Arrhythmia Flashcards
What are arrhythmias?
Abnormal heart rhythms resulting from an interruption to the normal electrical signals that coordinate the contraction of the heart muscle.
What are the four possible rhythms in a pulseless patient?
- Shockable rhythms: Ventricular tachycardia, Ventricular fibrillation
- Non-shockable rhythms: Pulseless electrical activity, Asystole
What defines a shockable rhythm?
A rhythm where defibrillation may be effective - VT and VF
What defines a non-shockable rhythm?
A rhythm where defibrillation will not be effective - Asystole, pulsless electrical activity (PEA)
What is narrow complex tachycardia?
A fast heart rate with a QRS complex duration of less than 0.12 seconds.
What are the four main differentials of narrow complex tachycardia?
- Sinus tachycardia
- Supraventricular tachycardia
- Atrial fibrillation
- Atrial flutter
How is sinus tachycardia characterized on an ECG?
Normal P wave, QRS complex, and T wave pattern.
What distinguishes supraventricular tachycardia (SVT) from sinus tachycardia?
SVT has an abrupt onset, very regular pattern without variability, while sinus tachycardia has a gradual onset and more variability.
How can atrial fibrillation be identified on an ECG?
Absent P waves and an irregularly irregular ventricular rhythm.
What is the typical atrial rate in atrial flutter?
Around 300 beats per minute.
What is the treatment for patients with narow complex tachycardia and life-threatening features in arrhythmias?
E.g. shock (Diastolic BP < 50), LOC, syncope, severe HF, muscle ischaemia
1st: Synchronised DC cardioversion (w/ sedation)
2nd: IV Amioderone
What is broad complex tachycardia?
A fast heart rate with a QRS complex duration of more than 0.12 seconds.
What are the categories of broad complex tachycardia?
- Ventricular tachycardia or unclear cause
- Polymorphic ventricular tachycardia (such as torsades de pointes)
- Atrial fibrillation with bundle branch block
- Supraventricular tachycardia with bundle branch block
What causes atrial flutter?
A re-entrant rhythm in either atrium due to an extra electrical pathway.
What is a prolonged QT interval?
A QT interval of more than 440 milliseconds in men and more than 460 milliseconds in women.
What does a prolonged QT interval represent?
Prolonged repolarisation of the heart muscle cells after a contraction.
What is torsades de pointes?
A type of polymorphic ventricular tachycardia characterized by a prolonged QR interval and afterdepolarisation causing spontaneous depolarisation –> twisting of the spikes on an ECG.
What are causes of prolonged QT interval?
- Long QT syndrome
- Medications (e.g., antipsychotics, sotalol)
- Electrolyte imbalances (e.g., hypokalaemia)
What is the initial management for torsades de pointes?
Magnesium infusion and correcting electrolyte disturbances.
What are ventricular ectopics?
Premature ventricular beats caused by random electrical discharges outside the atria.
What does bigeminy refer to in the context of ventricular ectopics?
Every other beat is a ventricular ectopic.
What is first-degree heart block?
(common in atheletes)
- Delayed conduction through the atrioventricular node
- PR interval prolonged ( >0.2 seconds, 5+ small squares)
- BUT every P waves HAS a QRS complex
What distinguishes Mobitz type 1 from Mobitz type 2 heart block?
Mobitz type 1 has progressively longer PR intervals until a QRS complex is dropped
Mobitz type 2 has intermittent failure with a normal PR interval - often a stereotyped loss of the QRS complex
What is third-degree heart block also known as?
Complete heart block.
What defines bradycardia?
A slow heart rate, typically less than 60 beats per minute.
What are some causes of bradycardia?
- Medications (e.g., beta blockers)
- Heart block
- Sick sinus syndrome
- Hypothermia
What is asystole?
The absence of electrical activity in the heart.
What is the first-line treatment for unstable patients at risk of asystole?
Intravenous atropine.
What are the options for temporary cardiac pacing?
- Transcutaneous pacing
- Transvenous pacing
What is the mechanism of action of atropine?
It inhibits the parasympathetic nervous system.
Treatment for SVT
1st = vagal manouvers
2nd = IV Adenosine (6mg - 12mg - 18mg)
When do you use the following drugs:
- Adenosine
- Amioderone
- Atropine
Adenosine = SVT
Amioderone = Narrow or broad complex tachycardia with life-threatening features after DC sardioversion
Atropine= Bradycardia/Asystole
