Published on May 18, 2016 and last reviewed on Sep 07, 2018 - 5 min read
The normal rhythm of the heart is called sinus rhythm. Any disturbance resulting from multi-factorial causes results in an abnormal heart rhythm. When the sinus rhythm is lost, it results in an arrhythmia. The branch of medicine dealing with abnormal heart rhythms is called electrophysiology.
Under basal conditions, the maximum rate of firing of cells occurs in the sinoatrial node. Under duress, the whole of the heart can start to generate an abnormal rhythm. When the SA node malfunctions, back-up rhythms come into force as a result of secondary pacemakers. This also happens when there is impedance to the conduction of normal electrical impulses in the conduction system. In summary, an arrhythmia results if the natural pacemaker of the heart malfunctions or if there is a blockade in the conduction system or when other parts of the heart serve to act as secondary pacemakers.
Broadly, arrhythmias are classified into,
The other common type of arrhythmias include premature contractions, supraventricular arrhythmias and ventricular arrhythmias.
Premature contractions that occur in the heart's upper chambers called premature atrial contractions (PACs) and those occurring in the heart's lower chambers are called premature ventricular contractions (PVCs). Premature beats are quite common and are asymptomatic most of the time. If symptomatic, they present with symptoms like flutter in the chest or skipped heart beats. These do not require active intervention unless they are part of a more serious symptom.
These are tachycardias that arise in the atrium. These include atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia (PSVT) and Wolff-Parkinson-White (WPW) syndrome.
1. Atrial Fibrillation (AF):
It is characterized by rapid and disorganized quivering of the walls of the atrial chambers. This quivering is called fibrillation. Atrial fibrillation occurs when the pacemaker activity shifts from the SAN to AVN or somewhere near the pulmonary veins. The common causes of atrial fibrillation include hypertension, rheumatic heart disease, alcohol usage and hyperthyroidism. The two common sequel of atrial fibrillation include stroke and heart failure. Stroke results when blood clots form in the atrial chamber and get embolized to the brain. The inefficient pumping of the atria results in the ventricles not getting adequate blood. As a result other vital organs are not suffused with blood. The body's increasing demand for blood is not met. The inefficient filling of the ventricles results in heart failure.
2. Atrial Flutter:
It is less common than atrial fibrillation. The heart beats in a fast and regular fashion and that is how it differs from atrial fibrillation wherein the rhythm is irregular and disorganized. The symptoms and complications of atrial flutter are similar to that of atrial fibrillation.
3. Paroxysmal Supraventricular Tachycardia (PSVT):
This begins and ends abruptly. It is common in young people and in especially those who indulge in vigorous and strenuous physical activity. The electrical impulses traversing from the atria to the ventricles have a 're-entry' pathway through which they re-enter the atria. Hence it is also called AV node re-entry tachycardia (AVNRT). Dual AV node pathways exist for the re-entry to occur. This results in an extra heart beat. Since it occurs in an episodic fashion, the term paroxysmal is used. The complications of PSVT include syncope, congestive heart failure, cardiomyopathy and myocardial infarction.
4. Wolff-Parkinson-White Syndrome:
This is a special type of PSVT. An aberrant pathway exists for conduction of electrical impulses.
Ventricular arrhythmias include ventricular tachycardia (VT) and the more dangerous ventricular fibrillation (V-fib). Ventricular arrhythmia usually lasts for a few seconds. If it lasts for a longer time it gets converted to ventricular fibrillation and can pose serious risks. Ventricular fibrillation is life threatening and needs immediate intervention in the form of defibrillation or what is more commonly known as DC shock. Torsades de pointes (twisting of points) is a type of ventricular fibrillation with a characteristic pattern on the ECG.
Any arrhythmia presents with one or more of the following symptoms:
It is imperative to rule out thyroid dysfunction or anxiety disorders.
1. Drug therapy:
Recent studies like HOT-CAFE (how to treat chronic atrial fibrillation) have concluded that rate control is as effective as rhythm control in the treatment of atrial fibrillation.
2. Interventional procedures:
In summary, arrhythmias represent a common and clinically vexing problem. Specialist cutting edge interventions are available in today's age for the treatment of these problems.
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