Long and short RP tachycardias
Long and short RP tachycardias are two groups of supraventricular tachycardias depending on the interval between the R wave and the P wave of the next cycle.
Short RP tachycardia
Typical (slow-fast tachycardia) AV nodal reentrant tachycardia [AVNRT] is the most common type of short RP supraventricular tachycardia. P waves are not seen in 80% of typical AVNRT because it is within the QRS. In 20% it is visible just after the QRS.
AVRT (accessory pathway mediated atrioventricular reentrant tachycardia) is the other form of short RP tachycardia in which the P wave falls at the end of the QRS.
Short RP tachycardia
Long RP tachycardias
Atypical (fast-slow tachycardia) AVNRT: Impulse travels down the fast pathway and back through the slow pathway.
Atrial tachycardia
PJRT – Permanent junctional reentrant tachycardia
Sinus tachycardia is also a differential diagnosis for long RP tachycardia, which has to be differentiated mainly by the P wave morphology and axis which will suggest the activation sequence.
There is an ECG series demonstrating both short RP and long RP tachycardia in Singapore Medical Journal (Free Full Text) [1].
Reference
- Singh D, Teo SG, Omar AR, Poh KK. Electrocardiography series. Narrow QRS-complex tachycardia: part 2. Singapore Med J. 2014 Sep;55(9):451-4.