Detection and reduction of phrenic nerve stimulation

An implantable medical device connectable to a plurality of electrodes electrically coupled to a heart of a patient in at least one electrode configuration, comprising:

• a pacing module configured to deliver pacing pulses to the heart using said at least one electrode configuration;
• a control module configured to instruct said pacing module to deliver pacing pulses having a predetermined pulse amplitude and/or width within the refractory period of the left ventricle, wherein said pacing pulses are repeatedly delivered during a number of cardiac cycles and wherein said pacing pulses are delivered at different predetermined delays relative to an onset of the refractory period of the left ventricle in different cardiac cycles;
• an impedance measurement module configured to measure impedance signals in time windows synchronized with said delivery of pacing pulses in said refractory period of the left ventricle using at least one electrode configuration;
• a phrenic nerve stimulation, PNS, detection module configured to:
• gather at least one impedance signal from each time window;
• create aggregated impedance signals using the impedance signals from the different time windows;
• and
• analyze the aggregated impedance signals to detect PNS.