Tomographic myocardial perfusion (SPECT) using 99mTc sestamibi-dipyridamole and 2-d-echocardiography with amrinone pre and post myocardial revascularization in 2 cases Perfusión miocárdica tomografica (SPECT) con sestamibi Tc99m-dipiridamol y ecocardiogra