This registry is designed to monitor the real world clinical performance and safety of the V8 device used to perform balloon aortic valvuloplasty (BAV). Additional analyses or calculations may be obtained from the imaging or evaluations already performed per the sites' standard of care

The study is an open-label observational study involving a minimum of 10 centers. A minimum of 100 patients, including a minimum of 30 stand-alone balloon aortic valvuloplasty (BAV) treatment patients, will be enrolled. Enrollment will continue until all 3 of these conditions are met.

BAV-only patients will be followed through a 6-month post-treatment telephone follow up. Patients treated with the V8 device for BAV as a bridge to transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR) or as an intraprocedural predilatation prior to TAVR, will exit the study at the time of the TAVR or SAVR implant or at 6 months post-BAV treatment, whichever comes first.

Inclusion Criteria:

• Symptomatic severe aortic stenosis (AS) patients who are not suitable candidates for aortic valve replacement surgery at the time of BAV procedure.
• Subject meets the Indication For Use.
• Probable survival to hospital discharge.
• Subject is competent, willing to comply with evaluations, understands risks, benefits and alternatives and has signed the Informed Consent Form. Alternatively, the legal guardian of the patient is able to give consent to participate.

Exclusion Criteria:

• Patient has undergone previous AVR
• Greater or equal to 3+ aortic insufficiency by echocardiogram obtained prior to planned BAV or intra-procedural predilation TAVR procedure
• Non-valvular AS
• Known congenital AV abnormality (e.g., bicuspid AV)
• Cardiogenic shock, as defined by a consistent systolic blood pressure <80 mmHg off vasopressors or <90 mmHg on vasopressors.
• Bacterial endocarditis ≤ 12 months prior to planned BAV procedure
• Unable to take aspirin (acetyl salicylic acid, ASA) or thienopyridine
• Any illness or condition which, in the Investigator's judgment, will compromise patient safety, or interfere with the interpretation of the treatment results
• Echocardiographic evidence of intracardiac mass, thrombus or vegetation.

Primary care clinic - Patients at each enrolling clinic who are to be treated with the InterValve V8 device for balloon aortic valvuloplasty (BAV) are eligible for enrollment.