Abstract
Idiopathic monomorphic ventricular tachycardia and premature ventricular complexes (PVCs) commonly arise from the right and left ventricular outflow tracts (VOT). Their mechanism is most commonly triggered activity from delayed after-depolarizations and successful ablation is performed at the site of earliest endocardial activation. Re-entrant mechanisms have been rarely described. We report a case of an otherwise healthy patient who ultimately underwent six electro-physiology studies (EPS) and suffered numerous implantable cardiac defibrillator (ICD) discharges prior to the successful radiofrequency ablation (RFA) of two idiopathic VOT tachycardias. During the sixth EPS, a proximal aortogram demonstrated a left aortic sinus of valsalva (LASV) aneurysm. Subsequntly, a novel and successful RFA strategy of aneurysm isolation was undertaken. The presence of multiple clinical or inducible VT morphologies and the characterization of a VT as re-entrant should raise concerns that a complex arrhythmogenic substrate is present and defining the anatomy with angiography or an alternative imaging modality is essential in achieving a successful ablation strategy.
Highlights
Sustained monomorphic ventricular tachycardia (SMMVT) is an arrhythmia that occurs almost exclusively in adolescents and young adults without structural heart disease
Our case is the first to describe ventricular tachycardia originating from an aortic sinus cusp aneurysm successfully treated with aneurysm isolation by radiofrequency ablation (RFA)
The tachycardia was induced with decremental pacing and fractionated electrograms were recorded within the aneurysm extending into early diastole during sinus rhythm and throughout diastole during ventricular tachycardia
Summary
Sustained monomorphic ventricular tachycardia (SMMVT) is an arrhythmia that occurs almost exclusively in adolescents and young adults without structural heart disease. An ECG revealed sustained monomorphic ventricular tachycardia at 230 beats/min with a left bundle branch block (LBBB) morphology, inferior axis, R wave transition in V3, and negative QRS complexes in lead 1, AVL and AVR (VT1, Figure 1). RFA lesions delivered at the earliest site of endocardial activation along the aorto-mitral continuity as described above (12 lesions for a total of 2 minutes and 37 seconds via a Biosense Webster 4 mm tip, non-irrigated, D-curve, 60 degree Celsius temperature limited ablation catheter at 50 watts) had no effect on the tachycardia. Bipolar pace mapping in the area of earliest endocardial activation was performed with no match in QRS morphology At this point, while still on an isoproterenol drip, spontaneous VT1 recurred, requiring a second 200 joule shock. The patient has remained arrhythmia free 7 years post ablation without anti-arrhythmic or beta blocker therapy
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