Abstract: Tachycardial arrhythmias are located and ablated by a combination of first and second catheters which are mutually attracted by magnetized regions at their distal ends. One of the catheters contains mapping electrodes and is initially used to ascertain the locus of the arrhythmia by conventional mapping. Once this is accomplished, the catheter is allowed to remain in position while the second catheter is inserted in such a manner that mutual magnetic attraction between the two occurs across cardiac tissue. One or the other of the two catheters also contains an ablation component at its tip, such that when the two catheter tips are held in position by virtue of their mutual magnetic attraction, ablation can be performed.