An Overview of Cardiac Arrhythmias
Old airport road, Bengaluru Feb 9, 2017
Cardiac Arrhythmias or irregularity in heat beat occurs when the electrical impulses that coordinate the heart rate are malfunctioning.
Cardiac arrhythmia can be classified as Ventricular Arrhythmias or Superventricular Arrhythmias and Bradycardia. Heart rate faster than 100 beats per minute in Ventricular Arrhythmias and heart rate less than 60 beats per minute in Bradycardia. Whereas, a normal heart rate in an adult is 60-100 per minute.
Usually, a person suffering an irregular heartbeat may feel like a flutter or a racing heartbeat which may look harmless. But, some may turn out to be bothersome and sometimes may even be life threatening.
Different types of Cardiac arrhythmia
Sinus node dysfunction commonly causes Bradycardia. Sinus node dysfunction is caused due to scar tissue that expands and, in the long run replaces the sinus node. Apart from that, the sinus node dysfunction can also be caused by coronary artery disease, severe liver disease, hypotension, hypothermia, or typhoid fever, a result of vasovagal hypertonia.
Symptoms- This may either not present any particular symptoms or it may tag along dizziness, fainting, and extreme fatigue
Sick sinus syndrome is caused by scarring near the sinus node (which sets the pace of the heartbeat) which is responsible for slowing of the impulses from traveling, disrupting or blocking the impulses from traveling. The heartbeat can be either Bradycardia or Tachycardia and slow down intermittently.
Conduction block is a block in the heart’s electrical pathways near the AV node. According to the location and the type of block, the impulses between the upper and lower halves of the heart can either be slow or blocked.
Supraventricular tachyarrhythmia is either an abnormality in the AV node or an abnormal pathway that bypasses the typical route for heartbeat signals. This usually starts in the parts of the heart above the ventricles.
Symptoms- Supraventricular tachyarrhythmias can cause palpitations, low blood pressure, and fainting.
Atrial fibrillation causes a rapid and irregular heartbeat, an atria quiver or “fibrillate” instead of a normal heartbeat. When a person suffers from atrial fibrillation, the heartbeat signals begin in different locations in the atria rather than in the sinus node. The AV node sends sporadic, rapid and irregular heartbeats of 80 to 160 beats per minute. This affects the efficiency of the heart to pump blood causing the blood to pool in the heart chambers and increases the risk of a blood clot.
Symptoms- Either it has no symptoms or it can cause palpitations, fainting, dizziness, weakness, shortness of breath and angina (the chest pain caused by a reduced blood supply to the heart muscle)
AV block or heart blocks are of three types. Firstly, the signal from the heart takes longer than normal to travel from the sinus node to the ventricles. Secondly, some signals from the heart beating are lost between the atria and the ventricles. And, finally, in some cases there are no signals from the heartbeat to reach the ventricles, the ventricles beat slowly without any direction from above.
Symptoms- AV block can cause an irregular pulse or slow pulse, a very slow heartbeat, dizziness, and fainting.
Ventricular tachycardia (VT) is an abnormal heart rhythm that begins in the right or left ventricle which can eventually lead to ventricular fibrillation if not treated. The ventricular tachycardia that can last for a few seconds is known as non-sustained VT and the ones that last for many minutes or hours is known as sustained VT.
Symptoms- Non-sustained VT either has any symptoms or can cause a mild fluttering in the chest. Sustained VT usually causes lightheadedness or loss of consciousness and it can be lethal.
Ventricular fibrillation is a cardiac emergency in which the ventricles to vibrate ineffectively producing no real heartbeat, causing unconsciousness, brain damage and death within minutes. It can be caused by a myocardial infarction, an electrical accident, lightning strike or drowning. Symptoms include absent pulse, unconsciousness, and death.
Long QT syndrome is a cardiac disorder that causes fast disordered heartbeats due to changes in the electrical system of the heart. Long QT syndrome leads to fainting and a life-threatening situation or sudden death.
Premature heartbeats is actually an extra beat, can trigger a longer lasting arrhythmia, especially in people with heart disease.
Risk factors of arrhythmia
Coronary artery diseases, other cardiac problems, and previous cardiac surgeries are a risk for almost any type of arrhythmia. Similarly, hypertension and diabetes can increase the risk of coronary artery disease which can in turn lead to arrhythmia. Apart from that, congenital heart disease and an overactive or underactive thyroid gland can raise the risk of cardiac arrhythmias.
Furthermore, there are certain over-the-counter cough and cold medications, as well as prescription medications that may lead to developing an arrhythmia. An obstructive sleep apnea can increase the risk of bradycardia, atrial fibrillation or other arrhythmias. Electrolyte levels that are too high or too low can affect the heart’s electrical impulses and contribute to the development of arrhythmias. Alcohol can affect the heart’s electrical impulses and increase the risk of atrial fibrillation.
The stimulants like caffeine, nicotine can cause the heart to beat faster and can contribute to the development of more serious arrhythmias. Illegal medications such as amphetamines and cocaine can lead to arrhythmias or to sudden death due to ventricular fibrillation.
Apart from the above conditions, there are certain arrhythmias that may increase the risk of developing the following stroke and heart failure.
Diagnosing cardiac arrhythmia
Electrocardiogram (ECG) can detect the electrical activity of the heart and measure the timing and duration of each electrical phase of the heartbeat.
Holter monitor can record the heart’s activities while performing normal daily activities. Holter monitor is a portable ECG device that can be worn for a day or more while doing your daily life.
Event monitor is a portable ECG device attached to the body to identify cardiac arrhythmias. The device has a button which the patient can press when having cardiac symptoms.
Echocardiogram test checks the well functioning of the heart. This diagnoses the cause of abnormal heart sounds, enlarged heart, unexplained chest pain or pressure, shortness of breath, or irregular heartbeats.
In case if the physician is not being able to diagnose an arrhythmia with the above tests, there are other tests like stress testwhich is being done during exercise sessions, tilt table test to examine heart and the nervous system as it responds to the change in the angle or position, electrophysiological testing and mapping to locate the arrhythmia and determine what may be causing the arrhythmia.
The treatment to arrhythmia completely depends on its causes and varies accordingly. Some arrhythmia can be treated with medication whereas in some surgical methods are required to treat them. The surgical procedures include Maze procedure and coronary bypass surgery. In Maze procedure, the surgeon makes a series of surgical incisions in the atria to create a pattern or maze of scar tissue in order to prevent the atria from conducting electricity. In coronary bypass surgery, persons with a severe coronary artery disease in addition to arrhythmias may require coronary bypass surgery to improve blood flow to the heart.
Change in Lifestyle- Recommended
It is proved that a change in lifestyle can prevent as well as control many disorders and diseases affecting the human body. Arrhythmia is not an exception. Make sure your diet is:
-Low in salt and solid fats and rich in fruits, vegetables, and whole grains.
– Exercise daily and keep you fit.
– Stop smoking and avoid second-hand smoke.
– Balance your weight to avoid the risk of developing heart diseases.
– Make your life easy and monitor blood pressure and cholesterol levels.
– Avoid drinking more than one drink per day.
-Finally, the most important. Maintain follow-up checkups.
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