Myocardial injury and its prevention in the perioperative setting

THAP11 down-regulation may contribute to cardio-protective effects of sevoflurane anesthesia: Evidence from clinical and molecular evidence

This study aimed to explore the potential target of the cardio-protective effect induced by sevoflurane anesthesia based on evidence from clinical samples and in vitro model. Forty patients undergoing mitral valve replacement were randomly allocated to receive sevoflurane or propofol-based anesthesia. Atrial muscle specimens were collected from all patients, of which 5 were used to perform transcriptomics analysis. The cTn-I concentration was tested before, at the end of, and 24 h after surgery. In in vitro study, the expression level of the identified target gene, i.e., THAP11, was studied in H9C2 cells treated with sevoflurane or propofol. Then, we studied cell viability using CCK-8 staining, apoptosis by using flow cytometry, and cell death by lactic acid dehydrogenase (LDH) detection in H9C2 cells exposed to oxygen glucose deprivation/reoxygenation (OGD/R) injury. THAP11 was the most significantly down-regulated gene in the transcriptomics analysis (P < 0.001), as confirmed in validation samples (P = 0.006). THAP11 mRNA levels in atrial muscle specimens were positively associated with cTn-I levels at 24-h postoperatively (determination coefficient = 0.564; P < 0.001). Sevoflurane treatment down-regulated THAP11 in H9C2 cell models, which promoted cell viability, inhibited cell apoptosis, and death in the OGD/R injury cell model. Up-regulation of THAP11 reduced the protective effect of sevoflurane treatment against OGD/R injury. Sevoflurane anesthesia down-regulates the expression of THAP11, which contributes to a cardio-protective effect. THAP11 down-regulation promotes cell viability, and inhibits cell apoptosis and death, thereby protecting again myocardial injury; it may therefore be a novel target for perioperative cardio-protection.

Comparison of the myocardial protective effect of sevoflurane versus propofol in patients undergoing heart valve replacement surgery with cardiopulmonary bypass

BACKGROUND

This study aimed to compare myocardial protective effects of anaesthesia with intravenous infusion of propofol versus inhalation of sevoflurane in patients undergoing heart valve replacement surgery with cardiopulmonary bypass.

METHODS

Seventy-six patients undergoing valve replacement with cardiopulmonary bypass were randomly assigned to propofol or sevoflurane anesthesia during the surgery, respectively. For assessing myocardial injury, cardiac troponin I (cTnI) and creatine kinase isozyme (CK-MB) were determined before induction (T₀), 0.5 h (T₁) and 3 h (T₂) after aortic unclamping, and 24 h (T₃) and 48 h (T₄) after surgery. The concentrations of interleukin (IL)-6 and IL-10 as the systemic inflammatory and anti-inflammatory markers were also measured at above time points.

RESULTS

In the sevoflurane group, the plasma concentrations of cTnI and CK-MB from T_l to T₄ and the levels of IL-6 and IL-10 from T₁ to T₂ were lower than those in the propofol group. Moreover, a higher ratio of automatic heart beat recovery and a shorter length of intensive care unit or hospital stay were found in the sevoflurane group comparing with the propofol group.

CONCLUSION

Sevoflurane anaesthesia produced more prominent myocardial protection and attenuated inflammatory response than propofol anaesthesia in patients with valve replacement surgery under cardiopulmonary bypass, resulting in shorter ICU and in-hospital stay.

RETROSPECTIVE CLINICAL TRIAL REGISTRATION

Identified as ChiCTR-IOR-16009979 at http://www.chictr.org.cn/ .

Avaliação dos valores de troponina I, eletrocardiograma e ecocardiograma em felinos sedados com cetamina e midazolam, suplementados ou não com oxigênio

Lesões no miocárdio, causadas por baixa perfusão e oxigenação cardíaca, podem ser ocasionadas por fármacos anestésicos, como a cetamina. Essas lesões podem ser identificadas por meio de biomarcadores específicos e, dentre estes, destaca-se a troponina I. O objetivo deste estudo foi avaliar as alterações cardiovasculares com base nos valores de troponina I (TnI), eletrocardiograma (ECG) e ecocardiograma em gatos sedados com cetamina e midazolam, suplementados ou não com oxigênio. Utilizaram-se 12 gatos machos, hígidos, nos quais se avaliaram os valores de troponina I, eletro e ecocardiografia, frequência cardíaca (FC) e pressão arterial sistólica (PAS) no momento basal (M0). Na sequência, os animais foram sedados com a associação de 10mg.kg-1 de cetamina e 0,5mg.kg-1 de midazolam pela via intramuscular. Decorridos aproximadamente 10 minutos, os animais foram alocados aleatoriamente em dois grupos: com e sem suplementação de oxigênio via máscara facial (GCO e GSO, respectivamente), sendo submetidos novamente aos exames citados. Foram coletadas amostras sanguíneas, para dosagem de TnI em seis, 12 e 24 horas após a administração dos agentes anestésicos. Não foram observadas alterações significativas na FC, na PAS e no ECG após a administração dos tratamentos em ambos os grupos. Os valores médios de TnI elevaram-se significativamente em T6 quando comparados ao basal em ambos os grupos, com médias de 0,507±0,335ng/mL no GSO e 0,777±0,505ng/mL no GCO. Na ecocardiografia, o débito cardíaco (DC) reduziu em M1 em ambos os grupos, quando comparados aos valores basais, sendo M0 0,472±0,115 e M1 0,234±0,08 no GSO e M0 0,356±0,095 e M1 0,222±0,09 no GCO, expressos em L/min. Conclui-se que a administração de cetamina e midazolam em gatos hígidos não promove alterações eletrocardiográficas, aumenta os valores de troponina I, com pico de seis horas após a administração, reduz o débito cardíaco, e que a suplementação de oxigênio 100% via máscara facial não atenua tais alterações.

Volatile anaesthetics and cardiac protection in abdominal surgery

BACKGROUND

Clinical studies have shown that sevoflurane is cardio-protective in cardiac surgery patients, but this effect is doubtful in general surgery patients. This study has researched the influence of sevoflurane on the perioperative cardiac function and the incidence of cardiac ischaemic events in abdominal surgical patients.

METHODS

Out of 80 patients scheduled for elective colorectal surgery, 42 received balanced sevoflurane-fentanyl anaesthesia, while 38 received intravenous midazolam-fentanyl anaesthesia. The cardiac index (CI) and cardiac function index (CFI) were measured by the PiCCO device, and Troponin I levels were measured at the beginning of surgery, as well as 4, 12 and 24 h afterwards. BNP was measured at the beginning of surgery, and 24 h afterwards. The data analysis was conducted using the Mann-Whitney nonparametric test, with statistical significance set at p < 0.05.

RESULTS

There was no statistical difference in perioperative Troponin I, BNP, CI and CFI values between the SEVO and TIVA groups throughout the perioperative period.

CONCLUSIONS

Sevoflurane had no effect on the cardiac biomarkers Troponin I and BNP, and on the PiCCO parameters of cardiac function in abdominal surgical patients. Further research on the preconditioning effect of volatile anaesthetics in general surgical population should be concentrated on the population of patients with a high perioperative cardiac risk.

Reduction of myocardial infarct size with ischemic "conditioning": physiologic and technical considerations

A wealth of evidence has revealed that the heart can be "conditioned" and rendered less vulnerable to ischemia-reperfusion injury via the upregulation of endogenous protective signaling pathways. Three distinct conditioning strategies have been identified: (1) preconditioning, the phenomenon where brief episodes of myocardial ischemia (too brief to cause cardiomyocyte death) limit necrosis caused by a subsequent sustained ischemic insult; (2) postconditioning, the concept that relief of myocardial ischemia in a staged or stuttered manner attenuates lethal ischemia-reperfusion injury; and (3) remote conditioning, or upregulation of a cardioprotective phenotype initiated by ischemia in a remote organ or tissue and "transported" to the heart. Progress has been made in defining the technical requirements and limitations of each of the 3 ischemic conditioning models (including the timing and severity of the protective stimulus), as well as elucidating the molecular mechanisms (in particular, the receptor-mediated signaling pathways) responsible for conditioning-induced myocardial protection. Moreover, phase III clinical trials are in progress, seeking to capitalize on the protection that can be achieved by postconditioning and remote conditioning, and applying these strategies in patients undergoing cardiac surgery or angioplasty for the treatment of acute myocardial infarction. There is, however, a potentially important caveat to the clinical translation of myocardial conditioning: emerging data suggest that the efficacy of ischemic conditioning is compromised in aging, diabetic, and hypertensive cohorts, the specific populations in which myocardial protection is most relevant. Successful clinical application of myocardial conditioning will therefore require an understanding of the potential confounding consequences of these comorbidities on the "conditioned" phenotype.

A comparative study of cardioprotective effect of three anesthetic agents by measuring serum level of troponin-T after coronary artery bypass grafting

BACKGROUND

Cardiac surgery is associated with some degree of myocardial injury. Preconditioning first described in 1986 was pharmacologic and non- pharmacologic. Among the long list of anesthetic drugs, isoflurane as an inhaling agent along with midazolam and propofol as injectable substances have been documented to confer some preconditioning effects on myocardium.

OBJECTIVES

In this study cardiac Troponin T (cTnT) ,as a reliable marker, was used for evaluating myocardial injury.

METHODS

This prospective double blind study was comprised of 60 patients scheduled for CABG and were randomly assigned into three groups who received infusion of propofol or midazolam or isoflorane. Surgical procedures and anesthetics were similar for 3 groups. cTnT measured preoperatively and at 12, 24 and 36hr after arrival in ICU.

RESULTS

There were no statistically significant differences in mean cTnT levels between three groups in the preoperative period and 12-24 hours after arrival in ICU. However, mean cTnT in 3 groups at 36 hours after arrival in ICU were different (P< 0.013) and cTnT level was significantly higher in midazolam group (P<0.001) and lowest in isoflurane group (P=0.002).

CONCLUSION

There were significant differences on cTnT levels between anesthetic groups of isofluran, midazolam and propofol at 36 hr after surgery. Preconditioning effect of isoflurane was higher than the other two groups.

Diet-induced obesity suppresses sevoflurane preconditioning against myocardial ischemia-reperfusion injury: role of AMP-activated protein kinase pathway

Obesity is a major risk factor for coronary artery disease, but its impact on anesthetic-induced cardioprotective actions is unexplored. We tested whether obesity inhibits anesthetic sevoflurane-induced preconditioning and whether this effect is mediated via the AMP-activated protein kinase (AMPK) signaling pathway. Sprague-Dawley rats were fed a high-fat (HF, 45% kcal as fat) or low-fat (LF, 10% kcal as fat) diet for 12 weeks. HF-fed rats developed metabolic disturbances including visceral obesity, hyperinsulinemia, hyperleptinemia and dyslipidemia. HF- or LF-fed rats subjected to 25 min of myocardial ischemia followed by 120 min of reperfusion were assigned to the following groups: control, sevoflurane preconditioning, sevoflurane plus AMPK inhibitor ara-A or AMPK activator A769662 alone. Infarct size was similar between the two control groups. Sevoflurane preconditioning significantly reduced infarct size in LF-fed rats but failed to induce cardioprotection in HF-fed rats. Phosphorylation of AMPK and endothelial nitric oxide synthase, as well as myocardial nitrite and nitrate, were also increased by sevoflurane preconditioning in LF-fed rats but not in HF-fed rats. Pretreatment with ara-A inhibited phosphorylation of AMPK and reversed sevoflurane preconditioning-induced cardioprotection in LF-fed rats, whereas it had no effects in HF-fed rats. In addition, sevoflurane preconditioning failed to enhance reactive oxygen species (ROS) generation in the myocardium of HF-fed rats compared with LF-fed rats. Direct activation of AMPK with A769662 equally increased phosphorylation of AMPK and reduced infarct size in both LF- and HF-fed rats. The results suggest that diet-induced obesity suppresses sevoflurane preconditioning-induced cardioprotective action, probably due to a diminished effect of sevoflurane preconditioning on activation of the ROS-mediated AMPK signaling pathway.

β-blockers and risk of all-cause mortality in non-cardiac surgery

Myocardial ischemia is a frequent complication in patients undergoing non-cardiac surgery and β-blockers may exert a protective effect. The main benefit of β-blockers in perioperative cardiovascular morbidity and mortality is believed to be linked to specific effects on myocardial oxygen supply and demand. β-blockers may exert anti-inflammatory and anti-arrhythmic effects. Randomized clinical trials which evaluated the effects of β-blockers on all-cause mortality in patients undergoing non-cardiac surgery have yielded conflicting results. In 9 trials, 10,544 patients with non-cardiac surgery were randomized to β-blockers (n = 5274) or placebo (n = 5270) and there were a total of 304 deaths. Patients randomized to β-blockers group showed a 19% increased risk of all-cause mortality (odds ratio [OR] 1.19, 95% confidence interval (CI) 0.95-1.50; p = 0.135). However, trials included in the meta-analysis differed in several aspects, and a significant degree of heterogeneity (I 2 = 46.5%) was noted. A recent analysis showed that the surgical risk category had a substantial influence on the overall estimate of the effect of β-blockers. Compared with patients in the intermediate-high-surgical-risk category, those in the high-risk category showed a 73% reduction in the risk of total mortality with β-blockers compared with placebo (OR 0.27, 95% CI 0.10-0.71, p = 0.016). These data suggest that perioperative β-blockers confer a benefit which is mostly limited to patients undergoing high-risk surgery.

Assessment of cardiac troponin I and C-reactive protein concentrations associated with anesthetic protocols using sevoflurane or a combination of fentanyl, midazolam, and sevoflurane in dogs

OBJECTIVE

To report serum cardiac troponin I (cTnI) and C-reactive protein (CRP) concentrations in dogs anesthetized for elective surgery using two anesthetic protocols.

STUDY DESIGN

Prospective, randomized clinical study.

ANIMALS

Twenty client-owned dogs presenting for elective ovariohysterectomy or castration.

METHODS

The dogs were randomized into two groups. All dogs were premedicated with glycopyrrolate (0.011 mg kg(-1)) and hydromorphone (0.1 mg kg(-1)) i.m. approximately 30 minutes prior to induction of anesthesia. Anesthesia in dogs in group 1 was induced with propofol (6 mg kg(-1)) i.v. to effect and in dogs in group 2 with diazepam (0.2 mg kg(-1)) i.v. followed by etomidate (2 mg kg(-1)) i.v. to effect. For maintenance of anesthesia, group 1 received sevoflurane (adjustable vaporizer setting 0.5-4%) and group 2 received a combination of fentanyl (0.8 microg kg(-1) minute(-1)) and midazolam (8.0 microg kg(-1) minute(-1)) i.v. plus sevoflurane (adjustable vaporizer setting 0.5-4%) to maintain anesthesia. Serum cTnI and CRP concentrations were measured at baseline and 6, 18, and 24 hours post-anesthetic induction. Biochemical analysis was performed at baseline. Lactate was obtained at baseline and 6 hours post-anesthetic induction. Heart rate and mean arterial blood pressure were measured intra-operatively.

RESULTS

Baseline serum cTnI and CRP concentrations were comparable between groups. A significant difference in serum cTnI or CRP concentrations was not detected post-operatively between groups at any time point. Serum CRP concentrations were significantly increased post-anesthetic induction in both groups, which was attributed to surgical trauma.

CONCLUSIONS AND CLINICAL RELEVANCE

There was no significant difference in serum cTnI and CRP concentrations between anesthetic protocols. Further investigation in a larger number of dogs is necessary to confirm the current findings.

Energetic myocardial metabolism and oxidative stress: let's make them our friends in the fight against heart failure

Heart failure (HF) is a syndrome causing a huge burden in morbidity and mortality worldwide. Current medical therapies for HF are aimed at suppressing the neurohormonal activation. However, novel therapies are needed for HF, independent of the neurohormonal axis, that can improve cardiac performance and prevent the progression of heart dysfunction. The modulation of cardiac metabolism may represent a new approach to the treatment of HF. The healthy heart converts chemical energy stored in fatty acids (FA) and glucose. Utilization of FA costs more oxygen per unit of ATP generated than glucose, and the heart gets 60-90% of its energy for oxidative phosphorylation from FA oxidation. The failing heart has been demonstrated to be metabolically abnormal, in both animal models and in patients, showing a shift toward an increased glucose uptake and utilization. The manipulation of myocardial substrate oxidation toward greater carbohydrate oxidation and less FA oxidation may improve ventricular performance and slow the progression of heart dysfunction. Impaired mitochondrial function and oxidative phosphorylation can reduce cardiac function by providing an insufficient supply of ATP to cardiomyocytes and by increasing myocardial oxidative stress. Although there are no effective stimulators of oxidative phosphorylation, several classes of drugs have been shown to open mitochondrial K(ATP) channels and, indirectly, to improve cardiac protection against oxidative stress. This article focuses on the energetic myocardial metabolism and oxidative status in the normal and failing heart, and briefly, it overviews the therapeutic potential strategies to improve cardiac energy and oxidative status in HF patients.

Helium breathing provides modest antiinflammatory, but no endothelial protection against ischemia-reperfusion injury in humans in vivo

BACKGROUND

The noble gas helium is devoid of anesthetic effects, and it elicits cardiac preconditioning. We hypothesized that inhalation of helium provides protection against postocclusive endothelial dysfunction after ischemia-reperfusion of the forearm in humans.

METHODS

Eight healthy male subjects were enrolled in this study with a crossover design. Each volunteer was randomly exposed to 15 min of forearm ischemia in the presence or absence of helium inhalation. Helium was inhaled at an end-tidal concentration of 50 vol% from 15 min before ischemia until 5 min after the onset of reperfusion ("helium conditioning"). Hyperemic reaction, a marker of nitric oxide bioavailability and endothelial function, was determined at 15 and 30 min of reperfusion on the forearm using venous occlusion plethysmography. Expression of the proinflammatory markers CD11b, ICAM-1, PSGL-1, and L-selectin (CD62L) on leukocytes and P-selectin (CD62P), PSGL-1, and CD42b on platelets were measured by flow cytometry during reperfusion.

RESULTS

Ischemia-reperfusion consistently reduced the postocclusive endothelium-dependent hyperemic reaction at 15 and 30 min of reperfusion. Periischemic inhalation of helium at 50 vol% did not improve postocclusive hyperemic reaction. Helium decreased expression of the proinflammatory marker CD11b and ICAM-1 on leukocytes and attenuated the expression of the procoagulant markers CD42b and PSGL-1 on platelets.

CONCLUSIONS

Although inhalation of helium diminished the postischemic inflammatory reaction, our data indicate that human endothelium, which is a component of all vital organs, is not amenable to protection by helium at 50 vol% in vivo. This is in contrast to sevoflurane, which protects human endothelium at low subanesthetic concentrations.

Sevoflurane but not propofol increases interstitial glycolysis metabolites availability during tourniquet-induced ischaemia-reperfusion

BACKGROUND

Ischaemia/reperfusion (I/R) is one of the main pathophysiological phenomena involved in the anaesthetic practice. The authors hypothesized that anaesthetic regimens can influence skeletal muscle tolerance to tourniquet-induced I/R that should be reflected by the interstitial metabolite levels of anaerobic glycolysis.

METHODS

Microdialysis probes were implanted in three groups of 10 patients each receiving either sevoflurane (SEVO), propofol (PRO), or spinal (SA) anaesthesia (for induction and maintenance). SA group was considered as a control group. Interstitial fluid was obtained during tourniquet-induced I/R and was analysed for interstitial glucose, lactate, pyruvate, and glycerol.

RESULTS

The microdialysis flow rate was 0.5 microl min(-1). Compared with the control group, the SEVO group had a higher level of both lactate and pyruvate and an increase in glucose during ischaemia. In contrast, the PRO group had a lower level of pyruvate, resulting in a significant higher increase (eight times from baseline) of the lactate pyruvate ratio. Glucose level remained low in this group. During reperfusion, lactate, pyruvate, and glucose remained at a significantly higher level in the SEVO group. In the PRO group, there was no difference in lactate, pyruvate, and glucose levels compared with the control group. The interstitial level of glycerol exhibits only few and comparable changes during I/R between the groups.

CONCLUSIONS

Our results indicate that there is a better availability of interstitial glycolysis metabolites (glucose, lactate, and pyruvate) in the skeletal muscle during ischaemia and reperfusion after sevoflurane exposure than after propofol, suggesting a potential preconditioning effect of sevoflurane on tourniquet-induced skeletal muscle I/R.

Desflurane Versus Propofol in Patients Undergoing Mitral Valve Surgery

OBJECTIVE

Myocardial ischemic damage is reduced by volatile anesthetics in patients undergoing coronary artery bypass graft surgery, but it is unknown whether this benefit exists in patients undergoing valvular surgery with ischemia-reperfusion injury related to cardioplegic arrest and cardiopulmonary bypass. This study compared cardiac troponin release in patients receiving either volatile anesthetics or total intravenous anesthesia for mitral valve surgery.

DESIGN

Randomized controlled study.

SETTING

University hospital.

PARTICIPANTS

One hundred twenty patients undergoing mitral valve surgery.

INTERVENTIONS

Fifty-nine patients received the volatile anesthetic desflurane for 30 minutes before cardiopulmonary bypass, whereas 61 patients received a total intravenous anesthetic with propofol. All patients had an opioid-based anesthetic for the mitral valve surgery.

MEASUREMENTS AND MAIN RESULTS

Peak postoperative troponin I release was measured as a marker of myocardial necrosis after mitral valve surgery. Patient mean age was 60 years, and 54% were men. There was no significant (p = 0.7) reduction in median (25th-75th percentiles) postoperative peak troponin, 11.0 (7.5-17.4) ng/dL in the desflurane group versus 11.5 (6.9-18.0) ng/dL in the propofol group. A subgroup of patients with concomitant coronary artery disease had the expected reduction (p = 0.02) of peak troponin I in those receiving desflurane, 14.0 (9.7-17.3) ng/dL, when compared with patients receiving total intravenous anesthesia, 31.6 (15.7-52.0) ng/dL.

CONCLUSIONS

Myocardial damage measured by cardiac troponin release was not reduced by volatile anesthetics in patients undergoing mitral valve surgery, whereas it was reduced in patients with concomitant coronary artery disease.

Adrenergic Receptor Genotype but Not Perioperative Bisoprolol Therapy May Determine Cardiovascular Outcome in At-risk Patients Undergoing Surgery with Spinal Block

Background:

Neuraxial blockade is used as primary anesthetic technique in one third of surgical procedures. The authors tested whether bisoprolol would protect patients at risk for cardiovascular complications undergoing surgery with spinal block.

Methods:

The authors performed a double-blinded, placebo-controlled, multicenter trial to compare the effect of bisoprolol with that of placebo on 1-yr composite outcome including cardiovascular mortality, nonfatal myocardial infarction, unstable angina, congestive heart failure, and cerebrovascular insult. Bisoprolol was given orally before and after surgery for a maximum of 10 days. Adrenergic receptor polymorphisms and safety outcome measures of bisoprolol therapy were also determined.

Results:

A total of 224 patients were enrolled. Spinal block could not be established in 5 patients. One hundred ten patients were assigned to the bisoprolol group, and 109 patients were assigned to the placebo group. The mean duration of treatment was 4.9 days in the bisoprolol group and 5.1 days in the placebo group. Bisoprolol therapy reduced mean heart rate by 10 beats/min. The primary outcome was identical between treatment groups and occurred in 25 patients (22.7%) in the bisoprolol group and 24 patients (22.0%) in the placebo group during the 1-yr follow-up (hazard ratio, 0.97; 95% confidence interval, 0.55–1.69; P = 0.90). However, carriers of at least one Gly allele of the β1-adrenergic receptor polymorphism Arg389Gly showed a higher number of adverse events than Arg homozygous (32.4% vs. 18.7%; hazard ratio, 1.87; 95% confidence interval, 1.04–3.35; P = 0.04).

Conclusions:

Perioperative bisoprolol therapy did not affect cardiovascular outcome in these elderly at-risk patients undergoing surgery with spinal block.

Pre-occlusion ischaemia, not sevoflurane, successfully preconditions the myocardium against further damage in porcine in vivo hearts

BACKGROUND

Sevoflurane is proposed to possess important tissue protective effects based on experimental ischaemia-reperfusion studies from models with collateral coronary flow, unlike that of the normal human or the porcine heart. The objective was to evaluate the infarct-reducing capability of pre-ischaemic sevoflurane inhalation on myocardial infarct size in a porcine model.

METHODS AND MATERIALS

The study comprised 33 pigs under pentobarbital anaesthesia. Animals were divided into three groups: control (CON), sevoflurane intervention (SEVO) and ischaemic preconditioning (IP). The distal left anterior descending coronary artery was occluded for 40 min with a percutaneous coronary intervention catheter. Before occlusion, group IP underwent two 5-min ischaemia cycles, whereas SEVO received two 5-min sevoflurane 4%v/v inhalation cycles. Animals were reperfused for 150 min. We then measured risk area (AAR) and infarct size (IS) after tetrazolium staining. The [IS/AAR-ratio] was calculated. Haemodynamics and transthoracic tissue-Doppler echocardiography were monitored.

RESULTS

Control animals developed a myocardial infarction in 46.4 (+/- 6.2)% (mean +/- SEM) of the AAR. Both SEVO and IP groups had infarction mitigated, to 34.4 (5.7)% and 23.1 (5.3)%, respectively; however, only in the IP group was this significant. No significant differences between groups with respect to AAR, haemodynamics or echocardiographic variables were found.

CONCLUSION

Pre-ischaemic sevoflurane was found to reduce the extent of myocardial necrosis, but the change was not significant, whereas IP reduced IS by 50% (P= 0.038). Cardioprotection is species related and no previous results from porcine models have found sevoflurane to reduce IS. Anaesthetic washout, insufficient exposure or collateral coronary blood supply, dissimilar to human, may account for positive results in rodent models.

[Mitochondria in anaesthesia and intensive care]

OBJECTIVE

Mitochondria play a key role in energy metabolism within the cell through the oxidative phosphorylation. They are also involved in many cellular processes like apoptosis, calcium signaling or reactive oxygen species production. The objectives of this review are to understand the interactions between mitochondrial metabolism and anaesthetics or different stress situations observed in ICU and to know the clinical implications.

DATA SOURCES

References were obtained from PubMed data bank (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) using the following keywords: mitochondria, anaesthesia, anaesthetics, sepsis, preconditioning, ischaemia, hypoxia.

DATA SYNTHESIS

Mitochondria act as a pharmacological target for the anaesthetic agents. The effects can be toxic like in the case of the local anaesthetics-induced myotoxicity. On the other hand, beneficial effects are observed in the anaesthetic-induced myocardial preconditioning. Mitochondrial metabolism could be disturbed in many critical situations (sepsis, chronic hypoxia, ischaemia-reperfusion injury). The study of the underlying mechanisms should allow to propose in the future new specific therapeutics.

Cardioprotective effects of novel tetrahydroisoquinoline analogs of nitrobenzylmercaptopurine riboside in an isolated perfused rat heart model of acute myocardial infarction

We have investigated the cardioprotective effects of novel tetrahydroisoquinoline nitrobenzylmercaptopurine riboside (NBMPR) analog nucleoside transport (NT) inhibitors, compounds 2 and 4, in isolated perfused rat hearts. Langendorff-perfused heart preparations were subjected to 10 min of treatment with compound 2, compound 4, or vehicle (control) followed by 30 min of global ischemia and 120 min of reperfusion. For determination of infarct size, reperfusion time was 180 min. At 1 microM, compounds 2 and 4 provided excellent cardioprotection, with left ventricular developed pressure (LVDP) recovery and end-diastolic pressure (EDP) increase of 82.9 +/- 4.0% (P<0.001) and 14.1 +/- 2.0 mmHg (P<0.03) for compound 2-treated hearts and 79.2 +/- 5.9% (P<0.002) and 7.5 +/- 2.7 mmHg (P<0.01) for compound 4-treated hearts compared with 41.6 +/- 5.2% and 42.5 +/- 6.5 mmHg for control hearts. LVDP recovery and EDP increase were 64.1 +/- 4.2% and 29.1 +/- 2.5 mmHg for hearts treated with 1 microM NBMPR. Compound 4 was the best cardioprotective agent, affording significant cardioprotection, even at 0.1 microM, with LVDP recovery and EDP increase of 76.0 +/- 4.9% (P<0.003) and 14.1 +/- 1.0 mmHg (P<0.03). At 1 microM, compound 4 and NBMPR reduced infarct size, with infarct area-to-total risk area ratios of 29.13 +/- 3.17 (P<0.001) for compound 4 and 37.5 +/- 3.42 (P<0.01) for NBMPR vs. 51.08 +/- 5.06% for control hearts. Infarct size was more effectively reduced by compound 4 than by NBMPR (P<0.02). These new tetrahydroisoquinoline NBMPR analogs are not only potent cardioprotective agents but are, also, more effective than NBMPR in this model.

Intravenous anesthesia for the patient with left ventricular dysfunction

Patients with heart failure have a diminished cardiac reserve capacity that may be further compromised by anesthesia. In addition to depression of sympathetic activity, most anaesthetics interfere with cardiovascular performance, either by a direct myocardial depression or by modifying cardiovascular control mechanisms. Etomidate causes the least cardiovascular depression. It is popular for induction of anesthesia in cardiac-compromised patients; however, it is not suitable for maintenance of anesthesia because it depresses adrenocortical function. Ketamine has a favorable cardiovascular profile related to central sympathetic stimulation and inhibition of neuronal catecholamine uptake. These counteract its direct negative inotropic effect. In patients with a failing myocardium, however, the negative inotropic effects may be unmasked, resulting in deterioration in cardiac performance and cardiovascular instability. Propofol is the most popular intravenous anesthetic for maintenance of anesthesia. It does have a negative inotropic effect, but the net effect on myocardial contractility is insignificant at clinical concentrations, probably because of a simultaneous increase in the sensitivity of the myofilaments to Ca2+. Propofol protects the myocardium against ischemia-reperfusion injury, an action derived from its antioxidant and free-radical-scavenging properties as well as the related inhibition of the mitochondrial permeability transition pore. For intravenous anesthesia, propofol is always combined with an opioid. Opioids have relatively few cardiovascular side effects and, in particular, do not cause myocardial depression. Indeed, they are cardioprotective, with antiarrhythmic activity, and induce pharmacologic preconditioning of the myocardium by a mechanism similar to the inhalational anesthetics.

Myocardial Damage Prevented by Volatile Anesthetics: A Multicenter Randomized Controlled Study

OBJECTIVE

The purpose of this study was to evaluate the effects of volatile anesthesia versus total intravenous anesthesia on cardiac troponin release in off-pump coronary artery bypass grafting (OPCAB).

DESIGN

The authors performed a multicenter randomized controlled study to compare cardiac troponin release in patients receiving either volatile anesthetics or total intravenous anesthesia for cardiac surgery on the beating heart, which is an excellent model of human myocardial ischemia.

SETTING

Three university hospitals.

PARTICIPANTS

The authors randomly assigned 57 patients to desflurane (volatile anesthetic) and 55 patients to propofol (intravenous anesthetic) in addition to an opiate-based anesthesia for OPCAB.

INTERVENTIONS

The 2 groups of patients received either desflurane (volatile anesthetic) or propofol in addition to an opiate-based anesthesia for OPCAB. Peak postoperative troponin I release was measured as a marker of myocardial necrosis. Prolonged hospitalization was considered as a secondary outcome.

MEASUREMENTS AND MAIN RESULTS

Patient mean age was 69 years, and 82% were men. There was a significant (p < 0.001) reduction in postoperative median (25th-75th percentiles) peak of troponin I in patients receiving volatile anesthetics, 1.2 (0.9-1.9) ng/dL, compared with patients receiving total intravenous anesthesia, 2.7 (2.1-4.0) ng/dL. This myocardial protection resulted in a reduced (p = 0.04) number (percentage) of patients requiring postoperative inotropes, 20 (35%) versus 31 (56%), and a reduced number (percentage) of patients submitted to prolonged hospitalization (> or =7 days), 7 (12%) versus 20 (36%) in the 2 groups (p = 0.005). One patient receiving total intravenous anesthesia died within 30 days of surgery.

CONCLUSIONS

Myocardial damage measured by cardiac troponin release could be reduced by volatile anesthetics during OPCAB. Because patients underwent cardiac surgery on the beating heart, these results could have implications for cardiac patients undergoing noncardiac surgery.

Volatile Anesthetic Preconditioning Attenuates Myocardial Apoptosis in Rabbits after Regional Ischemia and Reperfusion via Akt Signaling and Modulation of Bcl-2 Family Proteins

We tested whether isoflurane preconditioning inhibits cardiomyocyte apoptosis and evaluated the role of the phosphatidylinositol-3-kinase (PI3K)/Akt pathway in anesthetic preconditioning and determined whether PI3K/Akt signaling modulates the expression of pro- and antiapoptotic proteins in anesthetic preconditioning. Six-month-old New Zealand rabbits subjected to 40 min of myocardial ischemia followed by 180 min of reperfusion were assigned to the following groups: ischemia-reperfusion (I/R), isoflurane preconditioning and isoflurane plus PI3K inhibitors, wortmannin and 2-(4-morpholinyl)-8-phenyl-4H-l-benzopyran-4-one (LY294002) (0.6 and 0.3 mg/kg i.v., respectively). Sham-operated, wortmannin+I/R, wortmannin+sham, LY294002+I/R, and LY294002+sham groups were also included. Infarct size was assessed by triphenyltetrazolium chloride staining. Apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and activated caspase-3 assays. Akt phosphorylation, Bax, Bcl-2, Bad, and phosphorylated Bad (phospho-Bad) expression was assessed by immunoblotting. Isoflurane preconditioning reduced infarct size compared with the I/R group: 22+/-4 versus 41+/-5% (p<0.05). The percentage of apoptotic cells decreased in the isoflurane group (3.8+/-1.2%) compared with the I/R group (12.4+/-1.6%; p<0.05). These results were also confirmed by the activated caspase-3 assay. Wortmannin and LY294002 inhibited the effects of isoflurane. Myocardial infarction increased to 44+/-3 and 45+/-2% and the percentage of apoptotic cells was 11.9+/-2.1 and 11.7+/-3.3%, respectively. Akt phosphorylation and Bcl-2 and phospho-Bad expression increased after isoflurane preconditioning, whereas Bax expression decreased. These effects were inhibited by wortmannin and LY294002. The data indicate that isoflurane preconditioning reduces infarct size and myocardial apoptosis after I/R. Activation of PI3K and modulation of the expression of pro- and antiapoptotic proteins may play a role in isoflurane-induced myocardial protection.

Effect of three different anaesthetic agents on the postoperative production of cardiac troponin T in paediatric cardiac surgery

BACKGROUND

Paediatric cardiac surgery is associated with some degree of myocardial injury. Ischaemic preconditioning (IP) has been investigated widely in the adult population. Volatile agents have been shown to simulate IP providing extra protection to the myocardium during adult cardiopulmonary bypass (CPB) while propofol seems to act through different mechanisms. IP has not been investigated in the paediatric population to the same extent. Cardiac troponin T (cTnT) is a reliable marker of myocardial injury in neonates and children. We have investigated the relationship between three anaesthetic agents, midazolam, propofol, and sevoflurane, and postoperative production of cTnT.

METHODS

Ninety patients undergoing repair of congenital heart defect with CPB were investigated in a prospective randomized study. cTnT was measured four times during the first 24 h following admission to the paediatric intensive care unit. Other variables measured included arterial blood gases, lactate, fluid balance, use of inotropic drugs, PaO2/FiO2 ratio and ventilator hours.

RESULTS

cTnT was elevated in all three groups throughout the study period. The differences between the three groups were not statistically significant. Eight hours after admission to the intensive care unit cTnT concentrations tended to be higher in the midazolam group [mean (95% confidence intervals)]; 2.7 (1.9-3.5) ng ml(-1). Patients receiving a propofol-based anaesthesia had similar concentrations 2.6 (1.7-3.5) ng ml(-1) while those receiving sevoflurane tended to have a lower cTnT production 1.7 (1.3-2.2) ng ml(-1).

CONCLUSIONS

Midazolam, propofol, and sevoflurane appear to provide equal myocardial protection in paediatric cardiac surgery when using cTnT as a marker of myocardial damage.