Cardiac stimulating device

A cardiac stimulating method comprising:

• providing a lead connector connectable to an atrial lead having at least one electrode and a ventricular lead having at least one electrode;
• connecting an atrial pulse generator to the lead connector and configuring the atrial pulse generator to generate atrial stimulating pulses;
• connecting an atrial sensing unit to the lead connector and configuring the atrial sensing unit to sense electric events in an atrium of a heart;
• connecting a ventricular pulse generator to the lead connector and configuring the ventricular pulse generator to generate ventricular stimulating pulses;
• connecting a ventricular sensing unit to the lead connector and configuring the ventricular sensing unit to sense electric events in a ventricle of the heart, the ventricular sensing unit comprising an evoked response detector configured to detect an evoked response of the ventricle to a ventricular stimulating pulse generated by the ventricular pulse generator and delivered to the ventricle by the ventricular lead;
• connecting a controller to the atrial pulse generator, the atrial sensing unit, the ventricular pulse generator and the ventricular sensing unit and configuring the controller to control operation of the ventricular pulse generator according to a first mode or a second mode and configuring the controller to trigger a switch from the first mode to the second mode based on the evoked response detector failing to detect an evoked response to a delivered ventricular stimulating pulse;
• wherein in the first mode the controller is configured to prevent the ventricular pulse generator from generating a back-up if the evoked response detector does not detect an evoked response to a delivered ventricular stimulating pulse;
• and
• wherein in the second mode the controller is configured to control the ventricular pulse generator to generate a back-up pulse delivered to the ventricle by the ventricular lead if the evoked response detector does not detect an evoked response to a delivered ventricular stimulating pulse;
• and
• configuring a premature ventricular contraction detector to detect premature ventricular contractions in the ventricle, wherein the controller is configured to switch from a third mode to the first mode based on the premature ventricular contraction detector detecting a number of premature ventricular contractions during a defined time interval exceeding a threshold number, wherein in the third mode the controller is configured to control the atrial pulse generator to generate an atrial stimulating pulse following expiry of the first atrial escape interval and control the ventricular pulse generator to generate a back-up pulse delivered to the ventricle by the ventricular lead if the evoked response detector does not detect an evoked response to a delivered ventricular stimulating pulse.