This 35-year-old man received a Lumos VR-T single chamber defibrillator for the management of episodes of sustained VT in the background of hypertrophic cardiomyopathy. An event report (yellow color) was issued in the context of classified SVT.
Main programmed settings
Remote tracing
A very short EGM (Lumos defibrillator) was available, revealing a ventricular rhythm at the limit of the VT1 zone. In absence of sudden onset, the episode classification was SVT.
Programmer tracing
This tracing shows an episode of sinus tachycardia accurately identified by the defibrillator in absence of sudden onset. The evolution of the heart rate is characteristic, with a gradual acceleration, followed by a gradual slowing at the end of exercise. In this young patient, the programming of the lower limit of the VT1 zone (150 bpm) was probably too low, as the acceleration of the sinus rate was in the range of rates reached during relatively vigorous exercise, despite properly prescribed treatment with a beta-adrenergic blocker. In these young patients, whose chronotropic function is preserved, the best discrimination probably consists of avoiding, whenever possible, the overlap between a) the zone of diagnosis and therapies and b) the zone of sinus acceleration. The heart rate during the episodes of sustained VT preceding the defibrillator implantation ranged between 180 and 200 bpm (the patient was already treated with the same doses of beta-adrenergic blocker). An increase in the lower limit of the VT1 zone to 160 bpm eliminated the overlap.
