This study addresses a major problem in clinical cardiac electrophysiology: development of a successful approach to cure life-threatening postinfarction VT using catheter ablation. A key aspect to the success of catheter ablation is the ability to precisely localize the arrhythmogenic substrate. At present, catheter mapping techniques limit the application of postinfarction VT ablation since they are insufficient, cumbersome and time consuming due to the use of conventional catheter technology. The proposed experimental project involves an integrated mapping solution for postinfarction VT localization featuring a rapid and efficient procedure that will allow catheter ablation in a much larger patient group. This procedure will be evaluated in a closed-chest chronic infarct pig model and involves the interactive application of 62-lead body surface mapping and left ventricular endocardial mapping using an existing low-resolution global and a new high-resolution regional -polar multi strut basket catheter. The integrated mapping procedure will be performed in three consecutive steps: l) global body surface pace mapping using the low- resolution basket catheter to localize the region of the VT exit site; 2) regional body surface pace mapping using the high-resolution basket catheter to precisely localize the VT exit site; and 3) regional activation sequence mapping and entrainment mapping to determine the site of VT origin 8[unreadable]id ?ie site where concealed entrainment can be demonstrated.