Transesophageal echocardiography during percutaneous balloon mitral valvuloplasty. To ascertain the value of transesophageal echocardiography during percutaneous balloon mitral valvuloplasty, the present study was undertaken in 26 anesthesized patients (21 women and 5 men; mean age, 47 years) with symptomatic rheumatic mitral valve stenosis. In all but one patient the balloon dilation of the mitral valve was successful and Doppler-derived valve area increased (0.9 +/- 0.3 to 1.9 +/- 0.4 cm2). Transesophageal echocardiography provides continuous monitoring, as well as guidance of the procedure. Crossing the arterial septum, as well as delivery of the sheath through the mitral valve orifice and correct positioning of the balloon, was highly facilitated and reduced x-ray exposure time. The degree of mitral regurgitation and the presence of interatrial shunting at the end of the procedure could be readily assessed, making cineangiography not necessary. Complications of the procedure, such as pericardial effusion, could be detected before hemodynamic deterioration had occurred (one patient). The advantages of transesophageal echocardiography for routine monitoring of percutaneous mitral valvuloplasty, however, should be weighted against the added risk and expense of this support. 