arrhythmias an arrhythmia is… – disturbance of the electrical rhythm of the heart....
TRANSCRIPT
Arrhythmias
• 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
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
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
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.
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