Arrhythmias Flashcards
Cardiac arrest rhythms
Shockable:
Ventricular tachycardia
Ventricular fibrillation
Non-shockable:
Pulseless electrical activity (all activity except VF/VT including sinus rhythm without a pulse)
Asystole
Tachycardia treatment in unstable pt
3 synchronised shocks
Amiodarone infusion
Tachycardia with narrow complex
AF
Atrial flutter
Supraventricular tachycardia
Tachycardia with broad complex
Ventricular tachycardia
SVT with bundle branch block
AF variation?
Atrial flutter pathophysiology
Reentrant rhythm
Electrical signal recirculates atrium in self-perpetuating loop
Atrial contraction at 300bpm
Passess through AVN every 2nd lap due to long refractory period
Ventricular contraction at 150bpm
Atrial flutter associated conditions
Hypertension
Ischaemia heart disease
Cardiomyopathy
thyrotoxicosis
Atrial flutter ECG
sawtooth appearance of p waves
Atrial flutter treatment
Rate/rhythm control - beta blockers / cardioversion
Treat reversible cause
Radiofrequency ablation of reentrant rhythm
Anticoagulation based on CHA2DS2VASc score
No flecanide - 1:1 AV conduction - tachycardia
Atrial fibrillation pathophysiology
Disorganised electrical activity overrides SAN
Atrial contraction uncoordinated rapid and irregular
Irregular conduction of electrical impulses to ventricles
Irregularly irregular ventricular contractions
Tachycardia
Heart failure (poor filling duirng diastole)
Risk of stroke
AF presentation
Palpitations
SOB
Syncope
Associated conditions - stroke, sepsis, thyrotoxicosis
Irregularly irregular pulse differentials
AF
Ventricular ectopics - disappear when HR increases - exercise test
AF on ECG
Absent p waves
Narrow QRS tachycardia
Irregularly irregular ventricular rhythm
AF - valvular vs non-valvular
Valvular - moderate/severe mitral stenosis or mechanical heart valve - lead to AF
Non-valvular - any other valve pathology, and non-valve pathology
Causes of AF
mrs SMITH
Sepsis
Mitral valve pathology
Ischaemic heart disease
Thyrotoxicosis
Hypertension
AF principles of treatment
Rate / rhythm control
Anticoagulation to prevent stroke
AF rate control pathophysiology
Ventricles fill up by suction/gravity not atrial contraction
Heart rate below 100bpm = more time to fill up
First line
AF rate control options
- Beta blocker (atenolol 50-100mg OD)
- CCB (diltiazem) (not in heart failure)
- Digoxin (monitoring, risk of toxicity, only in sedentary people)
AF rhythm control indications
Reversible cause
New onset AF
Heart failure
Remain symptomatic despite rate control
AF immediate cardioversion indications
AF present for less than 48 hours
Haemodynamically unstable
AF delayed cardioversion indications
AF present for more than 48 hours
Stable
AF delayed cardioversion waiting
Anticoagulation for minimum of 3 weeks before
Otherwise clot mobilised - stroke
Rate control
AF pharmacological cardioversion
Flecanide
Amiodarone (if structural heart disease)
AF electrical cardioversion
Sedation/GA
Cardiac defibrillator
AF LT rhythm control
- Beta blockers
- Dronedarone (if successful cardioversion)
- Amiodarone (heart failure of LV dysfunction)
Paroxysmal AF
Intermittent
No longer than 48 hours
‘Pill in pocket’ approach if not underlying structural disease - flecanide
Anticoagulation
AF anticoagulation
Blood stagnation in atrial appendage
Thrombus - embolus - ischaemic stroke
Reduces risk of stroke by 2/3rds
3% risk of bleeds
Warfarin
Vitamin K antagonist
Prolongs prothrombin time
International normalised ratio (INR) = prothrombin time of normal adult vs prothrombin time of pt
Target INR = 2-3
INR affected by many antibiotics - influence P450 system in liver - influence warfarin
INR affected by diet (vit K / P450) - leafy green veg, cranberry juice, alcohol
Reversible with vitamin K
Half life of 1-3 days
DOACs
7-15 hour half life
No monitoring
No major interactions
Equal at preventing strokes / bleed risks
Reverse:
Andexanet alfa (apixiban and rivaroxaban)
Indarucizumab (dabigatran)
CHADSVASC
> 1 = consider anticoagiulation
Risk of stroke /TIA in pts with AF
Congestive heart failure
Hypertension
A2 = age>75 = 2
Diabetes
S2 = stroke/Tia = 2
Vascular disease
Age 65-74
Sex (female)
ORBIT
Risk of major bleeding while on anticoagulations
Low Hb/haemocrit
Age 75+
Previous GI / intracranial bleeding
Renal function (GFR<60)
Antiplatelet medications
HAS-BLED
Assess risk of bleeding
Hypertension
Abnormal renal and liver function
stroke
Bleeding
Labile INRs
Elderly
Drugs/alcohol
Supra-ventricular tachycardias definiton
electrical signal reenters atria from ventricles
Self-perpetuating electrical loop
Narrow complex tachycardia
SVT types
AVN reentrant tachycardia (through AVN)
AV reentrant tachycardia (accessory pathway - Wolff-parkinson-white syndrome)
Atrial tachycardia - other than SAN
SVT acute management
Continuous ECG monitering
Valsalva manoeuvre - blow against resistance
Carotid sinus massage
Adenosine
Verapamil
Direct current cardioversion
Adenosine
Slows cardiac conduction
Interrupts AVN / accessory pathway
Resets sinus rhythm
Rapid bolus into large proximal cannula
Asystole/bradycardia
Avoid if asthma, COPD, heart failure, heart block, hypotension
Warn pt about feeling of dying
6mg then 12mg then 12mg again
SVT LT management
Beta blockers
CCB
Amiodarone
Radiofrequency ablation
Wolff-Parkinson White Syndrome
Accessory pathway (bundle of Kent)
Radio frequency ablation of this = definitive treatment
ECG:
Short PR interval
Wide QRS complex
Delta wave
If AF/atrial flutter - electrical activity can pass onto ventricles via accessory pathway - polymorphic wide complex tachycardia (do not give antiarrhythmic medication in this case)
Radiofrequency ablation
Catheter ablation
Heat applied to abnormal area
AF
Atrial flutter
SVT
WPW syndrome
Torsades de pointes pathophysiology
Polymorphic ventricluar tachycardia
Prolonged QT interval (prolonged repolarisation)
Random spontaneous depolarisation (afterdepolarisations)
Ventricles stimulate recurrent contractions without normal repolarisation
Terminate or progress to VT - cardiac arrest
Torsades de pointes ecg
QRS height gets progressively smaller, then progressively larger
Causes of prolonged QT
Long QT syndrome
Antipsychotics
Citalopram
Flecanide
Sotalol
Amiodarone
Macrolide antibiotics
Hypokalaemia
Hypomagnesaemia
Hypocalaemia
Torsades de pointes acute management
Correct cause
Magnesium infusion
Defibrillation if VT occurs
Prolonged QT LT management
Avoid medications
Correct electrolyte disturbances
Beta blockers (not sotalol)
Pacemaker / implantable defibrillator
Ventricular ectopics definition
Premature ventricular beats
Random electrical discharges outside of atria
Ventricular ectopics ECG
individual, random, abnormal broad QRS complexes
Bigeminy
Ventricluar ectopics occur after every sinus beat
Ventricular ectopics management
Check for anaemia, electrolytes and thyroid abnormalitites
reassurance to healthy people
Seek expert advice if heart condition or symptoms other than palpitations
First degree heart block
Delayed AV conduction
Every atrial impulse leads to ventricular contraction
PR interval > 0.2s
Second degree heart block
Some atrial impulses do not make it to the ventricles
Wenckebach’s phenomenon (Mobitz type I):
Increasing PR interval
Until p wave no longer conducts to ventricles - absent QRS
PR interval then returns to normal
Mobitz type II:
Intermittent failure of AV conduction
Missing QRS complexes
3:1 block = every 3 p waves, a missing QRS
Risk of asystole
Third degree heart block
Complete
No observable relationship between p waves and QRS
Risk of asystole
AVN block/bradycardia treatment if unstable/risk of asystole
- Atropine 500mcg IV (anti-muscarinic - inhibit PNS - pupil dilation, urinary retention, dry eyes, constipation)
- Atropine repeated (up to 6 doses)
- Other inotropes (noradrenalin)
- Transcutaneous cardiac pacing
- Transvenous cardiac pacing
- Permanent implantable pacemaker when available
Pacemaker indications
Symptomatic bradycardia
Mobitz type to AV block
Third degree heart block
Severe heart failure (biventricular pacemaker)
Hypertrophic obstructive cardiomyopathy (ICD)
Pacemaker types
Single chamber - RA or RV
Dual chamber - RA and RV
Biventricular / triple chamber - RA, RV and LV - heart failure - cardiac resynchronisation therapy
Implantable cardioverter defibrillators - monitor and deliver shock if detect shockable arrythmia
Pacemaker ECG
Sharp vertical line on all leads
Before p or QRS = single
Before both = dual
Pacemaker info
Pulse generator and pacing leads
Implanted under left anterior chest wall / axilla
5 years
MRI compatible
