The measurement of left ventricular inflow by Doppler echocardiography provides a continuous, non-invasive assessment of parameters of diastolic function. We studied changes in left ventricular diastolic function during percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending coronary artery (LAD). In ten patients, the diastolic flow velocity profile across the mitral valve was measured by Doppler echocardiography, before and 60 s after inflation and 60 s after deflation of the balloon. The peak velocity of early diastolic filling (VE) significantly decreased during angioplasty, from 68 +/- 12 to 56 +/- 10 cm/s (p less than 0.001), while the peak velocity of late diastolic filling caused by atrial contraction (VA) showed no change. This resulted in a significant decline in the diastolic velocity ratio (VE/VA) from 1.11 +/- 0.47 to 0.92 +/- 0.35 (p less than 0.01). The total area under the diastolic flow velocity profile representing the total filling volume fell from 14.3 +/- 4.1 to 10.9 +/- 3.6 cm (p less than 0.001). The early diastolic filling fraction decreased from 68 +/- 5% to 64 +/- 7%, in favor of the filling fraction due to atrial contraction, which increased from 32 +/- 5%, to 36 +/- 7% (p less than 0.01). 60 s after deflation of the balloon, the parameters of diastolic filling returned to baseline values. We conclude from our results that diastolic dysfunction caused by angioplasty of the LAD results in a decrease in early diastolic left ventricular filling, which is completely reversible after 60 s.