The heart's electrical system regulates the rate and rhythm of the heartbeat. With each heartbeat, an electrical impulse travels from the top of the heart to the bottom, indicating the heart's muscles to contract and pump blood. A Heart Pacemaker (an electrical device) is required if the pumping of heart is too fast or too slow (Irregular heartbeats is called arrhythmias). In either case, the body does not get enough blood. So the pacemaker regulates the electrical system that controls heart rhythm.
Electrophysiology Study (EPS): Once the doctor suspects that there is a heart rhythm problem, he advises the patient to undergo EPS which is a diagnostic study to determine the following:
During an EP study, small, thin wire electrodes are passed through a vein in the groin. These wire electrodes are then threaded into the heart, using a specific type of X-ray, called fluoroscopy. Once they reach the heart, electrical signals are measured. Then the electrical signals are sent through the catheter in order to stimulate the heart tissue to try to initiate the abnormal heart rhythm disturbances for evaluation.
It is the most common type of arrhythmia. It occurs if fast, disorganized electrical signals lead the two upper chambers of the heart (atria) to contract very rapidly and irregularly.
Due to AF, the ventricles do not get completely filled with blood. Thus, they are not be able to pump sufficient blood to the lungs and body. This can cause signs and symptoms, such as - shortness of breath, palpitations, chest pain, dizziness, fatigue and weakness. If not noticed on time, AF an lead to stroke and heart failure.
Following are the options for treatment of Atrial Fibrillation :
Cardioversion is used to treat a fast or irregular heartbeat. During this procedure, low-energy shocks are given to patient's heart in order to trigger a normal rhythm.
Radiofrequency Ablation is another procedure performed in order to put the heart back into normal rhythm. RFA stops the electrical signals that come from places other than the SA node. During the procedure, thin wires are threaded into the heart through a vein in the arm or leg. One wire is used to find the diseased areas in the heart's electrical system. Then heat is transferred through another wire. This heat destroys a small amount of tissue in those diseased areas and stops abnormal heart beats. The wires are taken out, once all the problem areas are fixed.
Impulses escape into the atrium
Impulses cannot pass the ablated tissue
Pacemakers are commonly used to treat two types of arrhythmias:
Pacemakers include one to three wires that are each placed in different chambers of the heart.
In this procedure, only one lead is used, in either the right atrium or the right ventricle of heart. A single lead is commonly used when the normal pacemaker of the heart is not working sufficiently. However, to use this technique of pacing, the rest of the heart's normal conduction system should be functioning normally. The wires in a single chamber pacemaker generally carry pulses from the generator to the right ventricle (the lower right chamber of the heart). This often happens when the electrical flow gets slowed or blocked in the region of AV node and the normal impulses from the atrium do not reach the ventricle. This results in too slow a heart beat. The pacemaker system then keeps the heart beating at a steady rate.
These are pacemaker systems where a lead is used in the right atrium as well as the right ventricle. This type of pacing most closely resembles the heart's normal conduction pattern by pacing consecutively from atria to ventricle, thus maximizing the heart's pumping capacity. By having a lead in both the atria and ventricle the pulse generator is able to constantly regulate the heart's electrical activity in both the chambers. These are the most commonly used pacemakers currently.
The 3 wires in this procedure carry pulses from the generator to - right atrium, right ventricle and left ventricle (via the coronary sinus vein). The pulses then help in coordinating electrical signaling between the two ventricles. This procedure is used to treat the delay in heart ventricle contractions that occur in patients with advanced heart failure.
irregular heartbeats (arrhythmias), a problem with heart's electrical system. ICDs use electrical pulses or shocks to treat life-threatening arrhythmias that take place in the ventricles.
When ventricular arrhythmias occur, the heart is unable to pump blood well. To keep away from death, the arrhythmia must be treated immediately with an electric shock to the heart. This treatment is known defibrillation.
An ICD has wires with electrodes on its ends that connect to heart chambers. If the device detects any irregular rhythm in ventricles, it uses low-energy electrical pulses to re-establish a normal rhythm. If the low-energy pulses don't restore normal heart rhythm, the ICD then switches to high-energy pulses for defibrillation. The device can also switches to high-energy pulses if ventricles start to vibrate rather than contract strongly. The high-energy pulses end only a fraction of a second. Since it has a pacemaker built into it, a defibrillator also has the ability of stimulating the heart like a pacemaker, to facilitate in stopping fast rhythms, at times, and to prevent the heart from getting too slow.
Following are the two main types of programming for pacemakers:
A demand pacemaker monitors heart rhythm and only sends electrical pulses to heart if it is beating too slow or if it misses a beat.
A rate-responsive pacemaker speeds up or slows down heart rate depending on how active the patient is. To do this, the device monitors blood temperature , breathing,sinus node rate and other factors to determine patient's activity level.
Decision regarding which type of pacemaker amongst the above two is to be used, is taken by doctor on the basis of patient's condition.
Pacemaker needs to be checked regularly at an interval of about 3 months. Over a period of time, a pacemaker can stop working appropriately because of the following reasons:
Depending upon how active the pacemaker is, its batteries last between 5 and 15 years (average 6 to 7 years). The treating doctor replaces the generator along with the battery before the battery starts to run down.
Replacing the generator and battery is less-involved procedure than the original one to implant the pacemaker. The pacemaker wires also may need to be replaced in the long run. The doctor decides during follow up visits whether the pacemaker or its wires need to be replaced or not.