Arrhythmias Flashcards
What is an arrhythmia?
An arrhythmia is an abnormal heart rhythm resulting from an interruption to the normal electrical signals that coordinate the heart muscle’s contraction.
What are the two categories of cardiac arrest rhythms?
Shockable rhythms:
* Ventricular tachycardia (VT)
* Ventricular fibrillation (VF)
Non-shockable rhythms:
* Pulseless electrical activity (PEA)
* Asystole
What is narrow complex tachycardia?
Narrow complex tachycardia is a fast heart rate with a QRS complex duration of less than 0.12 seconds.
What are the four main differentials for narrow complex tachycardia?
- Sinus tachycardia
- Supraventricular tachycardia (SVT)
- Atrial fibrillation
- Atrial flutter
How can you distinguish SVT from sinus tachycardia?
SVT has an abrupt onset and very regular pattern, while sinus tachycardia has a more gradual onset with variability in the rate.
How can you identify atrial fibrillation on an ECG?
Atrial fibrillation can be identified by the absence of P waves and an irregularly irregular ventricular rhythm.
What is atrial flutter and how does it appear on an ECG?
Atrial flutter is caused by a re-entrant rhythm in the atria, resulting in a saw-tooth appearance on the ECG with a ventricular rate of around 150 beats per minute.
How is broad complex tachycardia defined?
Broad complex tachycardia refers to a fast heart rate with a QRS complex duration of more than 0.12 seconds (more than 3 small squares on ECG).
What are the types of broad complex tachycardia?
- Ventricular tachycardia (treated with IV amiodarone)
- Polymorphic ventricular tachycardia (treated with IV magnesium)
- Atrial fibrillation with bundle branch block (treated as AF)
- Supraventricular tachycardia with bundle branch block (treated as SVT)
What is torsades de pointes?
Torsades de pointes is a type of polymorphic ventricular tachycardia caused by prolonged QT interval, characterized by twisting QRS complexes on an ECG.
What are the causes of prolonged QT interval?
- Long QT syndrome
- Medications (e.g., antipsychotics, amiodarone)
- Electrolyte imbalances (e.g., hypokalaemia, hypomagnesaemia)
What is the treatment for torsades de pointes?
- Correct underlying causes (e.g., electrolyte disturbances or medications)
- Magnesium infusion
- Defibrillation if ventricular tachycardia occurs
What are ventricular ectopics?
Ventricular ectopics are premature ventricular beats caused by random electrical discharges outside the atria, often appearing as isolated, random, broad QRS complexes on an ECG.
What is bigeminy?
Bigeminy refers to a rhythm where every other beat is a ventricular ectopic, appearing as a normal beat followed by an ectopic beat, and so on.
How is heart block classified?
Heart block is classified into three types:
* First-degree: Delayed conduction, PR interval > 0.2 seconds
* Second-degree: Some P waves not followed by QRS (Mobitz type 1 and 2)
* Third-degree: Complete block, no relationship between P waves and QRS complexes
What is the treatment for third-degree heart block?
Third-degree heart block is managed with temporary cardiac pacing and potentially a permanent pacemaker.
What is sick sinus syndrome?
Sick sinus syndrome is a condition that causes dysfunction in the sinoatrial node, leading to sinus bradycardia, sinus arrhythmias, and prolonged pauses.
What is bradycardia, and when is it normal?
Bradycardia refers to a slow heart rate (<60 bpm), which can be normal in healthy, fit individuals without causing symptoms.
What is the management for unstable patients with bradycardia?
- Intravenous atropine (first line)
- Inotropes (e.g., isoprenaline)
- Temporary cardiac pacing (transcutaneous or transvenous)
- Permanent pacemaker if required
What is the role of atropine in bradycardia management?
Atropine is an antimuscarinic medication that works by inhibiting the parasympathetic nervous system, increasing the heart rate. It can cause side effects like pupil dilation and dry mouth.
