Arrhythmias are disorders of the heart where the heart beats too slow, too fast or in an irregular manner. Normally the heart beats in a specific rate and rhythm. In arrhythmias, the rate may increase or decrease. There will be abnormalities in the rhythm of heart beats as well.
Arrhythmias usually occur when there is overstimulation of heart muscles due to impaired electrical activity. They can also occur due to impaired conduction of electrical signals through the heart muscles.
Arrhythmias can occur to persons of all age groups.They can occur in new born babies and infants to the very elderly. Similarly, they occur in those who are very healthy and in those who are weak.It is said that nearly everyone will have had an arrhythmia or abnormal rhythm at some point of their lives.
Most of the arrhythmias are generally harmless and usually resolves by itself. There are various treatments that are available for the correction of arrhythmias. They range from lifestyle changes, medicines as well as medical and surgical procedures.
There are different types of heart arrhythmias. They are classified according to the heart rate and their area of origin. Certain types of arrhythmias are very dangerous and require immediate medical care. Certain other types of arrhythmias are less dangerous and usually causes very few symptoms. They are usually diagnosed during routine medical examinations. The characteristic features of certain common types of arrhythmias are described below.
Bradyarrhythmia’s or bradycardia
·In this type of arrhythmia, the heart beats too slow
·The heart rate will usually be below 60 or even 50
·Endurance athletes and sprinters will usually have a slower heart rate, and this should not be confused with bradycardia
·The main reasons for bradycardias are heart attacks, certain medicines, electrolyte imbalances, aging etc.
·A condition called ‘bundle branch block’ which impairs the conduction of signals can also cause bradycardia.
·Arrhythmias that start in the upper chambers of the heart, called the atria, are called supraventricular arrhythmias.
·All supraventricular arrhythmias are tachycardias.
·The heart rate will be more than 100 beats per minute
·In certain cases, the upper and lower chambers may beat at different rates.
Types of supraventricular arrhythmias include:
·Atrial fibrillation. This is the most common type of arrhythmia. The heart rate will be more than 300 beats per minute. The rhythm is also abnormal.
·Atrial flutter. Atrial flutter can cause the atria to beat at a rate of 250 to 350 times per minute. The upper and lower chambers may beat at different rates.
·Paroxysmal supraventricular tachycardia (PSVT)- In paroxysmal supraventricular tachycardia, there will be extra heart beats. PSVT begins and ends suddenly and are usually not dangerous. It tends to occur in young people during vigorous physical activity.
·These arrhythmias start in the lower chambers of the heart called the ventricles.
·They are very dangerous and require emergency medical care.
·Ventricular tachycardia if limited for only a few seconds often do not cause problems. But episodes that last longer can be dangerous and can turn into other more serious arrhythmias like ventricular fibrillation.
·Ventricular fibrillation can make the ventricles quiver instead of pumping normally.
·This will result in sudden cardiac arrest, and death can occur within a few minutes.
·Premature Ventricular Complexes (PVC) and Torsades de Pointes are certain rare types of ventricular arrhythmia.
Arrhythmias occur due to a variety of reasons and proper treatments can ensure correction of the same.
Heart arrhythmias are very common conditions that occur with regular frequency in the general population. In fact, expert studies suggest that almost everyone would have had some type of arrhythmia at some point of time in +their lives.
There are different types of arrhythmias. Arrhythmias cause a variation in heart rate (the number of times the heart beats in a minute). They also cause a variation to the normal rhythm of the heart beats.
Majority of these arrhythmias are self- corrective and resolve within a reasonable period, a few seconds, at best. The arrhythmias that lasts longer can have potentially serious complications.
There are different types of arrhythmias. The seriousness of an arrhythmia is judged by the type of arrhythmia.
A normal heart beats around 72 beats per minute. A heart rate below 60 and above 100 without a reason is considered abnormal. A heart rate below 60 is termed bradycardia and above 100 is termed tachycardia.
Bradycardia-In bradycardia the heartrate is below 60 beats per minute. If left untreated bradycardia may result in heart failure, hypertension or hypotension, angina etc. Pacemaker implantation can improve the condition significantly.
Atrial fibrillation-The heart rate is around 300 beats per minute. Heart failure and stroke can result if left untreated. People with diabetes, high BP, other heart problems and previous history of stroke are at increased risk.
Atrial flutter-In this condition the heart rate is between 300 to 350 beats per minute. There is inadequate pumping from the atria. This can cause pooling of blood in the atrial chambers. Heart failure and stroke are the major complications.
Paroxysmal supraventricular tachycardia (PSVT)- This is usually a benign condition and does not create any major complications
Ventricular tachycardia- In ventricular tachycardia, the ventricles contract too fast. Ventricular tachycardia may develop into a condition called ventricular fibrillation. In this condition, the ventricles contract too fast, but without any meaningful function. This is referred to as ‘quivering’ of ventricles. This is a medical emergency. Cardiac arrest and sudden death may happen, if treatment is not started immediately. Defibrillation is an emergency treatment to normalise the heart rate.
Arrhythmias are conditions that can cause various complications, if left untreated. Proper treatment and monitoring is essential to prevent the development of complications and the recurrence of arrhythmias.
Arrhythmias occur when there is a change in the normal rate or rhythm of heart beats. A heartbeat corresponds to a period of contraction and relaxation of the heart. In the contraction phase the heart pumps out blood, while during the relaxation phase the heart fills up with blood. The contractions and relaxations are well synchronised and keeps the circulatory system working properly.
Arrhythmias can occur in the upper chambers of the heart called the ventricles and also in the lower chambers called the ventricles. They occur when there is a faulty generation of signals in the heart muscles. Arrhythmias also occur when there is an impairment in the transmission of signals around the heart.
An area of the heart called as the SA node or sino-atrial node located in the right atrium is called the natural pacemaker of the heart. It is from the SA node that electrical impulses originate and travel around the heart. In certain situations, other areas of the heart may also generate electrical impulses. This upsets the normal rate and rhythm of the heart beats.
Arrhythmias can also occur when there is an impairment in the conduction of electrical signals generated by the SA node. Conditions like bundle branch blocks, heart blocks and long QT syndrome can affect the proper conduction of the signals around the heart. This results in improper transmission of impulses resulting in arrhythmias.
Some of the causes and risk factors of certain common types of arrhythmias are listed below.
Some of the risk factors in developing arrhythmias are
·Coronary artery disease- They may cause damage to the tissues of the heart resulting in improper conduction of signals
·High Blood Pressure, Diabetes and high cholesterol levels
·Smoking, alcohol or drug abuse
·Inactive lifestyle without any exercise
·Physical or mental stress
·Family history of arrhythmias or other heart diseases
·Certain prescription medications as well as over the counter medications
Some medicines can cause arrhythmias, but they are usually reversible, and the effects disappear once the medicines are withdrawn. Some of the common medicines that cause arrhythmias are
·Antibiotics like azithromycin, levofloxacin, amoxicillin, and ciprofloxacin etc can change your heart rate, too. It’s more likely to happen if you have heart disease.
·Anti-asthmatics like inhaled corticosteroids, long-acting beta-2 agonists, leukotriene modifiers oral methylxanthines etc.
·Thyroid medicines like levothyroxine
·Antidepressants like serotonin and norepinephrine reuptake inhibitors (SNRIs) like desvenlafaxine, duloxetine, and venlafaxine etc. and tricyclic antidepressants like amitriptyline, clomipramine, desipramine etc.
·Herbal supplements like bitter orange, valerian, hawthorn, ginseng, and ephedra.
Heart is the vital organ that pumps blood to various parts of the body. It has got two upper chambers called atria and two lower chambers called ventricles. The right atrium receives deoxygenated blood from various parts of the body. From the right atrium the deoxygenated blood passes on to the right ventricle and then to the lungs for oxygenation. The oxygenated blood from the lungs comes into the left atrium, from where it moves on to left ventricle. The left ventricle then pumps the blood to various parts of the body through the aorta which subdivides into various smaller arteries.
The heart beats continuously in a rhythmic manner with alternating periods of contractions and relaxations. During the relaxation phase the upper chambers of the heart called the atria receives blood from various parts of the body as well as the lungs. Then the atria contracts pumping blood into the lower chambers called the ventricles. Once the ventricle fills up with blood, they contract pumping blood into various parts of the body and the lungs. This alternating periods of relaxations and contractions keep the blood circulation going around the body. The relaxations and contractions of upper and lower chambers occur in a synchronised manner.
The contractions and relaxation of the muscles of the heart occur as a result of electrical impulses that are generated from an area called the sinus node. The sinus node is located in the right atrium. From the sinus node the impulses move around the atria and then passes on to the ventricles through an area called the AV node or Auriculo-Ventricular node. The impulses then force the muscles of the ventricles to contract. This completes one cycle that corresponds to a heartbeat. The cycle is repeated in a rhythmic and synchronised manner.
Arrhythmias occur when there is an impairment in the generation and transmission of electrical signals in the heart. At times, certain other parts of the heart other than the sinus node, the natural pacemaker of the heart, starts generating signals. This upsets the normal sinus rhythm creating arrhythmias.
Similarly, arrhythmias occur when the signals generated by the sinus node fails to travel properly throughout the heart. At times, the signals travel around the atria more faster causing them to beat faster. This results in atrial arrhythmias. Sometimes, the ventricles start contracting in a hastened manner resulting in ventricular tachycardias.
Bradycardias occur when electrical impulses take too much time to travel around the heart. This may be due to conditions called as conduction blocks, that impair the proper transmission or conduction of signals through the heart muscles. This causes the heart to beat at a much lower rate than normal.
Arrhythmias cannot be cured completely but they can be kept well under control. Most of the arrhythmias are generally harmless and usually resolve on their own.
Before starting any treatment, the doctor will take a detailed look at the following factors.
·Whether the arrhythmias are abnormal, or it just reflects a minor flaw in normal working of the heart
·Whether the arrhythmia is clinically significant and is causing disturbing symptoms
·Whether the arrhythmia will progress into a more serious type of arrhythmia
·Whether the arrhythmia can create serious complications
If the doctor feels that the arrhythmias are abnormal in nature and can cause complication, proper treatment is started. The goals of arrhythmia treatment are
·Prevent the formation of blood clots and thereby reduce the risk of strokes
·Keeping the heart rate within a relatively normal range
·Restoration of the normal heart rhythm of the heart to the maximum possible extent
·Treatment for the underlying heart condition that may be causing the arrhythmia
·Keeping the risk factors under control
Treatment for arrhythmias
Some of the common treatments for arrhythmias are given below. The type of treatment best suited will be decided by the doctor after due consideration of the patient’s condition.
These are very effective in controlling certain types of arrhythmias, especially symptomatic tachycardias. They may be given orally or even intravenously in emergency situations. These drugs work either by suppressing the abnormal generation of signals by the SA node or by depressing the transmission of impulses around the heart tissues. Some of the commonly used antiarrhythmic medications are
·Calcium channel blockers to reduce blood pressure
·Beta-blockers to reduce the heart rate and cardiac output
·Anticoagulants to prevent the formation of blood clots and prevent stroke
This is a minimally invasive surgical procedure that uses radiofrequency energy to destroy the abnormal tissues of the heart that create abnormal impulses. This procedure is very effective in treating supraventricular tachycardias.
The procedure is similar to other cardiac catheterisation procedures. The catheter is introduced into the heart through the blood vessels in the arms or groin. The catheter contains an electrode tip that produces radiofrequency vibrations. The catheter is slowly threaded towards the area of the heart that is to be destroyed. Once that particular area is reached, the electrode is activated to produce radiofrequency energy that produces heat. This heat is used to burn the abnormal tissues. The procedure usually has very few complications and the period of hospitalisation is about two to three days.
A pacemaker is a small electronic device that carries out the functions of the SA node, the bundle of tissue that generates electrical impulses in the heart. The SA node is often referred to as the natural pacemaker of the heart.
The pacemaker has two parts a battery powered generator that generates electrical impulses and two leads that transmit the impulses to the heart muscles. Both the generator and leads are implanted at the same time. The generator portion is implanted usually under the collar bone.
Once implanted the pacemaker takes over the generation and transmission of impulses into the heart. The frequency of the pacemaker is programmed according the condition of the patient. The pacemaker cannot prevent but can rectify any ectopic signals generated by different parts of the heart.
Implantable cardioverter defibrillators (ICD)
An implantable cardioverter defibrillator is an electronic device that can reduce the occurrence of a sudden cardiac arrest in those with severe ventricular fibrillation.
The device works by identifying the occurrence of a fibrillation and providing mild electric shocks to correct the heart rate. The device is only to be implanted only if conventional treatments to correct the underlying cause of arrhythmias fail.