Changes in renal medulla gene expression in a pre-clinical model of post cardiopulmonary bypass acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is a common and serious complication of cardiac surgery using cardiopulmonary bypass (CPB). The pathogenesis is poorly understood and the study of AKI in rodent models has not led to improvements in clinical outcomes. We sought to determine the changes in renal medullary gene expression in a novel and clinically relevant porcine model of CPB-induced AKI.

RESULTS

Adult pigs (n = 12 per group) were randomised to undergo sham procedure, or 2.5 hours CPB. AKI was determined using biochemical (Cr51 EDTA clearance, CrCl, urinary IL-18 release) and histological measures. Transcriptomic analyses were performed on renal medulla biopsies obtained 24 hours post intervention or from sham group. Microarray results were validated with real-time polymerase chain reaction and Western Blotting.Of the transcripts examined, 66 were identified as differentially expressed in CPB versus Sham pig's kidney samples, with 19 (29%) upregulated and 47 (71%) down-regulated. Out of the upregulated and downregulated transcripts 4 and 16 respectively were expression sequence tags (EST). The regulated genes clustered into three classes; Immune response, Cell adhesion/extracellular matrix and metabolic process. Upregulated genes included Factor V, SLC16A3 and CKMT2 whereas downregulated genes included GST, CPE, MMP7 and SELL.

CONCLUSION

Post CPB AKI, as defined by clinical criteria, is characterised by molecular changes in renal medulla that are associated with both injury and survival programmes. Our observations highlight the value of large animal models in AKI research and provide insights into the failure of findings in rodent models to translate into clinical progress.

Switching back to normal diet following high-fat diet feeding reduces cardiac vulnerability to ischaemia and reperfusion injury

Background

We have recently shown that hearts of mice fed high-fat diet exhibit increased vulnerability to ischaemia and reperfusion (I/R) in parallel to changes in catalase protein expression, mitochondrial morphology and intracellular diastolic Ca²⁺.

Aims

To determine whether switching from high-fat back to normal diet alters vulnerability to I/R and to investigate cardiac cellular remodelling in relation to the mechanism(s) underlying I/R injury.

Methods and Results

Male C57BL/6J mice were fed a high-fat diet for 19-22 weeks; after which a subset of mice was switched back to normal diet for 4-6 weeks. Hearts from mice switched back to normal diet were more resistant to reperfusion injury compared to hearts from mice fed only high-fat diet. This was associated with a significant reversal in catalase expression (western blotting) and recovery of size and density of mitochondria (electron microscopy). In contrast, switching back to normal diet did not alter cardiomyocyte contractility or Ca²⁺ transients compared to high-fat diet.

Conclusion

This study shows for the first time that switching the diet from high-fat back to normal reduces vulnerability to I/R. This effect is associated with changes in catalase levels and mitochondrial morphology without altering cardiomyocyte contractility or Ca²⁺ transients.

EZH2 modulates angiogenesis in vitro and in a mouse model of limb ischemia

Epigenetic mechanisms may regulate the expression of pro-angiogenic genes, thus affecting reparative angiogenesis in ischemic limbs. The enhancer of zest homolog-2 (EZH2) induces thtrimethylation of lysine 27 on histone H3 (H3K27me3), which represses gene transcription. We explored (i) if EZH2 expression is regulated by hypoxia and ischemia; (ii) the impact of EZH2 on the expression of two pro-angiogenic genes: eNOS and BDNF; (iii) the functional effect of EZH2 inhibition on cultured endothelial cells (ECs); (iv) the therapeutic potential of EZH2 inhibition in a mouse model of limb ischemia (LI). EZH2 expression was increased in cultured ECs exposed to hypoxia (control: normoxia) and in ECs extracted from mouse ischemic limb muscles (control: absence of ischemia). EZH2 increased the H3K27me3 abundance onto regulatory regions of eNOS and BDNF promoters. In vitro RNA silencing or pharmacological inhibition by 3-deazaneplanocin (DZNep) of EZH2 increased eNOS and BDNF mRNA and protein levels and enhanced functional capacities (migration, angiogenesis) of ECs under either normoxia or hypoxia. In mice with experimentally induced LI, DZNep increased angiogenesis in ischaemic muscles, the circulating levels of pro-angiogenic hematopoietic cells and blood flow recovery. Targeting EZH2 for inhibition may open new therapeutic avenues for patients with limb ischemia.

The effect of disease on human cardiac protein expression profiles in paired samples from right and left ventricles

BACKGROUND

Cardiac diseases (e.g. coronary and valve) are associated with ventricular cellular remodeling. However, ventricular biopsies from left and right ventricles from patients with different pathologies are rare and thus little is known about disease-induced cellular remodeling in both sides of the heart and between different diseases. We hypothesized that the protein expression profiles between right and left ventricles of patients with aortic valve stenosis (AVS) and patients with coronary artery disease (CAD) are different and that the protein profile is different between the two diseases. Left and right ventricular biopsies were collected from patients with either CAD or AVS. The biopsies were processed for proteomic analysis using isobaric tandem mass tagging and analyzed by reverse phase nano-LC-MS/MS. Western blot for selected proteins showed strong correlation with proteomic analysis.

RESULTS

Proteomic analysis between ventricles of the same disease (intra-disease) and between ventricles of different diseases (inter-disease) identified more than 500 proteins detected in all relevant ventricular biopsies. Comparison between ventricles and disease state was focused on proteins with relatively high fold (±1.2 fold difference) and significant (P < 0.05) differences. Intra-disease protein expression differences between left and right ventricles were largely structural for AVS patients and largely signaling/metabolism for CAD. Proteins commonly associated with hypertrophy were also different in the AVS group but with lower fold difference. Inter-disease differences between left ventricles of AVS and CAD were detected in 9 proteins. However, inter-disease differences between the right ventricles of CAD and AVS patients were associated with differences in 73 proteins. The majority of proteins which had a significant difference in one ventricle compared to the other pathology also had a similar trend in the adjacent ventricle.

CONCLUSIONS

This work demonstrates for the first time that left and right ventricles have a different proteome and that the difference is dependent on the type of disease. Inter-disease differential expression was more prominent for right ventricles. The finding that a protein change in one ventricle was often associated with a similar trend in the adjacent ventricle for a large number of proteins suggests cross-talk proteome remodeling between adjacent ventricles.

Preoperative anemia increases mortality and postoperative morbidity after cardiac surgery

Background

Anemia is an established adverse risk factor in cardiovascular disease. However, the effect of preoperative anemia is not well defined in heart surgery. This study evaluates the effect of preoperative anemia on early clinical outcomes in patients undergoing cardiac surgery.

Methods

A retrospective, observational, cohort study of prospectively collected data was undertaken on 7,738 consecutive patients undergoing heart surgery between April 2003 and February 2009. Of these, 1,856 patients with preoperative anemia were compared to 5,882 patients without anemia (control group). According to the World Health Organization, anemia was defined as hemoglobin level < 13 g/dl for men and <12 g/dl for women. Selection bias not controlled by multivariable methods was assessed with propensity-adjustment method.

Results

Overall mortality was 2.1%. Preoperative anemia was associated with tripling in the risk of death (4.6% vs 1.5%, p < 0.0001) and postoperative renal dysfunction (18.5% vs 6.5%, p < 0.0001). There was also a significant difference between the anemic and non-anemic group in the risk of postoperative stroke (1.9% vs 1.1%, p = 0.008), atrial fibrillation (36.7% vs 33%, p = 0.003) and length of hospital stay > 7 days (54% vs 36.7%, p < 0.0001). In propensity-adjusted, multivariable logistic regression, preoperative anemia was an independent predictor of mortality (odds ratio [OR] 1.44, 95% confidence interval [CI] 1.02 to 2.03), postoperative renal dysfunction (OR 1.73, 95% CI 1.43 to 2.1) and length of hospital stay > 7 days (OR 1.3, 95% CI 1.15 to 1.47).

Conclusion

In patients undergoing heart surgery, preoperative anemia is associated with an increased risk of mortality and postoperative morbidity.

Surgery for simple and complex subaortic stenosis in children and young adults: results from a prospective, procedure-based national database

OBJECTIVE

To identify the outcomes of surgically treated subaortic stenosis in a national population.

METHODS

From 2000 to 2013, 1047 patients aged < 40 years underwent 1142 subaortic stenosis procedures. Of the 1047 patients, 484 (46.2%) were considered to have complex stenosis (CS) because at or before the first operation they had mitral valve (MV) disease, aortic valve disease, aortic coarctation or an interrupted aortic arch.

RESULTS

The 30-day mortality was 0.7% for simple stenosis (SS), 2.3% for CS (P = .06), and 1.6% overall. Age < 1 year (P < .01), MV procedure (P = .02) and an interrupted aortic arch at the index procedure (P < .01) were risk factors for early death. Konno-type procedure early mortality was 2.4%. The 12-year survival was 97.1%, with a significant difference between SS and CS (hazard ratio [HR], 4.53; P = .02). Having MV disease alone (HR, 4.11; P = .02), MV disease plus aortic coarctation (HR, 6.73; P = .008), and age < 1 year (HR, 6.72; P < .001) were risk factors for late mortality. Freedom from subaortic reintervention overall was 92.3% and 88.5% at 5 and 12 years, respectively, much greater with CS than with SS (HR, 4.91; P < .0001). The independent risk factors for reintervention were younger age at the index procedure (HR, 0.1/y; P = .002), concomitant MV procedure (HR, 2.68; P = .019), ventricular septal defect plus interrupted aortic arch (HR, 3.19; P = .014), and ventricular septal defect plus aortic coarctation (HR, 2.41; P = .023). Undergoing a concomitant aortic valve procedure at the index procedure was protective (HR, 0.29; P = .025).

CONCLUSIONS

Patients with SS had excellent outcomes. However, those with CS had worse long-term survival and freedom from reintervention, with morbidity and mortality greatest in young patients with multiple lesions. Additional evaluation in large-scale prospective studies is warranted.

The effects of propofol cardioplegia on blood and myocardial biomarkers of stress and injury in patients with isolated coronary artery bypass grafting or aortic valve replacement using cardiopulmonary bypass: protocol for a single-center randomized controlled trial

Background

Despite improved myocardial protection strategies, cardioplegic arrest and ischemia still result in reperfusion injury. We have previously published a study describing the effects of propofol (an anesthetic agent commonly used in cardiac surgery) on metabolic stress, cardiac function, and injury in a clinically relevant animal model. We concluded that cardioplegia supplementation with propofol at a concentration relevant to the human clinical setting resulted in improved hemodynamic function, reduced oxidative stress, and reduced reperfusion injury when compared to standard cardioplegia.

Objective

The Propofol cardioplegia for Myocardial Protection Trial (ProMPT) aims to translate the successful animal intervention to the human clinical setting. We aim to test the hypothesis that supplementation of the cardioplegic solution with propofol will be cardioprotective for patients undergoing isolated coronary artery bypass graft or aortic valve replacement surgery with cardiopulmonary bypass.

Methods

The trial is a single-center, placebo-controlled, randomized trial with blinding of participants, health care staff, and the research team. Patients aged between 18 and 80 years undergoing nonemergency isolated coronary artery bypass graft or aortic valve replacement surgery with cardiopulmonary bypass at the Bristol Heart Institute are being invited to participate. Participants are randomly assigned in a 1:1 ratio to either cardioplegia supplementation with propofol (intervention) or cardioplegia supplementation with intralipid (placebo) using a secure, concealed, Internet-based randomization system. Randomization is stratified by operation type and minimized by diabetes mellitus status. Biomarkers of cardiac injury and metabolism are being assessed to investigate any cardioprotection conferred. The primary outcome is myocardial injury, studied by measuring myocardial troponin T. The trial is designed to test hypotheses about the superiority of the intervention within each surgical stratum. The sample size of 96 participants has been chosen to achieve 80% power to detect standardized differences of 0.5 at a significance level of 5% (2-tailed) assuming equal numbers in each surgical stratum.

Results

A total of 96 patients have been successfully recruited over a 2-year period. Results are to be published in late 2014.

Conclusions

Designing a practicable method for delivering a potentially protective dose of propofol to the heart during cardiac surgery was challenging. If our approach confirms the potential of propofol to reduce damage during cardiac surgery, we plan to design a larger multicenter trial to detect differences in clinical outcomes.

Trial Registration

International Standard Randomized Controlled Trial Number (ISRCTN): 84968882; http://www.controlled-trials.com/ISRCTN84968882/ProMPT (Archived by WebCite at http://www.webcitation.org/6Qi8A51BS).

Implications of using different methods to characterise anticoagulant control in patients with second generation mechanical heart valve prostheses

OBJECTIVE

Characterisation of anticoagulant control is fundamental to investigations of its association with clinical outcome. Anticoagulant control depends on several factors. This paper aims to illustrate the implications of different methods for measuring and analysing anticoagulant control in patients with second generation mechanical heart valve prostheses.

METHODS

International normalised ratio (INR) data collected during the 10-year follow-up of a randomised controlled trial were analysed. We considered the influence of: 3 different target INR ranges; anticoagulant control expressed as the proportion of INR readings (PoR) vs. anticoagulant control follow-up time (PoT); 3 ways of describing the profile of anticoagulant control over time.

RESULTS

Different target INR ranges dramatically influenced derived measures of anticoagulant control; the PoT within the target range varied from 88% for the widest to 28% for narrowest range. Overall distributions of PoR and PoT observations were similar but differed by up to ± 20% for individuals; PoT exceeded PoR when control was good but was less than PoR when control was poor. Classifying PoT outside the target range showed that widely varying combinations of PoT too high and too low are possible across individuals.

CONCLUSIONS

Researchers' choices about methods for measuring and quantifying anticoagulant control markedly influence the values derived from INR readings. The use of different methods across studies makes it difficult or impossible to compare findings and to establish an evidence base for clinical practice. Methods for quantifying anticoagulant control should be standardised.

Arterial blood pressure and vascular function in human saphenous vein

Hypertension is a risk factor for accelerated saphenous vein (SV) graft disease and endothelial dysfunction in a number of vascular territories. We examined the relationship between blood pressure (BP) and vascular function in SV from 94 male patients undergoing coronary artery bypass grafting (CABG). Patients were pretreated with respect to cholesterol (3.4±1.2 mmol/L) and BP (systolic 139±22 mmHg, diastolic 74±13 mmHg). All patients were taking aspirin, 85% statins, 50% angiotensin-converting enzyme inhibitors and 70% beta-blockers. We demonstrate in human SV rings ex vivo that increased BP has no effect on acetylcholine-mediated vasodilatation (p=0.58), nor on the constrictor response to L-NMMA (p=0.98), but has a positive association with the constrictor response to phenylephrine (p=0.008) and a negative correlation with the vasodilator response to sodium nitroprusside (p=0.03). These results may provide further explanation for the high incidence of early vein graft failure after CABG in hypertensive patients and support an aggressive approach to optimize BP before surgery.

Hearts from mice fed a non-obesogenic high-fat diet exhibit changes in their oxidative state, calcium and mitochondria in parallel with increased susceptibility to reperfusion injury

Rationale

High-fat diet with obesity-associated co-morbidities triggers cardiac remodeling and renders the heart more vulnerable to ischemia/reperfusion injury. However, the effect of high-fat diet without obesity and associated co-morbidities is presently unknown.

Objectives

To characterize a non-obese mouse model of high-fat diet, assess the vulnerability of hearts to reperfusion injury and to investigate cardiac cellular remodeling in relation to the mechanism(s) underlying reperfusion injury.

Methods and Results

Feeding C57BL/6J male mice high-fat diet for 20 weeks did not induce obesity, diabetes, cardiac hypertrophy, cardiac dysfunction, atherosclerosis or cardiac apoptosis. However, isolated perfused hearts from mice fed high-fat diet were more vulnerable to reperfusion injury than those from mice fed normal diet. In isolated cardiomyocytes, high-fat diet was associated with higher diastolic intracellular Ca²⁺ concentration and greater damage to isolated cardiomyocytes following simulated ischemia/reperfusion. High-fat diet was also associated with changes in mitochondrial morphology and expression of some related proteins but not mitochondrial respiration or reactive oxygen species turnover rates. Proteomics, western blot and high-performance liquid chromatography techniques revealed that high-fat diet led to less cardiac oxidative stress, higher catalase expression and significant changes in expression of putative components of the mitochondrial permeability transition pore (mPTP). Inhibition of the mPTP conferred relatively more cardio-protection in the high-fat fed mice compared to normal diet.

Conclusions

This study shows for the first time that high-fat diet, independent of obesity-induced co-morbidities, triggers changes in cardiac oxidative state, calcium handling and mitochondria which are likely to be responsible for increased vulnerability to cardiac insults.

A multi-centre randomised controlled trial of Transfusion Indication Threshold Reduction on transfusion rates, morbidity and healthcare resource use following cardiac surgery: study protocol

Thresholds for red blood cell transfusion following cardiac surgery vary by hospital and surgeon. The TITRe2 multi-centre randomised controlled trial aims to randomise 2000 patients from 17 United Kingdom centres, and tests the hypothesis that a restrictive transfusion threshold will reduce postoperative morbidity and health service costs compared to a liberal threshold. Patients consent to take part in the study pre-operatively but are only randomised if their haemoglobin falls below 9 g/dL during their post-operative hospital stay. The primary outcome is a binary composite outcome of any serious infectious or ischaemic event in the first three months after randomisation. Many challenges have been encountered in the set-up and running of the study.

Iatrogenic intraoperative type A aortic dissection following cardiac surgery

Background

An increase in the incidence of intraoperative aortic dissection has been reported recently, attributed to the increasingly elderly patient population undergoing cardiac surgery and more off-pump coronary artery bypass. We performed this study to examine current trends, identify risk factors for iatrogenic dissection, and compare iatrogenic intraoperative aortic dissection with spontaneous aortic dissection.

Methods

The 15,144 consecutive patients who underwent cardiac surgery from April 1999 to April 2011 were studied retrospectively on data collected prospectively.

Results

Iatrogenic type A aortic dissection following cardiac surgery was diagnosed intraoperatively in 7 (0.04%) patients. Of the 4784 patients who had off-pump coronary artery bypass, only 2 (0.04%) developed iatrogenic intraoperative aortic dissection. Patients in the iatrogenic aortic dissection group were older by a decade (median age 72 vs. 62 years, p = 0.01). The cannulation site in conventional coronary artery bypass grafting and injury by the side-biting clamp in off-pump coronary artery bypass were the most common causes of dissection. Atheromatous disease was identified at the site of cannulation in 5 (71.4%) of the 7 cases.

Conclusions

Intraoperative aortic dissection remains a rare and unpredictable complication of cardiac surgery, with worse outcomes than spontaneous aortic dissection. Increased age and atheromatous disease at the site of cannulation are significant risk factors for iatrogenic dissection. In this series, off-pump coronary artery bypass did not appear to be a risk factor for iatrogenic aortic dissection.

Bedside tool for predicting the risk of postoperative atrial fibrillation after cardiac surgery: the POAF score

Background

Atrial fibrillation (AF) remains the most common complication after cardiac surgery. The present study aim was to derive an effective bedside tool to predict postoperative AF and its related complications.

Methods and Results

Data of 17 262 patients undergoing adult cardiac surgery were retrieved at 3 European university hospitals. A risk score for postoperative AF (POAF score) was derived and validated. In the overall series, 4561 patients (26.4%) developed postoperative AF. In the derivation cohort age, chronic obstructive pulmonary disease, emergency operation, preoperative intra‐aortic balloon pump, left ventricular ejection fraction <30%, estimated glomerular filtration rate <15 mL/min per m² or dialysis, and any heart valve surgery were independent AF predictors. POAF score was calculated by summing weighting points for each independent AF predictor. According to the prediction model, the incidences of postoperative AF in the derivation cohort were 0, 11.1%; 1, 20.1%; 2, 28.7%; and ≥3, 40.9% (P<0.001), and in the validation cohort they were 0, 13.2%; 1, 19.5%; 2, 29.9%; and ≥3, 42.5% (P<0.001). Patients with a POAF score ≥3, compared with those without arrhythmia, revealed an increased risk of hospital mortality (5.5% versus 3.2%, P=0.001), death after the first postoperative day (5.1% versus 2.6%, P<0.001), cerebrovascular accident (7.8% versus 4.2%, P<0.001), acute kidney injury (15.1% versus 7.1%, P<0.001), renal replacement therapy (3.8% versus 1.4%, P<0.001), and length of hospital stay (mean 13.2 versus 10.2 days, P<0.001).

Conclusions

The POAF score is a simple, accurate bedside tool to predict postoperative AF and its related or accompanying complications.

Feasibility and safety of minimized cardiopulmonary bypass in major aortic surgery

OBJECTIVES

Conventional cardiopulmonary bypass causes haemodilution and is a trigger of systemic inflammatory reactions, coagulopathy and organ failure. Miniaturized cardiopulmonary bypass has been proposed as a way to reduce these deleterious effects of conventional cardiopulmonary bypass and to promote a more physiological state. The use of miniaturized cardiopulmonary bypass has been reported in low-risk patients undergoing valve and coronary artery bypass graft (CABG) surgery. However, little is known about its application in major aortic surgery.

METHODS

From February 2007 to September 2010, 49 patients underwent major aortic surgery using the Hammersmith miniaturized cardiopulmonary bypass (ECCO, Sorin). Data were extracted from medical records to characterize preoperative comorbidities (EuroSCORE), perioperative complications and the use of blood products. The same data were collected and described for 328 consecutive patients having similar surgery with conventional cardiopulmonary bypass at the Bristol Heart Institute, our twinned centre, during the same period.

RESULTS

The miniaturized cardiopulmonary bypass group had a median EuroSCORE of 8 [inter-quartile range (IQR): 5-11], 13% had preoperative renal dysfunction and 20% of operations were classified as emergency or salvage. Thirty-day mortalities were 6.4; and 69, 67 and 74% had ≥ 1 unit of red cells, fresh frozen plasma (FFP) and platelets transfused, respectively. Eight percent of patients experienced a renal complication, and 8% a neurological complication. The conventional cardiopulmonary bypass group was similar, with a EuroSCORE of 8 (IQR: 6-10); 30-day mortalities were 9.4; and 68, 62 and 74% had ≥ 1 unit of red cells, FFP and platelets transfused, respectively. The proportions experiencing renal and neurological complications were 14 and 5%.

CONCLUSIONS

Our experience suggests that miniaturized cardiopulmonary bypass is safe and feasible for use in major aortic cardiac surgery. A randomized trial is needed to evaluate miniaturized cardiopulmonary bypass formally.

Effect of adding postoperative noninvasive ventilation to usual care to prevent pulmonary complications in patients undergoing coronary artery bypass grafting: a randomized controlled trial

OBJECTIVE

We compared the efficacy of noninvasive ventilation with bilevel positive airway pressure added to usual care versus usual care alone in patients undergoing coronary artery bypass grafting.

METHODS

We performed a 2-group, parallel, randomized controlled trial. The primary outcome was time until fit for discharge. Secondary outcomes were partial pressure of carbon dioxide, forced expiratory volume in 1 second, atelectasis, adverse events, duration of intensive care stay, and actual postoperative stay.

RESULTS

A total of 129 patients were randomly allocated to bilevel positive airway pressure (66) or usual care (63). Three patients allocated to bilevel positive airway pressure withdrew. The median duration of bilevel positive airway pressure was 16 hours (interquartile range, 11-19). The median duration of hospital stay until fit for discharge was 5 days for the bilevel positive airway pressure group (interquartile range, 4-6) and 6 days for the usual care group (interquartile range, 5-7; hazard ratio, 1.68; 95% confidence interval, 1.08-2.31; P = .019). There was no significant difference in duration of intensive care, actual postoperative stay, and mean percentage of predicted forced expiratory volume in 1 second on day 3. Mean partial pressure of carbon dioxide was significantly reduced 1 hour after bilevel positive airway pressure application, but there was no overall difference between the groups up to 24 hours. Basal atelectasis occurred in 15 patients (24%) in the usual care group and 2 patients (3%) in the bilevel positive airway pressure group. Overall, 30% of patients in the bilevel positive airway pressure group experienced an adverse event compared with 59% in the usual care group.

CONCLUSIONS

Among patients undergoing elective coronary artery bypass grafting, the use of bilevel positive airway pressure at extubation reduced the recovery time. Supported by trained staff, more than 75% of all patients allocated to bilevel positive airway pressure tolerated it for more than 10 hours.

Superior haemodynamic stability during off-pump coronary surgery with thoracic epidural anaesthesia: results from a prospective randomized controlled trial

OBJECTIVES

Off-pump coronary artery bypass (OPCAB) surgery is a technically more demanding strategy of myocardial revascularization compared with the standard on-pump technique. Thoracic epidural anaesthesia, by reducing sympathetic stress, may ameliorate the haemodynamic changes occurring during OPCAB surgery. The aim of this randomized controlled trial was to evaluate the impact of thoracic epidural anaesthesia on intraoperative haemodynamics in patients undergoing OPCAB surgery.

METHODS

Two hundred and twenty-six patients were randomized to either general anaesthesia plus epidural (GAE) (n = 109) or general anaesthesia (GA) only (n = 117). Mean arterial blood pressure (MAP), heart rate (HR) and central venous pressure (CVP) were measured before sternotomy and subsequently after positioning the heart for each distal anastomosis.

RESULTS

Both groups were well balanced with respect to baseline characteristics and received a standardized anaesthesia. The MAP decreased in both groups with no significant difference (mean difference (GAE minus GA) -1.11, 95% CI -3.06 to 0.84, P = 0.26). The HR increased in both groups after sternotomy but was significantly less in the GAE group (mean difference (GAE minus GA) -4.29, 95% CI -7.10 to -1.48, P = 0.003). The CVP also increased in both groups after sternotomy, but the difference between the groups varied over time (P = 0.05). A difference was observed at the third anastomosis when the heart was in position for the revascularization of the circumflex artery (mean difference (GAE minus GA) +2.09, 95% CI 0.21-3.96, P = 0.03), but not at other time points. The incidence of new arrhythmias was also significantly lower in the GAE compared with the GA group (OR = 0.41, 95% CI 0.22-0.78, P = 0.01).

CONCLUSION

Thoracic epidural with general anaesthesia minimizes the intraoperative haemodynamic changes that occur during heart positioning and stabilization for distal coronary anastomosis in OPCAB surgery.

Controlled reoxygenation cardiopulmonary bypass is associated with reduced transcriptomic changes in cyanotic tetralogy of Fallot patients undergoing surgery

In cyanotic patients undergoing repair of heart defects, high level of oxygen during cardiopulmonary bypass (CPB) leads to greater susceptibility to myocardial ischemia and reoxygenation injury. This study investigates the effects of controlled reoxygenation CPB on gene expression changes in cyanotic hearts of patients undergoing surgical correction of tetralogy of Fallot (TOF). We randomized 49 cyanotic TOF patients undergoing corrective cardiac surgery to receive either controlled reoxygenation or hyperoxic/standard CPB. Ventricular myocardium biopsies were obtained immediately after starting and before discontinuing CPB. Microarray analyses were performed on samples, and array results validated with real-time PCR. Gene expression profiles before and after hyperoxic/standard CPB revealed 35 differentially expressed genes with three upregulated and 32 downregulated. Upregulated genes included two E3 Ubiquitin ligases. The products of downregulated genes included intracellular signaling kinases, metabolic process proteins, and transport factors. In contrast, gene expression profiles before and after controlled reoxygenation CPB revealed only 11 differentially expressed genes with 10 upregulated including extracellular matrix proteins, transport factors, and one downregulated. The comparison of gene expression following hyperoxic/standard vs. controlled reoxygenation CPB revealed 59 differentially expressed genes, with six upregulated and 53 downregulated. Upregulated genes included PDE1A, MOSC1, and CRIP3. Downregulated genes functionally clustered into four major classes: extracellular matrix/cell adhesion, transcription, transport, and cellular metabolic process. This study provides direct evidence that hyperoxic CPB decreases the adaptation and remodeling capacity in cyanotic patients undergoing TOF repair. This simple CPB strategy of controlled reoxygenation reduced the number of genes whose expression was altered following hyperoxic/standard CPB.