Arterial hypotension is a frequent complication of general anesthesia and a significant contributor to postoperative complications. It is a critical marker for the development of acute renal failure and postoperative myocardial infarction. Chronic heart failure (CHF) patients are increasingly encountered in the operating room, and their perioperative morbidity and mortality are substantial, with specific management lacking precise recommendations.

The main objective is to assess the impact of a diluted norepinephrine bolus on cardiac output in chronic heart failure patients experiencing arterial hypotension after anesthesia induction.

Arterial hypotension is a frequent complication of general anesthesia and a significant contributor to postoperative complications. It is a critical marker for the development of acute renal failure and postoperative myocardial infarction. Chronic heart failure (CHF) patients are increasingly encountered in the operating room, and their perioperative morbidity and mortality are substantial, with specific management lacking precise recommendations. The potential indications for norepinephrine use are expanding due to dilution methods allowing peripheral catheter administration, particularly for addressing arterial hypotension during general anesthesia induction. However, these indications are primarily based on common practices, and the impact of norepinephrine on cardiac output in patients with chronic heart failure is poorly understood. The main objective is to assess the impact of a diluted norepinephrine bolus on cardiac output in chronic heart failure patients experiencing arterial hypotension after anesthesia induction.

Inclusion Criteria:

• Adult patients
• Heart failure patients with left ventricular failure with a ventricular ejection fraction less than or equal to 40% evaluated by trans-thoracic echocardiography less than a year ago and specifying in particular the patient's filling pressures at the state stable.
• Patients under treatment adapted to the level of heart failure according to the 2021 European Society of Cardiology recommendations.
• Scheduled surgery under general anesthesia.
• Invasive hemodynamic monitoring planned by the anesthetist-resuscitator (irrespective of potential inclusion in the protocol): arterial catheter and central venous line for measurement of CVP (central venous pressure).
• Postoperative monitoring planned in intensive care or intensive care
• Presence of controlled mechanical ventilation with tidal volumes between 8 and 10 ml/kg of ideal weight.
• Presence of arterial hypotension after induction of general anesthesia, and before surgical stimulation.
• Patient affiliated to a social security scheme or equivalent
• No opposition from the patient.

Exclusion Criteria:

• Chronic heart failure patients with right ventricular failure.
• Patients presenting signs of acute pulmonary edema, Pulmonary arterial hypertension (PAH), severe valvular disease, intracardiac shunt.
• Patients operated on under general anesthesia but maintaining spontaneous ventilation.
• Patients with respiratory compliance disorders with compliances greater than 30 cm of water.
• Patients with intra-abdominal hypertension.
• Patients with supraventricular or ventricular arrhythmia.
• Patients treated with catecholamines prior to the procedure.
• Patients operated on for urgent surgeries
• Patient under guardianship, curatorship or safeguard of justice
• Pregnant or breastfeeding women.

The study population includes patients with heart failure and left ventricular failure with a ventricular ejection fraction less than or equal to 40%.