 MPG increased significantly after injection of ISDN (from 0.0±0.0 to 00.0±0.0 mmHg; *P*\<0.00).\ **Abbreviations:** MPG, mean pressure gradient; ISDN, isosorbide dinitrate; PW, pressure wire.](mder-0-000Fig0){#f0-mder-0-000}  ![Relationship of hyperemic 