Transseptal vs Retrograde Aortic Ventricular Entry to Reduce Systemic Emboli

Inclusion Criteria: 1. Men and women ≥ 18 years of age 2. Planned/scheduled endocardial ventricular tachycardia (VT) or premature ventricular contraction (PVC) catheter ablation procedure 3. For this patient, the current plan of the operator must be to pursue a catheter ablation target in the left ventricular endocardium that can be accessed by either a transseptal puncture or retrograde aortic approach 4. Life expectancy of at least 1 year 5. Willing and able to undergo pre- and post-ablation MRIs 6. Willing and able to return and comply with scheduled follow up visits (through the 6 month follow-up) 7. Willing and able to provide written informed consent Exclusion Criteria: 1. Planned epicardial ablation that would include a coronary angiogram (during the index ventricular tachycardia (VT) or premature ventricular contraction (PVC) catheter ablation procedure) 2. Any contraindication to MRI (as defined by the institution performing the MRI) 3. Clinical contraindication to a retrograde aortic approach as determined by the treating physician, including: 1. Severe aortic stenosis 2. Mechanical aortic valve 4. Clinical contraindication to a transseptal puncture as determined by the treating physician, including: 1. Severe Mitral valve stenosis 2. Mechanical Mitral valve 3. Atrial septal defect (ASD) or Patent foramen ovale (PFO) closure device that would preclude a transseptal puncture 4. Mitraclip or Alfieri mitral valve repair that would preclude a transseptal puncture 5. Planned or known need to perform either a retrograde aortic approach or transseptal approach (such as to target another site during the same procedure) 6. Inability to speak, read, and write in the English language at a 6th grade level (required for the Neurocognitive Function Testing) 7. Current mental impairment or other diagnosis which precludes accurate assessment of neurocognitive function or which may not allow patient to understand the nature, significance and scope of the study 8. Inability to perform neurocognitive function testing after \> 24 hours free of sedating medications