This study will test the hypothesis that many human heart rhythm disorders are caused by small localized sources, where brief ablation may successfully eliminate the heart rhythm disorder.

The investigators will enroll patients with documented rapid heart rates from the bottom chambers of the heart (ventricular tachyarrhythmias).

During electrophysiological study, the investigators will map the localized sources of these heart rhythm disorders.

1. The 'active' group will prospectively receive brief ablation at localized sources (Focal Impulse and Rotor Modulation, FIRM).
2. The control group will be a historical cohort who have received traditional ablation for this disorder.

All patients will be followed for up to 1 year to ensure that they have no recurrent arrhythmias.

Inclusion Criteria:

1. Documented ventricular tachyarrhythmias.
2. Undergoing clinically indicated EP study with ablation.

Exclusion Criteria:

1. Unwillingness or inability to provide informed consent.

Patients with documented rapid heart rhythms involving the bottom chambers of the heart.