Arrhythmias Flashcards
definition of
- bradycardia
- tachycardia
bradycardia = < 60 bpm tachycardia = > 100 bpm
causes of sinus bradycardia
physiological
beta blockers
ischaemia
sick sinus syndrome
hypothermia
acute management of bradycardia
1st line: 500 micrograms atropine - can repeat doses up to 3g
2nd line options: isoprenaline / transcutaneous pacing if unstable
a narrow complex tachycardia (QRS <0.12s) originates where?
above the AV node - an ‘SVT’
what causes an SVT
an electrical signal re-entering the atria from the ventricles - creates a self perpetuating electrical loop
what are the main types of SVT
- Atrioventricular nodal re-entrant tachycardia: re-entry point is back through AV node
- Atrioventricular re-entrant tachycardia: re-entry point is an accessory pathway (e.g. Wolf Parkinson White)
- Atrial tachycardia: electrical activity originates somewhere other than SA node
1st line management for an SVT
vagal manœuvres - valsalva - carotid sinus massage
2nd line management for SVT
if vagal manoeuvre unsuccessful:
- IV adenosine
- IV verapamil in asthmatics
DC cardioversion if above unsuccessful
what is the accessory pathway called in Wolf Parkinson white
Bundle of Kent
ECG changes in Wolf Parkinson White
slurred upstroke of QRS - delta wave
short PR
left axis deviation (right sided pathway)
Definitive treatment of Wolf Parkinson White
radio frequency ablation
characteristic appearance of atrial flutter on ECG
Sawtooth baseline
characteristic appearance of atrial fibrillation on ECG
irregularly irregular
absent P waves
1st line drug for controlling rate in atrial fibrillation + flutter
beta-blocker
what patients are offered immediate cardioversion for AF?
If AF present for < 48 hours or severely unstable
options for cardioversion in AF
pharmacological:
- flecainide
- amiodarone if structural heart disease
electrical:
- DC cardioversion
what patients are suitable for delayed cardioversion in AF?
what must be done beforehand?
AF present for > 48 hours + stable
anticoagulate for 3 weeks prior
what is first degree heart block
fixed prolonged PR interval (>0.2s)
what is second degree heart block: Mobitz Type 1
gradual lengthening of PR interval until a QRS complex is dropped
what is second degree heart block: Mobitz Type 2
fixed prolonged PR interval with QRS complexes dropped in
- 2: 1 (every other p wave followed by QRS)
- 3:1 ( 2 P waves with no QRS followed by 1 P wave with a QRS)
what is 2:1 heart block
2 P waves for each QRS complex
( 1 P wave not followed by QRS, next P wave followed by QRS)
what is third degree heart block
complete heart block
- no relationship between P waves + QRS
what types of heart block require pacing
Mobitz type 1 if symptomatic
Mobitz type 2 + 3rd degree – permanent pacing
what is bifasicular heart block
RBBB with left axis deviation
what is trifasicular block
RBBB + Left axis deviation + 1st degree heart block (fixed prolonged PR)
ECG appearance of ventricular tachycardia
regular broad QRS
>100 bpm
no P or T waves
management of VT in
- stable patient
- unstable patient
stable = amiodarone
unstable = DC cardioversion
what is Torsades de Pointes
polymorphic VT that occurs in patients with long QT
precipitated by:
- hypokalaemia / hypocalcaemia / hypomagnesmia
- amiodarone, citalopram, macrolides
management of torsades de pointes
correct electrolyte disturbances / remove causative drugs
magnesium sulphate infussion
defibrillation if VT occurs
when does ventricular fibrillation occur
post MI
What rhythms can be shocked
pulseless VT
VF
what are ventricular ectopics
premature ventricular beats
- individual random broad QRS complexes on background of normal ECG
what is ventricular bigeminy
ventricular ectopic following every sinus beat
what is an escape beat
a beat that comes late
what is ventricular hypertrophy?
most common cause?
increase in left ventricle muscle mass not volume
hypertension
voltage criteria for LVH
negative component in V2 and positive component in V5 must add to > 7
affect of LVH on the heart
strain
- shows as ST depression
- blood supply cant match demand
