The purpose of the study is to assess the effectiveness and safety of a new device called an Intramural Needle Ablation Catheter (INA catheter). The INA catheter is used for locating and ablating ventricular arrhythmias that have failed standard radiofrequency ablation. This approach is desirable because some people have ventricular arrhythmias that originate deep within the heart muscle where it is not abolished by ablation with standard catheters.

The investigators seek to determine whether the INA catheter can potentially help people who have ventricular arrhythmias that have failed standard radiofrequency ablation. The investigators also want to determine if it is likely to be safe, without excessive side effects.

Inclusion Criteria:

Monomorphic ventricular tachycardia (VT) or incessant ventricular arrhythmia (defined as >20% of beats due to ventricular arrhythmia including unifocal premature ventricular contractions (PVCs ), couplets, nonsustained VT) that is causing a decline in left ventricular (LV) ejection fraction to less than 0.50.

Arrhythmia meets the following criteria:

1. Ventricular arrhythmia is recurrent and symptomatic

2. prior antiarrhythmic drug therapy has failed due to recurrent ventricular arrhythmia, toxicity, or intolerance

   • Age 18 or older
   • Left ventricular (LV) ejection fraction > 0.10 as estimated by echocardiography or contrast ventriculography within the previous 90 days
   • Failed prior VT or PVC ablation due to spontaneous recurrence of the arrhythmia or frequent PVCs.
   • Able and willing to comply with all pre-, post-, and follow-up testing and requirements
   • Signed Informed Consent

Exclusion Criteria:

• Patients with idiopathic VT defined as VT that originates from a region without evidence of scar detected by MRI or voltage mapping in a patient without other evidence of heart disease that is not causing significant depression of ventricular function.
• Definite protruding left ventricular thrombus on pre-ablation echocardiography when LV ablation is required.
• Thrombotic myocardial infarction within the preceding two (2) months.
• Other disease process that is likely to limit survival to less than 12 months.
• Class IV heart failure, unless heart failure is due to frequent or incessant VT.
• Contraindication to heparin.
• Allergy to radiographic contrast dye.
• Severe aortic stenosis
• Severe mitral regurgitation with a flail mitral valve leaflet.
• Significant congenital anomaly or medical problem that in the opinion of the principal investigator would preclude enrollment into the study.
• Enrolled in another investigational study evaluating a drug or device.
• Unstable angina that is not due to frequent or incessant VT.
• Women who are pregnant.
• Thrombocytopenia (platelet count < 50,000) or coagulopathy.
• Acute non-cardiovascular illness or systemic infection.
• Cardiogenic shock unless it is due to incessant VT

6 months