Differential diagnosis of wide QRS tachycardia: A review

FIGURE 1. (1) Ashman's phenomenon. The rhythm is atrial fibrillation. A long cycle (560 ms) followed by a short cycle (320 m) results in right bundle branch morphology aberrancy that last for 3 beats. (B) Acceleration‐dependent aberrancy. As the heart rate increases from 82 beats per minute to 88 bpm the QRS duration increases from 80 msec. to 160 ms Rhythm remains sinus. (C) Deceleration‐dependent aberrancy. As the heart rate decreases from 92 beats per minutes to 50 bpm as a result of 2:1 AV block, QRS duration increases from 80 to 120 ms

FIGURE 2. (A) Sinus rhythm, left bundle branch block. (B) SVT. The QRS morphology and frontal plane axis are identical to that in sinus rhythm

FIGURE 3. 12 lead electrocardiogram of VT showing AV dissociation. The P waves are marked by black dots that march through the QRS complexes. The RR interval from the VT beat to the fusion beat (F) is the same as the R‐R interval of the adjacent VT beats. Capture beats (C) are narrow and occur early. Preserved Q waves during the ventricular tachycardia. Deep and wide Q waves are seen in V1 and V2 suggestive of old anterior wall myocardial infarction. There is dominant R in aVR and northwest (right superior quadrant) axis

FIGURE 4. (A) SVT with right bundle branch block morphology: Triphasic QRS complexes are noted in V1 and V2. In V6 the R/S ratio is >1 (R wave amplitude is 1.1 mV and S wave amplitude is 0.8 mV). (B) VT with right bundle branch block morphology. The R wave in V1 is monophasic and the R/S ratio in V6 is <1

FIGURE 5. (A) SVT with left bundle branch block morphology: There is a narrow sharp R wave in lead V1 and V2. In V6 the R/S ratio is >1 and there is no qR pattern. (B) VT with left bundle branch block morphology: note a notch in the descending limb of the QRS in V1 (black arrowhead). There is an RS pattern in lead V2 (black line). The duration from the onset of the QRS complex to the end of the S wave is 130 ms, suggestive of VT (Brugada criteria)

FIGURE 6. The R wave in V1 during sinus rhythm is small and narrow. During VT, the R wave amplitude and duration has increased (>40 ms)

FIGURE 7. (A) Positive concordance. All the QRS complexes from V1 to V6 have positive polarity. (B) Negative concordance. All the QRS complexes from V1 to V6 have negative polarity

FIGURE 8. Left panel shows sinus rhythm with left bundle branch block. The same patient developed WQRST with the right bundle branch block pattern due to VT

FIGURE 9. Initial and terminal velocity of conduction. Vi (Velocity in mV in initial 40 ms), Vt (Velocity in mV in terminal 40 ms) ratio of <1 suggests a diagnosis of VT

FIGURE 11. Artifacts: Artifacts can be mistaken for nonsustained ventricular tachycardia. In this rhythm strip, sinus rhythm QRS complexes are identified by red dots

FIGURE 10. Atrial fibrillation with antegrade conduction through the left lateral accessory pathway resulting in pre‐excited tachycardia. Note shortest pre‐excited R‐R interval of <200 ms (Black dot)

FIGURE 12. Ventricular paced rhythm. A dual chamber pacemaker is programmed in the DDD mode that tracks atrial activity during atrial tachycardia and paces in the ventricle (red dots). When the P wave falls during the refractory period the tracking stops. The next beat (arrow) shows atrial and ventricular paced beats