Torsades de pointes and polymorphic VT

Q: What is the difference between Torsades de Pointes and polymorphic Ventricular Tachycardia (VT)?

Answer: 

Torsades de Pointes, meaning "twisting of points,"  is a rapid and distinct polymorphic VT associated with baseline prolonged QTc interval.

If baseline QTc interval is normal, it is technically called polymorphic VT, not torsades de pointes.

In Torsades de Pointes, continuously changing axis of polymorphic QRS morphologies is observed during each episode. It is typically initiated by bradycardia or, as called, 'pause dependent,' with a short-long-short coupling interval, i.e., PVC (short RR interval), a compensatory pause (long RR interval), and a second PVC (short RR interval).

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References:

1. Passman R, Kadish A. Polymorphic ventricular tachycardia, long Q-T syndrome, and torsades de pointes. Med Clin North Am. 2001 Mar;85(2):321-41. doi: 10.1016/s0025-7125(05)70318-7. PMID: 11233951.

2. Tsuji Y, Yamazaki M, Shimojo M, Yanagisawa S, Inden Y, Murohara T. Mechanisms of torsades de pointes: an update. Front Cardiovasc Med. 2024 Mar 5;11:1363848. doi: 10.3389/fcvm.2024.1363848. PMID: 38504714; PMCID: PMC10948600.

3. Rosso R, Hochstadt A, Viskin D, Chorin E, Schwartz AL, Tovia-Brodie O, Laish-Farkash A, Havakuk O, Gepstein L, Banai S, Viskin S. Polymorphic ventricular tachycardia, ischaemic ventricular fibrillation, and torsade de pointes: importance of the QT and the coupling interval in the differential diagnosis. Eur Heart J. 2021 Oct 7;42(38):3965-3975. doi: 10.1093/eurheartj/ehab138. PMID: 33693589.