Arrhythmia

An arrhythmia is an abnormal heart rhythm — the heart beats too fast, too slow, or irregularly. Some arrhythmias are harmless; others can cause serious symptoms or life-threatening events including cardiac arrest and stroke. Many are easily treatable once diagnosed.

Common types

• Atrial fibrillation (AFib) — irregular, often fast heartbeat. The most common arrhythmia. Raises risk of stroke substantially.
• Supraventricular tachycardia (SVT) — sudden fast regular heartbeat
• Atrial flutter — related to AFib
• Ventricular tachycardia (VT) — fast rhythm from the lower chambers; can be life-threatening
• Ventricular fibrillation (VF) — chaotic rhythm causing cardiac arrest; requires immediate defibrillation
• Bradycardia — abnormally slow heart rate; some people need a pacemaker
• Heart block — problem with electrical conduction; covered in a separate page
• Premature beats — extra beats; usually harmless

Symptoms

• Palpitations — awareness of fast, slow, or irregular heartbeat
• Dizziness, lightheadedness
• Fainting
• Breathlessness
• Chest discomfort
• Weakness, fatigue
• Stroke — sometimes the first sign of AFib (new weakness, facial droop, slurred speech — dial 112)

Causes and risk factors

• Heart disease — coronary artery disease, heart failure, valve disease
• High blood pressure
• Previous heart attack
• Cardiomyopathies
• Thyroid disorders (overactive thyroid is a common cause of AFib)
• Electrolyte imbalances
• Excess alcohol, caffeine, certain medicines
• Sleep apnoea
• Stress
• Diabetes
• Congenital heart abnormalities

Diagnosis

• ECG — the key test
• Holter monitor — 24-48 hour continuous ECG recording
• Event recorder or implantable loop recorder — for infrequent symptoms
• Echocardiogram
• Blood tests including thyroid
• Exercise testing, electrophysiology study in selected cases

Treatment

• Medicines — to control heart rate or rhythm; different classes for different arrhythmias
• Blood thinners — for AFib, to prevent stroke
• Cardioversion — electrical shock to restore normal rhythm
• Catheter ablation — targeting the heart tissue that creates the abnormal rhythm; widely available in Indian cardiac centres
• Pacemaker — for slow rhythms
• Implantable defibrillator (ICD) — for life-threatening ventricular arrhythmias or high-risk patients
• Treat underlying conditions — thyroid, sleep apnoea, alcohol, high blood pressure

If you have palpitations, fainting, or unexplained breathlessness, see a doctor — a simple ECG often starts the assessment. AFib especially deserves attention because it's often silent and stroke-causing.