The purpose of the study is to determine the relationship between non-invasive measurement of left ventricular diastolic pressure (LVDP) using the Vivio System, compared with invasively measured LVDP via direct measurement during left heart catheterization.

Prospective study to document the utility of Vivio in quantifying LVDP, using directly measured LVDP collected during left heart catheterization as the comparator.

Inclusion Criteria:

1. Adult subjects >21 years of age.
2. Referred for non-emergent left heart catheterization inclusive of direct measurement of LVDP as part of routine clinical management, to be performed from a femoral or radial access site.
3. Willing and able to participate in all study evaluations and allow access to medical records, including medical testing records.
4. Ability to understand and sign informed consent or have a legally authorized representative to provide informed consent on behalf of the subject.

Exclusion Criteria:

1. Acute coronary syndrome, or documented MI within a week of scheduled catheterization, cardiogenic shock, or the need for intravenous inotropic or mechanical circulatory support.
2. Carotid pulse is not palpable by a trained study researcher.
3. History of carotid sinus hypersensitivity (fainting in response to minimal touching or positioning of the neck).
4. History of significant or symptomatic carotid artery disease, including TIA, ultrasound evidence of >60% carotid stenosis, or at the discretion of the investigator; history of carotid artery stenting or surgery.
5. Open skin lesions at the site of Vivio application / examination.
6. Contraindication to placing a catheter in the LV in the judgement of the investigator (e.g., mechanical aortic valve, left ventricular thrombus, etc.).
7. Inability to obtain brachial artery blood pressure.