An implantable medical device system includes an elongated lead body carrying a hydrophone. In some embodiments, the elongated lead body has outer surface and an opening along the outer surface. The hydrophone is configured to receive acoustical signals through the opening of the lead body and generate an electrical signal representative of sounds produced at a targeted location along a patients cardiovascular system. In some examples, the lead body outer surface has a shaped contour for directing the opening for receiving the sounds from a direction of the targeted location. A processor is enabled to receive signals from the hydrophone and detect a cardiac condition in response to the signals.
