Abstract: A medical system and corresponding method for forming intramyocardial channels in cardiac tissue of a patient's heart are disclosed. The channel forming system may be configured in two basic embodiments: (a) a first embodiment where a transluminal steering and delivery system comprises a guide catheter or sheath which functions largely apart from and independent from other components of channel forming system (with the notable exception of a means for extending and retracting a piercing means from a distal end of the guide catheter or sheath, and (b) a second embodiment where a transluminal steering and delivery system is integrated into and combined with other components of the channel forming system, such as a piercing means, means for delivering radio-frequency energy to the piercing means, and temperature sensing means.