Antitachycardia Pacing: Averting Shock!

The above 12-lead electrocardiograms (ECG) were obtained in a patient with severe non-ischemic cardiomyopathy with an implantable defibrillator. The onset of sustained ventricular tachycardia (VT) is evident in Figure A (red arrow) with a short cycle length. Shortly after, in Figure 2, the defibrillator initiates rapid ventricular anti-tachycardia pacing (ATP) at a cycle length shorter than that of the VT (red arrow), in an attempt to overdrive pace the VT. The pacemaker spikes can be seen together with a shift in axis indicative of satisfactory capture of the ventricles. This resulted in restoring sinus tachycardia with left bundle branch block, seen in Figure C, thereby averting a defibrillator shock.