左西孟旦在心脏外科手术的应用

心脏外科手术中体外循环后心功能障碍的病人常需要正性肌力药物的支持.传统的正性肌力药由于存在增加心肌氧耗和致心律失常的危险,临床应用受到一定限制.左西孟旦,一种新型强心剂-钙增敏剂,其强心作用机制是增加心肌收缩蛋白对钙离子的敏感性,并通过激活KATP发挥扩血管和抗缺血效应.现有的临床资料表明左西孟旦在治疗术中高危或合并左心功能不全的心脏手术病人以及帮助病人顺利脱离体外循环方面具有很好的应用前景.     

Levosimendan in cardiac surgery

OBJECTIVE: Levosimendan is a new calcium sensitizer with inodilatory properties. There is growing clinical experience with levosimendan given to cardiac surgical patients. The aim of this report was to evaluate the effects of perioperative use of levosimendan in surgical patients with high perioperative risk, compromised left ventricular (LV) function, or difficulties in weaning from cardiopulmonary bypass (CPB). DESIGN: Case series. SETTING: Single-institution, university hospital. PARTICIPANTS: Patients undergoing cardiac surgery. MEASUREMENTS AND MAIN RESULTS: Sixteen cardiac surgical patients received levosimendan infusion with a maximum duration of 29 hours. Eight were initiated preoperatively and 8 postoperatively. Coronary artery disease was the main operative indication in 10 of 16 cases, and 75% of the patients were high-risk patients. RESULTS: Continuous levosimendan infusion increased cardiac index significantly in both groups compared with preoperative baseline. Pulmonary capillary wedge pressure and systolic blood pressure did not change significantly. Norepinephrine and epinephrine were the most common concomitant vasoactive medications. Most importantly, weaning from CPB was successful in all patients even after failure to wean the patient with catecholamines. One high-risk patient in the preoperative group and 2 patients in the postoperative group died in the hospital. Another patient died during the 1-year follow-up. CONCLUSION: Levosimendan can be used for postoperative rescue therapy for patients difficult to wean from CPB. Also, elective preoperative initiation of levosimendan seems applicable to patients with high perioperative risk or compromised LV function.     

Levosimendan in cardiac surgery: current best available evidence

Recent upsurge in referral of patients with high perioperative risk or compromised left ventricular function for cardiac surgery has lead to an increasing use of pharmacologic support in the form of vasodilator and inotropic therapy to achieve improvement of tissue perfusion in the perioperative period or to support weaning from cardiopulmonary bypass. Traditionally, perioperatively used inotropic agents, epinephrine, dobutamine, and milrinone, are limited by significant increases in myocardial oxygen consumption, proarrhythmia, or neurohormonal activation. Levosimendan, a new inodilator for the treatment of decompensated heart failure, has also shown promise in elective therapy of cardiac surgical patients with high perioperative risk or compromised left ventricular function, as well as in rescue therapy of patients with difficult weaning from cardiopulmonary bypass. This review article briefly discusses the pharmacology of levosimendan and evaluates current best available evidence to assess the safety and efficacy of levosimendan usage in cardiac surgery.     

Effects of normothermic cardiopulmonary bypass on bispectral index

This study investigated the changes in the hypnotic component of anaesthesia, estimated by the bispectral index of the electroencephalogram, during normothermic cardiopulmonary bypass. Twenty-six patients (20 men, 6 women), aged 61 +/- 11 years (Mean +/- SD) scheduled for cardiac surgery were premedicated with hydroxyzine and meperidine. Anaesthesia was induced and maintained with a computer-controlled continuous infusion (not adjusted for haemodilution) of sufentanil (effect site concentration 0.4-0.6 ng mL-1) and a manually adjusted continuous infusion of propofol (4.4 +/- 1.8 mg kg-1 h-1). Cardiopulmonary bypass was normothermic with moderate haemodilution. Bispectral index was measured with a referential montage before, 30 s, 1, and 3 min after cardiopulmonary bypass onset, before and after aortic cross-clamping, 30 min after cardiopulmonary bypass onset, before and after aorta cross-clamp release and before and after weaning from cardiopulmonary bypass. Bispectral index values were 48 +/- 8 before cardiopulmonary bypass onset, 50 +/- 10 before, and 48 +/- 8 after end of cardiopulmonary bypass (P = NS). No patient had increases in bispectral index values during cardiopulmonary bypass consistent with awakening. We conclude that with the anaesthetic regimen presented in this study bispectral index values do not change during normothermic cardiopulmonary bypass.     

Acute and temporary ventricular support with BioMedicus centrifugal pump.

BACKGROUND: Short-term ventricular and pulmonary support can be provided by the Medtronic BioMedicus (Eden Prairie, MN) centrifugal pump, which is available in most cardiovascular surgery centers. This versatile pump can provide support during cardiopulmonary resuscitation, cardiopulmonary bypass, extracorporeal membrane oxygenation, and ventricular assistance. A common use of the pump is to provide ventricular assistance for patients after cardiotomy or cardiogenic shock. METHODS: From January 1986 to September 1995, 141 patients at The Methodist Hospital in Houston, Texas were placed on the BioMedicus centrifugal pump after postcardiotomy cardiac failure. Patient treatment and postimplant complications are discussed. RESULTS: Fifty-four percent of the patients were weaned; however, only 22% survived to discharge. There was a very high mortality rate in the early stage after support was discontinued, after weaning, and after device removal. CONCLUSIONS: A high incidence of complications and death is likely related to the period of attempted weaning from cardiopulmonary bypass before the initiation of ventricular support. When weaning a patient from the pump during cardiopulmonary bypass or during ventricular assistance, it is important to optimize preload, after-load, ventricular function, and cardiac rhythm. In patients who have had postcardiotomy support, avoiding fluid overload, low colloid oncotic pressure, hypoperfusion, and use of excessive inotropic and vasoactive medications improve results.     

Prophylactic amrinone for weaning from cardiopulmonary bypass

This prospective, randomised, double-blind, controlled clinical study was performed at a single tertiary referral centre to test the hypothesis that the prophylactic administration of amrinone before separation of a patient from cardiopulmonary bypass decreases the incidence of failure to wean, and to identify those patients who could be predicted to benefit from such pre-emptive management. Two hundred and thirty-four patients, scheduled to undergo elective cardiac surgery, were randomly allocated to receive either a bolus dose of 1.5 mg x kg(-1) amrinone over 15 min, followed by an infusion of 10 microg x kg(-1) x min(-1), or a bolus of placebo of equal volume followed by an infusion of placebo. Treatment with amrinone or placebo was initiated upon release of the aortic cross-clamp, before weaning from cardiopulmonary bypass. Anaesthetic technique, monitoring and myocardial preservation methods were standardised for both groups. Significantly fewer patients failed to wean in the group that received prophylactic amrinone than in the control group (7 vs. 21%, p = 0.002). Amrinone improved weaning success regardless of left ventricular ejection fraction, although this benefit was statistically significant only in the group with left ventricular ejection fractions > 55%. Of the 32 patients who failed to wean from cardiopulmonary bypass, 14 had normal pre-operative left ventricular ejection fractions.     

Coronary artery bypass grafting for a patient with bronchial asthma seceeded from cardiopulmonary bypass by additional bypass for spasm of radial artery graft: a case report

A 78-year-old male who had a bronchial asthma underwent coronary artery bypass grafting (CABG) using the left internal thoracic artery and the radial artery. The patient could not be weaned from the cardiopulmonary bypass because the radial artery which anastomosed to the obtuse marginal artery (OM) had a spasm after CABG. An additional bypass using a long saphenous vein to OM was carried out immediately. It brought a weaning from cardiopulmonary bypass. If the cardiac function after CABG is insufficient in patients with bronchial asthma, CABG must be re-done immediately, considering that they cause the arterial spasm more than patients without bronchial asthma.     

Cardioprotective effects of carnitine in extensive aortocoronary bypass grafting: a double-blind, randomized, placebo-controlled clinical trial

The cardioprotective effects of carnitine were tested in patients undergoing multiple aortocoronary bypass grafting. Intermittent aortic cross-clamping at 28 degrees C was used. Mean total cross-clamping time was 30 +/- 11 min. Patients were randomized into three groups: a control group receiving placebo (group 1), a group pretreated with 3 g carnitine intravenously before cardiopulmonary bypass (CPB) (group 2), and a group pretreated with 6 g carnitine intravenously (group 3). The markers of myocardial ischemia included levels of adenosine triphosphate, its catabolites, and creatine phosphate in transmural left ventricular biopsy specimens taken at the beginning and end of CPB, as well as hemodynamic recovery during weaning from CPB and for the next 24 h. The intravenous infusion of carnitine (3 or 6 g) had no hemodynamic effect. At the end of CPB myocardial tissue levels of adenosine triphosphate and creatine phosphate did not differ significantly among the groups (P greater than 0.05). Recovery of cardiac function during weaning from CPB and for the following 24 h was similar in all three groups (P greater than 0.05). It is concluded that pretreatment with carnitine neither facilitates weaning from cardiopulmonary bypass in patients undergoing aortocoronary bypass surgery nor favorably affects hemodynamic function during the next 24 h.     

End-tidal CO2 for prediction of cardiac output following weaning from cardiopulmonary bypass

This prospective study included 32 patients undergoing cardiopulmonary bypass (CPB) for elective coronary artery bypass grafting correlates the respiratory end-tidal CO2 (ETCO2) during partial separation from CPB with cardiac output (CO) following weaning from CPB. After induction of general anesthesia, a pulmonary artery catheter was inserted for measurement of cardiac output by thermodilution. Patients were monitored using a 5-lead ECG, pulse oximeter, invasive blood pressure monitoring, rectal temperature probe, and end-tidal capnography. At the end of surgery, patients were weaned from CPB in a stepwise fashion. Respiratory ETCO2 and in-line venous oximetry were continuously monitored during weaning. The ETCO2 was recorded at quarter pump flow and after complete weaning from CPB. Following weaning from CPB, CO was measured by thermodilution. The CO values were correlated with the ETCO2 during partial bypass and following weaning from bypass. Regression analysis of ETCO2 at quarter-flow and post-bypass CO showed significant correlation (r = 0.57, p < .001). Also, regression analysis of ETCO2 after complete weaning from bypass and post-bypass CO showed significant correlation (r = 0.6, p = .002). The correlation between ETCO2 and CO showed that an ETCO2 >30 mm Hg during partial CPB will always predict an adequate CO following weaning from CPB. An ETCO2 <30 mm Hg may denote either a low or a normal cardiac output and hence other predictive parameters such as SvO2 must be added.     

Endotoxemia in coronary artery bypass surgery: a comparison of the off-pump technique and conventional cardiopulmonary bypass

OBJECTIVES: The endotoxemia associated with cardiac surgery is thought to be dominantly influenced by the use of cardiopulmonary bypass. The objectives of this study were to assess the relative contribution of cardiopulmonary bypass on endotoxemia apart from cardiac surgical access and to improve our understanding of the potential benefits of off-pump procedures. METHODS: Thirty patients undergoing coronary artery bypass grafting were followed up prospectively. The patients were divided into 2 equal groups: those who underwent bypass grafting through a sternotomy incision without cardiopulmonary bypass (off-pump group) and those who underwent bypass grafting through a sternotomy incision with cardiopulmonary bypass (CPB group). Blood sampling for endotoxin, lactate, and cardiac index measurements were performed during the following time points: (1) after sternotomy; (2) during the coronary occlusion period in the off-pump group and during aortic clamping in the CPB group; (3) after removal of the coronary occlusion sutures in the off-pump group and after removal of the aortic clamp in the CPB group; (4) 30 minutes after the completion of all distal anastomoses in the off-pump group and immediately after weaning from cardiopulmonary bypass in the CPB group; (5) 1 hour postoperatively; and (6) 12 hours postoperatively. RESULTS: Endotoxin and lactate levels were significantly (P <.05) lower in the off-pump group at all sampling time points, except after sternotomy. CONCLUSIONS: In conclusion, this study has shown that endotoxemia during coronary artery bypass surgery seems mainly to be associated with cardiopulmonary bypass procedure. The relatively lower endotoxin levels observed in off-pump surgery might contribute to improved postoperative recovery.     

The effect of olprinone administered after cardio-pulmonary bypass during open heart surgery, evaluated by its plasma concentrations and hemodynamic changes]

Plasma concentrations and hemodynamic effects of olprinone were evaluated in seventeen patients undergoing open heart surgery. The patients were randomized into the bolus group (15 micrograms.kg-1 bolus dose +0.1 microgram.kg-1.min-1 infusion, n = 9) and the non-bolus group (0.1 microgram.kg-1.min-1 infusion, n = 8). Plasma concentrations and hemodynamic variables were measured before CPB (cardiopulmonary bypass; baseline), 5, 60 min after weaning from CPB, and 3, 6 hours after the end of surgery. Plasma concentrations in the non-bolus group were significantly lower than those of bolus group at any point except for 3 hours after the end of surgery. In the bolus group, increases in the cardiac index and stroke volume index were significantly higher compared with the non-bolus group. From these results we conclude that olprinone given in bolus (15 micrograms.kg-1) followed by continuous infusion (0.1 microgram.kg-1.min-1) is efficacious and safe during weaning from CPB.     

Cardiopulmonary bypass for complex cardiac surgery using bivalirudin anticoagulation in a patient with heparin antibodies

BACKGROUND: The presence of antibodies directed against heparin necessitates the use of an alternative anticoagulant in patients undergoing cardiac surgery. Bivalirudin is a short-acting direct thrombin inhibitor that has been used successfully in routine cardiac surgical cases. Experience in complicated cases requiring extended cardiopulmonary bypass is limited, however. We report the successful use of bivalirudin in a patient who underwent complex cardiac surgery. METHOD: A 42-year-old patient with aortic regurgitation due to endocarditis who had heparin antibodies underwent a Ross procedure for aortic valve replacement using bivalirudin as anticoagulant during cardiopulmonary bypass (CPB). Bivalirudin was given with a bolus of 1 mg/kg and a continuous infusion of 2.5 mg/kg/hours during CPB. Monitoring of bivalirudin was performed using the ecarin clotting time (ECT). RESULTS: After 128 minutes of extracorporeal circulation, the patient was weaned from CPB without problems. After termination of CPB, modified ultrafiltration (MUF) was commenced. Perioperatively, six units of fresh frozen plasma were transfused. The 12-hour postoperative blood loss was 550 mL. The postoperative course was uneventful and the patient was discharged from hospital after 5 days. CONCLUSION: Bivalirudin can be safely used for anticoagulation during CPB even in complex cardiac surgery.     

Schwere akzidentelle Hypothermie mit Kreislaufstillstand und extrakorporaler Erwärmung

In patients with severe hypothermia and cardiac arrest, active rewarming is recommended by extracorporeal circulation with cardiopulmonary bypass. The current guidelines for resuscitation of the European Resuscitation Council now include the recommendation regarding patients with hypothermia remaining comatose after initial resuscitation to accomplish an active rewarming only up to a temperature of 32-34 degrees C and to maintain a mild hypothermia for 12-24 h. We report the case of a 2-year-old boy who suffered from severe hypothermia after falling into ice-cold water. On discovery cardiac arrest with asystole was present and the first measured temperature was 23.8 degrees C. Resuscitation led to restoration of spontaneous circulation. The patient was rewarmed by extracorporeal circulation with cardiopulmonary bypass to 33 degrees C then mild hypothermia was maintained for a further 12 h. On the third day after the accident the patient was extubated and after a further 9 days was discharged without any sequelae.     

Propofol—fentanyl anaesthesia for coronary artery surgery and cardiopulmonary bypass

A two-stage propofol infusion combined with fentanyl was used to maintain anaesthesia during coronary artery surgery in patients with good ventricular function. Whole blood propofol concentrations were measured at frequent intervals; plasma protein binding was measured before, during and after cardiopulmonary bypass. An initial infusion rate of 10 mg/kg/hour provided good protection from the pressor response to sternotomy. A predictable steady state concentration was achieved in the prebypass period with a maintenance infusion rate of 3 mg/kg/hour. The onset of bypass resulted in a small decrease in propofol concentration as a result of haemodilution. Induced hypothermia resulted in an increase in propofol concentration which returned rapidly to the prebypass steady state value during rewarming. The free propofol fraction increased during cardiopulmonary bypass. No patient had any recall of operative events or required inotropic support during weaning from bypass.     

新型正性肌力药左西孟旦的作用机制及临床应用

左西孟旦是一种新型正性肌力药--钙增敏剂,可通过钙敏作用增强心肌收缩力,激活K+通道使血管扩张,且并不增加心肌氧耗和心率,因而具有改善心功能和心肌保护等作用.可应用于治疗急性失代偿心力衰竭、心肌缺血后心脏收缩力异常、心肌顿抑以及用于心脏手术期间循环的调控等方面.     

Effect of combined infusion of nitroglycerin and nicardipine on femoral-to-radial arterial pressure gradient after cardiopulmonary bypass

Nitrates and calcium channel blockers are frequently administered during cardiac surgery. We simultaneously measured femoral arterial pressure and radial arterial pressure to investigate whether nitrates, in conjunction with calcium channel blockers, would influence the central-to-peripheral arterial pressure gradient. Combined nitroglycerin and nicardipine infusion during cardiac surgery involving coronary artery bypass grafting or valve replacement resulted in a significant increase above baseline levels in the femoral-to-radial arterial pressure gradient at 60 min after cardiopulmonary bypass. In control patients there was no significant increase in the femoral-to-radial arterial pressure gradient at 60 min after completion of cardiopulmonary bypass. A subsequent study in patients given nitroglycerin and nicardipine identified that the difference in the systolic arterial pressure between femoral and radial arteries was observed 15, 60, and 120 min after completion of cardiopulmonary bypass. However, there was no difference in the mean arterial pressure between femoral and radial arteries throughout the same period. We conclude that combined infusion of nitroglycerin and nicardipine, a new calcium channel blocker, intensifies the magnitude and duration of the femoral-to-radial arterial pressure gradient after cardiopulmonary bypass.     

The use of the novel calcium sensitizer levosimendan in critically ill patients

Levosimendan, a novel calcium sensitizer, enhances cardiac contractility by increasing myocyte sensitivity to calcium, and induces vasodilation. In this prospective observational study the haemodynamic effects of levosimendan in postoperative critically ill patients are reported. Twelve patients with the need for inotropic support were studied. One dose of levosimendan (12.5 mg) was administered at a rate of 0.1-0.2 microg kg(-1).min(-1), either alone or in addition to pre-existing inotropic therapy. Haemodynamic measurements were obtained at baseline, and at 3 h, 6 h, 12 h, and 24 h after the start of the levosimendan infusion. Levosimendan significantly increased cardiac output from (mean+/-SD) 4.3+/-0.91.min(-1) to 5.2+/-1.51 min(-1) after 24h (P=0.013), by increases in stroke volume (baseline 47+/-15 ml, after 24h 57+/-25 ml, P=0.05), as heart rate remained unchanged. Systemic vascular resistance decreased from 1239+/-430 dyn.sec.cm(-5) at baseline to 963+/-322 dyn.sec. cm(-5) at 24h (P<0.001). Pre-existing inotropic therapy present in ten patients remained unchanged or was reduced. In postoperative critically ill patients, infusion of levosimendan exerted favourable haemodynamic responses. Levosimendan increased cardiac output by increasing stroke volume, which might be attributed primarily to its inotropic properties. Due to its cyclic adenosine monophosphate independent positive inotropic effects, levosimendan may be of value as adjunctive therapy to other inotropic drugs in critically ill patients.     

Rescue peri-operative management of the patient with giant electrical storm and severe left ventricular dysfunction: support by levosimendan and intraaortic balloon counterpulsation

We present a case of a 62-year-old male patient (coronary heart disease, and stenosis of aortic valve) with severe left ventricular dysfunction (left ventricular ejection fraction 20%, left ventricular end-diastolic diameter 80 mm, end-diastolic volume 329 ml) who developed giant electrical storm (on the whole 115 episodes of pulseless ventricular tachycardia treated by antiarrhythmics and electrical discharges) with low-elevation of cardiac biomarkers. The patient was referred to emergent cardiac surgery (double coronary bypass grafting, aortic valve replacement, and implantation of left ventricular epicardial electrode). Levosimendan and intraaortic balloon counterpulsation were used for successful weaning from the cardiopulmonary bypass; no other arrhythmia appeared in the post-bypass period. Postoperatively no arrhythmic events were detected, and repeated echocardiographic examinations of the patient in good general condition showed gradual improvement of left ventricular ejection fraction (30-35%), likewise in other parameters (left ventricular end-diastolic diameter 72 mm, end-diastolic volume 285 ml).     

Lidocaine for prevention of reperfusion ventricular fibrillation after release of aortic cross-clamping

OBJECTIVE: To determine the efficacy of a bolus of lidocaine administered by way of the pump before releasing the aortic cross-clamp (ACC) in preventing the occurrence of reperfusion ventricular fibrillation. DESIGN: Prospective, randomized study. SETTING: University hospital. PARTICIPANTS: Patients undergoing coronary artery bypass graft surgery (n = 34). INTERVENTIONS: Seventeen patients received 100 mg of lidocaine by way of the pump 2 minutes before releasing the ACC, and a control group of 17 patients received 5 mL of normal saline. MEASUREMENTS AND MAIN RESULTS: In the control group, the incidence of reperfusion ventricular fibrillation was 70%, which was significantly decreased to 11% in the lidocaine group. A higher cardiac output after weaning from cardiopulmonary bypass was observed in the lidocaine group; this may be attributed to the lower incidence of reperfusion ventricular fibrillation and consequently the lower need for defibrillation by electric countershocks. CONCLUSIONS: The results suggest that a bolus of 100 mg of lidocaine administered 2 minutes before release of the ACC can safely decrease the incidence of reperfusion ventricular fibrillation and is associated with better hemodynamics after weaning from cardiopulmonary bypass.     

Emergency cardiopulmonary bypass for cardiopulmonary-cerebral resuscitation

Cardiopulmonary bypass (C-P bypass) was performed on two patients who had not responded to conventional cardiopulmonary resuscitation (CPR). The first patient, a 56-y-o male, with bilateral pulmonary thromboembolism repeatedly underwent cardiac massage and electric defibrillation for recurrent ventricular fibrillation. A veno-arterial bypass route was prepared during cardiac massage, and bypass circulation was started 3 hours after the onset of the first ventricular fibrillation. Soon after the initiation of C-P bypass, the physical status and EEG of the patient improved. The patient regained consciousness within a few hours and later underwent open chest pulmonary embolectomy. The second patient, a 44-y-o male, developed refractory cardiogenic shock near the end of aortocoronary bypass graft operation. Under closed chest massage, a femoro-femoral cardiopulmonary bypass operation was started. Soon after the initiation of the bypass circulation and IABP, peripheral circulation improved markedly, and consciousness returned within several hours. Though the first patient finally died from far advanced pulmonary embolism, he was conscious as long as the C-P bypass was continued for two days. In the second patient, the cardiac function gradually improved after the 3rd day. C-P bypass was tapered and discontinued on the 5th day. Emergency veno-arterial bypass for CPR is effective means to maintain life until the cardiopulmonary and cerebral functions are restored. Recent advances in emergency C-P bypass are introduced and a new acronym extracorporeal lung and heart assist, ECLHA, is proposed. Emergency ECLHA with veno-arterial cannulations through percutaneous puncture will become a promising adjunct of cardiopulmonary-cerebral resuscitation in the near future.