Abstract: In an implantable medical device system such as a pacemaker system, there is provided a system and method for measuring lead impedance so as to obtain reliable data concerning any indication of the need to replace the lead. A relatively short duration low current AC burst is delivered after a standard pacing pulse, at a time to coincide with the heart's refractory period. The pulse is long enough in duration, e.g., 50-125 ms and preferably around 100 ms, to achieve the benefit of substantially steady state measurement, but short enough to substantially avoid the possibility of inducing any cardiac arrhythmia. The current level of the burst is limited to about 30 microamps, providing a further factor of safety against inducing an unwanted arrhythmia. The PPAC technique is adaptable for automatic measurement within an implantable device, or for implementation involving an external programmer which triggers the test.