Pacemaker (artificial): Pacemaker (artificial) is an electronic device which produces regular electrical pulses which can be used to artificially create heart beats. Heart has a biological pacemaker known as the SA node (sinoatrial node).
In what situations are electronic pacemakers used?
Pacemakers are used when the heart rate becomes too slow and cannot be brought up well with medications. The cause for a fall in heart rate can be temporary or permanent. When the cause is expected to be reversible like a heart block along with a heart attack, a temporary pacemaker is used. If the cause appears to be permanent in nature and reversible factors are reliably excluded, a permanent pacemaker is used.
Two important reasons for implanting a permanent pacemaker are sick sinus syndrome and complete heart block. In sick sinus syndrome, the natural pacemaker of the heart is diseased and unable to produce regular signals to maintain a reasonable heart rate. Complete heart block is total blockage of signals from the SA node which prevents them from reaching the lower chambers of the heart (ventricles). This is due to a disease of the conduction system of the heart (electrical wiring of the heart!).
Is the implantation procedure a major surgery?
No. Device implantation can be done under local anaesthesia in an adult. In children it will require general anaesthesia because they are often frightened and may no cooperate well by keeping quiet during the procedure. The device has two components – pulse generator circuitry which is hermetically sealed and the electrical lead which connects the pulse generator to the heart. Pulse generator is implanted under the skin below the collar bone. The lead is introduced into a vein behind the collar bone (subclavian vein), through which it reaches the heart. The device senses the electrical signals of the heart and gives pulses when spontaneous signals are not sensed (demand pacemaker).
What are the different types of pacemakers?
Different types of devices are available depending on the intended use. Temporary devices are meant to be kept outside the body and connected with leads into the heart. They are removed when the heart rate improves. Permanent devices are different types. Those which pace only a single chamber, those which can pace two chamber and still advanced ones which can pace three chambers. The last one paces one upper chamber and two lower chambers. Their role is slightly different in that they are not used to treat low heart rate. They are called heart failure devices and are used to treat those with low pumping function of the heart. Treatment with those devices are technically called cardiac resynchronization therapy.
Single chamber devices can pace either the upper or lower chamber (any one) depending on where the lead tip is placed. Where to place the lead tip is decided on what type of slow heart is the person having. In sick sinus syndrome it may be enough to pace the upper chamber, while in complete heart block the lower chamber has to be paced. Dual chamber devices pace both and upper and lower chambers in a natural sequence. Hence they are also called physiological pacemakers (not natural!).
What precautions have the person with pacemaker follow while using electrical devices?
The electronic circuitry of the device can interact with electromagnetic radiation. Hence one should keep away from sources of heavy electromagnetic radiation like a powerful radio transmitter. Most other day to day devices can be used with certain precautions. Should keep away from theft detection devices as they can cause electromagnetic interference. Mobile phones can be used at distance. The usual recommendation is to use it on the opposite ear, depending on which side the device has been implanted. Those with implanted devices are given an identification card which can be shown at airport and other similar locations where electromagnetic devices are likely to be used for security check.