Ventricular tachycardia (VT) is a life-threatening, fast heart rhythm that starts in the lower chambers of the heart (the ventricles). This fast heartbeat is caused by abnormal electrical pathways located in the heart tissue. A standard procedure called a catheter ablation has been used for several years to help correct these abnormal pathways and, in some cases, improve or even eliminate the ventricular tachycardia.

During a VT ablation it is routine to monitor your vital signs (blood pressure, heart rate, and oxygen saturation in your blood). If you choose to participate in this study we will also monitor your cerebral oximetry, the amount of blood flow and oxygen saturation to your brain during the ablation.

By doing this study, we hope to have a better understanding of patients' blood and oxygen flow to their brain during an episode of Ventricular Tachycardia (VT).

Inclusion Criteria:

• Able to give informed consent
• Have implantable defibrillator in-situ and are undergoing ablation procedure for ventricular tachycardia

Exclusion Criteria:

• Patients who have been hypotensive with systolic blood pressure of < 80mm Hg prior to procedure
• Cerebral event as defined by Cerebrovascular Accident or Transient Ischemia Attack within six months prior to procedure

Participants will be selected from those that visit University of Kansas Medical Center Cardiology clinics.