ECG A: AVNRT, AVRT

ECG clinical diagnoses alphabet

3. AVNRT
This is the commonest cause of
palpitations in patients with structurally
normal hearts.
AVNRT is typically paroxysmal.
It may occur spontaneously or upon
provocation (exertion, caffeine, alcohol,
salbutamol, amphetamines).
It is more common in women(75%)than
men.

4. AVNRT
The tachycardia typically
ranges between 140-280
bpm and it is regular in
nature.

5. AVNRT
There is afunctionalre-
entry circuit within the AV
nodethat causes this
arrhythmia.

6. PATHWAYS WITHIN THE AV NODE ARE:

7. ECG FEATURES
Regular tachycardiaof about 140-280 bpm.
QRS complexes are usuallynarrow (<120ms).
ST-segment depression may be seen with or without
underlying coronary artery disease.
QRS alternansis phasic variation in QRS amplitude
associated with AVNRT and AVRT.
P waves exhibitretrograde conductionwith P-wave
inversion in leads DII, DIIIand aVF.
P waves may be buried in the QRS complex, visible after
the QRS complex or very rarely visible before the QRS
complex.

8. SLOW-FAST AVNRT (COMMON TYPE)
80-90% of AVNRT
P waves are often hidden
(embedded in the QRS
complexes).
Pseudo R’ wave may be seen
in V1 or V2.
Pseudo S waves may be seen
in leads DII, DIII or aVF.
TypicalSVT appearance in
ECG with absent P waves and
tachycardia.

9. SLOW-FAST AVNRT
narrow QRS complexes
150 bpm
no visible P waves
pseudo R’ waves in V1-2
Pseudo R´

10. FAST-SLOW (UNCOMMON)
QRS-P-T complexes!
Retrograde P waves are visible
between the QRS and T wave.

11. FAST-SLOW (UNCOMMON)
Retrograde P waves are visible after
each QRS complex (V2-V3).

12. SLOW-SLOW AVNRT (ATYPICAL AVNRT)
P wave appears
before the QRS
complex.

13. AVNRT
Slow-fastNo visible P waves
Fast-slowP waves visible after the QRS
Slow-slowP wavesvisible before the
QRS

15. AVRT
AVRT is a form of paroxysmal
supraventricular tachycardia.
It is often triggered by premature
atrial or premature ventricular beats.

16. ORTHODROMIC AVRT
Rate is usually 200-300 bpm.
P waves may be buried in QRS complex or
retrograde.
QRS complexes are usually <120 ms.
QRS alternans is a phasic variation in QRS
amplitude associated with AVNRT and AVRT.
T wave inversion is common.
ST segment depression may be seen in ECG.

17. ANTIDROMIC AVRT
Rate is usually 200-300 bpm.
Wide QRS complexes are due to
abnormal ventricular depolarisation
via accessory pathway.