated with an improvement in Inspiratory and Expiratory muscle strength.
Respiratory muscle weakness may be one of the mechanisms underlying dyspnea in Rheumatic Mitral Stenosis. This has potential therapeutic implications.
Chandrasekar Palaniswamy, No Financial Disclosure Information; No Product/Research Disclosure Information