Effects of Propofol, Desflurane, and Sevoflurane on Recovery of Myocardial Function after Coronary Surgery in Elderly High-risk Patients

Background: The present study investigated the effects of propofol, desflurane, and sevoflurane on recovery of myocardial function in high-risk coronary surgery patients. High-risk patients were defined as those older than 70 yr with three-vessel disease and an ejection fraction less than 50% with impaired length-dependent regulation of myocardial function.

Methods: Coronary surgery patients (n = 45) were randomly assigned to receive either target-controlled infusion of propofol or inhalational anesthesia with desflurane or sevoflurane. Cardiac function was assessed perioperatively and during 24 h postoperatively using a Swan-Ganz catheter. Perioperatively, a high-fidelity pressure catheter was positioned in the left and right atrium and ventricle. Response to increased cardiac load, obtained by leg elevation, was assessed before and after cardiopulmonary bypass (CPB). Effects on contraction were evaluated by analysis of changes in dP/dtmax. Effects on relaxation were assessed by analysis of the load-dependence of myocardial relaxation. Postoperative levels of cardiac troponin I were followed for 36 h.

Results: After CPB, cardiac index and dP/dtmax were significantly lower in patients under propofol anesthesia. Post-CPB, leg elevation resulted in a significantly greater decrease in dP/dtmax in the propofol group, whereas the responses in the desflurane and sevoflurane groups were comparable with the responses before CPB. After CPB, load dependence of left ventricular pressure drop was significantly higher in the propofol group than in the desflurane and sevoflurane group. Troponin I levels were significantly higher in the propofol group.     

Sevoflurane but not propofol preserves myocardial function in coronary surgery patients

BACKGROUND: Sevoflurane has been shown to protect against myocardial ischemia and reperfusion injury in animals. The present study investigated whether these effects were clinically relevant and would protect left ventricular (LV) function during coronary surgery. METHODS: Twenty coronary surgery patients were randomly assigned to receive either target-controlled infusion of propofol or inhalational anesthesia with sevoflurane. Except for this, anesthetic and surgical management was the same in all patients. A high-fidelity pressure catheter was positioned in the left ventricle and the left atrium. LV response to increased cardiac load, obtained by leg elevation, was assessed before and after cardiopulmonary bypass (CPB). Effects on contraction were evaluated by analysis of changes in dP/dt(max). Effects on relaxation were assessed by analysis of the load dependence of myocardial relaxation (R = slope of the relation between time constant tau of isovolumic relaxation and end-systolic pressure). Postoperative concentrations of cardiac troponin I were followed during 36 h. RESULTS: Before CPB, leg elevation slightly increased dP/dt(max) in the sevoflurane group (5 +/- 3%), whereas it remained unchanged in the propofol group (1 +/- 6%). After CPB, leg elevation resulted in a decrease in dP/dt(max) in the propofol group (-5 +/- 4%), whereas the response in the sevoflurane group was comparable to the response before CPB (5 +/- 4%). Load dependence of LV pressure fall (R) was similar in both groups before CPB. After CPB, R was increased in the propofol group but not in the sevoflurane group. Troponin I concentrations were significantly lower in the sevoflurane than in the propofol group. CONCLUSIONS: Sevoflurane preserved LV function after CPB with less evidence of myocardial damage in the first 36 h postoperatively. These data suggest a cardioprotective effect of sevoflurane during coronary artery surgery.     

Cardioprotective properties of sevoflurane in patients undergoing aortic valve replacement with cardiopulmonary bypass

In coronary surgery patients the use of a volatile anesthetic regimen with sevoflurane was associated with a better recovery of myocardial function and less postoperative release of troponin I. In the present study we investigated whether these cardioprotective properties were also apparent in the cardiac surgical setting of aortic valve replacement (AVR) surgery for the correction of aortic stenosis. Thirty AVR surgery patients were randomly assigned to receive either target-controlled infusion of propofol or inhaled anesthesia with sevoflurane. Cardiac function was assessed perioperatively using a pulmonary artery catheter. Perioperatively, a high-fidelity pressure catheter was positioned in the left ventricle. Postoperative concentrations of cardiac troponin I were followed for 48 h. After cardiopulmonary bypass (CPB), stroke volume and dP/dt(max) were significantly higher in the patients with sevoflurane. Post-CPB, the effects of an increase in cardiac load on dP/dt(max) were similar to pre-CPB in the sevoflurane group (1.0 % +/- 5.4% post-CPB versus 1.3% +/- 8.6% pre-CPB) but more depressed in the propofol group (-8.2% +/- 4.4% post-CPB versus 0.1% +/- 4.9% pre-CPB). The rate of relaxation was significantly slower post-CPB in the propofol group. Postoperative levels of troponin I were significantly lower in the sevoflurane group. Our data indicate that the use of a volatile anesthetic regimen in AVR surgery was associated with better preservation of myocardial function and a reduced postoperative release of troponin I.     

Sevoflurane but Not Propofol Preserves Myocardial Function in Coronary Surgery Patients

Background: Sevoflurane has been shown to protect against myocardial ischemia and reperfusion injury in animals. The present study investigated whether these effects were clinically relevant and would protect left ventricular (LV) function during coronary surgery.

Methods: Twenty coronary surgery patients were randomly assigned to receive either target-controlled infusion of propofol or inhalational anesthesia with sevoflurane. Except for this, anesthetic and surgical management was the same in all patients. A high-fidelity pressure catheter was positioned in the left ventricle and the left atrium. LV response to increased cardiac load, obtained by leg elevation, was assessed before and after cardiopulmonary bypass (CPB). Effects on contraction were evaluated by analysis of changes in dP/dtmax. Effects on relaxation were assessed by analysis of the load dependence of myocardial relaxation (R = slope of the relation between time constant [tau] of isovolumic relaxation and end-systolic pressure). Postoperative concentrations of cardiac troponin I were followed during 36 h.

Results: Before CPB, leg elevation slightly increased dP/dtmax in the sevoflurane group (5 +/- 3%), whereas it remained unchanged in the propofol group (1 +/- 6%). After CPB, leg elevation resulted in a decrease in dP/dtmax in the propofol group (-5 +/- 4%), whereas the response in the sevoflurane group was comparable to the response before CPB (5 +/- 4%). Load dependence of LV pressure fall (R) was similar in both groups before CPB. After CPB, R was increased in the propofol group but not in the sevoflurane group. Troponin I concentrations were significantly lower in the sevoflurane than in the propofol group.     

地氟烷在二尖瓣置换手术中对缺血再灌注心肌的保护作用

在心脏外科手术中心肌缺血再灌注(ischemia-reperfusion,I-R)损伤的防治是急需解决的问题。缺血预处理(ischemic preconditioning,IPC)具有心肌保护作用[1,2]。研究显示挥发性麻醉药也具有类似IPC的麻醉药预处理(anesthetic-induced preconditioning,APC)作用[3,4],能减轻I-R后     

Effects of desflurane and sevoflurane on length-dependent regulation of myocardial function in coronary surgery patients

BACKGROUND: Desflurane and sevoflurane have negative inotropic effects. The current study investigated whether these effects resulted in an altered left ventricular response to increased cardiac load and affected length-dependent regulation of myocardial function. Length-dependent regulation of myocardial function refers to the ability of the heart to improve its performance when preload is increased. METHODS: A high-fidelity pressure catheter was positioned in the left ventricle and left atrium in 20 coronary surgery patients with a preoperative ejection fraction greater than 40%. Studies were performed before the initiation of cardiopulmonary bypass. Left ventricular response to increased cardiac load, obtained by leg elevation, was assessed during control conditions and during increasing concentrations of desflurane (2, 4, and 6% end tidal; n = 10) or sevoflurane (1, 2, and 3% end tidal; n = 10). Effects on contraction were evaluated by analysis of changes in maximal rate of pressure development. Effects on relaxation were assessed by analysis of changes in minimum rate of pressure development and by analysis of the load dependence of myocardial relaxation (R = slope of the relation between time constant tau of isovolumic relaxation and end-systolic pressure). Peak left atrial-left ventricular pressure gradients were analyzed during early left ventricular filling. RESULTS: With both desflurane and sevoflurane, maximal and minimum rates of pressure development decreased while tau increased. Peak left atrial-left ventricular pressure gradients remained unchanged. The hemodynamic effects of leg elevation were similar at the different concentrations. Changes in parameters of contraction and relaxation during leg elevation were coupled and were not altered by desflurane or sevoflurane. CONCLUSIONS: Despite their negative inotropic and lusitropic effects, neither desflurane nor sevoflurane adversely affect length-dependent regulation of left ventricular function. In the conditions of our study, the ability of the left ventricular to respond to increased cardiac load is not altered by the use of desflurane or sevoflurane.     

Induced preconditioning of cardiac performance in coronary bypass surgery--sevoflurane vs propofol

Twenty ASA III and IV adult patients scheduled for elective coronary artery surgery were included in the study. Anesthesia was induced and maintained with either sevoflurane (sevoflurane group; n = 10) or propofol (propofol group; n = 10). All preoperative cardiac medications were continued until the morning of surgery. There were significant decreases in mean arterial blood pressure, cardiac index and ejection fraction after CPB in propofol group compared with sevoflurane. Further, the plasma creatine kinase myocardial isoenzyme concentrations were significantly higher in propofol group but did not approach the critical values needed for diagnosis of myocardial infarction. Conclusion: It is concluded that, sevoflurane appears to be associated with better hemodynamic stability before and after CPB than propofol. This could be attributed to cardioprotective effect of sevoflurane during ischemia and reperfusion.     

Effects of Desflurane and Sevoflurane on Length-dependent Regulation of Myocardial Function in Coronary Surgery Patients

Background: Desflurane and sevoflurane have negative inotropic effects. The current study investigated whether these effects resulted in an altered left ventricular response to increased cardiac load and affected length-dependent regulation of myocardial function. Length-dependent regulation of myocardial function refers to the ability of the heart to improve its performance when preload is increased.

Methods: A high-fidelity pressure catheter was positioned in the left ventricle and left atrium in 20 coronary surgery patients with a preoperative ejection fraction greater than 40%. Studies were performed before the initiation of cardiopulmonary bypass. Left ventricular response to increased cardiac load, obtained by leg elevation, was assessed during control conditions and during increasing concentrations of desflurane (2, 4, and 6% end tidal; n = 10) or sevoflurane (1, 2, and 3% end tidal; n = 10). Effects on contraction were evaluated by analysis of changes in maximal rate of pressure development. Effects on relaxation were assessed by analysis of changes in minimum rate of pressure development and by analysis of the load dependence of myocardial relaxation (R = slope of the relation between time constant [tau] of isovolumic relaxation and end-systolic pressure). Peak left atrial-left ventricular pressure gradients were analyzed during early left ventricular filling.

Results: With both desflurane and sevoflurane, maximal and minimum rates of pressure development decreased while [tau] increased. Peak left atrial-left ventricular pressure gradients remained unchanged. The hemodynamic effects of leg elevation were similar at the different concentrations. Changes in parameters of contraction and relaxation during leg elevation were coupled and were not altered by desflurane or sevoflurane.     

七氟醚和异丙酚对冠状动脉旁路移植术患者心肌保护作用比较的Meta分析

目的 采用Meta分析法比较七氟醚和异丙酚对冠状动脉旁路移植术患者心肌的保护作用.方法 通过电子数据库检索比较冠状动脉旁路移植术患者七氟醚和异丙酚心肌保护作用的临床随机对照研究,文献检索至2008年9月.由两位作者分别对研究质量进行评估,并提取有关资料,主要包括患者术前情况、术中情况、体外循环后心脏指数、术后心肌肌钙蛋白Ⅰ水平、机械通气时间、正性肌力药物使用情况、ICU停留时间、住院时间、术后死亡、心肌梗死、心肌缺血和房颤的发生情况,采用RevMan 5.0软件进行Meta分析.结果 共纳入13项前瞻性临床随机对照研究,包括696例患者,其中七氟醚组402例,异丙酚组294例.两组患者术后机械通气时间、正性肌力药物使用率、术后病死率、心肌梗死和房颤的发生率差异无统计学意义(P>0.05).与异丙酚组相比,七氟醚组患者体外循环后心脏指数升高,术后心肌肌钙蛋白Ⅰ水平和心肌缺血发生率降低,ICU停留时间和住院时间缩短(P<0.05).结论 冠状动脉旁路移植术患者七氟醚的心肌保护作用优于异丙酚.     

Haemodynamic changes during halothane, sevoflurane and desflurane anaesthesia in dogs before and after the induction of severe heart failure

BACKGROUND AND OBJECTIVE: The effects of desflurane and sevoflurane on the failing myocardium are still uncertain. We investigated the effects of different concentrations of sevoflurane, desflurane and halothane in dogs with pacing induced chronic heart failure. METHODS: Global (left ventricular pressure, left ventricular dP/dt, Konigsbergtransducer) and regional myocardial function (systolic segment length shortening, ultrasonic crystals) were measured in chronically instrumented dogs with tachycardia induced severe congestive heart failure. Measurements were performed in healthy dogs and after induction of heart failure in the awake state and during anaesthesia with 0.75, 1.0, 1.25 and 1.75 minimum alveolar concentration (MAC) of halothane, sevoflurane or desflurane. RESULTS: The anaesthetics reduced dP/dtmax in a dose-dependent manner in healthy dogs (dP/dtmax decreased to 43-53% of awake values at 1.75 MAC). Chronic rapid left ventricular pacing increased heart rate and left ventricular end-diastolic pressure and decreased mean arterial pressure, left ventricular systolic pressure and dP/dtmax. The reduction in contractility was similar in the failing myocardium (to 41-50% of awake values at 1.75 MAC). Segmental shortening was reduced during anaesthesia by 50-62% after pacing compared with 22-44% in normal hearts. While there were similar effects of the different anaesthetics on diastolic function in healthy dogs, after induction of heart failure a more pronounced increase of the time constant of isovolumic relaxation and a greater decrease of dP/dtmin was observed with sevoflurane than with desflurane, indicating a stronger depression of diastolic function. CONCLUSIONS: While the negative inotropic effects of sevoflurane and desflurane were similar in normal and in the failing myocardium in vivo, desflurane led to a better preservation of diastolic function in the failing myocardium.     

Evaluation of left ventricular function in anesthetized patients using femoral artery dP/dt(max)

OBJECTIVE: The purpose of this study was to compare dP/dt(max) estimated from a femoral artery pressure tracing to left ventricular (LV) dP/dt(max) during various alterations in myocardial loading and contractile function. PARTICIPANTS: Seventy patients scheduled for elective coronary artery bypass surgery. METHODS: All patients were instrumented with a high-fidelity LV catheter, a pulmonary artery catheter, and a femoral arterial catheter. In 40 patients, hemodynamic measurements were performed before and after passive leg raising and before and after calcium administration (5 mg/kg); and in 30 other patients, hemodynamic measurements were performed before and after dobutamine infusion (5 microg/kg/min over 10 minutes). RESULTS: LV and femoral dP/dt(max) were significantly correlated (r = 0.82, p < 0.001), but femoral dP/dt(max) systematically underestimated LV dP/dt(max) (bias = -361 +/- 96 mmHg/s). Passive leg raising induced significant increases in central venous pressure and LV end-diastolic pressure, but femoral dP/dt(max), stroke volume, and LV dP/dt(max) remained unaltered. Calcium administration induced significant and marked increases in LV dP/dt(max) (23% +/- 9%) and femoral dP/dt(max) (37% +/- 14%) associated with a significant increase in stroke volume (9% +/- 2%). Dobutamine infusion also induced significant and marked increases in LV dP/dt(max) (25% +/- 8%) and femoral dP/dt(max) (35% +/- 12%) associated with a significant increase in stroke volume (14% +/- 3%). Overall, a very close linear relationship (r = 0.93) and a good agreement (bias = -5 +/- 17 mmHg/s) were found between changes in LV dP/dt(max) and changes in femoral dP/dt(max). A very close relationship was also observed between changes in LV dP/dt(max) and changes in femoral dP/dt(max) during each intervention (leg raising, calcium administration, and dobutamine infusion). CONCLUSION: Femoral dP/dt(max) underestimated LV dP/dt(max), but changes in femoral dP/dt(max) accurately reflected changes in LV dP/dt(max) during various interventions.     

Dose dependent effects of cardiac beta2 adrenoceptor gene therapy

BACKGROUND: Adenoviral-mediated gene transfer during cardiopulmonary bypass (CPB) achieves efficient myocardial transgene expression. The optimal vector dose required to produce not only increased beta adrenoceptor (betaAR) density but, more importantly, enhanced left ventricular (LV) function is unknown. In addition, it is unclear if absent extracardiac expression in preliminary studies represented cardiac specific, as opposed to selective gene delivery, as a consequence of low vector doses. MATERIALS AND METHODS: Adenoviral vector encoding the human beta(2) adrenoceptor (Adeno-beta(2)AR) was delivered to cardioplegic arrested hearts of neonatal piglets during CPB in three doses ranging from 5 x 10(11) total viral particles (tvp) to 2 x 10(12) tvp. Control animals received adenoviral vector encoding beta galactosidase (Adeno-betagal) or PBS (PBS). LV and liver betaAR density and in vivo LV function were assessed 5 days later. RESULTS: Elevated LV betaAR density was present after delivery of Adeno-beta(2)AR at all doses. Piglets which received 5 x 10(11) tvp and 1 x 10(12) tvp Adeno-beta(2)AR demonstrated enhanced LV dP/dt(max) but in those receiving 2 x 10(12) tvp LV dP/dt(max) was unchanged. Moreover, at this higher dose of adenoviral vector the detrimental effects of cardiac inflammation and extracardiac gene overexpression became apparent. CONCLUSIONS: Although the highest increase in cardiac betaAR density occurred after high-dose Adeno-beta(2)AR, LV dP/dt(max) was not enhanced. Moreover, significant extracardiac gene expression was present at this dose, emphasizing the need for careful dose response studies in gene therapy. However, cardiac selective beta(2)AR overexpression does occur following adenoviral vector delivery during CPB and cardioplegic arrest resulting in enhanced LV dP/dt(max).     

Effects of halothane, sevoflurane and desflurane on the force-frequency relation in the dog heart in vivo

PURPOSE: Frequency potentiation is the increase in force of contraction induced by an increased heart rate (HR). This positive staircase phenomenon has been attributed to changes in Ca2+ entry and loading of intracellular Ca2+ stores. Volatile anesthetics interfere with Ca2+ homeostasis of cardiomyocytes. We hypothesized that frequency potentiation is altered by volatile anesthetics and investigated the influence of halothane (H), sevoflurane (S) and desflurane (D) on the positive staircase phenomenon in dogs in vivo. METHODS: Dogs were chronically instrumented for measurement of left ventricular (LV) pressure and cardiac output. Heart rate was increased by atrial pacing from 120 to 220 beats x min(-1) and the LV maximal rate of pressure increase (dP/dt(max)) was determined as an index of myocardial performance. Measurements were performed in conscious dogs and during anesthesia with 1.0 minimal alveolar concentrations of each of the three inhaled anesthetics. RESULTS: Increasing HR from 120 to 220 beats x min(-1) increased dP/dt(max) from 3394 +/- 786 (mean +/- SD) to 3798 +/- 810 mmHg sec(-1) in conscious dogs. All anesthetics reduced dP/dt(max) during baseline (at 120 beats x min(-1): H, 1745 +/- 340 mmHg x sec(-1); S, 1882 +/- 418; D, 1928 +/- 454, all P < 0.05 vs awake) but did not influence the frequency potentiation of dP/dt(max) (at 220 beats x min(-1): H, 1981 +/- 587 mmHg x sec(-1); S, 2187 +/- 787; D, 2307 +/- 691). The slope of the regression line correlating dP/dt(max) and HR was not different between awake and anesthetized dogs. Increasing HR did not influence cardiac output in awake or anesthetized dogs. CONCLUSION: These results indicate that volatile anesthetics do not alter the force-frequency relation in dogs in vivo.     

Impact of acute myocardial edema on left ventricular function.

Studies of the impact of myocardial edema on left ventricular (LV) systolic function show conflicting results. We sought to evaluate the impact of increased myocardial water content (MWC) on LV systolic and diastolic function. Anesthetized dogs (n = 12) were instrumented with myocardial ultrasonic crystals and an LV micromanometer. Systolic function was measured by preload recruitable stroke work (PRSW) and dP/dt(max). Diastolic function was measured by -dP/dt(max) and the isovolumic relaxation constant tau (t). Myocardial water content (MWC) was determined using microgravimetry. In six dogs (coronary sinus hypertension, CSH group) we produced myocardial edema by inflating a coronary sinus balloon for 2 h (30-40 mm Hg). In six other dogs (Plegisol, PLEG group) cardiopulmonary bypass (CPB) was initiated (12.3 +/- 0.8 min), the aorta was cross-clamped (117 +/- 19 s), and 700 mL 4 degrees C crystalloid, hyperkalemic cardioplegic solution (Plegisol) was administered into the aortic root (62 +/- 4 mm Hg). After declamping and reperfusion (7.2 +/- 1.0 min), the dogs were separated from CPB. Myocardial function parameters and MWC were measured for 2 h after edema generation. In the CSH group, MWC significantly increased from 75.9 +/- 0.3% to 77.6 +/- 0.3% (p < .05). In the PLEG group, MWC increased from 75.8 +/- 0.3% to 77.7 +/- 0.3% (p < .05). PRSW and dP/dt(max) did not decrease in either group. Diastolic parameters did not change significantly. We conclude that acute myocardial edema without myocardial injury does not impair LV function.     

Choice of primary anesthetic regimen can influence intensive care unit length of stay after coronary surgery with cardiopulmonary bypass

BACKGROUND: Volatile anesthetics protect the myocardium during coronary surgery. This study hypothesized that the use of a volatile agent in the anesthetic regimen would be associated with a shorter intensive care unit (ICU) and hospital length of stay (LOS), compared with a total intravenous anesthetic regimen. METHODS: Elective coronary surgery patients were randomly assigned to receive propofol (n = 80), midazolam (n = 80), sevoflurane (n = 80), or desflurane (n = 80) as part of a remifentanil-based anesthetic regimen. Multiple logistic regression analysis was used to identify the independent variables associated with a prolonged ICU LOS. RESULTS: Patient characteristics were similar in all groups. ICU and hospital LOS were lower in the sevoflurane and desflurane groups (P < 0.01). The number of patients who needed a prolonged ICU stay (> 48 h) was also significantly lower (propofol: n = 31; midazolam: n = 34; sevoflurane: n = 10; desflurane: n = 15; P < 0.01). Occurrence of atrial fibrillation, a postoperative troponin I concentration greater than 4 ng/ml, and the need for prolonged inotropic support (> 12 h) were identified as the significant risk factors for prolonged ICU LOS. Postoperative troponin I concentrations and need for prolonged inotropic support were lower in the sevoflurane and desflurane group (P < 0.01). Postoperative cardiac function was also better preserved with the volatile anesthetics. The incidence of other postoperative complications was similar in all groups. CONCLUSIONS: The use of sevoflurane and desflurane resulted in a shorter ICU and hospital LOS. This seemed to be related to a better preservation of early postoperative myocardial function.     

Heterotopic transplantation as a model to study functional recovery of unloaded failing hearts

OBJECTIVES: Recent studies have demonstrated cardiac improvement in patients supported with a ventricular assist device, suggesting that reverse remodeling and myocardial recovery are possible. We developed an animal model of cardiac unloading by adapting a heterotopic transplantation technique and used it to examine the pattern of functional recovery in the left ventricle of the failing heart. METHODS: Heart failure was induced in adult New Zealand rabbits by coronary artery ligation with subsequent myocardial infarction. Animals undergoing sham operation served as a control group. After 4 weeks or 3 months, failing hearts were transplanted into the necks of recipient rabbits. A left ventricular latex balloon connected to subcutaneous tubing allowed repeated physiologic analysis on days 1 and after transplantation and then every 5 days until day 30. RESULTS: Contractility (left ventricular dP/dt(max)) and relaxation (left ventricular dP/dt(min)) were significantly lower in transplanted postinfarction hearts as compared to control hearts immediately after transplantation. Both left ventricular dP/dt(max) and left ventricular dP/dt(min) responses to increased preload and to beta-adrenergic stimulation progressively improved to a significantly higher level after 30 days of left ventricular unloading for the hearts that were transplanted 4 weeks after myocardial infarction. However, this functional improvement was not detected in failing hearts transplanted 3 months after infarction. CONCLUSIONS: This model of cardiac unloading appears at least partially to mimic conditions of ventricular assist devices. If performed early in the development of heart failure, it permits improvement of contractile dysfunction and restoration of cardiac responsiveness to mechanical and beta-adrenergic stimulation. Therefore this model may constitute a novel alternative in the study of reverse remodeling in unloaded failing hearts.     

Mild hypothermia impairs left ventricular diastolic but not systolic function.

Hypothermia is a component of myocardial protection during cardiopulmonary bypass (CPB) and cardioplegic arrest (CA). Patients in the early post CPB period often show mild hypothermia and cardiac dysfunction. We sought to investigate the impact of hypothermia on left ventricular (LV) function. Anesthetized dogs (n = 12) were instrumented with myocardial ultrasonic crystals and LV micromanometer. Systolic function was measured by preload recruitable stroke work (PRSW). Diastolic function was measured by -dP/dt(max) and tau. In six dogs (Norm group), body temperature was maintained at baseline levels. In another six dogs (Hypo group), body temperature dropped gradually over the time course of the experiment. The body temperature in the Hypo group decreased from 37.0 +/- 0.3 degrees C to 35.2 +/- 1.0 degrees C. -dP/dt(max) decreased and tau increased significantly with hypothermia but were stable in the Norm group. Both tau and -dP/dt(max) showed a linear relationship to the body temperature (r =.91 and r = .93, respectively). PRSW did not change and cardiac output decreased with hypothermia. Thus, even mild hypothermia impairs LV diastolic but not systolic function. Cardiac output is temperature sensitive and therefore rewarming of patients post-CPB has priority.     

Sevoflurane but not propofol preserves myocardial function during minimally invasive direct coronary artery bypass surgery

Volatile anesthetics exert cardioprotective properties in experimental and clinical studies. We designed this study to investigate the effects of sevoflurane on left ventricular (LV) performance during minimally invasive direct coronary artery bypass grafting (MIDCAB) without cardiopulmonary bypass. Fifty-two patients scheduled for MIDCAB surgery were randomly assigned to a propofol or a sevoflurane group. Apart from the anesthetics used, there was no difference in surgical and anesthetic management. After determination of cardiac troponin T, creatine kinase, and creatine kinase MB, electrocardiographic (ECG) data and echocardiography variables (myocardial performance index and early to atrial filling velocity ratio) the left anterior descending coronary artery (LAD) was clamped until anastomosis with the left internal mammary artery was completed. During LAD occlusion and during reperfusion, echocardiography measurements were repeated. Blood samples were obtained repeatedly for up to 72 h. After LAD occlusion, myocardial performance index and early to atrial filling velocity ratio in the propofol group deteriorated significantly from 0.40 +/- 0.12 and 1.29 +/- 0.35 to 0.49 +/- 0.10 and 1.13 +/- 0.22, respectively, whereas there was no change in the sevoflurane group. In the propofol group myocardial performance index remained increased (0.47 +/- 0.11) compared with baseline during reperfusion. There were no significant differences in ECG and laboratory values between groups. In conclusion, during a brief period of ischemia in patients undergoing MIDCAB surgery, sevoflurane preserved myocardial function better than propofol.     

地氟醚七氟醚对糖尿病患者罗库溴铵肌松效应影响的比较

目的 比较地氟醚和七氟醚对糖尿病患者罗库溴铵肌松效应的影响.方法 择期2型糖尿病腹部手术患者60例,年龄45～64岁,ASA分级Ⅱ级,采用随机数字表法分为3组,每组20例:地氟醚组(DD组)、七氟醚组(SD组)和异丙酚组(PD组).静脉注射咪达唑仑、异丙酚和芬太尼行麻醉诱导后启动肌松监测,3组分别用异丙酚、地氟醚和七氟醚维持麻醉.记录肌松维持时间和恢复指数.于静脉注射罗库溴铵后10、20、30、40、50、60、70、80、90、100、110、120 min时记录T1/T0比值及T4/T1比值[四个成串刺激(train-of-four stimulation, TOF)比值].结果 DD组和SD组患者罗库溴铵的维持时间[(61±17),(60±18) min]、恢复指数[(36±12),(35±10) min]之间差异无统计学意义(P＞0.05),且均大于PD组(P＜0.05).DD组、SD组患者静脉注射罗库溴铵后60～120 min时T1/T0比值和TOF比值差异无统计学意义(P＞0.05),且均大于PD组(P＜0.05).结论 地氟醚和七氟醚对糖尿病患者罗库溴铵肌松效应的影响差异无统计学意义.     

Contraction-relaxation coupling and impaired left ventricular performance in coronary surgery patients

BACKGROUND: Dependence of left ventricular (LV) relaxation on cardiac systolic load is a function of myocardial contractility. The authors hypothesized that, if a tight coupling would exist between LV contraction and relaxation, the changes in relaxation rate with an increase in cardiac systolic load would be related to the changes in LV contraction. METHODS: Coronary surgery patients (n = 120) with preoperative ejection fraction >40% were included. High-fidelity LV pressure tracings (n = 120) and transgastric transesophageal echocardiographic data (n = 40) were obtained. Hearts were paced at a fixed rate of 90 beats/min. Effects on contraction were evaluated by analysis of changes in dP/dt(max) and stroke area. Effects on relaxation were assessed by analysis of R (slope of the relation between tau and end-systolic pressure). Correlations were calculated with linear regression analysis using Pearson's coefficient r. RESULTS: Baseline LV end-diastolic pressure was 10+/-3 mm Hg (mean +/- SD). During leg raising, systolic LV pressure increased from 93+/-9 to 107+/-11 mm Hg. The change in dP/dt(max) was variable and ranged from -181 to +254 mm Hg/s. A similar variability was observed with the changes in stroke area, which ranged from -2.0 to +5.5 cm2. Changes in dP/dt(max) and in stroke area were closely related to individual R values (r = 0.87, P<0.001; and r = 0.81, P<0.001, respectively) and to corresponding changes in LV end-diastolic pressure (r = 0.81, P< 0.001; and r = 0.74, P<0.001, respectively). CONCLUSIONS: A tight coupling was observed between contraction and relaxation. Leg raising identified patients who developed a load-dependent impairment of LV performance and increased load dependence of LV relaxation.