A pacemaker is a medical device that creates electrical impulses and delivers them through electrodes to the heart's chambers, either the upper atria or lower ventricles, to force the targeted chambers to contract and pump blood. This is not to be confused with the natural cardiac pacemaker. .
The pacemaker controls how the heart's electrical conduction system works in this way.Because the heart's natural pacemaker is either too slow or there is a block in the electrical conduction pathway, the main function of a pacemaker is to keep the heart rate adequate. Modern pacemakers may be externally programmed, which enables a cardiologist—specifically a cardiac electrophysiologist—to choose the best pacing modes for each patient.
The majority of pacemakers are on-demand devices, which stimulate the heart in response to the circulatory system's dynamic need. Others release impulses at a set frequency.An implanted cardioverter-defibrillator is a particular kind of pacemaker that combines the functions of a pacemaker and a defibrillator in a single implantation device. Others, known as biventricular pacemakers, increase the synchronisation of the ventricles (the lower heart chambers) by stimulating various locations inside them with a number of electrodes.