Arrhythmias Flashcards
What are some possible symptoms of arrhythmias?
Palpitations SOB Dizziness (presyncope) LOC (syncope) Sudden cardiac death Angina Heart failure
Which investigations should be done for a suspected arrhythmia?
12 lead ECG Exercise ECG (for ischaemia, exercise induced arrhythmia) 24 hour Holter ECG Echocardiogram Electrophysiological study
What is the purpose of an electrophysiological study?
Trigger the arrhythmia and study its mechanism/pathway
Opportunity to treat the arrhythmia by delivering radio frequency ablation to extra pathway
What is pre-excitation a sign of and what does it look like on an ECG?
Wolf-Parkinson-White (pre-excitation of the ventricles)
- slurred upstroke of QRS = delta wave
- wide QRS
What is normal sinus arrhythmia?
Variation in HR during respiratory cycle due to reflex changes in vagal tone
–> inspiration decreases vagal tone –> increases HR
What are some causes of sinus bradycardia?
- physiological e.g. athlete
- drugs e.g. beta-blockers
- ischaemia - common after inferior STEMI
What are the treatment options for sinus bradycardia?
- atropine if acute
- pacing if haemodynamic compromise
What are some causes of sinus tachycardia?
Physiological:
- anxiety
- fever
- hypotension
- anaemia
Drugs
What is the treatment of sinus tachycardia?
Treat the cause
Beta-blockers
What is the treatment for atrial ectopic beats?
- generally no treatment
- avoid stimulants e.g. caffeine, cigarettes
- beta-blockers may help
What are the possible mechanisms of SVT?
- AV nodal re-entry
- accessory pathway
- atrial ectopic
What is the acute management of SVT?
Increase vagal tone (manoeuvres)
Slow conduction at AVN
–> IV adenosine/verapamil
Give some examples of vagal manoeuvres for infants, children and adults
Infants –> ice water to face
Children –> blow through straw (valsalva), carotid massage
Adults –> breath holding, carotid massage, cough, NG tube, gag reflex
What is the chronic management of SVT?
- Avoid stimulants
- Electrophysiological study + radio frequency ablation –> first line in young symptomatic patients
- Beta-blockers e.g. propranolol, atenolol
What is 1st degree AV block?
PR interval longer than normal –> (> 0.2 seconds)
- not really ‘block’, QRS follows every P wave but takes longer
What is the management of 1st degree AV block?
No treatment
Long term follow up as may develop into more serious block over time
What is 2nd degree AV block?
Intermittent dropped beats:
Mobitz I and II
What is Mobitz I?
Progressive lengthening of thePR interval –> eventual dropped beat
What is Mobitz II?
Usually 2:1 or 3:1 dropped beats
What is the management of Mobitz II?
Permanent pacemaker
–> may progress to 3rd degree block
What is 3rd degree AV block?
No APs from the SA node get through the AV node
–> no link between P waves and QRS complexes
What is the management of 3rd degree AV block?
Ventricular pacing
What are the ventricular arrhythmias?
- ventricular ectopics or premature ventricular complex (PVC)
- ventricular tachycardia
- ventricular fibrillation
- asystole
What are some causes of ventricular ectopics?
- structural: LVH, HF, myocarditis
- metabolic: electrolytes
- may be a marker of inherited cardiac condition
When should ventricular ectopics be investigated further?
If they are worse on exercise
What are the management options for ventricular ectopics?
Beta-blockers
Ablation of focus
What are some causes of VT (broad complex tachycardia)?
Mostly significant heart disease e.g. coronary artery disease, previous MI
Electrolytes
Drugs that prolong QT e.g. sotalol
Rarer causes: cardiomyopathy, inherited long QT, Brugada syndrome
How does VT usually present?
May be stable but usually haemodynamically compromised
- -> large, sustained reduction in BP
- -> life threatening
What are some of the ECG findings in VT?
- QRS rapid, wide and distorted
- T wave large with deflections opposite QRS
- ventricular rhythm regular
- P waves not visible
- PR not measurable
What is the acute management of VT?
Direct current cardioversion (DCCV) if unstable
If stable, consider pharmacological cardioversion but prepare for DCCV
–> amiodarone
Look for causes and treat
What is the long term management of VT?
Correct cause if possible e.g. revascularisation, HF management
Implantable cardiac defibrillators (ICD) if life threatening
VT catheter ablation
Are AADs used in the long term management of VT?
No - ineffective and associated with worse outcomes
What is ventricular fibrillation?
Chaotic ventricular electrical activity
–> heart loses the ability to function as a pump
What is the management of ventricular fibrillation?
CPR and defibrillation
Which ECG changes might be seen in hypokalaemia?
- small T waves
- ST depression
- prolonged QT
- prominent U waves
Which ECG changes might be seen in hyperkalaemia?
- tall tented T waves
- broad QRS
- absent/flat P waves
