| 摘要 |
A method and apparatus for automatic determination of a pacemaker patient's pacing stimulation threshold. Circuitry is provided in a pacemaker for obtaining a signal reflecting cardiac impedance, which is known to reliably reflect certain aspects of cardiac function. Circuitry is also provided for monitoring the cardiac impedance waveform during a predetermined capture detect window following delivery of stimulating pulses. One or more values are derived which characterize the morphology of the impedance waveform during the capture detect window associated with each stimulation pulse delivered. These values are compared to predetermined control values in order to assess whether a stimulation pulse has achieved cardiac capture. The assessment of whether cardiac capture has been achieved is also based partly upon the conventional sensing of atrial and/or ventricular cardiac signals occurring during the capture detect window. In one embodiment of the invention, the control values against which impedance waveform characterization values are compared are obtained by delivering a series of stimulation pulses having sufficient energy to ensure that capture is achieved, and by monitoring the impedance waveform during delivery of these pulses. |
