Recent days we see a rapid increase in patients suffering from heart diseases. Those patients have to be treated with care and immediately. So, all the hospitals are furnished with special care units with pacemakers and defibrillators. Depending on nature of heart problem, people are given temporary pacing or permanent pacing during the surgery. The electrical activity of heart is as follows. In our heart, electrical impulses are originated from the natural cardiac pacemaker located at Sinu atrial node. (SA). This helps for regular heart beat generation. Each electrical impulse passes through myocardium, AV node and depolarizes at atrium. After a short time, at AV node impulses travel to ventricles and causes depolarization of ventricles. There is another medical condition where person may have heart blocks. There are three stages of heart block. In order to overcome this heart block issues, a person is fit with pacemaker to make the heart beat normal. SA node is the artificial pacemaker of the heart.
Pacemakers are the device that is capable of producing artificial pulse for the heart to work normally. It has two main components as Generator and Electrodes. Pulse generator should develop pulse at a ratio 1:10000. It should be capable to produce negative pulse to avoid muscle ionization. The pulses produced are variable in nature, such that energy given to the heart can be controlled. Duration of each pulse is 1 to 2 milli seconds. The pulse repetition rate is 70 pulses/min. usually unipolar or bipolar electrodes are chosen for electrode setup. The electrical stimulation to the pacemaker can be of two type’s external and internal stimulation. There are different types of batteries used namely Mercury cell, Lithium cells and rechargeable batteries.
Types of Pacemakers
There are two types of pacemakers.
The entire unit is placed inside the human body. It is used for the patient whose SA node has completely failed to function or for who suffers from heart block. The device is placed with a surgery. Pulse generator is placed in a pocket below right or left clavicle. For women it is placed near pectoral muscle. Electrodes are connected to the generator, and they contact the myocardium directly. The location of pacemaker depends on the factor like Nature of heart disease, type of electrode used and pacemaker operation mode. This does not have external power supply. It already consists of battery that can work continuously for a time.
Here external pulse generator circuit and electrode are used. They are placed inside myocardium. This type id suitable for patient who suffers from temporary heart block and disorders. It is very importantly used for patients who suffer from arthymias and coronary disease. Since the generator is placed external, they are connected to electrodes via wires and introduced into ventricles. The setup is attached with belt on the lower arm of the patient.
Difference Between Internal Pacemakers and External Pacemakers
|This type of pacemaker is placed outside the body in a form of watch or miniature device. It fits into the pocket size. One terminal of the device goes to the heart via vein.||This type is placed inside the heart of the patient via surgical procedure. It is placed near chest, abdomen. Here output the lead is connected to heart muscles directly.|
|It uses endocardiac electrodes that makes contact with inner chamber of heart.||It uses myocardia electrodes that make contact with outer heart muscles wall.|
|The procedure does not require any open heart surgery.||It requires small open heart surgery.|
|Replacement of battery is easy and can be done without help of doctors.||Replacement of battery needs a small surgery.|
|There is minimal interaction from foreign bodies. So it creates less pain and swelling.||There is maximum interaction from foreign bodies. So it creates more pain and swelling|
|This type of pacemaker is affected more due to external disturbances.||The setup is 100% safe from external disturbances.|
|External type of pacemaker is used for temporary heart regulations.||Internal pacemakers are used for permanent heart regularity.|