Devices, systems and methods are provided for deployment of one or more functional devices, such as therapeutic and/or diagnostic medical devices and/or positioning devices, at various locations relative to a defined operative path. The devices, systems, and methods can include a guide system and a positioning element. The guide system defines the operative path when deployed within a patient's body. The positioning element cooperates with the guide system to define one or more positions relative the defined operative path from which the one or more functional devices are deployed. The present inventions allow for the accurate and reliable placement of the one or more functional devices at the one or more positions relative the operative path. In one embodiment, the functional device is an ablation device adapted to ablate cardiac tissue for the treatment of cardiac arrhythmias, such as atrial fibrillation.
