Arrhythmias (Sandilands flow chart)

Question 1

What ECG morphologies are used to categories tachycardias?

Answer 1

• Narrow vs Broad complex QRS
• Regular vs irregular R-R intervals
• Presence of P waves

Question 2

Name 4 regular arrhythmias associated with P waves and narrow QRS complexes

Answer 2

• Sinus tachycardia
• Atrial flutter
• SVT (AVRT)
• Ectopic atrial tachycardia

Question 3

Name the regular narrow QRS complex arrhythmia without P waves

Answer 3

AVN re-entrant tachycardia

Question 4

Describe atrioventricular re-enterant tachycardia

Answer 4

Formation of an accessory pathway between the atria and ventricles enable conduction to spread up from the ventricles into the atria.

The atria contract earlier than the SAN ➔ tachycardia unto 200-300bpm

Question 5

Define Wolff-Parkinson-White Syndrome

Answer 5

Episodes of tachycardia, with the presence of a congenital accessory pathways (Bundle of Kent).

Asymptomatic referred to as having WPW pattern on ECG.

Delta waves are characteristic of WPW.

Question 6

Describe AVN re-entrant tachycardia

Answer 6

Premature atrial beat travels down (anterograde) the slow alpha pathway and up (retrograde) the fast beta pathway whilst it is still in its long refractory period.

This creates a slow-fast (typical AVNRT) re-entry loop that continuously depolarises the bundle of His ➔ tachycardia.

Question 7

Outline the presentation of AVRT and AVNRT

Answer 7

Short-duration symptoms of palpitations, SoB, dizziness, syncope (rare). Rarely life-threatening.

Commonly terminated by Valsalva manoeuvres.

Question 8

Outline management of AVRT and AVNRT

Answer 8

Acute:
- Valsalva manoeuvre or carotid sinus massage
- IV adenosine: highly effective for AVRT and AVNRT
NB. Adenosine contraindicated in asthmatics

Long-term:

• Rate control (Beta-blockers, CCBs, digoxin)
• DC cardioversion
• Accessory pathway ablation: definitive Tx

Question 9

Differentiate Atrial Fibrillation and Atrial Flutter

Answer 9

Atrial fibrillation is an irregular-irregular tachycardia without P waves. Wavy baseline is typical. Disorganised contraction of atria.

Atrial flutter is a regular tachycardia with P waves. Sawtoothing is typical. Generally faster rate than AF. Organised contraction of atria ➔ more impulses pass the AVN

Question 10

Outline the types of ventricular arrhythmia

Answer 10

• Life-threatening ventricular tachyarrhythmias
• Normal heart ventricular tachycardia
• Non-sustained ventricular tachycardia
• Ventricular ectopics

Question 11

State 4 causes of VT

Answer 11

• MI
• Drugs
• Hypokalaemia
• Hypomagnesemia
• Long QT syndrome - torsades de pointes