A pacemaker system is a device capable of generating artificial pacing impulses and delivering them to the heart.
It consists of a pulse generator,lead and appropriate electrodes.
In the past few years electronic pacemaker systems have become extremely important in saving and sustaining the lives of cardiac patients whose normal pacing function of the heart have been impaired.
Pacemakers: its past history Conception of idea
Chloroform was popular in the late 1860s, but when it was used, occasional respiratory and cardiac arrest occurred, as an occasional complication of chloroform anesthesia
To restart the heart, Green in the United Kingdom  applied the output of a 300V battery using hand-held electrodes applied to the base of the neck and the lower left chest.
Interestingly, the electrode applied to the lower left chest stimulated the ventricles. The other electrode applied to the base of the neck delivered current to the phrenic nerve and twitched the diaphragm, causing a brisk inspiratory motion.
Lillehei et al.  reported the use of right ventricular catheter electrodes with an external pacemaker to pace 66 patients. The pacemaker was built by Earl Bakken, a biomedical engineer, the founder of Medtronic Inc. in 1949, which soon became the pioneer pacemaker company.
Earl's first wearable, battery-powered, transistorized cardiac pacemaker
" Back at the garage, I dug out a back issue of Popular Electronics magazine in which I recalled seeing a circuit for an electronic, transistorized metronome. The circuit transmitted clicks through a loudspeaker; the rate of the clicks could be adjusted to fit the music. I simply modified that circuit and placed it, without the loudspeaker, in a four-inch-square, inch-and-thick metal box with terminals and switches on the outside - and that, as they say, was that. "
Dr. Rune Elmqvist (1958) designed the world's first implantable pacemaker. It included a pulse generator delivering about two volts with an impulse period of two milliseconds. The original transistors showed large leakage currents and were found not suitable.
Problems of the early pacemakers: breakage of electrode wires, short battery life, the need for surgery for pacemaker and lead implantation
Chardack  described a durable electrode wire made from the alloy that is used in the escapement spring of watches. It was sutured to the epicardium, and a thoracotomy was required.
Pacemaker Evaluation i.e. type of pacemaker (fixed rate or demand rate),time since implanted, pacemaker rate at the time of implantation, and half-life of the pacemaker battery. Effect of the Magnet Application on Pacemaker Function.
Narcotic and inhalational techniques can be used successfully.
Skeletal myopotentials, electroconvulsive therapy, succinylcholine fasciculation, myoclonic movements, or direct muscle stimulation can inappropriately inhibit or trigger stimulation, depending on the programmed pacing modes.
Etomidate and ketamine should be avoided as these cause myoclonic movements.
Pacemaker function should be verified, before and after initiating mechanical ventilation.
If rate responsive mode it should be deactivated before surgery.
Fatal arrhythmias and deaths have been reported with the use of electrocautery leading to failure of pacemaker. Between 1984-1997, the US-FDA was notified of 456 adverse events with pulse generators, 255 from electrocautery and significant number of device failures.
Measures to decrease the possibility of adverse effects due to electrocautery
unipolar cautery (grounding plate should be placed close to the operative site and as far away as possible from the site of pacemaker)
Electrocautery should not be used within 15cm of pacemaker.