Cardiac Arrhythmias – diagnosis and treatment options

Dr Shyamkishore Lairikyengbam *

(Heart) By BodyParts3D/Anatomography (Anatomography) [CC BY-SA 2.1 jp (http://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)], via Wikimedia Commons

Introduction: A cardiac arrhythmia or dysrhythmia is a group of cardiac conditions caused by malfunction in the electrical conduction system of the heart causing it to beat irregularly, too fast called tachycardia or beat it too slowly called bradycardia. Symptoms may include palpitation or feeling a pause between heart beats, lightheadedness, shortness of breath, or chest pain, collapse. While some arrhythmias are not serious, other predispose a person to complications such as stroke or heart failure, may even result in cardiac arrest and sudden cardiac death (SCD).

Arrhythmias may be grouped into four main types: Supraventricular arrhythmias originate in the atria such as premature atrial contractions, atrial tachycardia, paroxysmal supraventricular tachycardia (PSVT) accessory pathway tachycardias (a fast heart rate caused by an extra, abnormal electrical pathway or connection between the atria and ventricles) (AVRT, WPW), AV nodal re-entrant tachycardia (AVNRT ), Atrial Fibrillation and Atrial Flutter.

Ventricular arrhythmias originate in the ventricles such as premature ventricular contraction ( PVCs ), Ventricular Tachycardia (VT), Ventricular Fibrillation (VF). Brady-arrhythmias are slow heart that may be caused by disease in the heart’s conduction system, such as in the sinoatrial (SA) node, atrioventricular (AV) node or His Purkinje network. These can include Sick Sinus Syndrome (SSS) and Complete Heart Block (CHB).

Cardiac Ion-channelopathy: These sub-group of arrhythmia result from Congenital Genetical Defects and result in serious and often fatal cardiac arrhythmia called VT or VF e.g Brugada Syndrome, Long QT Syndrome.

Diagnosis: History is the initial pointer to a correct diagnosis. Certain recreational drugs e.g. amphetamine, cocaine can cause various cardiac arrhythmia. A simple Electrocardiogram ( ECG ) can identify a certain cardiac arrhythmia e.g. PSVT, WPW, AF, VT, Brugada Syndrome, Long QT Syndrome etc.

Echocardiogram is required to rule out structural heart disease e.g. Hypertrophic Cardiomyopathy, Ventricular scar after heart attack, Arrhythmogenic right ventricle etc. Ambulatory ECG for 24 hours to 7 days (Holter monitor) non-invasively or invasively (implantable loop recorder, ILR) for many months can identify serious arrhythmia (not detected on Holter monitor).

In difficult cases, Electrophysiology Study ( EPS ) may be required in the Specialised Cardiac Catheterisation Laboratory to induce cardiac tachy-arrhythmia or “unearth” brady-arrhythmia e.g SSS.

Treatment options:

Drug therapy:

Vaughan Williams Classification is widely used. According to this there are four classes of anti-arrhythmic drugs.
Class I (which blocks fast sodium ion and potassium ion channels).
Class I(a): procainamide, quinidine, disopyramide.
Class I(b): lidocaine, phenytoin, mexiletine.
Class I(c): flecainide, propafenone.
Class II (blocks beta-adrenergic receptors).
e.g. propranolol, metoprolol, timolol.
Class III (predominantly blocks potassium channels and prolong repolarisation)
e.g. Sotalol, Amiodarone, bretylium.
d) Class IV (predominantly blocks the slow calcium channel).
e.g. Verapamil, Diltiazem.

Radio Frequency Ablation (RF Ablation) in which RF energy is delivered from an external generator and destroys the abnormal tissue by controlled heat production. This therapy become the treatment of choice for most Reentrant tachycardias, WPW Syndrome and Atrial Flutter. It has very often been used to ablate various ventricular tachycardia e.g. Idiopathic V.T, V.T. due to post-myocardial infraction scar. It is also used for treatment of Atrial Fibrillation (AF) but success rate is much lower than that of PSVT.

Pacemaker Implantation for symptomatic Bradycardia e.g. Complete Heart Block, Sick Sinus Syndrome.

Implantable Cardiovertor Defibrillator (ICD) for Ventricular Fibrillation/Fast Ventricular Tachycardia secondary to Myocardial Infarction, V.F/V.T associated with Brugada Syndrome, Long QT Syndrome etc.

Summary:

Cardiac arrhythmia may predispose to serious complication including sudden cardiac death. If detected early appropriate treatment either with drug therapy or interventional cardiological procedures namely RF Ablation, Implantation of Pacemaker or ICD will help patients with serious cardiac arrhythmia avoid disabling palpitation or sudden cardiac death.

Such interventional facilities are available in most full-fledged heart hospitals. Such highly specialised cardiac interventional facilities are available in SKY Hospital and Research Centre, Imphal.