Arrhythmias Flashcards
Arrhythmia cardiac causes
IHD
Cardiomyopathy
Myo/pericarditis
Aberrant conduction pathways
Structural changes
Arrhythmia non-cardiac causes
Caffeine, smoking, alcohol
Drugs (beta2-agonists, digoxin, l-dopa, tricyclics)
Metabolic imbalance
Phaeochromocytoma
Pneumonia
Arrhythmia history qs
Detailed history of palpitations (speed, rate, precipitating factors)
Drug Hx
Family Hx of cardiac disease + sudden death
Syncope during exercise
Continuous ECG monitoring options
Telemetry - in hospital for high risk (e.g. post STEMI)
Exercise ECGs
Holter monitors (worn during daily life)
Loop recorders - pt clicks button to save, following event
Pacemakers + ICDs store data of activity
What is sick sinus syndrome
Usually caused by SAN fibrosis, typically in elderly
Variable dysfunction, can be tachy or brady, or both
Sick sinus syndrome management
VTE prophylaxis if AF episodes
Permanent pacemakers for symptomatic bradycardia/ sinus pauses
Narrow complex tachycardia definition
ECG shows rate >100bpm and QRS <120ms
Ventricles depolarised via normal conduction pathways
Irregular narrow complex tachycardias
Sinus arrhythmia/ sinus rhythm + ectopic beats
AF
Atrial flutter with variable block, irregular ventricular rhythm
Multifocal atrial tachycardia (usually associated with COPD)
Regular narrow complex tachycardias
Sinus tachycardia from SAN
Focal atrial tachycardia (Atrial cell group outpaces SAN) Atrial flutter (sawtooth baseline, ventricular rate is factor of 300)
AVRT - atria->AVN->ventricles->atria via accessory pathway
AVNRT (circuits within AVN)
Junctional tachycardia - AVN cells pace
Bundle branch block
All tachycardia initial emergency management
Check pulse -> arrest protocol if not present, otherwise:
O2 if sats<90, IV access + 12 lead ECG
Check for adverse signs then get expert help if present
Narrow complex tachycardia emergency management with adverse signs
Expert help
Sedation
Up to 3 DC shocks:
70-120J for first (120-150 in AF)
then 120-360J for subsequent
Correct K, Mg, Ca abnormalities
Amiodarone 300mg IV over 20mins, consider repeat shock then 900mg/24h IVI via central line
Tachycardia adverse signs
Shock
Chest pain/ Ischaemia on ECG
Heart failure
Syncope
Narrow complex tachycardia emergency management no adverse signs
No regular rhythm then treat as AF
Start continuous ECG trace if regular rhythm, vagal manoeuvres (carotid sinus massage, Valsalva)
If failed then adenosine 6mg bolus IV, then 12mg, further 12mg if necessary
Verapamil 2.5-5mg over 2 mins if adenosine CI/ fails
If sinus rhythm achieved, assess ECG and consider referral
If sinus not achieved, potential atrial flutter so rate control with beta-blocker + expert help
Acute AF treatment
If onset <48h or effectively anti-coagulated >3wk, consider cardioversion with shock or flecanide 300mg PO (if no structural damage) or amiodarone 300mg IVI over 20-60mins
Rate control
Anticoagulation with warfarin NOAC
Acute AF treatment - rate control
Rate control:
Beta-blocker (bisoprolol 1-10mg IV) or
Rate-limiting Ca channel blocker e.g. Verapamil 5-10mg IV (not with bb)
Digoxin 500µg PO in heart failure
Amiodarone (may also control rhythm)
Broad complex tachycardia definition
ECG shows rate >100 and QRS >120ms
If no clear QRS then VF or asystole
Broad complex tachycardia differentials
VF
VT
Torsade de pointes (polymorphic VT, VT with varying axis)
Antidromic AVRT
Narrow complex tachycardia combined with BBB or metabolic broad QRS
ECG making VT more likely than SVT
+ve/-ve concordance in all chest leads
QRS>160ms
LAD
AV dissociation
Fusion/capture beats
RSR’ pattern where R is taller than R’
Ventricular ectopic beat types
Bigeminy - ectopic alternate beats
Trigeminy - every 3rd beat is ectopic
Couplet - 2 ectopic beats together
Triplet - 3 ectopic beats together
When to investigate ventricular ectopics
> 60/hour
Couplets/triplets
Post-MI
Broad complex tachycardia emergency management with adverse signs
Expert help
Sedation
Up to 3 DC shocks, 120-150J for first then 150-360J for subsequent
Correct K, Mg, Ca abnormalities
Amiodarone 300mg IV over 20mins, consider repeat shock then 900mg/24h IVI via central line
Further cardioversion if needed
For refractory, expert help + consider procainamide/ overdrive pacing
Broad complex tachycardia emergency management no adverse signs
Correct electrolyte problems
If regular rhythm:
Give amiodarone 300mg IV over 20mins then 900mg/24h
If known SVT + BBB, treat as narrow complex
If irregular rhythm:
Expert help
If no success, sedation then synchronised DC shock 150-200J, 150-360J x2
AF features
300-600bpm
Irregularly irregular
Apical pulse greater rate than radial
1st heart sound variable intensity
AF causes
Heart failure
MI
PE
HT
Hyperthyroidism
Caffeine/alcohol
Post-op
AF tests
ECG: absent P waves, irregular QRS
Echo for LA enlargement, mitral valve disease, poor LV function
Chronic AF management
Anticoagulation
Beta-blocker/ Verapamil for rate control, digoxin added if needed
Rhythm control with elective DC cardioversion (echo first for thrombi) or Flecainide for pharm cardioversion
AVN ablation with pacing in refractory to rhythm control
Sotalol/ flecainide PRN for paroxysmal infrequent AF with BP>100 systolic + no LV dysfunction
Atrial flutter treatment
Same as AF regarding rate + rhythm control
DC cardioversion preferred to pharm, start with 70-120J
Anticoagulation in chronic AF
CHADSVASC score, balanced against risks for anticoagulation with HAS-BLED score
Acute AF anticoagulation
Use heparin until full assessment
Apixaban or warfarin for 3wks before cardioversion if high risk of emboli
Indications for temporary pacing
Symptomatic bradycardia unresponsive to atropine
Suppression of drug-resistant tachyarrhythmias
Post anterior MI with (complete AV block, Mobitz type I/II AV block, non-adjacent bi/tri fascicular block)
Post inferior MI unless rate >40-50 + narrow QRS
Special situation e.g. anaesthesia/ surgery
Indications for PPM
Complete AV block
Mobitz II AV block
Persistent AV block after MI
Symptomatic bradycardias
Drug-resistant tachyarrhythmias
Heart failure
Pacemaker letter codes
1 - Paced: (A)tria, (V)entricles, (D)ual chamber
2 - Sensed: (A)tria, (V)entricles, (D)ual chamber, n(O)ne
3 - Response: (T)riggered, (I)nhibited, (D)ual
4 - Pacemaker response: (R)ate modulation, (P)rogrammable, (M)ultiprogrammable
5 - will (P)ace pt in tachy; will (S)hock pt in tachy; (D)ual ability to do both; n(O)ne of these
What is cardiac resynchronisation therapy
Improves sync of cardiac contraction in those with ejection fraction <35% and QRS>120ms
Involves septal and lateral AV wall pacing ± atrial lead ± defib
What is a pacemaker fusion beat
Union of native depolarisation + pacemaker impulse
What is a pacemaker pseudofusion beat
Pacemaker impulse just after native, so ineffective but distorts QRS morphology
What is a pacemaker pseudopseudofusion beat
DVI pm gives atrial spike with native QRS complex, atrial output is ineffective
What is pacemaker syndrome
Single-chamber pacing retrograde conduction to atria which contract during ventricular systole, retrograde flow into pulmonary veins
What is pacemaker-mediated tachycardia
Retrograde conduction to atrium sensed by pm + ventricle shock given, causes retrograde atrial conduction again so loop
Congenital arrythmogenic conditions
WPW
LQTS
Arrhytmogenic RV cardiomyopathy
Brugada
What is WPW
Congenital accessory conduction pathway between atria + ventricles
Causes short PR, wide QRS with slurred upstroke (∂ wave) and ST-T changes on ECG
WPW types
Type A: +ve ∂ wave on V1
Type B: -ve ∂ wave on V1
What are Long QT syndromes
Channelopathies resulting in prolonged repolarisation
Predisposes pt to ventricular arrhythmias classically Torsades de pointes
What is ARVC
RV myocardium replaced with fibro-fatty material
Causes epsilon wave, T inversion and broad QRS in V1-V3 on ECG
What is Brugada
Sodium channelopathy
Causes coved ST elevation in V1-V3 + suggestive clinical hx
Torsades de pointes treatment
IV MgSO4
Bifascicular block conditions
RBBB
Left anterior/posterior hemiblock
Trifascicular block conditions
RBBB
Left anterior/posterior hemiblock
1st ˚ heart block
