Various different implementations of lead systems are disclosed for use with implantable stimulation systems. Generally, the lead systems incorporate, within an elongate lead body, one or more electrical conduits that connect to one or more distal electrodes, and a liquid-filled pressure transmission catheter lumen that extends proximally from a distal entry port. Use of the lead systems allows accurate pressure sensing at a location near where the electrodes are positioned. In addition, a defibrillator lead is disclosed having such features, and a system using that lead is capable of directly monitoring pressure within a heart chamber, and using that information to confirm the delivery of a defibrillation pulse.