Arrhythmia Flashcards
Narrow QRS complex
- < 0.12
- indicates supraventricular origin
Wide QRS complex
- > 0.12
- indicates ventricular origin
Types of bradyarrhythmias
- AV block (first, second I, second II, third degree)
- Sick sinus syndrome
Classifying tachyarrhythmias
- regular vs. irregular
- narrow vs. wide QRS
Irregular, narrow QRS tachyarrythmias
- atrial fibrillation
- atrial flutter
Irregular, wide QRS tachycardia
- polymorphic VT
- Torsades de pointes
- Wolff-parkinson-white syndrome
Regular, narrow QRS tachyarrhythmias
- sinus tachycardia
- atrial flutter (with consistent AV conduction)
- paroxysmal supraventricular tachycardia (AV nodal reentry SVT, SA nodal reentry SVT)
Regular, wide QRS tachyarrhythmias
- monomorphic VTs (ventricular tachy, ventricular fibrillation)
Managing regular, narrow complex tachycardia (haemodynamically stable)
Acute:
1. vagal maneouvers (valsalva, carotid sinus massage)
2. IV adenosine (6mg, 12mg, 18mg)
3. Consider trying verapamil
3. electrical cardioversion
Prevention:
- beta-blockers
- radio-frequency ablation
Managing haemodynamically unstable tachycardia
SVT and VT
- synchronised DC cardioversion (up to 3 times)
- perform under sedation
Managing irregular, narrow-complex tachycardia (haemodynamically stable)
Atrial fibrillation or atrial flutter
> 48 hours:
- do not treat with cardiovesion until anti-coagulated for at least 3 weeks (reduce risk dislodging thrombus)
- if haemo unstable- can give LMWH prior to immediate cardioversion
< 48 hours:
- chemical cardioversion using flecainide, propafenone, or amiodarone
Long-term management of arrhythmias
- radio-frequency ablation
- beta-blockers or calcium channel blockers
Managing broad-complex QRS tachycardia (haemodynamically unstable)
immediate electrical cardioversion
Managing broad-complex QRS tachycardia (haemodynamically stable)
Chemical cardioversion:
- amiodarone
- lidocaine
Drugs fail?
- electrophysiological study
- implantable cardioverter defibs
Which drug is contraindicated in VTs?
VERAPAMIL
Atrial fibrillation
Most common, sustained arrhythmia
Types of atrial fibrillation
- first presentation
- paroxysmal (< 7 days, self-terminating )
- persistent (> 7 days, not self-terminating)
- permanent (cardioversion failed, rate control)
Clinical features of atrial fibrillation
Symptoms:
- SOB
- palpitations
- syncope
- chest pain
Signs:
- irregularly irregular pulse
ECG findings in atrial fibrillation
- irregularly irregular rhythm
- narrow QRS complex
- tachycardia (> 100)
- absent p-waves
General management of atrial fibrillation
- rate and rhythm control
- stroke risk reduction
Rhythm control in atrial fibrillation
Acute:
- electrical cardioversion
- chemical - flecainide, amiodarone
Long-term:
- beta-blockers
- amiodarone
- domperidone (dopamine antagonist)
Rate control in atrial fibrillation
- beta-blocker (atenolol)
- calcium channel blocker (diltiazem)
- digoxin
Reducing stroke risk in atrial fibrillation
- long-term anticoagulation
- DOACs most common
- warfarin
Determining stroke risk in atrial fibrillation
CHA2DS2VaS
CHA2DS2VaS
Congestive HF (1)
Hypertension (1)
Age (> 75 (2), 65-75 (1))
Diabetes (1)
Stroke, TIA, thromboembolism (2)
Vascular disease (1)
Sex - female (1)
Interpreting CHA2DS2VaS scores for anti-coagulation
0 = no anticoagulation needed
1 = men consider, females not needed
2 = offer anticoagulation
What to do if CHA2DS2VaS score is 0
Echo to rule out valvular cause of AF
Determining bleeding risk in patients requiring anti-coagulation for AF
ORBIT
haemoglobin low (anaemia) (2)
age > 74 (1)
bleeding hx. (2)
renal impairment (GFR < 60) (1)
on antiplatelets (1)
Torsades de pointes
- ‘twisting of the points’
- polymorphic VT with long QT interval
Managing torsades de pointes
IV magnesium sulphate
Causes of long QT on ECG
- congenital
- antiarrhythmics
- tricyclic antidepressants
- macrolides (e.g. erythromycin)
- electrolyte disturbance
- hypothermia
- subarachnoid haemorrhage
- myocarditis
