<正> Objective: To explore whether successful valvuloplasty increases mitral valve reserve capacity in patients with mitral stenosis. Methods: Thirty-eight patients with pure rheumatic mitral stenosis underwent isoproterenol stress echocardiography before and after successful percutaneous balloon valvuloplasty. The mitral valve area （by direct planimetry of two-dimensional echocardiography）

mean transmitral pressure gradient （by continuous-wave Doppler echocardiography）

and cardiac output （by M-mode echocardiography） were measured at rest and under isoproterenol infusion to achieve heart rate of different stages. Results:Between the measurements before and after valvuloplasty

significant differences were observed in the mitral valve area （0. 91±0. 28 vs 1. 87±0. 23 cm2

P<0. 01）

mean transmitral pressure gradient （12. 5±6. 3 vs 3. 9±1. 9 mmHg

P<0. 01） and cardiac output （3. 93±1. 44 vs 4. 73±1. 01 L/min

P<0. 05） at rest. Before valvuloplasty

the mean transmitral pressure gradient increased signi