This study is designed to monitor the safety and performance of the V8 balloon when used as a postdilatation balloon in self-expanding Transcatheter Aortic Valve Implantation (TAVI) device procedures. The study product is CE marked for balloon aortic valvuloplasty (BAV), and is being investigated for an expanded intended use.

The study is a prospective, multi-center, single arm open-label clinical study involving up to 5 centers and a minimum of 20 subjects. Up to 50 subjects may be enrolled in this study. The first 3 post-dilatation procedures for each investigator will be considered roll-ins and not included in the main study analyses. Subjects will exit the study at hospital discharge or 7 days post treatment, whichever comes first. The expected duration of the clinical investigation is approximately 6 months.

Subjects implanted with the CoreValve or other commercially available self-expanding TAVI and with the use of the V8 as a postdilatation balloon may be enrolled in this study. The subject will exit the study after the predischarge ECHO where the Paravalvular Leak (PVL) measurements are taken or resolution of a V8 related AE (if applicable).

Inclusion Criteria:

• Subjects with severe symptomatic aortic stenosis (AS) indicated and scheduled for a transcatheter aortic valve implant (TAVI) with the Medtronic CoreValve or another self-expanding TAVI device.
• The TAVI device size is determined preoperatively with CTA according to standard guidelines. Patients may undergo transfemoral, subclavian, or transaortic approach.
• Balloon postdilatation (BPD) is carried out after CoreValve or other self-expanding TAVI device implantation if, based on operator's judgment, BPD is indicated because of presence of paravalvular leak (PVL).
• Hemodynamically stable for 3 - 10 minutes after the TAVI procedure.
• 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.

Exclusion Criteria:

• Cardiogenic shock, as defined by a consistent systolic blood pressure <80 mmHg off vasopressors or <90 mmHg on vasopressors.
• PVL occurring secondary to excessively high or low valve positioning.
• Trauma or significant structural damage to underlying native tissue calls for emergent intervention or threatens long-term outcome prior to the BPD.
• Patients receiving two valves (i.e. aortic THV valve in valve).
• Patients with AS secondary to congenital valve disease including bicuspid aortic valve.
• PVL occurring due to TAVI device under sizing. Example of determining the undersizing is to calculate the Cover Index which represents the percent of over sizing of the nominal transcatheter heart valve (THV) area compared to the measured native valve annulus area. Under sizing is defined as TAVI screening CTA with a pre procedure cover index by area of <5%.
• Vulnerable subjects and any subjects incapable of giving consent, including patients with incurable diseases, patients in emergency situations, ethnic minority groups, homeless persons, nomads, refugees, minors, and subjects with cognitive impairment, such as persons with a mental illness or dementia.

Primary care clinic - Patients at each enrolling clinic who are to be treated with the Medtronic CoreValve or other self-expanding TAVI device are eligible for enrollment.