Improvement in inspiratory muscle function after percutaneous mitral valvuloplasty in mitral stenosis. Preliminary report

Background: It has been proved that there is an inspiratory muscle dysfunct ion in mitral stenosis; Although its causes still remain unknown. Aim: to e valuate the effect of percutaneous balloon mitral valvuloplasty (PMV) on in spiratory muscle performance (IMP) in patients with mitral stenosis (mitral area < 1.5 cm(2)). Patients and methods: We studied IMP in 8 patients (35 +/- 10 years) before and 3 months after successful PMV. Inspiratory muscle strength was studied by measuring maximal statistical inspiratory mouth pre ssure (MIP). Endurance was evaluated using a two minute incremental thresho ld loading test in order to obtain the maximal sustainable inspiratory pres sure (SIP), with the maximal sustainable load (MSL) the patients could sust ain for 2 minutes. Results: Mitral valvuloplasty increased mean cardiac ind ex from 3.1 +/- 0.3 to 4.15 +/- 0.3 l/min/m(2) (p<0.01), and significantly decreased mean pulmonary and capillary pressures. The MIP value (118 +/- 6 cmH(2)O), similar to that of normal group, increased to 137 +/- 7 cmH(2)O ( p<0.01). SIP and maximal sustainable load were 52 +/- 2 cmH(2)O and 294 +/- 29 g respectively, lower than normal subjects (p<0.05). They increased aft er PMV to 80 +/- 3 cmH(2)O and 463 +/- 26 g respectively (p<0.001). Conclus ions: PMV improved inspiratory muscle function in patients with severe mitr al stenosis, probably secondary to a decrease work of breath and improvemen t of ventricular function.