NORM-HF Pivotal Study

INCLUSION CRITERIA: 1. Adults 18 years of age or older. 2. Provide informed consent for participation in the clinical study and be willing and able to comply with the required assessments, treatment instructions, and clinical follow-up visits according to the specified schedule. 3. Patients meeting diagnostic criteria for HF diagnosis for greater than 90 days and are on optimally tolerated medical therapy for at least 30 days, as recommended according to current AHA/ACC/HFSA or ESC HF guidelines with any intolerance or contraindications documented, regardless of ejection fraction, as evidenced by meeting either 3a, 3b OR 3c criterion below: 1. NYHA functional class II with documented HF decompensation within the previous 12 months resulting in a primary HF hospitalization, HF treatment in a hospital day-care setting or unscheduled visit to a healthcare provider for administration of an intravenous diuretic to treat HF AND NT-proBNP ≥1000 pg/mL. For those patients presenting with atrial fibrillation or flutter, NT-proBNP ≥1,600 pg/mL. OR 2. NYHA functional class III with documented HF decompensation within the previous 12 months resulting in a primary HF hospitalization, HF treatment in a hospital day-care setting or unscheduled visit to a healthcare provider for administration of an intravenous diuretic to treat HF AND NT-proBNP ≥ 600 pg/mL. For patients presenting with atrial fibrillation or flutter, NT-pro BNP ≥900 pg/mL. OR 3. NYHA functional class III AND NT-proBNP ≥1000 pg/mL. For patients presenting with atrial fibrillation or flutter, NT-proBNP ≥1,600 pg/mL. 4. Patients must be prescribed a daily dose of loop diuretic of 40mg or more furosemide, or equivalent, for the two weeks prior to screening. 5. Patients must be able to have their daily dose of loop diuretic be increased by at least 1.5 times. 6. IVC diameter within the landing zone of between 14mm and 28mm. 7. Minimum IVC landing zone length of 60 mm. 8. Patients have sufficient cellular and/or Wi-Fi Internet coverage at home and can access the internet on a phone or a computer at home. EXCLUSION CRITERIA 1. Presence of advanced end stage HF, suggested by but not limited to: * Persistent NYHA functional class IV HF (ACC/AHA/ESC). * Current treatment with intravenous vasopressors or inotropes. * Received, or are likely to receive in the next 6 months, an advanced therapy (e.g., mechanical circulatory support or cardiac transplant or previously listed for transplant). * Receiving end of life HF care. 2. Severe right sided valvular disease or a right sided mechanical valve. 3. Patients with abdominal circumference of greater than 143 cm (56 inches) at screening. 4. Patients with an estimated Glomerular Filtration Rate (eGFR) \< 25 mL/min/1.73m2 or receiving ultrafiltration or chronic dialysis. 5. Presence of end stage hypertrophic cardiomyopathy, end stage restrictive cardiomyopathy, end stage pericardial constriction, end stage cardiac amyloidosis, or other infiltrative cardiomyopathy such as hemochromatosis or sarcoidosis. 6. Significant congenital heart disease that would impair ability to implant the IVC sensor or complicate interpretation of the reading (e.g., fontan circulation physiology). 7. Major non-heart-failure-related CV event (i.e., unstable angina, Type 1 myocardial infarction (MI), percutaneous coronary intervention, open heart surgery, or stroke, etc.) within 90 days prior to consent. 8. Implanted with Cardiac Resynchronization Therapy (CRT)-Pacemaker (CRT-P), CRT Defibrillator (CRT-D), Cardiac Contractility Modulation (CCM), or implantable neuromodulation devices used to treat HF symptoms within 90 days prior to consent. 9. Implanted or planned implantation of a pulmonary artery pressure (PAP) monitor. 10. Patients that are pregnant, nursing or planning a pregnancy within 1 year of screening. 11. Anticipated life expectancy \< 12 months due to another etiology or severity of HF. 12. Any condition that, in the opinion of the Investigator, would not allow for implantation or utilization of IVC sensor. 13. Current or anticipated participation in any other clinical study during the duration of this study not pre-approved by the Sponsor. 14. Patients with active systemic infection at screening. 15. Patients with hypersensitivity or allergy to antiplatelet agents or Sensor components (Nitinol, Polyurethane \[PU\], Nylon, Polyethylene Terephthalate \[PET\], and Gold) or contrast media that will not be managed with a clinical site-specific allergy protocol. 16. Unable to tolerate dual antiplatelet therapy for at least 30 days following implant of the respective sensor or unable to continue oral anticoagulation if currently prescribed. 17. Patients with an in vivo IVC filter, abnormal IVC or femoral venous anatomy, known congenital malformation or absence of IVC, or occlusive or free-floating thrombus in the IVC, iliac, or common femoral veins. 18. Patients who have procedures planned that require venous femoral access within 3 months of the Sensor implantation. 19. Patients with pulmonary embolism, venous thrombosis, or thromboembolism in the 6 months prior to screening and/or with ongoing concerns of hypercoagulability due to underlying conditions e.g., thrombophilia.