1. Arrhythmias

3. An arrhythmia is… • disturbance of the electrical rhythm of the heart. • Classification • Supraventicular (sinus, atrial, junctional) and.. • Ventricular • Main mechanisms • Disorders of impulse formation or automaticity • Abnormalities of impulse conduction • Re-entry • Triggered activity

7. Supraventricular I • Sinus • Sinus arrhythmia -> alteration of heart rate during respiration – not pathological, pronounced in children • Sinus bradycardia and tachycardia • Atrial tachycardia – automaticity, sinoartial disease • Narrow complex tachycardia with abnormal P waves • Atrial flutter – large re-entry circuit (RA encircling tricuspid) • 300/min, some form of AV block • Saw tooth flutter waves • Atrial fibrillation – re-entry, or continued ectopic firing • Paroxysmal or persistent

10. Supraventricular II • AV node re-entrant tachycardia (AVNRT) • 120-140 tachycardia, why polyuria? • WPW Syndrome, atrioventricular re-entrant tachycardia • Abnormal band of conducting tissue connects the ventricles and the atria • Resembles purkinje tissue, acts as an accessory pathway, 50% asymptomatic • If different pathways have different speeds -> re-entrant -> with symptoms => WPW syndrome • Delta wave is characteristic

13. AV block • First degree – delayed progression through AV node • Second degree • Type 1 – PR gradually increase until a QRS complex is missed. • Type 2 – Occasionally P wave does not result in a QRS complex. • Third degree – complete heart block.

16. SA block • First degree – delay between firing of the SA node and depolarisation of the atria • Second degree • Type 1 – conduction time between SA node and surrounding atrial tissue becomes progressively longer – eventually a cycle is missed. • Type 2 – time between SA node and propagation to atria is normal but at some point a cycle is just missed. • Third degree – failure to conduct impulses