| 摘要 |
<p>This invention relates to a cardiac pacemaker circuit in which a stimulating electrode (11) is embedded in a patient's atrium or ventricle and a reference electrode (13) positioned outside the heart or on the same lead within the heart. Stimulus pulses are applied across the two electrodes (11, 13), these replacing the evoked pulses. On termination of the stimulus pulse the amount of charge stored between the two electrodes (11, 13) is monitored and a pulse applied to the stimulating electrode (11) to reduce this charge to a level at which the intrinsic pulses of the evoked heart response can be monitored. The evoked heart response can then be used for diagnosis whilst the pacemaker circuit is in operation. If the stored charge were not reduced then the charge would mask the intrinsic pulses and the pacemaker would have to be switched off before these could be monitored for diagnosis.</p> |
