198 resultados para Ischaemia


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Aims Technological advances in cardiac imaging have led to dramatic increases in test utilization and consumption of a growing proportion of cardiovascular healthcare costs. The opportunity costs of strategies favouring exercise echocardiography or SPECT imaging have been incompletely evaluated. Methods and results We examined prognosis and cost-effectiveness of exercise echocardiography (n=4884) vs. SPECT (n=4637) imaging in stable, intermediate risk, chest pain patients. Ischaemia extent was defined as the number of vascular territories with echocardiographic wall motion or SPECT perfusion abnormalities. Cox proportional hazard models were employed to assess time to cardiac death or myocardial infarction (MI). Total cardiovascular costs were summed (discounted and inflation-corrected) throughout follow-up. A cost-effectiveness ratio = 2% annual event risk), SPECT ischaemia was associated with earlier and greater utilization of coronary revascularization (P < 0.0001) resulting in an incremental cost-effectiveness ratio of $32 381/LYS. Conclusion Health care policies aimed at allocating limited resources can be effectively guided by applying clinical and economic outcomes evidence. A strategy aimed at cost-effective testing would support using echocardiography in low-risk patients with suspected coronary disease, whereas those higher risk patients benefit from referral to SPECT imaging.

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Introduction: Endothelin-1 is a potent vasoconstricting growth peptide. In physiologic conditions basal levels maintain vascular homeostasis, conversely in pathological situations it may be expressed in response to chronic and acute vascular injury. Elevated levels of plasma ET-1 have been identified in sub-populations at risk of ischaemic heart disease (IHD) including smokers, diabetics and hyerlipidaemic subjects and in patients with atherosclerotic disease. This peptide may be chronically expressed, such as in congestive heart failure where it has been used as a prognostic marker of disease severity and also acutely, after cardiac revascularisation surgery, possibly as a result of endothelial injury and ischaemia. Aims: The objectives of this study were to (1) identify basal endothelin-1 concentrations in a young healthy control group with no risk factors for IHD (control group 1); (2) to compare; (1) venous plasma ET-1 levels preoperatively and post-operatively in patients undergoing CABG surgery, (3) to compare pre-operative plasma ET-1 levels from the CABG group with an age and gender matched control group (control group 2) and (4) combine all three groups to assess correlations between plasma ET-1 and the various risk factors for IHD, including smoking, hypertension, hyperlipidemia, diabetes and family history. Methods: Venous specimens were collected in chilled EDTA tubes and samples measured using an ELISA assay (Biomedica), following the standard protocol for human EDTA plasma. Results: Forty CABG patients (5F, 35M, mean age 66 yrs), 15 control group 1 subjects (8F, 7M, mean age 29 yrs) and 30 control group 2 subjects (5F, 25M, mean age 61 yrs) participated in the study. No significant difference was detected in plasma ET-1 levels between the controls (1) and (2), and the CABG group, where plasma ET-1 levels were 3.37+/ 5.19 pmol/L, 1.99+/3.74 pmol/L and 1.28+/1.27 pmol/L, respectively. There was a non-significant elevation in post-op ET-1 plasma in comparison with the pre-op levels (2.50+/0.51 Vs 1.45+/6.44). There were also no statistical correlation between risk factors for IHD including smoking, hypertension, NIDDM, hyperlipidemia or family history when data from both patient and controls groups was merged. Conclusion: Contrary to other findings, plasma ET-1 does not appear to a valid marker for IHD or factors which are strongly associated with the pathogenesis of this disease.

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Purpose: To investigate the presence of silent cardiac ischaemic episodes and the status of autonomic function in consecutive, newly diagnosed and untreated primary open-angle glaucoma patients. Methods: Twenty-four consecutively diagnosed glaucoma patients and 22 age-matched controls were subjected to ambulatory 24-h blood pressure (BP) and electrocardiogram (ECG) monitoring by using Cardiotens-01 (Meditech Ltd). Based on the ECG recordings, heart rate variability (HRV) frequency domain parameters [low-frequency (LF), high-frequency (HF) and LF/HF ratio] were calculated and analysed in the two study groups. Results: Glaucoma patients demonstrated higher LF and LF/HF values than normal subjects for both the active period (p = 0.020 and 0.029) and the passive period (p = 0.044 and 0.049 respectively). HRV parameters were similar in patients and controls suffering from silent cardiac ischaemia (p > 0.05); however, glaucoma patients with normal ECG demonstrated higher LF and LF/HF values during the active period of the 24-h measurement period than control subjects characterized by the same cardiac activity (p = 0.010 and 0.021 respectively). Conclusion: Independent of a history and/or clinical signs of cardiovascular disease, glaucoma patients exhibit abnormal autonomic function. © 2007 The Authors.

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Inadequate blood flow to an organ, ischaemia, may lead to both local and remote tissue injury characterized by oedema, increased microvascular permeability to protein and degradation of connective tissue components. This damage is probably caused by the accumulation and inappropriate activation of neutrophils which occurs when the tissue is reperfused. To test this hypothesis a number of in vitro models of the sequential stages of ischaemia/reperfusion injury were examined. Methods were initially developed to examine the adhesion of neutrophils to monolayers of a cultured endothelial cell line (ECV304) after periods of hypoxia and reoxygenation. Neutrophil migration in response to factors secreted by the treated endothelial cells was then assessed. The genesis of an inappropriate oxidative burst by the neutrophil upon exposure to endothelial chemoattractants and adhesion molecules was also measured. Finally to appraise how tissue function might be affected by endothelial cell hypoxia the contractility of vascular smooth muscle was examined. Neutrophil adhesion to ECV304 cells, which had been hypoxic for 4 hours and then reoxygenated for 30 minutes, was significantly increased. This response was probably initiated by reactive oxygen species (ROS) generated by the endothelial cells. Blockage of their production by allopurinol reduced the heightened adhesion. Similarly removal of ROS by superoxide dismutase or catalase also attenuated adhesion. ROS generation in turn caused the release of a soluble factor (s) which induced a conformational change on the neutrophil surface allowing it to bind to the intercellular adhesion molecule 1 (ICAM-1) on the endothelial cell. Soluble factor (s) from hypoxia/reoxygenated endothelial cells also had a powerful neutrophil chemoattractant ability. When neutrophils were exposed to both hypoxic/reoxygenated endothelial cells and the soluble factor (s) released by them a large oxidative burst was elicited. This response was greatest immediately after reoxygenation and one hour later was diminishing suggesting at least one of the components involved was labile. Analysis of the supernatant from hypoxic/reoxygenated endothelial cell cultures and studies using inhibitors of secretion suggested platelet activating factor (PAF) may be a major component in this overall sequence of events. Lesser roles for IL-8, TNF and LTB4 were also suggested. The secretory products from hypoxia/reoxygenated endothelial cells also affected smooth muscle contractility having an anti-vasoconstrictor or relaxation property, similar to that exerted by PAF.

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S-glutathionylation occurs when reactive oxygen or nitrogen species react with protein-cysteine thiols. Glutaredoxin-1 (Glrx) is a cytosolic enzyme which enzymatically catalyses the reduction in S-glutathionylation, conferring reversible signalling function to proteins with redox-sensitive thiols. Glrx can regulate vascular hypertrophy and inflammation by regulating the activity of nuclear factor κB (NF-κB) and actin polymerization. Vascular endothelial growth factor (VEGF)-induced endothelial cell (EC) migration is inhibited by Glrx overexpression. In mice overexpressing Glrx, blood flow recovery, exercise function and capillary density were significantly attenuated after hindlimb ischaemia (HLI). Wnt5a and soluble Fms-like tyrosine kinase-1 (sFlt-1) were enhanced in the ischaemic-limb muscle and plasma respectively from Glrx transgenic (TG) mice. A Wnt5a/sFlt-1 pathway had been described in myeloid cells controlling retinal blood vessel development. Interestingly, a Wnt5a/sFlt-1 pathway was found also to play a role in EC to inhibit network formation. S-glutathionylation of NF-κB components inhibits its activation. Up-regulated Glrx stimulated the Wnt5a/sFlt-1 pathway through enhancing NF-κB signalling. These studies show a novel role for Glrx in post-ischaemic neovascularization, which could define a potential target for therapy of impaired angiogenesis in pathological conditions including diabetes.

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AIMS: Hydrogen sulfide (H2S) is a vasoactive gasotransmitter that is endogenously produced in the vasculature by the enzyme cystathionine γ-lyase (CSE). However, the importance of CSE activity and local H2S generation for ischaemic vascular remodelling remains completely unknown. In this study, we examine the hypothesis that CSE critically regulates ischaemic vascular remodelling involving H2S-dependent mononuclear cell regulation of arteriogenesis. METHODS AND RESULTS: Arteriogenesis including mature vessel density, collateral formation, blood flow, and SPY angiographic blush rate were determined in wild-type (WT) and CSE knockout (KO) mice at different time points following femoral artery ligation (FAL). The role of endogenous H2S in regulation of IL-16 expression and subsequent recruitment of monocytes, and expression of VEGF and bFGF in ischaemic tissues, were determined along with endothelial progenitor cell (CD34/Flk1) formation and function. FAL of WT mice significantly increased CSE activity, expression and endogenous H2S generation in ischaemic tissues, and monocyte infiltration, which was absent in CSE-deficient mice. Treatment of CSE KO mice with the polysulfide donor diallyl trisulfide restored ischaemic vascular remodelling, monocyte infiltration, and cytokine expression. Importantly, exogenous H2S therapy restored nitric oxide (NO) bioavailability in CSE KO mice that was responsible for monocyte recruitment and arteriogenesis. CONCLUSION: Endogenous CSE/H2S regulates ischaemic vascular remodelling mediated during hind limb ischaemia through NO-dependent monocyte recruitment and cytokine induction revealing a previously unknown mechanism of arteriogenesis.

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Cardiac Syndrome X (CSX), the presence of angina pectoris with objective signs of myocardial ischaemia despite angiographically normal epicardial coronary arteries, appears to be due to coronary microvascular dysfunction and is known to be associated with an elevation of several inflammatory biomarkers, suggesting a possible role for inflammation in its pathogenesis. We aimed to further characterise this relationship by prospectively analysing a wide variety of molecular biomarkers in a cohort of CSX patients thereby charting the changes in biomarkers throughout the natural history of CSX from its initial diagnosis to eventual disease quiescence. We found that CSX patients, when compared to healthy controls, have a persistent low-grade systemic inflammatory response characterised by an elevation of Tumour Necrosis Factor and Interferon-gamma, regardless of the presence of contemporaneous signs or symptoms of disease activity. Interleukin-6 and C-reactive Protein (CRP) are only elevated when patients have clinical evidence of disease activity and may be state markers in CSX. Moreover, CRP levels appear to correlate with signals of disease severity such as the time taken to develop symptoms during exercise stress testing. We have also demonstrated that the enzyme Indoleamine-2,3- dioxygenase is upregulated in active disease thus providing a possible explanation for the increased burden of psychological disease encountered in CSX. Analysis of the microRNA transcriptome showed that miR-143 is significantly under-expressed in CSX patients. This could allow phenotype switching in vascular smooth muscle cells with the resultant vascular remodelling causing reduced vessel responsiveness to local rheological stimuli and reduced luminal diameter with consequent increased microvascular resistance during times of increased myocardial oxygen demand, thereby limiting maximal hyperaemia during exercise. Our findings corroborate many previous hypotheses regarding the role of inflammation in CSX, generate new insights into possible pathogenic mechanisms and offer new therapeutic targets for the future management of this important cardiological condition.

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Obestatin is a 23-amino acid C-terminally amidated gastrointestinal peptide derived from preproghrelin and which forms an alpha helix. Although obestatin has a short biological half-life and is rapidly degraded, it is proposed to exert wide-ranging pathophysiological actions. Whilst the precise nature of many of its effects is unclear, accumulating evidence supports positive actions on both metabolism and cardiovascular function. For example, obestatin has been reported to inhibit food and water intake, body weight gain, and gastrointestinal motility, and to also mediate promotion of cell survival and prevention of apoptosis. Obestatin-induced increases in β-cell mass, enhanced adipogenesis and improved lipid metabolism have been noted along with upregulation of genes associated with β-cell regeneration, insulin production and adipogenesis. Furthermore, human circulating obestatin levels generally demonstrate an inverse association with obesity and diabetes, whilst the peptide has been shown to confer protective metabolic effects in experimental diabetes, suggesting that it may hold therapeutic potential in this setting. Obestatin also appears to be involved in blood pressure regulation and to exert beneficial effects on endothelial function, with experimental studies indicating that it may also promote cardioprotective actions against, for example, ischaemia-reperfusion injury. This review will present a critical appraisal of the expanding obestatin research area and discuss the emerging therapeutic potential of this peptide for both metabolic and cardiovascular complications of diabetes. 

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Multiple myeloma (MM) is a plasmocytic malignant proliferation of a single clone resulting in an overabundance of monoclonal immunoglobulins. MM commonly presents with bone disorders, renal failure, anaemia and hypercalcaemia. Hyperviscosity syndrome is rare, as are vaso-occlusive symptoms. The authors report a dramatic case of an 80-year-old woman admitted to the emergency department with full-blown distal gangrene. The culprit turned out to be a MM, unusually presenting with symptomatic hyperviscosity and peripheral occlusive ischaemia. This catastrophic and particularly dramatic presentation is almost unprecedented, with only a few cases reported worldwide.

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Objectives: To contribute to current knowledge on the vascular risk of oestrogens. Materials and methods: A 44-year-old woman received a 11.25 mg Leuprolide exteneded release injection to control bleeding from a 7 cm uterine fibroid tumour; 45 days later, she had a stroke due to right frontal lobe ischaemia. Thrombolysis induced complete remission. Three years previously, while taking a birth control pill, the patient had suffered from a stroke that involved her left temporal lobe. She was heterozygous for Factor V R2 H1299R locus and homozygous for the 4G/4G mutation of the PAI-1 gene. Even though her homocysteine level was normal, the patient was homozygous for the MTHFR C677T mutation and although she had never had severe bleeding, she was also homozygous for Factor XIII V34L. Results and conclusion: This patient’s prothrombotic condition could have been enhanced by leuprolide since its stimulatory effect on oestrogen production would still have been minimally present at the time of cerebral thrombosis.

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Purtscher-like retinopathy is associated with retinal hemorrhages and ischaemia probably due to the complement-mediated leukoembolization. It is a rare and severe angiopathy found in conditions such as acute pancreatitis. Case. We present a case of a 53-year-old man who presented with a Purtscher-like retinopathy associated with the development of acute pancreatitis in the context of a Klatskin tumour (a hilar cholangiocarcinoma). The ophthalmologic evaluation revealed the best corrected visual acuity (BCVA) of 20/32 in the right eye (RE) and of 20/40 in the left eye (LE); biomicroscopy of anterior segment showed scleral icterus and fundoscopy revealed peripapillary cotton-wool spots, optic disc edema, and RPE hypo- and hyperpigmentation in the middle peripheral retina in both eyes with an intraretinal hemorrhage in the LE. 15 months after the initial presentation, without ophthalmological treatment, there was an improvement of BCVA to 20/20 in both eyes and optical coherence tomography (OCT) revealed areas of reduction of retinal nerve fiber layer thickness corresponding to the previous cotton-wool spots. Conclusion. Purtscher-like retinopathy should not be neglected in complex clinical contexts. Its unclear pathophysiology determines an uncertain treatment strategy, but a meticulous follow-up is compulsory in order to avoid its severe complications.

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Amphetamine enhances recovery after experimental ischaemia and has shown promise in small clinical trials when combined with motor or sensory stimulation. Amphetamine, a sympathomimetic, might have haemodynamic effects in stroke patients, although limited data have been published. Subjects were recruited 3-30 days post ischaemic stroke into a phase II randomised (1:1), double blind, placebo-controlled trial. Subjects received dexamphetamine (5mg initially, then 10mg for 10 subsequent doses with 3 or 4 day separations) or placebo in addition to inpatient physiotherapy. Recovery was assessed by motor scales (Fugl-Meyer, FM), and functional scales (Barthel index, BI and modified Rankin score, mRS). Peripheral blood pressure (BP), central haemodynamics and middle cerebral artery blood flow velocity were assessed before, and 90 minutes after, the first 2 doses. 33 subjects were recruited, age 33-88 (mean 71) years, males 52%, 4-30 (median 15) days post stroke to inclusion. 16 patients were randomised to placebo and 17 amphetamine. Amphetamine did not improve motor function at 90 days; mean (standard deviation) FM 37.6 (27.6) vs. control 35.2 (27.8) (p=0.81). Functional outcome (BI, mRS) did not differ between treatment groups. Peripheral and central systolic BP, and heart rate, were 11.2 mmHg (p=0.03), 9.5 mmHg (p=0.04) and 7 beats/minute (p=0.02) higher respectively with amphetamine, compared with control. A non-significant reduction in myocardial perfusion (Buckberg Index) was seen with amphetamine. Other cardiac and cerebral haemodynamics were unaffected. Amphetamine did not improve motor impairment or function after ischaemic stroke but did significantly increase BP and heart rate without altering cerebral haemodynamics.

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Stem cell therapy for ischaemic stroke is an emerging field in light of an increasing number of patients surviving with permanent disability. Several allogenic and autologous cells types are now in clinical trials with preliminary evidence of safety. Some clinical studies have reported functional improvements in some patients. After initial safety evaluation in a Phase 1 study, the conditionally immortalised human neural stem cell line CTX0E03 is currently in a Phase 2 clinical trial (PISCES-II). Previous pre-clinical studies conducted by ReNeuron Ltd, showed evidence of functional recovery in the Bilateral Asymmetry test up to 6 weeks following transplantation into rodent brain, 4 weeks after middle cerebral artery occlusion. Resting-state fMRI is increasingly used to investigate brain function in health and disease, and may also act as a predictor of recovery due to known network changes in the post-stroke recovery period. Resting-state methods have also been applied to non-human primates and rodents which have been found to have analogous resting-state networks to humans. The sensorimotor resting-state network of rodents is impaired following experimental focal ischaemia of the middle cerebral artery territory. However, the effects of stem cell implantation on brain functional networks has not previously been investigated. Prior studies assessed sensorimotor function following sub-cortical implantation of CTX0E03 cells in the rodent post-stroke brain but with no MRI assessments of functional improvements. This thesis presents research on the effect of sub-cortical implantation of CTX0E03 cells on the resting- state sensorimotor network and sensorimotor deficits in the rat following experimental stroke, using protocols based on previous work with this cell line. The work in this thesis identified functional tests of appropriate sensitivity for long-term dysfunction suitable for this laboratory, and investigated non-invasive monitoring of physiological variables required to optimize BOLD signal stability within a high-field MRI scanner. Following experimental stroke, rats demonstrated expected sensorimotor dysfunction and changes in the resting-state sensorimotor network. CTX0E03 cells did not improve post-stroke functional outcome (compared to previous studies) and with no changes in resting-state sensorimotor network activity. However, in control animals, we observed changes in functional networks due to the stereotaxic procedure. This illustrates the sensitivity of resting-state fMRI to stereotaxic procedures. We hypothesise that the damage caused by cell or vehicle implantation may have prevented functional and network recovery which has not been previously identified due to the application of different functional tests. The findings in this thesis represent one of few pre-clinical studies in resting-state fMRI network changes post-stroke and the only to date applying this technique to evaluate functional outcomes following a clinically applicable human neural stem cell treatment for ischaemic stroke. It was found that injury caused by stereotaxic injection should be taken into account when assessing the effectiveness of treatment.

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Congenital heart disease (CHD) is the most common birth defect, causing an important rate of morbidity and mortality. Treatment of CHD requires surgical correction in a significant percentage of cases which exposes patients to cardiac and end organ injury. Cardiac surgical procedures often require the utilisation of cardiopulmonary bypass (CPB), a system that replaces heart and lungs function by diverting circulation into an external circuit. The use of CPB can initiate potent inflammatory responses, in addition a proportion of procedures require a period of aortic cross clamp during which the heart is rendered ischaemic and is exposed to injury. High O2 concentrations are used during cardiac procedures and when circulation is re-established to the heart which had adjusted metabolically to ischaemia, further injury is caused in a process known as ischaemic reperfusion injury (IRI). Several strategies are in place in order to protect the heart during surgery, however injury is still caused, having detrimental effects in patients at short and long term. Remote ischaemic preconditioning (RIPC) is a technique proposed as a potential cardioprotective measure. It consists of exposing a remote tissue bed to brief episodes of ischaemia prior to surgery in order to activate protective pathways that would act during CPB, ischaemia and reperfusion. This study aimed to assess RIPC in paediatric patients requiring CHD surgical correction with a translational approach, integrating clinical outcome, marker analysis, cardiac function parameters and molecular mechanisms within the cardiac tissue. A prospective, single blinded, randomized, controlled trial was conducted applying a RIPC protocol to randomised patients through episodes of limb ischaemia on the day before surgery which was repeated right before the surgery started, after anaesthesia induction. Blood samples were obtained before surgery and at three post-operative time points from venous lines, additional pre and post-bypass blood samples were obtained from the right atrium. Myocardial tissue was resected during the ischaemic period of surgery. Echocardiographic images were obtained before the surgery started after anaesthetic induction and the day after surgery, images were stored for later off line analysis. PICU surveillance data was collected including ventilation parameters, inotrope use, standard laboratory analysis and six hourly blood gas analysis. Pre and post-operative quantitation of markers in blood specimens included cardiac troponin I (cTnI) and B-type natriuretic peptide (BNP), inflammatory mediators including interleukins IL-6, IL-8, IL-10, tumour necrosis factor (TNF-α), and the adhesion molecules ICAM-1 and VCAM-1; the renal marker Cystatin C and the cardiovascular markers asymmetric dymethylarginine (ADMA) and symmetric dymethylarginine (SDMA). Nitric oxide (NO) metabolites and cyclic guanosine monophosphate (cGMP) were measured before and after bypass. Myocardial tissue was processed at baseline and after incubation at hyperoxic concentration during four hours in order to mimic surgical conditions. Expression of genes involved in IRI and RIPC pathways was analysed including heat shock proteins (HSPs), toll like receptors (TLRs), transcription factors nuclear factor κ-B (NF- κ-B) and hypoxia inducible factor 1 (HIF-1). The participation of hydrogen sulfide enzymatic genes, apelin and its receptor were explored. There was no significant difference according to group allocation in any of the echocardiographic parameters. There was a tendency for higher cTnI values and inotropic score in control patients post-operatively, however this was not statistically significant. BNP presented no significant difference according to group allocation. Inflammatory parameters tended to be higher in the control group, however only TNF- α was significantly higher. There was no difference in levels of Cystatin C, NO metabolites, cGMP, ADMA or SDMA. RIPC patients required shorter PICU stay, all other clinical and laboratory analysis presented no difference related to the intervention. Gene expression analysis revealed interesting patterns before and after incubation. HSP-60 presented a lower expression at baseline in tissue corresponding to RIPC patients, no other differences were found. This study provided with valuable descriptive information on previously known and newly explored parameters in the study population. Demographic characteristics and the presence of cyanosis before surgery influenced patterns of activity in several parameters, numerous indicators were linked to the degree of injury suffered by the myocardium. RIPC did not reduce markers of cardiac injury or improved echocardiographic parameters and it did not have an effect on end organ function; some effects were seen in inflammatory responses and gene expression analysis. Nevertheless, an important clinical outcome indicator, PICU length of stay was reduced suggesting benefit from the intervention. Larger studies with more statistical power could determine if the tendency of lower injury and inflammatory markers linked to RIPC is real. The present results mostly support findings of larger multicentre trials which have reported no cardiac benefit from RIPC in paediatric cardiac surgery.