Spontaneous ventricular parasystole initiating ventricular tachycardia

Ventricular parasystolic rhythms are rarely hemodynamically significant. However, ventricular parasystolic beats, like fixed rate ventricular pacing stimuli, have the theoretical potential to initiate repetitive beating when they fall in the vulnerable period. In the case presented here, spontaneously occurring ventricular parasystolic beats were able to initiate hemodynamically significant ventricular tachycardias. The ventricular tachycardia, however, did not disturb the parasystolic rhythm whose beats continued to occur as expected and were able to terminate the tachycardia. Thus, ventricular tachycardia could be terminated by a ventricular parasystolic beat which originated in the same focus as the ventricular parasystolic beat which initiated the tachycardia.