Patent ID: 8233983

Claim:
An implantable heart stimulator comprising: a pulse generator that emits stimulation pulses each having an amplitude, said amplitude being variable; at least one electrode lead connected to said pulse generator and configured to conduct pulses emitted by said pulse generator to a heart; sensing circuitry connected to said at least one electrode lead to receive a signal therefrom indicative of electrical cardiac activity, said sensing circuitry detecting capture or non-capture of the heart in response to the pulses delivered by said at least one electrode lead; a processor connected to said sensing circuitry, said processor being configured to evaluate the capture and non-capture detection by said sensing circuitry and to control said pulse generator to set a timing and said amplitude of said stimulation pulses; said processor being configured to conduct a search to determine a threshold value for a pulse amplitude required for achieving capture, said processor being configured to conduct said search at each of successive points in time respectively separated by a selected time period, and to set said amplitude of said stimulation pulses to a value exceeding said threshold value by a predetermined margin, and to set said predetermined margin as a function of said selected time period expressed as k*T, wherein k is a first constant and T is selected said time period; and a housing configured for implantation in a patient, containing said pulse generator, said sensing circuitry and said processor.