Duration of cardiopulmonary bypass compared with changes in the plasma protease systems.

Forty patients undergoing elective coronary artery bypass grafting were investigated concerning association between duration of cardiopulmonary bypass (CPB) and changes in the plasma protease systems. Spontaneous enzyme activity, proenzymes and functional inhibition capacities in the fibrinolytic, plasma kallikrein-kinin and coagulation systems were measured before, during and after CPB and in the immediate postoperative period. No clear relationship was revealed between changes in the measured variables and the duration of CPB.     

Changes in antiplasmin and plasmin activities during extreme hemodilution and open heart surgery in dogs.

The effects of extreme hemodilution and open heart surgery on antiplasmin and plasmin activities were investigated in dogs. Assays for plasmin and antiplasmin activities were performed with a chromogenic peptide substrate for plasmin. After hemodilution and during cardiopulmonary bypass (CPB), plasmin activity on the substrate was observed and levels of both "fast-reacting" and "total" antiplasmins fell. The plasmin activity was shown to be due to the formation of alpha2-macroglobulin-plasmin complex which exhibited amidolytic activity on the chromogenic substrate. The falls in antiplasmin activity together with the appearance of the alpha2-macroglobulin-plasmin complex revealed that activation of the fibrinolytic system had occurred. After the operation and following reinfusion of autologous blood, decreased plasmin and increased antiplasmin activities were observed. On the first and sixth days following the operation plasmin activities were still slightly higher than pre-operation values, whilst antiplasmin activities were normal.     

Binding of fentanyl and alfentanil to the extracorporeal circuit

Adsorption of fentanyl and alfentanil to the cardiopulmonary bypass (CPB) equipment was studied in vitro by adding one of the analgesics to the priming solution consisting of either saline or a mixture of saline and blood. Opiate concentrations in the solutions were measured during a 60-min circulation period of a closed CPB system. When the saline prime was used, 29% of the predicted fentanyl level of 30 ng ml-1 was found at the end of the experiment, while the recovery of alfentanil was 80% of the calculated level of 1500 ng ml-1. When blood was added to the prime, experiments with fentanyl produced similar results to those with pure saline prime, but recovery exceeding the calculated concentration was obtained with alfentanil. The difference between the alfentanil levels in the two primes may reflect the poor distribution of this analgesic into red blood cells. In another set of experiments, the CPB circuit was primed with fentanyl or alfentanil and circulated for 10 min before connection of the apparatus to patients undergoing cardiac surgery under high-dose opiate anaesthesia. This priming prevented the steep reduction in plasma opiate concentration regularly observed during the institution of CPB. It is concluded that in a clinically relevant dose range a smaller fraction of alfentanil is sequestered by the CPB apparatus than fentanyl.     

Investigation of Limulus test during and after cardiopulmonary bypass--analysis of Limulus positive substance and particles in the cardiopulmonary bypass circuit

Patients undergoing heart surgery with cardiopulmonary bypass (CPB) frequently have positive Limulus test without any remarkable signs of endotoxemia. CPB circuit could be one of the possible causes of this phenomenon, but the exact mechanism has not been studied. Accordingly, a prospective study was made in 41 patients undergoing heart surgery with CPB. Limulus test were performed on the samples of priming fluids of CPB including the plasma and urine of those patients during and after surgery. Besides the Limulus test, the CPB fluids were analysed by the false positive test. Microscopic examinations were carried out on the priming fluids before and after using a 40 microns filter during recirculation without washing the CPB circuit and the fluid from a 4 microns filter been washed by 2000 ml of Martose-10 in order to find out the presence of any foreign particles in the CPB circuit. The size and the number of particles were measured by coulter counter. The studies revealed the following facts, 1) Limulus test; most of the samples from priming fluids (31/35), plasma circulating the CPB (36/36), urine during CPB (22/25) and plasma (34/35) and urine (21/30) just after the surgery revealed positive. However, only 4 samples from plasma at 3POD and 2 samples from urine at 2POD revealed positive, 2) false positive test of the samples from priming fluids was negative meaning the Limulus positive substances are not endotoxin, 3) under microscopic analysis and coulter counter, there were about 40 particles over 50 microns per ml of priming fluids before washing the CPB circuit.(ABSTRACT TRUNCATED AT 250 WORDS)     

Aprotinin Reduces the Expression of P-Selectin on the Surface of Platelet and Leukocyte-Platelet Conjugates

P-Selectin, an adhesion molecule expressed on the surfaces of activated platelets and the vascular endothelium, mediates platelet binding to monocytes and neutrophils. Monocytes and neutrophils produce superoxide anion by activated platelets through p-selectin. Aprotinin, a serine protease inhibitor, inhibits plasmin to activate platelets during cardiopulmonary bypass (CPB). A total of 25 patients were studied to clarify the effects of aprotinin on p-selectin expression during CPB. Nine patients were not given aprotinin (control group), and 16 were given aprotinin of 2 million U in the priming solution (aprotinin group). The platelet count and soluble p-selectin in the plasma, p-selectin on the surface membranes of platelets, and leukocyte-platelet conjugate levels were measured during and after CPB. The platelet count was maintained well in the aprotinin group. The increases of soluble p-selectin in the plasma, platelet surface p-selectin, and leukocyte-platelet conjugates were less in the aprotinin group than in the control group (p < 0.05). In conclusion, aprotinin in patients undergoing CPB may reduce the early inflammatory reactions induced by p-selectin.     

Cerebral production of adrenomedullin afer hypothermic cardiopulmonary bypass in adult cardiac surgical patients.

Adrenomedullin is a potent vasodilatory peptide originally identified in human pheochromocytoma. Plasma adrenomedullin increases during and after cardiopulmonary bypass (CPB). However, the site at which production of adrenomedullin is augmented has not been identified. In the present study, we examined the contribution of the cerebral vasculature to the production of adrenomedullin in patients before, during, and after CPB. Ten patients undergoing coronary artery bypass grafting with mild hypothermic CPB were studied. Cerebral blood flow was measured using the Kety-Schmidt method before, during, and after CPB. Plasma adrenomedullin concentrations from radial artery and internal jugular bulb blood were measured by radioimmunoassay, and cerebral adrenomedullin production was evaluated. Adrenomedullin production in the cerebral vasculature was significantly enhanced after CPB and correlated with aortic cross-clamping time. The cerebral adrenomedullin production may contribute to the increased plasma level of adrenomedullin after CPB. IMPLICATIONS: Plasma adrenomedullin has been reported to increase in humans after cardiac surgery involving cardiopulmonary bypass. In this study, we demonstrated that cerebral adrenomedullin production may contribute to the increased plasma level of adrenomedullin after cardiopulmonary bypass.     

Swine as a model for cardiovascular research: improved cardiopulmonary bypass techniques

A large-animal model is essential for the assessment of functional parameters in cardiovascular surgical research. To date the canine model has been used successfully because of its availability and tolerance to cardiopulmonary bypass. However, because of decreased availability and increased cost, an alternative animal model is now needed. The swine model has been used in experimental cardiac procedures, but complications during cardiopulmonary bypass have presented a formidable challenge. These complications include enormous fluid shifts from the vascular bed, increased metabolic acidosis, and marked hemoglobinuria. To eliminate these deleterious complications within the swine model, a number of technical alterations were achieved. The priming solution used for the extracorporeal circuit was altered to consist of 1000 mL lactated Ringer's solution. 500 mL 20% mannitol, 500 mL 6% dextran in 5% detrose solution. 50 mEq sodium bicarbonate, and 10,000 IU heparin. The extracorporeal circuit employed the use of membrane oxygenation. Three different blood flow rates (150, 175, and 200 mL/kg min-1) were studied. We conclude that the optimum blood flow rate for cardiopulmonary bypass in swine is in the range of 175-200 mL/kg min-1. Membrane oxygenation results in less damage to blood during cardiopulmonary bypass. The asanguinous hyperosmolar priming solution is beneficial for cardiopulmonary bypass in swine to greatly reduce fluid shifts, prevent metabolic acidosis, and eliminate hemoglobinuria.     

Cardiopulmonary bypass and host defense functions in human beings: I. Serum levels and role of immunoglobulins and complement in phagocytosis

In patients undergoing open-heart surgical procedures, the serum levels of immunoglobulins and complement were determined as well as the functional capacity of these defense proteins as opsonins to facilitate phagocytosis by polymorphonuclear leukocytes. A considerable decrease in serum levels of the proteins studied was found after cardiopulmonary bypass (CPB). As a result, the opsonic capacity of post-CPB plasma was diminished. After correction for hemodilution, however, no difference between pre- and post-CPB plasma, as measured by the activity of thermolabile (e.g., complement C3) and thermostabile (e.g., immunoglobulin IgG) opsonins, could be demonstrated. It is concluded that CPB causes a quantitative but no functional decrease in levels of IgG and C3.     

Inflammatory system activation during cardiopulmonary bypass as an indicator of biocompatibility: a randomized comparison of bubble and membrane oxygenators

As the exposure of blood to foreign material during cardiopulmonary bypass (CPB) leads to triggering of inflammatory systems, the inflammatory response was used as an indicator of the biocompatibility of oxygenators. Activation of complement and neutrophil granulocytes during CPB was studied in 96 patients undergoing coronary bypass, with randomized comparisons between four different oxygenators, two of bubble and two of membrane type. Seven patients undergoing thoracotomy without CPB served as controls. During CPB there was significant complement activation, measured as changes in the ratio C3d/C3, with no demonstrable difference between the bubble and membrane oxygenator groups. Such change was not seen in the controls. Neutrophil granulocytes released significant amounts of the granule proteins lactoferrin and myeloperoxidase during CPB, but not during thoracotomy without CPB. The plasma concentrations of lactoferrin and myeloperoxidase were significantly lower in the membrane oxygenator groups, possibly indicating better biocompatibility. The strong inflammatory response with both oxygenator types, however, indicates that presently used CPB devices have unsatisfactory biocompatibility.     

Enhanced responsiveness of circulatory neutrophils after cardiopulmonary bypass: increased aggregability and superoxide producing capacity

Cardiac surgery with cardiopulmonary bypass (CPB) induces a whole body inflammatory response that sometimes leads to postoperative organ dysfunction, and neutrophil activation plays an important role in this reaction. Neutrophil priming has been described as a change in neutrophil status such that neutrophils show enhanced responsiveness to a second activating stimulus. We hypothesized that neutrophil priming occurs by cardiac surgery with CPB and is temporally related to the neutrophilia after surgery. To evaluate primed circulatory neutrophil status, we measured aggregation activity stimulated by N-formyl-methyl-leucyl-phenyl-alanine (FMLP) and free radical producing activity by tumor necrosing factor (TNF) alpha in peripheral blood samples. Eleven adult patients undergoing elective cardiac surgery with CPB were studied. Blood samples were taken before surgery, at the end of bypass, 12 h after surgery, and 7 days after surgery. Aggregation activity and superoxide generation were significantly elevated 12 h after surgery when compared to presurgery values, indicating that cardiac surgery is associated with circulatory neutrophil priming. The number of neutrophils markedly increased at the end of cardiopulmonary bypass and reached a peak 12 h after surgery. The circulatory neutrophils of cardiac surgical patients become primed after surgery, coincident with the peak neutrophil count. These results suggest that circulatory neutrophils after cardiac surgery with CPB have enhanced responsiveness and are predisposed to systemic inflammation.     

The plasma supplemented modified activated clotting time for monitoring of heparinization during cardiopulmonary bypass: a pilot investigation

The standard celite or kaolin activated clotting time (ACT) correlates poorly with heparin levels during cardiopulmonary bypass (CPB). We compared a modified kaolin ACT, in which plasma was supplemented, to a standard undiluted kaolin ACT for monitoring heparin levels during CPB. Fifteen patients undergoing normothermic CPB were enrolled in this prospective study. Heparin management was performed according to the Hepcon HMS results (Medtronic, Minneapolis, MN). The ACTs were performed with the ACT II device (Medtronic). Hepcon HMS calculations, standard kaolin ACTs, and plasma supplemented modified ACTs (mACTs), prepared by diluting blood samples 1:1 with human plasma (Behring, Marburg, Germany), were measured every 30 min during CPB. The data obtained were correlated to the plasma chromogenic anti-Xa activity as a reference assay for heparin levels. A total of 64 samples were evaluated. The chromogenic anti-Xa activity ranged from 0.2 to 5.5 IU/mL. The Hepcon HMS calculations ranged from 2.7-8.2 IU/mL of heparin, the standard ACT ranged from 424 to >999 s, and the mACT ranged from 210 to 801 s. The correlation to the chromogenic anti-Xa method was r = 0.43 for the standard kaolin ACT and r = 0.69 for the plasma mACT. The plasma mACT provided an improved correlation to chromogenically measured levels of anti-Xa activity during CPB. The improved correlation most likely results from a correction of the effects of the impairment of the coagulation system caused by hemodilution and consumption of procoagulants on extracorporeal surfaces. IMPLICATIONS: During cardiopulmonary bypass, the plasma modified kaolin activated clotting time (ACT) provides a better correlation with heparin levels than the standard kaolin ACT.     

Priming solutions for cardiopulmonary bypass: comparison of three colloids

The present study was designed to compare the differences in the clinical effects of three colloidal solutions, albumin, urea-linked gelatin, and succinyl-linked gelatin, when used as priming fluids for cardiopulmonary bypass (CPB) under alpha-stat conditions. A consecutive series of 105 patients scheduled for cardiac surgery were randomized into three identically managed groups, except for the CPB prime. Variables relating to acid-base status, oncotic activity, metabolism, coagulation, and postoperative evaluation were measured. Marked differences in acid-base status, colloid osmotic pressure, additional prime requirements, blood lactate, urine output, and the need for buffer solutions occurred among groups, with the succinyl-linked gelatin group having better results than the other groups. Changes in hemodynamics, oxygen consumption, and blood-glucose levels during CPB did not vary among groups. There were also no important intergroup differences in hematologic and clotting variables or postoperative parameters such as blood loss or use of blood products. Electrolyte changes were similar except for a significant increase in ionized calcium that occurred in the urea-linked gelatin group after bypass. The results indicate that succinyl-linked gelatin is an adequate and safe alternative to human albumin for use as a colloid during CPB under alpha-stat conditions.     

Fluid shift is moderate and short-lived during acute crystalloid hemodilution and normothermic cardiopulmonary bypass in piglets

BACKGROUND: Crystalloids are commonly used as priming solutions during cardiopulmonary bypass (CPB). Consequently, hemodilution is a regular occurrence at the start of a CPB. This study describes the time-course variations of hemodynamic parameters, plasma volume (PV) and fluid exchange following crystalloid hemodilution at start of normothermic CPB. METHODS: Forty-five anesthetized piglets were given 60-min normothermic CPB. Ringer's solution was used as priming solution and maintenance fluid. Fluid input/losses, PV, colloid osmotic pressures (plasma/interstitium), hematocrit, and s-proteins were measured, and fluid extravasation rates (FER) and intravascular protein-masses calculated. RESULTS: Start of CPB resulted in a 25-30% hemodilution. To keep the fluid level of the CPB-reservoir constant after start of bypass, fluid addition [2.08 +/- 0.36 (mean +/- SEM) ml kg(-1) min(-1)] was necessary during the first 5 min. Thereafter the fluid needs to be leveled off [0.17 +/- 0.03 ml kg(-1) min(-1) (10-60 min), P < 0.001]. Fluid extravasation rate increased immediately following hemodilution from a baseline value of 0.08 +/- 0.01 to 1.75 +/- 0.34 ml kg(-1) min(-1) with a delayed decrease compared to fluid additions, to reach a 'steady-state' level of 0.22 +/- 0.03 ml kg(-1) min(-1) after 30 min (P < 0.001). Differences in time-course variations between fluid added and fluid extravasated were accompanied by changes in PV and mean arterial pressure. The colloid osmotic gradient decreased about 50% throughout the study and could partly explain the increased FER. CONCLUSION: Acute crystalloid hemodilution contributes to fluid overload during normothermic CPB. The resulting increase in fluid extravasation is, however, moderate, short-lived and levels off to baseline values within 30 min.     

Reduction of complement activation during bypass by prime manipulation

Complement activation is believed to be of importance in the development of complications arising after cardiopulmonary bypass. The effect on complement activation of priming the extracorporeal circuit with crystalloid alone, crystalloid plus albumin, or crystalloid plus the plasma expander polygeline was assessed in 36 patients undergoing coronary artery operations with cardiopulmonary bypass using a bubble oxygenator. Activation of the alternative and common complement pathways was monitored before, during, and after the bypass period by measuring concentrations of factor B and its fragment Ba and C3 and its fragment C3d. Complement activation occurred in all three groups of patients, with no difference between the crystalloid and crystalloid-albumin groups. In contrast, Ba fragment concentrations were persistently and significantly lower during and after bypass in the polygeline group, denoting reduced complement activation. C3d levels also showed a tendency to be lower in this group. Our results indicate that addition of polygeline to the priming solution reduces complement activation. Because complement activation is associated with morbidity after cardiopulmonary bypass, addition of polygeline to the priming solution may offer an inexpensive method of reducing morbidity after cardiopulmonary bypass.     

Changes in hemostasis during pediatric heart surgery: impact of a biocompatible heparin-coated perfusion system

BACKGROUND: This study describes the response in hemostasis during open-heart surgery with cardiopulmonary bypass (CPB) in children (<== 10 kg) and tests the hypothesis that the use of a biocompatible perfusion system, in comparison with a conventional system, causes less hemostatic activation. METHODS: Prospective, randomized, controlled clinical study. Forty consecutive children <== 10 kg were included and divided into two groups: group bioc. (n = 19) treated with a fully heparin-coated system, centrifugal pump, and a closed circuit, and group conv. (n = 21) treated with an uncoated system, roller pump, and a hard shell venous reservoir. Concentrations of plasma thrombin-antithrombin (TAT), D-dimer, tissue plasminogen activator antigen (t-PA ag), and the complex consisting of tissue plasminogen activator and its inhibitor plasminogen activator inhibitor-1 (t-PA-PAI-1) were measured. RESULTS: The biochemical variables measured increased significantly in both groups during the study period. There was less activation of fibrinolysis during cardiopulmonary bypass (t-PA ag: p = 0.009) in patients treated with the biocompatible perfusion system than in patients treated with the conventional system. A trend in favor of the biocompatible system based on the D-dimer and TAT data (p = 0.07 for both measurements) was observed but no significant intergroup differences regarding these variables or t-PA-PAI-1 were found. CONCLUSIONS: Open-heart surgery with cardiopulmonary bypass in children (<== 10 kg) causes transient activation of the coagulation and fibrinolytic systems. This study demonstrates that the use of a biocompatible perfusion system results in a lower extent of activation of fibrinolysis during CPB than the use of a conventional system.     

Effect of cardiopulmonary bypass on plasma levels of nifedipine

Blood levels of many medications are acutely lowered by cardiopulmonary bypass (CPB). Because nifedipine is often used to provide protection from coronary ischemia, a determination of the effect of CPB on plasma nifedipine levels might help to determine the potential clinical benefit of nifedipine during and after bypass. Four samples of blood were drawn from each of eight patients undergoing cardiac surgery: one before, two during, and one after CPB. Although plasma levels of nifedipine declined during and after bypass (P less than 0.05, analysis of variance), the time-course and slope of the decline indicate that this was an effect of normal metabolism of the drug rather than an effect of physiologic changes occurring during CPB. An important additional finding was that the majority of patients had subtherapeutic levels of nifedipine before bypass, suggesting that additional nifedipine given during and after surgery might be of benefit. The effect of the CPB circuit itself was also examined in vitro by mixing nifedipine into a pump prime solution that was then recirculated with 2 U of outdated blood while levels of nifedipine were measured for 3 h. Plasma levels did not change in either a CPB circuit exposed to light or kept in a darkened room.     

Normothermic beating heart surgery with assistance of miniaturized bypass systems: the effects on intraoperative hemodynamics and inflammatory response

The use of miniaturized cardiopulmonary bypass (CPB) circuits and avoidance of cardioplegic arrest are attempts to reduce the inflammatory response to cardiac surgery. We studied the effects of beating heart surgery (BHS) with assistance of simplified bypass systems (SBS) on global hemodynamics, myocardial function and the inflammatory response to CPB. We hypothesized that the use of SBS was associated with less hemodynamic instability after CPB resulting from attenuation of the inflammatory response when compared with surgery performed with a conventional CPB (cCPB) circuit. Forty-five patients undergoing coronary artery bypass grafting were prospectively studied. Fifteen patients were randomized to the use of a cCPB circuit, cold crystalloid cardioplegia, and moderate hypothermia. Two groups of 15 patients underwent BHS during normothermia with assistance of two different SBS consisting of only blood pump and oxygenator. Hemodynamic variables were assessed with transpulmonary thermodilution and transesophageal echocardiography. Plasma levels of proinflammatory and antiinflammatory mediators were measured perioperatively. After CPB, variables of global hemodynamics and systolic ventricular function did not differ among groups. Left ventricular diastolic function was impaired after CPB equally in all groups (P < 0.01 versus pre-CPB). At the end of surgery, there was more need for vasopressor (norepinephrine) support in both SBS groups than in the cCPB group (P < 0.01). After CPB, the release of interleukin (IL)-6 did not differ significantly among groups, whereas plasma levels of IL-10 were higher in the cCPB group (P < 0.01 versus SBS). The extent of myocardial necrosis (Troponin T) was comparable in all groups. We conclude that in our study, miniaturizing bypass systems and avoidance of cardioplegic arrest were not effective in improving hemodynamic performance and in attenuating the proinflammatory immune response after CPB.     

Comparative effectiveness of methylprednisolone and zero-balance ultrafiltration on inflammatory response after pediatric cardiopulmonary bypass

Studies have demonstrated that systemic inflammatory response syndrome (SIRS) remains one of the major causes of cardiopulmonary bypass (CPB)-associated organ injury during pediatric cardiac surgery. The purpose of this investigation was to compare the effectiveness of methylprednisolone (MP) and zero-balance ultrafiltration (ZBUF) on SIRS during pediatric CPB. Thirty infants undergoing open-heart surgeries were randomized to receive either MP in the priming solution (group M, n = 15) or ZBUF during CPB (group Z, n = 15). All the patients survived. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-10 (IL-10) were measured before CPB (T1), 5 min after the start of CPB (T2), at the termination of CPB (T3), the fourth hour (T4), and the eighth hour (T5) postoperatively. The results showed that the plasma concentrations of TNF-alpha in the Z group were significantly less than those in the M group at T4 and T5 (P < 0.05), and the plasma concentrations of IL-6 were significantly less than those in the M group at T4 (P < 0.05); the plasma concentrations of IL-8 in the Z group were significantly less than those in the M group at T5 (P < 0.05). There was no difference between two groups on the plasma concentrations of IL-10. The duration of postoperative mechanical ventilation was (9.6 +/- 0.8 h) in the M group and (7.8 +/- 0.4 h) in the Z group (P < 0.05). This study showed that application of ZBUF is more effective to decrease the level of inflammatory mediators including TNF-alpha, IL-6, and IL-8 than administration of MP after pediatric CPB.     

Calcium, magnesium and phosphate during and after hypothermic cardiopulmonary bypass without temperature correction of acid base status

The plasma concentration variations of calcium, magnesium and phosphate were studied in ten patients during and after hypothermic cardiopulmonary bypass (CPB) without temperature correction of acid base status. During the study, pH remained stable, but all the other studied components varied significantly (P less than 0.001). At the start of CPB, the mean ionized calcium concentration increased 25%, and magnesium and phosphate decreased 29% and 40%, respectively, from their control values. At the end of blood cooling, ionized calcium was still 11% above its initial value, magnesium 50% above, and phosphate 39% below. Before weaning from CPB, ionized calcium remained 10% above its initial level, magnesium 41% above, and phosphate 26% below. After CPB, the different divalent ions returned to their initial levels within 1 h for ionized calcium, 6 h for phosphate and 9 h for magnesium. One day post-CPB, ionized calcium was at its start level, magnesium 13% lower, and phosphate 36% higher. During cardiac surgery, the acid base regulation without temperature correction (so-called "alpha stat mode") avoided the appearance of carbon dioxide acidosis. There were widespread disturbances of the divalent ions concentrations, due principally to the different fluids used during CPB, pump priming fluids and cardioplegic solution.     

N-乙酰半胱氨酸对体外循环下心脏瓣膜置换术患者心肌缺血再灌注损伤的影响

目的 探讨N-乙酰半胱氨酸对体外循环(CPB)下心脏瓣膜置换术患者心肌缺血再灌注损伤的影响.方法 择期CPB下行心脏瓣膜置换术的风湿性心脏病患者22例,性别不限,年龄21-60岁,ASA Ⅱ或Ⅲ级,心功能Ⅱ或Ⅲ级,随机分为2组(n=11):对照组(C组)和N-乙酰半胱氨酸组(N组).N组预充液中加入N-乙酰半胱氨酸100 mg/kg,停搏液中加入50 mg/kg,C组给予生理盐水替代.于麻醉诱导前10 min和术毕时,记录HR、MAP、中心静脉压(CVP)、肺动脉压(PAP)、肺毛细血管楔压(PCWP)、心输出量(CO)和心脏指数(CI).于切皮前即刻、主动脉开放后0.5、6、12和24 h时,采集桡动脉血样行血气分析,采集中心静脉血样测定血浆白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)、丙二醛(MDA)、心肌肌钙蛋白I(cTnI)的浓度和超氧化物歧化酶(SOD)活性.于CPB前即刻和停机即刻,取心肌组织,计数凋亡细胞,观察心肌细胞超微结构.结果 与c组比较,N组HR、MAP、CVP、PAP、PCWP、pH值、红细胞压积、动脉血氧分压、动脉血二氧化碳分压和剩余碱差异无统计学意义(P>0.05),主动脉开放后TNF-α、IL-6、cTnI和MDA的浓度降低,SOD活性升高,CPB停机即刻心肌凋亡细胞计数降低,术毕CO和CI升高(P<0.05或0.01),心肌病理损伤减轻.结论 N-乙酰半胱氨酸可减轻体外循环下心脏瓣膜置换术患者心肌缺血再灌注损伤.