Patients with renal insufficiency who undergo cardiac surgery with cardiopulmonary bypass (CPB) are at significant risk for exacerbation of renal dysfunction postoperatively. This in turn is associated with an increased risk of prolonged intensive care unit (ICU) length of stay, other comorbidities including surgical complications and 30-day mortality. Renal impairment is generally identified based on an increase in serum creatinine concentration and/or a certain magnitude decrease in estimated glomerular filtration rate (eGFR).

The JuxtaFlow® Renal Assist Device (RAD) is designed to sustain or enhance glomerular filtration perioperatively for patients with renal insufficiency by applying a mild controlled negative pressure to the collecting system via the renal pelvis, thereby increasing effective filtration pressure and reducing tubular pressure. This mechanism is designed to support the kidneys' functions during times of renal stress that would be associated with intrarenal edema, volume overload, increased venous pressure, and inflammatory response. By supporting renal function, specifically during the acute stress of CPB, JuxtaFlow holds promise to protect nephron function, decrease renal hypoxia, and provide multifactorial kidney function support to maintain their ability to manage future stress.

Inclusion Criteria:

To be eligible for participation in this study, an individual must meet all the following criteria:

1. A candidate for elective or urgent on-pump coronary artery bypass grafting (CABG) and/or valvular surgery

2. Male or Female age 22 to 85 years

3. Estimated glomerular filtration rate (eGFR) 15 - 60 mL/min/1.73m2

4. Signed and dated informed consent

5. Female patients of childbearing potential must:

   1. have negative pregnancy test at the informed consent visit,
   2. be using previously initiated approved and effective contraception from the informed consent visit through completion of the study *The only recommended contraception is condoms.

Exclusion Criteria:

An individual who meets any of the following criteria will be excluded from participation in this study:

1. Any individual, or their legally authorized representative (LAR), who does not understand the requests and risks of participating in the clinical trial or is unable to give informed consent
2. Pregnancy or lactation
3. Prior cardiac surgery within the last 6 months
4. Hemodynamic instability as determined by the Principal Investigator
5. Immunosuppression
6. Active infections (e.g. HIV, Tbc, and all types of Hepatitis)
7. History of polycystic kidney disease
8. Patients with only one active kidney or one poorly functioning kidney
9. Evidence of current kidney obstruction (e.g., Kidney stones)
10. Evidence of current hydronephrosis
11. Active upper and/or lower urinary tract infections
12. Malignancy; oncological Surgery within 5 years or ongoing antitumoral treatment
13. Ongoing sepsis or endocarditis
14. Patients who have an expected 30-day postoperative mortality greater than 10% as determined by the Principal Investigator
15. Any secondary condition as determined by the investigator that would place the subject at an increased risk or preclude the subject's full compliance with the study procedures, including injuries to the urinary organs and/or external genitals; or severe BPH
16. Unexplained/unexpected gross hematuria as determined by the Investigator
17. Current or planned treatment with an investigational drug (IND), device (IDE), or other investigational intervention within 3 months prior to or during participation in this clinical trial
18. Patients who have a current unrepaired ureteral avulsion as determined by the investigator
19. Patients otherwise contraindicated for urological interventions, including ureter guidewire placement via bladder cystoscopy and ureteral catheterization, or otherwise contraindicated for any of the other study procedures