Idiopathic Polymorphic Ventricular Tachycardia: a “Benign Disease” with a Touch of Bad Luck?

Figures

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  Fig. 1. A female patient with a very long history of palpitations. She fi rst presented in 1985 at the age of 35 years with frequent RVOT extrasystoles, including ventricular bigeminy (A). In 1997 (age 47), she had recurrent syncope with documented polymorphic VT (B). She underwent ICD implantation but declined drug or ablation therapy. Her left ventricular function remains normal despite almost incessant bigeminy (C). 18 years after her initial arrhythmic event, she experienced non-sustained polymorphic VT (ventricular rate approaching 300 beats/min), documented by her ICD (D). She continues to be in good health. Modifi ed from Viskin et al.8) RVOT: right ventricular outfl ow tract, VT: ventricular tachycardia, ICD: implantable cardioverter-defi brillator.

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  Fig. 2. Typical non-sustained monomorphic VT originated from an extrasystole that clearly began after the end of the T-wave (A). The same patient later developed ventricular extrasystoles of the same morphology, but with a shorter coupling interval. The fi rst extrasystole in the precordial leads began during the descending limb of the T-wave (best appreciated in V5-V6) (B). Ventricular extrasystoles with an even shorter coupling interval (the extrasystoles originated shortly after the peak of the T-wave) triggered non-sustained polymorphic VT. The coupling interval of the extrasystoles initiating polymorphic VT (C) was clearly shorter than the coupling interval preceding monomorphic VT in the same patient (A). Modifi ed from Viskin et al.8) VT : ventricular tachycardia.

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  Fig. 3. Examples of polymorphic RVOT VT initiated by extrasystoles without a short coupling interval. (A) Patient #1 in the original series by Noda et al.10) (B) Documentation of RVOT polymorphic VT during an event of spontaneous vagal syncope triggered by venipuncture, as reported by Kataoka et al.28) Both patients had typical RVOT extrasystoles documented by 12-lead ECG. Reproduced from Noda et al.10) and Kataoka et al.28) RVOT: right ventricular outflow tract, VT: ventricular tachycardia, ECG: electrocardiogram.

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  Fig. 4. A 20-year-old male with idiopathic VF. Cardiac arrest was the presenting symptom. Ventricular extrasystoles were fortuitously recorded only once. He received recurrent ICD shocks for VF until he was treated with quinidine. Note that the coupling interval initiating VF was very short (300 sec) (D). Also, note that, in the three episodes of non-sustained polymorphic VT recorded in a 12-lead monitor (A-C), not only was the first beat of VT similar for all events, but the subsequent beats were also similar for all events. ICD: implantable cardioverter-defibrillator, VF: ventricular fibrillation, VT: ventricular tachycardia.

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  Fig. 5. Relationship between the basic cycle length and the coupling interval, prematurity index and QT index in patients with and without malignant RVOT VT in the series by Igarashi et al.18) (A-C) Definitions of prematurity index and QT index as reported by Igarashi for patients with RVOT VT18) (using the same definitions we proposed when reporting on the mode of onset of idiopathic VF 15 years earlier).9) In the series by Igarashi, the basic sinus rate was slower immediately preceding the onset of polymorphic VT (D). Consequently, the prematurity index and the QT index (F, G) were shorter, even though the coupling interval was not different (in comparison to the coupling interval of extrasystoles or monomorphic VT) (E). Reproduced from Igarashi et al.18) RVOT: right ventricular outflow tract, VT: ventricular tachycardia, VF: ventricular fibrillation.