OBJECTIVE:To analyze the clinical outcomes of surgical treatment of severe heart valve disease at medium and high altitudes (2260-4700 m above sea level) and to explore strategies to reduce serious perioperative complications and improve early survival rates. Methods:From January 2004 to January 201, 124 patients with severe heart valve disease underwent valve replacement in our hospital. Among them, 23 cases were mitral valve replacement, 19 cases were mitral valve replacement + tricuspid valvuloplasty, 9 cases were aortic valve replacement, 57 cases were mitral valve + aortic valve replacement + tricuspid valvuloplasty, 7 cases were mitral valve replacement + coronary artery bypass grafting, and 5 cases were tricuspid valve replacement. Results: 10 cases of early death (including 5 cases of severe hypocapnia, 2 cases of ventricular fibrillation due to severe arrhythmia, 2 cases of acute renal failure, and 1 case of systemic multi-organ failure due to pulmonary multi-drug resistant bacterial infection, 8.06%). There were 78 cases with follow-up from 3 months to 6 years, and 7 cases died. Conclusion: For patients with severe heart valve disease in middle and high altitude areas, it is necessary to effectively improve cardiac function, increase myocardial reserve, lower pulmonary artery pressure, improve pulmonary function and liver and kidney function before surgery, shorten the aortic block time as much as possible, preserve the subvalvular structure of mitral valve as much as possible, and correct the tricuspid regurgitation status above the medium amount, as well as timely management of various early surgical complications, which can improve the success rate of surgery and The success rate of surgery can be improved and the mortality rate can be effectively reduced. The surgery is a very risky procedure, with many postoperative complications and high mortality. However, in recent years, clinicians have gained a better understanding of the pathophysiological changes, and the concept of myocardial protection, surgical skills and perioperative management techniques have improved significantly, therefore, the surgical efficacy and medium and long-term results have improved significantly. In our cardiac surgery department, 124 cases of severe heart valve disease were performed from January 2004 to January 2015, which are reported as follows:1 Clinical data and methods1.1 General data There were 53 male cases and 71 female cases in this group. The age ranged from 24 to 65 years old, with an average of 41.6±17 years old. All of them were rheumatic heart valve disease, 81 cases of aortic valve and mitral valve double valve lesions; 23 cases of mitral valve lesions and 9 cases of aortic lesions. Among them, 6 cases had mitral valve closed dilatation followed by valve replacement; 97 cases had combined tricuspid valve insufficiency. The preoperative cardiac function was graded by NYHA as grade III in 68 cases, grade IV in 56 cases, left ventricular ejection fraction (EF) 32%-56%, average 47.2%, left ventricular end-diastolic diameter 57-105 mm, average 70.6mm, combined left atrial appendage thrombosis in 11 cases, combined diabetes mellitus in 5 cases, combined coronary artery disease in 7 cases, moderate or above pulmonary impairment in 43 cases, and different degrees of liver and renal impairment in 57 cases. 57 cases. The cardiothoracic ratio ranged from 0.63 to 0.98 (mean 0.73). The electrocardiogram showed that there were 79 cases of atrial fibrillation, 43 cases of right ventricular hypertrophic strain, 26 cases of left ventricular hypertrophic strain, and 42 cases of biventricular hypertrophic strain. The whole group was operated under moderate or deep hypothermic extracorporeal circulation, and myocardial protection was provided by aortic root or coronary artery orifice infusion of high potassium stopping solution plus local ice saline cooling. In some cases of double or triple valve replacement, continuous retrograde perfusion from the coronary sinus was performed. After blocking the aorta, myocardial protection is provided by infusion of a high potassium 4:1 warming solution (1), followed by another infusion of a potassium-containing warming solution 10 minutes before opening the aorta. The procedures: mitral valve replacement (MVR) in 23 cases, aortic valve replacement (MIR) in 9 cases, mitral valve replacement + tricuspid valvuloplasty (MVR+TVP) in 19 cases, mitral valve + aortic valve replacement + tricuspid valvuloplasty (BVR+TVP) in 57 cases, and mitral valve replacement + coronary artery bypass grafting (MVR+CABG) in 7 cases. One hundred and fifty-eight mechanical valves were used. All mitral valve replacements were performed with continuous sutures or interrupted sutures, and all aortic valve replacements were performed with 12-15 interrupted mattress sutures; the De’Vega method of annuloplasty with graft-forming rings was used in 79 cases of combined tricuspid valve insufficiency. The duration of extracorporeal circulation in all cases ranged from 77 to 260 min, with an average of 103 min; the duration of aortic blockade ranged from 43 to 200 min, with an average of 79 min; the heart was resuscitated automatically in 79 cases and by electric shock in 45 cases. The patient’s blood volume, colloid osmotic pressure and red blood cell pressure were adjusted to maintain a stable circulatory status, protect liver and kidney function, and continue to use vasoactive drugs and positive inotropic drugs. 2 Results There were 10 deaths in this group, including 5 deaths due to severe hypocapnia, 2 deaths due to severe arrhythmia leading to ventricular fibrillation, 2 deaths due to acute renal failure, and 1 death due to pulmonary multi-drug resistant bacterial infection causing systemic multiple organ failure. There was one case of death due to systemic multiorgan failure caused by multi-drug resistant bacteria in the lung, 8.06%. There were 78 cases with follow-up from 3 months to 6 years, and 7 cases died. The remaining 114 cases were successfully discharged from the hospital. Postoperative cardiac function recovered to grade I in 15 cases, grade II in 65 cases, and grade III in 43 cases.3 Discussion3.1 Judgment of severe heart valve disease All 124 patients in this group met the criteria for severe heart valve disease (1): (1) cardiac function grade IV; (2) moderate or above pulmonary impairment; (3) cardiothoracic ratio >0.70; (4) echocardiography showed left ventricular end-diastolic internal diameter >60 mm; (5) The electrocardiogram shows left ventricular hypertrophy with strain or biventricular hypertrophy; (6) double valve replacement; (7) liver, kidney, brain and other organ function damage. 3.2 Adequate preoperative preparation, preoperative should be strengthened to improve cardiac function, the application of cardiotonic diuretic, vasodilator drugs, preoperative routine intravenous drip polarization fluid to increase myocardial reserve, improve myocardial tolerance to ischemia and hypoxia. At the same time, we should strengthen respiratory function exercise and improve general nutrition, and actively correct anemia and hypoproteinemia, so as to reduce postoperative complications and mortality. Pulmonary hypertension is one of the high-risk factors for severe heart valve surgery at high altitude (2), therefore, preoperative pulmonary artery pressure-lowering therapy should be performed, and for those with combined moderate pulmonary hypertension or above, prostaglandins and milrinone should be used to relieve pulmonary hypertension and reduce pulmonary complications, which is conducive to postoperative recovery. 3.3 Myocardial protection is a key factor for successful surgery in severe valve disease, and the use of high-potassium cold blood stop solution Myocardial protection can be achieved by adequate synthesis of high-energy phosphate in myocardial cells for storage (1), which can reduce reperfusion injury. In patients with preoperative giant heart and poor cardiac function, the whole body tissue, especially the myocardial tissue, is obviously edematous; extracorporeal circulation often causes increased capillary permeability and systemic water accumulation, resulting in multi-organ dysfunction. Therefore, planned and purposeful application of ultrafiltration can eliminate excess water from the body, concentrate blood, increase the oxygen-carrying capacity of blood, and reduce edema in organs and tissues, which is conducive to the recovery of cardiac and renal function after surgery [2].3.4 Preserving the integrity of the subvalvular structure of the mitral valve and preserving left ventricular function (1,2), some studies have demonstrated that after mitral valve replacement with complete preservation of the subvalvular structure, the early left ventricular anterobasal, anterolateral, and left ventricular 3.5 Active management of tricuspid valve lesions For moderate tricuspid valve insufficiency or above, the tricuspid valve must be treated at the same time to improve right ventricular function, relieve pulmonary hypertension, and facilitate postoperative recovery. Therefore, it is necessary to actively correct the tricuspid regurgitation status and improve the right heart function. We used De’Vega annuloplasty with a shaped ring for tricuspid valvuloplasty, which resulted in good perioperative recovery and satisfactory long-term results. 3.6 Postoperative treatment Patients with giant left ventricle should continue to apply positive inotropic drugs and sodium nitroprusside after surgery to improve myocardial contractility, reduce cardiac load, and ensure blood supply to important tissues and organs (3). Postoperatively, it is appropriate to extend the duration of ventilator support, strengthen airway management, adequately repay oxygen debt, extend the duration of dobutamine and dobutamine use, and adjust the amount of rehydration according to blood pressure, left atrial pressure, central venous pressure and urine volume. At the same time, diuretic dehydration therapy should be intensified to eliminate interstitial edema. After small left ventricle surgery, we should prevent left heart failure due to excessive preload, and apply positive inotropic drugs for at least 2 weeks for left ventricular atrophy, and cardiac stimulants for at least 6 months after discharge (1, 2). Timely left heart assisted circulation (ECOM) or intra-aortic bursal counterpulsation (IABP) is an effective and reliable treatment for postoperative low cardiac output, and renal insufficiency should be treated with continuous ultrafiltration (CRT) or dialysis as early as possible. In conclusion, patients with severe heart valve disease at high altitude are severely ill and in poor physical condition, with high surgical risk, frequent complications, and a certain mortality rate, but as long as the indications are strictly mastered, adequate preoperative evaluation and comprehensive treatment, intraoperative strengthening of myocardial protection, minimization of myocardial block time, effective correction of heart valve lesions (destruction and functional failure), postoperative strengthening of monitoring, and timely and effective management of various complications , clinical studies have confirmed that timely surgical treatment of patients with severe heart valve disease can significantly benefit patients and can improve life treatment and survival rates. References 1 Zhou XM Huang J Li LM et al, Surgical treatment of critical heart valve disease, Journal of Clinical Surgery, 2007 (3) 188–190. 2 Mao WK Wang LM Lu L et al, Journal of Hyperbaric Medicine, 2008, Vol. 18 (4) 30–32. 3 Li XH Xu ZY Han L et al, Shandong Medicine, 2011, Vol. 51 (2) 52–53.