- Arrhythmia refers to any abnormality in the rhythm of the heartbeat, whether in rate, regularity, or conduction of electrical impulses through the heart.
- Under normal conditions, the heart’s rhythm is governed by the sinoatrial (SA) node, which acts as the natural pacemaker, generating impulses that spread through the atria, atrioventricular (AV) node, and ventricles. In arrhythmia, this orderly conduction is disturbed, leading to heartbeats that may be too fast (tachycardia), too slow (bradycardia), irregular, or chaotic. While some arrhythmias are harmless and asymptomatic, others can significantly impair cardiac output, increase the risk of stroke, or even cause sudden cardiac death.
- The causes of arrhythmias are diverse, including structural heart diseases (e.g., coronary artery disease, heart failure, valvular disorders), electrolyte imbalances, genetic mutations affecting ion channels, and external factors such as medications, caffeine, alcohol, or illicit drugs. Conditions like hypertension, diabetes, thyroid disorders, and sleep apnea also predispose individuals to rhythm disturbances. Inherited syndromes, such as long QT syndrome, Brugada syndrome, and Wolff–Parkinson–White syndrome, represent genetic forms of arrhythmias that can manifest early in life.
- Arrhythmias are classified based on their origin and pattern. Supraventricular arrhythmias, which arise from the atria or AV node, include atrial fibrillation (AF), atrial flutter, paroxysmal supraventricular tachycardia (PSVT), and Wolff–Parkinson–White syndrome. AF, the most common sustained arrhythmia, is characterized by chaotic atrial activity leading to irregular ventricular response and a high risk of thromboembolism and stroke. Ventricular arrhythmias, originating in the ventricles, include ventricular tachycardia (VT) and ventricular fibrillation (VF), both of which can be life-threatening and are common causes of sudden cardiac death. Bradyarrhythmias, such as sinus node dysfunction and AV block, involve abnormally slow rhythms and can result in syncope or fatigue due to reduced cardiac output.
- Clinical manifestations vary widely, from being completely asymptomatic to presenting with palpitations, dizziness, chest pain, shortness of breath, or syncope. Severe arrhythmias can cause hemodynamic instability, cardiac arrest, or sudden death. Diagnosis relies on electrocardiography (ECG), which provides a direct record of cardiac electrical activity. Holter monitoring, event recorders, and implantable loop recorders are useful for detecting intermittent arrhythmias. Additional investigations, such as echocardiography, cardiac MRI, and electrophysiological studies, help evaluate underlying structural or conduction abnormalities.
- Management of arrhythmias depends on the type, severity, and underlying cause. For supraventricular arrhythmias, options include rate control (using beta-blockers, calcium channel blockers, or digoxin), rhythm control (using antiarrhythmic drugs such as amiodarone or flecainide), and anticoagulation to prevent stroke in atrial fibrillation. Catheter-based radiofrequency ablation is an effective and often curative approach for many supraventricular arrhythmias. Ventricular arrhythmias may require urgent interventions such as cardioversion or defibrillation, long-term use of implantable cardioverter-defibrillators (ICDs), or ablation therapy. Bradyarrhythmias that cause significant symptoms or risk of sudden death are typically treated with permanent pacemaker implantation.
- Preventive strategies include lifestyle modification, management of cardiovascular risk factors, and treatment of underlying conditions such as hypertension or hyperthyroidism. Advances in genomics, bioelectronic devices, and ablation techniques have significantly improved outcomes in arrhythmia management, while ongoing research into gene therapy and stem cell-based approaches offers potential future solutions.
