The clinical research protocol failed to obtain approval from the Institutional Review Board (IRB).

This study is a parallel group, single blind, randomized controlled trial. Patients with pulmonary hypertension who met the inclusion criteria and planned to undergo elective cardiac surgery under cardiopulmonary bypass from July 1, 2022 to December 1, 2024 in the Department of cardiac surgery of the First Affiliated Hospital of Shandong First Medical University were selected. After removing the aortic blocking forceps, the experimental group immediately injected the test drug (pituitrin 0.04u/ (kg · h)) intravenously, The control group was immediately injected with the corresponding dose of normal saline by intravenous pump. The main outcome was the composite endpoint of all-cause mortality 30 days after operation or common complications after cardiac surgery (stroke, requiring mechanical ventilation for more than 48 hours, deep sternal wound infection, cardiac reoperation, extracorporeal membrane oxygenation, atrial fibrillation or acute renal injury).

Cardiac surgery is the most important treatment for serious coronary heart disease, valvular heart disease, congenital heart disease and other heart diseases. Its postoperative mortality and serious complications have also been widely concerned, especially in patients with pulmonary hypertension. The persistent pulmonary hypertension and systemic vascular paralysis during the perioperative period are the main causes of early postoperative death and serious complications such as organ failure.Catecholamine vasoactive drugs commonly used in cardiac surgery may aggravate the condition of pulmonary hypertension, while the use of drugs to reduce pulmonary hypertension, such as nitric oxide, prostaglandins and phosphodiesterase inhibitors, may worsen the state of systemic vascular paralysis.

Vasopressin and oxytocin are two effective components in pituitrin, and vasopressin is the main component that exerts strong vasoconstrictive effect.Vasopressin binds to receptors distributed in vascular smooth muscle, pituitary and kidney, and exerts its effects by regulating adenosine triphosphate sensitive K+ channel function, nitric oxide production and enhancing vascular response to catecholamine.In addition, oxytocin can also bind to the receptors distributed in the heart and vascular endothelium, and play a role by releasing atrial natriuretic peptide and nitric oxide.Therefore, pituitrin can not only constrict systemic circulation vessels and increase systemic circulation pressure, reduce pulmonary artery pressure and pulmonary vascular resistance, but also protect the heart and kidney.

Therefore, this study intends to explore whether pituitrin has an impact on the prognosis of patients with pulmonary hypertension after cardiac surgery, so as to provide reference for its clinical application.

Inclusion Criteria:

• age ≥18 years and ≤80 years;
• scheduled for elective cardiopulmonary bypass heart surgery (adult congenital heart disease surgery, coronary artery bypass grafting, valve replacement, valvuloplasty, heart transplantation and aortic surgery);
• Patients who had pulmonary hypertension (Mean pulmonary artery pressure at rest ≥ 25mmhg or pulmonary artery systolic pressure (PASP) ≥ 40mmhg as shown by echocardiography);
• sign informed consent.

Exclusion Criteria:

• use pituitrin or vasopressin before operation;
• Patients who had acute coronary syndrome;
• preoperative use of left ventricular assist devices other than intra aortic balloon - pump (IABP);
• Patients who had liver, thyroid and adrenal diseases, severe lung diseases, diabetes;
• Patients who had preoperative renal insufficiency (The increase of serum creatinine (SCR) within 48 h ≥ 0.3mg/dl (or ≥ 26.5 μ mol/L)； Or it is known or speculated that the increase of SCR in the past 7 days is more than 1.5 times of the basic value; Or 0.5ml/kg urine volume per hour for 6H);
• Patients who had severe carotid artery stenosis, preoperative stroke, mental disorder and other difficult to communicate and cooperate;
• Patients who had peripheral vascular disease, allergy to vasopressin or pituitrin, severe hyponatremia (na+ < 130 mmol/l), acute mesenteric ischemia, pregnancy, malignant tumors, required ECMO and underwent emergency surgery or reoperation;
• Patients who had participated in other clinical studies in recent 3 months.