diagram illustrating a technique for detection of changing heart condition based on conduction time in general the process may include launching a stimulation wave front from the right ventricular lead 18 68 detecting a local cardiac depolarization at the left ventricular lead 22 70 and measuring the conduction time between the right and left ventricular leads 18 22 72 the conduction time may be determined based on the time required for the depolarization initiated by the stimulation wave front to propagate across the heart tissue from right ventricular lead 18 to left ventricular lead 22 and cause a depolarization in left ventricle 42 in the example of fig4 the stimulation wave front is transmitted from the right ventricular endocardial lead 18 with the resulting depolarization being sensed by the left ventricular epicardial lead 22 however an opposite arrangement may be used in which the stimulation wave front is transmitted from the left ventricular epicardial lead 22 and the resulting depolarization is sensed by the right ventricular endocardial lead 18 moreover in some embodiments both leads may be endocardial leads or both leads may be epicardial leads the process involves determining conduction time and then comparing the conduction time to a threshold conduction time 74 more specifically in certain embodiments the process compares a change in the conduction time to a change threshold again the change in conduction time may be determined by comparing a mean or median conduction time over a series of samples to a mean or median conduction time for a preceding series of samples if the change in conduction time exceeds the.