Arrhythmia

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Arrhythmia is the term used for irregular heartbeat. With every heart beat (normal or irregular), an electrical signal or impulse travels through the heart muscles which causes them to contract. With every contraction, the heart pumps out blood which is circulated throughout the body. The heartbeat becomes irregular when this electrical impulse does not work properly. It causes the heart to either beat too fast (tachycardia) or too slow (bradychardia). Sometimes, the heart beat is neither fast nor slow but may still be inconsistent due to early contraction of heart muscles. Many a times arrhythmia does not cause any harm. Most of us occasionally experience irregular heartbeats.

However, when the heart beat goes too far from a normal heartbeat and takes longer time to return to normal, it may have harmful effects. Such cases may result due to weak heart muscles or damage to the heart, and can also be life-threatening. Sometimes during arrhythmia, the heart may become incapable of pumping enough blood to the body. This can cause severe damage to the brain as well as other organs of the body. There are several reasons why the heart beat may become irregular. Conditions like diabetes, drug abuse, heart disease, stress, smoking and alcoholconsumption, heart attack increases the likelihood of arrhythmia. For a healthy individual the normal heart rate varies between 60-100 beats per minute (while resting). The fitter you are, the better your heart will function.

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Types

Ventricular fibrillation: One of the most deadly types of arrhythmia is ventricular fibrillation. Here, the ventricles begin to quiver instead of pumping blood. Because there is no effective heartbeat, blood pressure drops drastically cutting off blood supply to the organs leading to collapse and cardiac arrest. Death ensues if the person does not get medical attention immediately.

Ventricular tachycardia: This is another type of malignant arrhythmia. In this type the ventricle beats very rapidly at  rate of around 150 to 250 per minute. Again at this rate the hearts pumping becomes very weak and the vital organs donot get blood as per need. Blood pressure may remain too low. This condition again needs immediate medical attention.

Atrial fibrillation: Another type is atrial fibrillation, which occurs when there is arrhythmia in the atrium. It’s a common type of arrhythmia where the electrical impulses becomes uncoordinated making your heart beat as fast as 300 times per minute. Atrial fibrillation can also be dangerous as the blood pools in the atrium because it doesn’t pump all the blood into the ventricle. This causes a blood clot (thrombus) to form. The clot can break off and travel to another part of the body leading to severe complications like a stroke.

Supraventricular tachycardia: In this kind of arrhythmia both atria and ventricle beat at a very fast rate of 150 to 250 per minute. Depending on the heart rate at that time the symptoms may vary. If the heart rate is too high, blood pressure tends to be low and patient becomes severely symptomatic. This kind of problem sometimes happen at early age due to abnormal electrical connections between atria and ventricle, which is present from birth.

Heart failure: Another complication of atrial fibrillation is heart failure. It occurs when the heart can’t pump enough blood to meet the body’s needs. Fatigue, shortness of breath, and fluid retention are common symptoms of this condition.

Causes

A normal heartbeat ranges from 60 to 100 beats per minute while at rest, but in conditioned athletes, it may be as low as 60 beats per minute. This number may go up or beyond 100 beats if you are exercising.

If you are not a conditioned athlete and your heartbeat is less than 60 beats per minute, you are probably having arrhythmia called bradycardia. In the same way, if you are at rest and your heart rate is greater than 100 beats a minute, the arrhythmia is called tachycardia. Read about Tachycardia or increased heart rate — 5 causes you should know.

The causes of bradycardia are enumerated below.

Sick sinus syndrome: Sinus node is a region of right atrium from where the heart beat originates. In some people this may be weak leading to generation  of impulse at a slower rate. Low level of thyroid hormone in the body also can cause sinus bradycardia.

Complete heart block: In some situations, the atria generates normal heart beat but it gets blocked while going down to activate the ventricle at AV node. AV node is the junction point of atria and ventricle. Mostly this is because of age related degeneration of AV node tissue.

The causes of tachycardia:

WPW syndrome: In this situation there is an extra connection between atria and ventricle apart from AV node. So the impulse which comes down via the AV node to activate the lower chamber can sometimes go back to the atria via the  extra connection. This leads to re-entry of the impulse back to atria. This impulse again comes down the ventricle via AV node. In this way a re-entry mediated tachycardia developes.

Atrial fibrillation: Atrial fibrillation  is because of rapid and disorganised contraction of the atrial chamber. Usually this is due to rapid heart beat originating from hyperactive tissues present near the veins draining blood from lungs to atria. This also happens in valve disease when the atria gets stretched out due to valve narrowing or regurgitation.

Ventricular tachycardia: It is a situation when the ventricle beats very rapidly of its own. It is mostly due to diseased heart muscles with scars leading to re-entry circuits. Heart attack is a common condition leading to myocardial scars and re-entry circuits.

If this fluctuation in the heart rate is severe or lasts long enough — so that it affects how well the heart works — the heart may not be able to pump enough blood to the body. Leading you to feel tired, lightheaded or may make you pass out.

Risk Factors

Certain cardiovascular disorders such as CAD (coronary artery disease), cardiomyopathy, high blood pressure, a previous heart attack, and a recent heart attack, can all lead to arrhythmia. Apart from that, arrhythmia can also be caused due to diabetes, hyperthyroidism, stress, alcohol and drug abuse, smoking, certain medicines, dietary supplements and herbal treatment, air pollution and electric shock.

Symptoms

Arrhythmia is fairly subjective and so are the symptoms. That being said, the common symptoms of arrhythmia are, bradycardia (slow heartbeat), tachycardia (fast heartbeat), or fluttering, shortness of breath, chest pain, lightheadedness or dizziness, fainting or feeling faint.

One might feel these symptoms intermittently and it might not mean that something is gravely wrong, but if these symptoms occur suddenly and frequently, you should see a doctor immediately. (Read: Expert tips to prevent heart disease)

Diagnosis

Before treating your arrhythmia, the doctor will first ask about any triggers you might have like heart disease or thyroid problem. After that he/she will try to find out where the arrhythmia starts in the heart and whether it’s abnormal through some diagnostic tests such as and ECG (electrocardiogram), Holter monitor, echo electrocardiogram, stress test where you will be asked to exercise on a treadmill or stationary bicycle while your heart activity is monitored), tilt table test (where you are asked to lie flat on a table and the table is then tilted as if you were standing up.

In Holter test a small machine records the ECG for a prolonged period, mostly 24 to 48 hours. When the arrhythmia is intermittent, Holter detects it more efficiently than a standard ECG.

Some times your doctor may do a test known as electrophysiology study. This is done to ascertain the exact nature of arrhythmia. Many times during electrophysiology study itself, radiofrequency ablation is performed to correct the arrhythmia. RF ablation emits radiofrequency current at catheter tip to the underlying tissue which is the root cause of arrhythmia and completely cures the arrhythmia problem.

Your doctor will observe how your heart responds to the change in angle) and electrophysiological testing and mapping (where your doctor will insert catheters in various parts of your body. At the tip of these catheters are electrodes that will collect information about your heart’s electrical impulses).

Treatment

The method of treatment will depend on your age, if you have any pre-existing conditions, your family history, medications you might be taking, as well as the severity and symptoms of your arrhythmia.

There are a number of treatment options:

Lifestyle changes: Your doctor will ask you to make lifestyle changes that will keep your heart healthy. You may be advised to eat heart-healthy foods, exercise regularly, increase physical activity and cut down on stress, alcohol and caffeine.

Medications: You may be advised to have certain medication, that when taken exactly as per prescription can help prevent heart attack, stroke, and prevent the progression of coronary artery disease. There are 4 types of medicines to treat arrhythmia: anti-arrhythmic drugs such as lidocaine, propranolol, etc. calcium channel blockers such as amlodipine and diltiazem beta blockers such as acebutolol and metoprolol to decrease heart rate anticoagulants or blood thinners (in addition to other medicines) such as aspirin and warfarin to make it harder for the blood to clot and to prevent stroke.

Invasive treatment options: Apart from the medication, there are minimally invasive methods such as cardiac ablation which can treat many types of arrhythmias. The procedure destroys or ablates specific cells in your heart that cause your arrhythmia.

Defibrillation: In case you suffer from atrial fibrillation, defibrillation is a procedure for you. In this, a mild electric shock is given to the heart to re-establish normal contraction rhythms of the heart.

Implantable devices: Implantable devices such as pacemaker for bradycardia and implantable cardioverter-defibrillator (ICD) for ventricular arrhythmias may also be used for treatment.

Surgery: Apart from all this, there are surgeries to help ease your troubles, namely the maze procedure (here a number of incisions are made on the walls of the left and right atrium. These incisions form scar tissues that disrupt the uneven electrical impulses) and coronary bypass surgery. (Read: Take the natural route to heart health – home remedies that work!)

Complications

Some arrhythmias may be life-threatening if not treated right away, so do not ignore your symptoms even if they seem harmless. Let your doctor be the judge of it.

 

The content has been verified by Dr. Santosh Kumar Dora, Cardiac Electro Physiologist, Asian Heart Institute, Mumbai.

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