Renal failure is present in 40% of heart failure patients, and is one of the main comorbidities of heart failure. Follow-up with pulmonary artery pressure (PAP) monitoring has shown a reduction in mortality and frequency of hospitalization in patients with heart failure alone in the CHAMPION trial. Patients with New York Heart Association class III heart failure and a hospitalization in the previous 12 months were included in that study. They benefited from the CardioMEMS™ HF device with a sensor implanted in the pulmonary artery to measure PAP. According to that study, the information led to more precise and early adaptation of therapy by avoiding the onset of heart failure symptoms and reducing the number of hospitalizations. However, in that study, patients with impaired renal function (Glomerular Filtration Rate\<25 mL/min/1.73m2) were excluded, limiting the indication for treatment in those patients, and the evolution of renal function during the study was not reported. Patients with heart failure AND advanced renal failure are defined as having a cardio-renal syndrome, with strong interaction between these 2 organs. In the event of predominant right heart failure, they may require treatment by renal replacement or dialysis. There seems to be a link between high venous pressure, renal repercussions and the need for dialysis. Additional follow-up data in this clinical situation are needed to confirm this link and to suggest the interest of continuous PAP monitoring to improve the management of these patients with cardio-renal syndrome with severe renal impairment defined by a Glomerular Filtration Rate\< 30 ml/min/1.73m2 (KDIGO Cardio-renal 2019). This pilot study aims to evaluate how tolerable the CARDIOMEMS™ HF device in patients with cardio-renal syndrome and obtain the first information on the relationship between cardiac hemodynamics and renal function in this population.