PURPOSE: To evaluate the effect of a bicuspid aortic valve on the hemodynamic response to a treadmill ramp protocol in pediatric patients. METHODS: We evaluated 18 patients with a bicuspid aortic valve (BAV) and 18 normal subjects (C), age and size matched, using a Ramp Treadmill protocol. Neither group was treated with a Beta Blocker. Resting aortic valve peak gradient (PG) and shortening fraction (SF) were evaluated by echocardiography for the BAV group. Systolic blood pressure (SBP), cardiac output and stroke volume (SV) were obtained at rest and maximal exercise. Maximal oxygen pulse (MO2P), percent predicted oxygen pulse (%PO2P) and respiratory exchange ratio (RER) were obtained at maximal exercise. RESULTS: There were no significant differences between the BAV and C groups in age (14.6 ± 2.1 vs 15.8 ± 3.1(yr)), height (1.63 ± 0.1 vs 1.66 ± 0.12(m)) or weight (55.7 ± 15.1 vs 57.6 ± 13.2 (kg)). The BAV group had a resting PG of 16.5 ± 8 mmHg and a SF of 39.5 ± 4.9 %. The SBP in the BAV group was significantly decreased at rest (113 ± 9 vs 120 ± 10 mmHg) p<0.05) and exercise (160 ± 14 vs 174 ± 19 (mmHg) p<0.02) compared to the C group. BAV group had a significantly decreased SV (56 ± 13 vs 64 ± 21 (ml/beat) p<0.04) compared to C at rest. The decreased MO2P in the BAV group approached significance (6.6 ± 1.7 vs 7.6± 1.6 ml/beat P=0.06) compared to C. In BAV, %PO2P was significantly decrease (94 ± 24 vs 113 ± 18 (%) p<0.01). Max RER was not significantly different in BAV and C groups (1.19 ± 0.08 vs 1.19 ± 0.06). MO2P significantly correlated to cardiac output (r=0.67 p<0.05). Significance was set at p< 0.05. CONCLUSION: BAV and C groups reached the same intensity of exercise as reflected by the RER. The BAV group had decreased systolic blood pressure and O2Pulse response to exercise. These data suggest that in the face of a mild aortic valve gradient and normal shortening fraction, these BAV patients had a diminished hemodynamic response to exercise.