Flashcards in *Arrhythmias Deck (125)
What is an arrhythmia?
Abnormality of heart rate or rhythm
What are the 2 broad anatomical types of arrhythmias?
What are the names of the 3 internal tracts that connect the SA node and AV node?
Anterior, middle and posterior internodal tracts
What are ectopic beats?
Name when you have several of these in a row?
Beats or rhythms that originate in places other than the SA node (when the latent pacemaker fires at a rate faster than the SA node)
Ectopic rhythm - ectopic focus dictates the entire rhythm
Are ectopic beats/ rhythms dangerous?
Depends how the affect the cardiac output
How can arrhythmias be categorised based on rate?
What are the 4 types of atrial tachycardia? (SVT)
Ectopic atrial tachycardia
What are the 2 types of atrial bradycardia?
What are the 3 types of atrioventricular node arrhythmias?
AV node re-entry
What are the 4 types of ventricular arrhythmias??
Premature ventricular complex
What are the clinical causes of arrhythmias? (5)
Abnormal anatomy e.g. left ventricular hypertrophy, accessory pathways
Autonomic e.g. sympathetic stimulation (nervousness, hyperthyroidism), increased vagal tone
Metabolic e.g. hypoxic myocardium, ischaemic myocardium, electrolyte imbalances
Inflammation e.g. viral myocarditis]Drugs
Genetics (mutations of cardiac ion channels) e.g. congenital long QT syndrome
What are the 5 mechanisms of arrhythmias?
Defects in impulse formation (altered automaticity, triggered activity)
Defects in impulse conduction (re-entry, accessory tracts, conduction block)
What is altered automaticity?
When a latent pacemaker takes over the SA nodes function as the normal pacemaker of the heart (causes escape or ectopic beats) - can occur physiologically when the ANS modulates the SA nods activity e.g. caused by drugs, ischaemia
What is triggered activity?
When abnormal action potentials are triggered by a preceding action potential resulting in the heart cells beating twice e.g. tornadoes de points
What is re-entry?
Self-sustaining electrical circuit stimulates an area of the myocardium to be stimulated repeatedly
What is conduction block?
Any disease that disrupts electrical conduction may reduce conduction or cause heart block
What are accessory pathways?
Additional electrical conduction pathway between 2 areas of the heart e.g. WPW
What effect does hypothermia have on phase 4 of AP slope?
Decreases it (altered automaticity)
What effect does hyperthermia have on phase 4 of action potential slope?
Increases it (altered automaticity)
What effect do hypoxia and hypercapnia have on phase 4 of AP slope?
increase it (altered automaticity)
What effect does hypokalaemia have on phase 4 of AP slope?
Increases it (also prolongs repolarisation and increases ectopics)
Symptoms of arrhythmias?
Palpitations (a noticeably rapid, strong or irregular heart beat)
Sudden cardiac death
Worsen pre-exisiting conditiosn e.g. angina
Investigations of arrhythmias? (&)
12 lead ECG
24 hours ECG hotter monitoring
Electrophysiological (EP) study
Why is an ECG done for arrhythmias?
To assess rhythm
Signs of previous MI, pre-excitation (WPW)
What sign on an ECG suggests a previous MI?
Pathological Q waves
Why perform an exercise ECG in a patient with suspected arrhythmia?
To assess for ischaemia
Exercise induced arrhythmia
Why perform a 24 hour hotter ECG in a patient with suspected arrhythmia?
To assess for paroxysmal arrhythmia
To link symptoms to underlying heart rhythm
Why perform an echo in a patient with suspected arrhythmia?
To assess for structural heart disease
Why perform an electrophysiological study in a patient with a suspected arrhythmia?
To trigger the arrhythmia and study its mechanism
Opportunity to treat by ablation at the same time