Cardiac Arrhythmia PDF

CARDIAC ARRHYTHMIA Conductive System Arrhythmias  Disturbance of heart rhythm and/or conduction.  Arrhythmia :  Tachyarrhythmia  bradyaarrhythmia  Mechanism of tachyarrhythmia  Increased automaticity (produced by repeated spontaneous depolarisation of an ectopic foc...

CARDIAC ARRHYTHMIA Conductive System Arrhythmias  Disturbance of heart rhythm and/or conduction.  Arrhythmia :  Tachyarrhythmia  bradyaarrhythmia  Mechanism of tachyarrhythmia  Increased automaticity (produced by repeated spontaneous depolarisation of an ectopic focus).  triggered activity(secondary depolarization arising from an incompletely repolarised cell membrane)  Re-entry. Re-entery Mechanism of brady-arrhythmia Bradycardia may be due to: Reduced automaticity, e.g. sinus bradycardia. Blocked or abnormally slow conduction, e.g. AV block. Classification of Arrhythmia  Supraventricular arrhythmia:  Ventricular arrhythmia: Symptoms of cardiac arrhythmias  Bradycardias cause symptoms that reflect low cardiac output: fatigue, lightheadedness and syncope.  Tachycardias cause rapid palpitation, dizziness, chest discomfort or breathlessness.  Extreme tachycardias can cause syncope because the heart is unable to contract or relax properly at extreme rates. Extreme bradycardias or tachycardias can precipitate sudden death or cardiac arrest. Investigations for cardiac arrhythmias ECG ECG Ambulatory ECG(Holter) Implantable loop recorder Management of cardiac arrhythmia Atropine sulphate  Increases the sinus rate and SA and AV conduction, and is the treatment of choice for severe bradycardia or hypotension due to vagal overactivity.  Adenosine  It produces transient AV block lasting a few seconds. It is used to terminate supraventricular tachycardias when the AV node is part of the re-entry circuit Digoxin  It slows conduction and prolongs the refractory period in the AV node, this effect helps to control the ventricular rate in atrial fibrillation and may interrupt supraventricular tachycardias involving the AV node. Therapeutic procedures:  Pacemaker  External defibrillation and cardioversion  Catheter ablation  Implantable cardiac defibrillators (ICD) External defibrillation and cardioversion Implantable cardiac defibrillators (ICD) VT cardioversion by ICD Catheter ablation Sinus Rhythms spot.com  Sinus Arrhythmia  Sinus Bradycardia  Sinus Tachycardia  Sick sinus syndrome Rhythm Rate? 30 bpm Regularity? regular P waves? normal PR interval? 0.12 s QRS duration? 0.10 s Interpretation? Sinus Bradycardia Causes of Sinus Bradycardia MI Sinus node disease (sick sinus syndrome) Hypothermia Hypothyroidism Cholestatic jaundice Raised intracranial pressure Drugs, e.g. β-blockers, digoxin, verap Rhythm Rate? 130 bpm Regularity? regular P waves? normal PR interval? 0.16 s QRS duration? 0.08 s Interpretation? Sinus Tachycardia Causes of Sinus Tachycardia * Anxiety Fever Anaemia Heart failure Thyrotoxicosis Phaeochromocytoma Drugs, e.g. β-agonists (bronchodilators) Sinus arrhythmia Sinus arrhythmia Sick sinus syndrome Sick sinus syndrome