5. Regular or regularly irregular
Narrow complex
tachycardia
QRS<120 ms
=SVT
QRS width
Irregularly
irregular
1.Afib
2.MAT
(P waves of
≥3 different
morphologies)
6. Regular or regularly irregular
1.AVNRT
2.AVRT
3.Atrial tachycardia
4.Atrial flutter
Beside sinus tachy
Narrow complex
tachycardia
QRS<120 ms
=SVT
QRS width
Irregularly
irregular
1.Afib
2.MAT
(P waves of
≥3 different
morphologies)
7. Dual AV node pathways and AVNRT
Some individuals have dual AV node
pathways (up to 20% of individuals).
Normally, conduction spreads through the
fast pathway and gets blocked in the slow
pathway. However, after a PAC, the
electrical activity cannot spread through
the fast pathway (which is still in a
refractory period), but can get conducted
through the slow pathway which then
conducts both down to the ventricle and up
to the atrium, through the recovered “fast
pathway”, thus creating a tachycardia with
retrograde P waves
9. Retrograde P wave
Pseudo-r’ in V1 + Pseudo S in inf leads
Arrows point to the retrograde P that is
superimposed on ST segment and looks
as a notch on ST segment
10. ECG of the previous pt in sinus rhythm after adenosine. Note the
difference (no “pseudo-r’ “ or “pseudo S”)
11. Regular or regularly irregular
Look for P waves
Assess RP interval
Short RP (<1/2 RR)
-AVNRT
-AVRT
-Atrial tachycardia
Long RP (>1/2 RR)
-Atrial tachycardia
-Atypical AVNRT
Sawtooth P,
esp. rate~150
-Atrial flutter
Narrow complex
tachycardia
QRS<120 ms
=SVT
QRS width
Irregularly
irregular
1.Afib
2.MAT
(P waves of
≥3 different
morphologies)
