A catheter system (100) for placement within a treatment site (106) at a vessel wall (208A) or a heart valve includes an energy source (124), a balloon (104), an energy guide (122A), and a tissue identification system (142). The energy source (124) generates energy. The balloon (104) is positionable substantially adjacent to the treatment site (106). The balloon (104) has a balloon wall (130) that defines a balloon interior (146). The balloon (104) is configured to retain a balloon fluid (132) within the balloon interior (146). The energy guide (122A) is configured to receive energy from the energy source (124) and guide the energy into the balloon interior (146) so that plasma is formed in the balloon fluid (132) within the balloon interior (146). The tissue identification system (142) is configured to spectroscopically analyze tissue within the treatment site (106). A method for treating a treatment site (106) within or adjacent to a vessel wall (208A) or a heart valve can utilize any of the catheter systems (100) described herein.