Arrhythmias Flashcards
What are arrhythmias?
Abnormalities in the cardiac rhythm generated by abnormal electrical conduction, usually by ectopic beats
What are ectopic beats?
Beats that originate in places other than the SA node
What is re-entry?
Where there is more than one conduction pathway, with different speeds of conduction
What are the types of supra-ventricular arrhythmia?
Tachycardia:
- Atrial fibrillation
- Atrial flutter
- Ectopic atrial tachycardia
Bradycardia:
- Sinus bradycardia
- Sinus pauses
Where do supra ventricular arrhythmias originate?
Within or above the AV node
What is sinus arrhythmia?
Where the heart is in sinus rhythm but the heart rate is irregular
What are the types of ventricular arrhythmia?
Ventricular ectopic
Ventricular tachycardia
Ventricular fibrillation
Asystole
Are supraventricular and ventricular arrhythmias narrow or broad complex?
Supraventricular - narrow complex
Ventricular - broad complex
What are the types of AV node arrhythmia?
AV re-entry tachycardia AV block (1st, 2nd or 3rd degree)
What are the causes of arrhythmia?
Abnormal anatomy Autonomic nervous system Metabolic Inflammation (viral myocarditis) Drugs Genetic
What are the ways in which abnormal anatomy can cause arrhythmia?
LV hypertrophy
Accessory pathways
Congenital heart defect
What are the ways in which the autonomic nervous system can cause arrhythmia?
Sympathetic stimulation: stress, exercise, hyperthyroidism
Increased vagal tone causing bradycardia
What are the metabolic causes of arrhythmia?
Hypoxia (chronic pulmonary disease, pulmonary embolism) Ischaemic myocardium (acute MI, angina) Electrolyte imbalances (K+, Ca2+, Mg2+)
In what way can genetics cause arrhythmia?
Mutation of genes encoding cardiac ion channels, e.g. congenital long QT syndrome
What is atrial fibrillation?
Disorganised electrical activity, resulting in irregular ventricular response
What are the symptoms of atrial fibrillation?
Palpitations
What are the three types of atrial fibrillation, and how are they classed?
Paroxysmal - <48 hours
Persistent - >48 hours
Permanent - unable to return to normal sinus rhythm
What does an ECG show in atrial fibrillation?
No P waves
Irregularly irregular
Isoelectric line deviation
Ventricular rate 30-200bpm
What is the treatment to control rate in atrial fibrillation?
Combination of digoxin and a beta blocker/verapamil
AV node ablation
What is the treatment to control rhythm in atrial fibrillation?
Class I (disopyramide) or III (amiodarone) DCCV
When should you anti-coagulate in atrial fibrillation?
If prosthetic valves or CHADVAS score >2
What is atrial flutter?
Atrial re-entry tachycardia, leading to rapid atrial rate.
Not all P-waves make it to the ventricles, so atria ‘flutter’
What are the symptoms of atrial flutter?
Palpitations
What does an ECG show in atrial flutter?
Sawtooth pattern
Multiple P waves before a QRS
Ventricular rate of approx 300bpm
What is the treatment for atrial flutter?
Electrical cardioversion
Radiofrequency ablation
Class III drugs (amiodarone)
What is Wolf-Parkinson White syndrome?
Atrial re-entry tachycardia with accessory excitatory pathway through the Bundle of Kent
What are the symptoms of Wolf-Parkinson White syndrome?
Palpitations
Tachycardia
What does an ECG show in Wolf-Parkinson White syndrome?
Short PR interval Sloping QRS (delta wave)
What is the treatment for Wolf-Parkinson White syndrome?
DCCV
Beta blockers, calcium channel blockers
Catheter ablation
What are the symptoms of ventricular tachycardia?
Dizziness Hypotension Palpitations Cardiac arrest Patients usually have other heart conditions
What does an ECG show in ventricular tachycardia?
Wide complexes
Polymorphisms (torsade de pointes)
Mountains
What is the treatment for unstable ventricular tachycardia?
DCCV
What is the treatment for pulseless ventricular tachycardia?
Defibrillation
What is the treatment for stable ventricular tachycardia?
Amiodarone + class I (lignocaine)
What is ventricular fibrillation?
Rapid irregular conduction with useless effect
Life threatening, cardiac arrest often follows
What are the symptoms of ventricular fibrillation?
Syncope
Cardiac arrest
What re the signs of ventricular fibrillation on ECG?
Wandering baseline
Irregular
Random waveforms
No identifiable QRS
What is the treatment for ventricular fibrillation?
Defibrillation
Magnesium chloride
Implantable cardioverter defibrillator if long term
What is 1st degree heart block?
PR interval longer than normal (>2 seconds)
Does not require treatment, just long term follow up
What is 2nd degree heart block, Mobitz I?
Progressive lengthening of the PR interval, eventually resulting in a dropped beat
What is 2nd degree heart block, Mobitz II?
Some missing P waves
What is 3rd degree heart block (complete heart block)?
No action potentials from the SA node/atria get through, no connection between P wave and QRS
What is there a risk of in a trial fibrillation?
Embolic stroke
What are the signs of ectopic atrial tachycardia on ECG?
Varying PR and RR interval, some beats come early
Which heart rhythms are shockable?
Ventricular tachycardia or fibrillation
Which heart rhythms would you do CPR on?
Pulseless electrical activity
Asystole
Complete AV block
