Narrow complex tachycardias

Narrow Complex Tachycardias

Definition: Tachycardia (QRS frequency >100/min) with QRS duration <100ms

Origin: Atria, sinus node, atrioventricular node, His bundle

Types:

1. Sinus tachycardia
2. Inappropriate sinus tachycardia
3. Sinoatrial reentrant tachycardia
4. Atrial tachycardia
5. Multifocal atrial tachycardia
6. Atrioventricular reentrant tachycardia
7. Atrioventricular nodal reentrant tachycardia
8. Junctional ectopic tachycardia
9. Atrial fibrillation
10. Atrial Flutter

1. Sinus Tachycardia (ST)

Characteristics: 

• ST is characterized by a heart rate of >100 bpm with a normal P wave morphology and axis and a normal PR interval. 
• Onset and termination are gradual.

Clinical significance: 

• Normal in young children
• In adults it is seen in physiological stress (physical exercise, anxiety)or pathological stress (fever, hypotension, heart failure, thyrotoxicosis etc)

Treatment: TREAT UNDERLYING CAUSE

2. Inappropriate sinus tachycardia (IST)

also called "Chronic non paroxysmal sinus tachycardia"

Characteristics:

• IST is characterised by P waves with an axis and morphology corresponding to those during sinus rhythm. 
• Elevated resting heart rate and/or exaggerated heart rate response to excersise.
• The onset and termination are gradual. 
• Unknown cause. Abnormal autonomic control. Often related with Postural Orthostatic Tachycardia Syndrome (POTS).
• No apparent heart disease or other cause of sinus tachycardia

Treatment: TREAT UNDERLYING CAUSE

3. Sinoatrial reentrant tachycardia (SNRT)

At the 8th beat (arrow) there is an abrupt increase in heart rate. This tachycardia has a P wave morphology identical to sinus rhythm. Due to the abrupt onset SNRT is the working diagnosis.

Characteristics: 

Treatment:

4. Atrial tachycardia

5. Multifocal atrial tachycardia

6. Atrioventricular reentrant tachycardia

7. Atrioventricular nodal reentrant tachycardia

8. Junctional ectopic tachycardia

9. Atrial fibrillation

10. Atrial Flutter