RHythmia mAPping and Signal acquisitiOn for Data analYsis (RHAPSODY)

Inclusion Criteria: 1. Age 18 or above, or above legal age and willing and capable of giving informed consent specific to national law 2. Scheduled for standard of care catheter-based endocardial mapping for atrial or ventricular tachyarrhythmias using a commercial Rhythmia Mapping System. Exclusion Criteria: 1. Prothrombotic or bleeding tendency due to coagulopathy or blood dyscrasia 2. Inability to tolerate heparin therapy (e.g. heparin induced thrombocytopenia, allergy, etc.) 3. Prosthetic or stenotic valves in the chamber where the intended mapping will occur, or in the path of the catheter access route 4. Active systemic infection or sepsis 5. Hemodynamic instability or shock at baseline precluding ablation in the assessment of the investigator. 6. Presence of intracardiac thrombus, tumor, or other abnormality which precludes catheter introduction 7. Women who are pregnant or lactating 8. Cardiac surgery within the past 90 days 9. Acute myocardial infarction within 3 months 10. Stable/unstable angina or ongoing myocardial ischemia 11. Subjects with an active heart failure decompensation 12. Long QT Syndrome, Brugada Syndrome, or Torsade de Pointes 13. Congenital heart disease with or without corrective surgery that would complicate a mapping procedure 14. Subjects having untreatable allergy to contrast media 15. Vascular pathology or tortuosity precluding standard vascular access techniques 16. Subjects who are currently enrolled in another investigational study or registry that would directly interfere with the current study, except when the patient is participating in a mandatory governmental registry, or a purely observational registry with no associated treatments. Each instance should be brought to the attention of the sponsor to determine eligibility.