Arrhythmias Flashcards
(35 cards)
Tachyarrhythmias definition
How to manage?
Step 1
Heart rate > 100bpm
Is there a pulse? Arrest or peri-arrest?
If pulse then move on to step 2
Tachyarrhythmias management
There is a pulse
What is step 2?
Any adverse features?
- Mycardial ischameia
- Syncope
- Shock - Systolic BP <90
- Heart failure
Management of tachyarrhythmia with adverse features
- Synchronised DC cardioversion - up to 3 shocks
- Amiodarone 300mg IV over 20-30 minutes
Tachyarrhythmia management step 3
Tachyarrhythmia with no adverse features
ECG findings - Check QRS + rhythm
- Broad QRS (regular)
- Broad QRS (irregular)
- Narrrow QRS (regular)
- Narrow QRS (irregular)
Causes of broad complex regular tachyarrhythmias
- Ventricular tachycardia (VT) - most common
- SVT with BBB
How to manage ventricular tachycardia?
- Monitor for adverse features (risk of decaying to cardiac arrest)
- Amiodarone 300mg IV over 20 minutes
- Amiodarone 900mg IV over 24 hours
Causes of broad complex irregular tachyarrhythmias
- Torsades de pointes
- Atrial fibrillation + bundle branch block (use previous ECGs to help distinguish)
What causes torsades de pointes?
QT prolongation
Features of torsades de pointes
- Polymorphic VT = multiple different QRS shapes
- QT prolongation
- Distinguish from VF by presence of a pulse
How to manage torsades de pointes?
Magnesium sulphate 2g IV
Definition of supraventricular tachycardia
SVT describes any tachyarrhythmia that arises from above the level of the bundle of His
Key examples of supraventricular tachycardia
- Atrial fibrillation
- Atrial flutter
- Paroxysmal supraventricular tachycardia
Main causes of narrow complex regular tachycardia
- Sinus tachycardia (most common but not pathological)
- Atrial flutter with regular AV conduction
- AVNRT
- AVRT
Management of pathological narrow complex regular tachycardia
- Monitor for adverse features
- Vagal manoeuvres
- Carotid massage or Valsalva manoeuvre
- Adenosine 6mg IV as a rapid bolus
- Continuous ECG trace
- Feeling of impending doom
- Adenosine 12mg IV (can give twice)
- If no response consider atrial flutter (AVNRT/AVRT less likely)
Causes of sinus tachycardia
- Exercise
- Pulmonary embolism
- Infection (causing hypoxia, acidosis or sepsis)
- Pain
- Anxiety
- Drugs: caffeine, cocaine, salbutamol, tricyclics antidepressants
Definition of atrial flutter
A type of sinus tachycardia that arises due to a re-entry circuit within the right atrium, resulting in an atrial rate of ~300bpm
Causes of atrial flutter
Pirates
- Pulmonary - PE and COPD
- Ischaemic heart disease
- Rheumatic heart disease
- Anaemia, alcohol and advancing age
- Thyroid disease - hyperthyroidism
- Electrolytes - Mg2+ (low), K+ (low/high)
- Sepsis and sleep apnoea
What pulse is expected in atrial flutter?
Around 150bpm
Ventricular rate is determined by tha AV conduction ratio (most common 2:1). This is a physiological heart block/
What is AVNRT?
What heart rate is seen?
Atrioventricular nodal re-entry tachycardia
140-280 bpm
Difference between AVNRT and AVRT
AVRNT: a functional re-entry circuit within the AV node
AVRT: an anatomical circuit
Causes of AVNRT
- Occur spontaneously
- Exertion
- Drugs: caffeine, alcohol, sympathomimetics
AVNRT pathophysiology
Premature atrial complex (PAC) (due to exertion/drugs/spontaneous), fast pathway still in refractory period so conduction travels around slow pathway (which has a shorter refractory period).
If the slow pathway conducts all the way around the fast pathway before anterograde fast conduction, a circus rhythm occurs.
Pathophysiology of AVRT
- An anatomical circuit exitsts that bypasses the AV node
- This accessory pathway, sometimes called the bundle of Kent, is a key feature of Wolff-Parkinson-White syndrome
- AVRT arises due to a re-entry circuit
Causes of narrow complex irregular tachyarrhythmias
- Atrial fibrillation (AF) - most common
- Atrial flutter with variable block


