Genetic Polymorphisms and the Risk of Stroke After Cardiac Surgery

Carbon Dioxide, Blood Pressure, and Perioperative Stroke: A Retrospective Case-Control Study

BACKGROUND

The relationship between intraoperative physiology and postoperative stroke is incompletely understood. Preliminary data suggest that either hypo- or hypercapnia coupled with reduced cerebrovascular inflow (e.g., due to hypotension) can lead to ischemia. This study tested the hypothesis that the combination of intraoperative hypotension and either hypo- or hypercarbia is associated with postoperative ischemic stroke.

METHODS

We conducted a retrospective, case-control study via the Multicenter Perioperative Outcomes Group. Noncardiac, nonintracranial, and nonmajor vascular surgical cases (18 yr or older) were extracted from five major academic centers between January 2004 and December 2015. Ischemic stroke cases were identified via manual chart review and matched to controls (1:4). Time and reduction below key mean arterial blood pressure thresholds (less than 55 mmHg, less than 60 mmHg, less than 65 mmHg) and outside of specific end-tidal carbon dioxide thresholds (30 mmHg or less, 35 mmHg or less, 45 mmHg or greater) were calculated based on total area under the curve. The association between stroke and total area under the curve values was then tested while adjusting for relevant confounders.

RESULTS

In total, 1,244,881 cases were analyzed. Among the cases that screened positive for stroke (n = 1,702), 126 were confirmed and successfully matched with 500 corresponding controls. Total area under the curve was significantly associated with stroke for all thresholds tested, with the strongest combination observed with mean arterial pressure less than 55 mmHg (adjusted odds ratio per 10 mmHg-min, 1.17 [95% CI, 1.10 to 1.23], P < 0.0001) and end-tidal carbon dioxide 45 mmHg or greater (adjusted odds ratio per 10 mmHg-min, 1.11 [95% CI, 1.10 to 1.11], P < 0.0001). There was no interaction effect observed between blood pressure and carbon dioxide.

CONCLUSIONS

Intraoperative hypotension and carbon dioxide dysregulation may each independently increase postoperative stroke risk.

EDITOR’S PERSPECTIVE

Narrative review of the systemic inflammatory reaction to cardiac surgery and cardiopulmonary bypass

Background

Data from large cardiac surgery registries have been depicting a downward trend of mortality and morbidities in the last 20 years. However, despite decades of medical evolution, cardiac surgery and cardiopulmonary bypass still provoke a systemic inflammatory response, which occasionally leads to worsened outcome. This article seeks to outline the mechanism of the phenomenon.

Methods

A thorough review of the literature has been performed. Criteria for considering studies for this non‐systematic review were as follows: observational and interventional studies investigating the systemic inflammatory response to cardiac surgery, experimental studies describing relevant molecular mechanisms, and essential review studies pertinent to the topic.

Results

The intrinsic variability of the inflammatory response to cardiac surgery, together with its heterogenous perception among clinicians, as well as the arduousness to early discriminate high‐responder patients from those who will not develop a clinically relevant reaction, concurred to hitherto unconclusive randomized controlled trials. Furthermore, peremptory knowledge about the pathophysiology of maladaptive inflammation following heart surgery is still lacking.

Conclusions

Systemic inflammation following cardiac surgery is a frequent entity that occasionally becomes clinically relevant. Specific genomic differences, age, and other preoperative factors influence the magnitude of the response, which elements display extreme redundancy and pleiotropism that the target of a single pathway cannot represent a silver bullet.

Germline Genetic Variants of Viral Entry and Innate Immunity May Influence Susceptibility to SARS-CoV-2 Infection: Toward a Polygenic Risk Score for Risk Stratification

The ongoing COVID-19 pandemic caused by the novel coronavirus, SARS-CoV-2 has affected all aspects of human society with a special focus on healthcare. Although older patients with preexisting chronic illnesses are more prone to develop severe complications, younger, healthy individuals might also exhibit serious manifestations. Previous studies directed to detect genetic susceptibility factors for earlier epidemics have provided evidence of certain protective variations. Following SARS-CoV-2 exposure, viral entry into cells followed by recognition and response by the innate immunity are key determinants of COVID-19 development. In the present review our aim was to conduct a thorough review of the literature on the role of single nucleotide polymorphisms (SNPs) as key agents affecting the viral entry of SARS-CoV-2 and innate immunity. Several SNPs within the scope of our approach were found to alter susceptibility to various bacterial and viral infections. Additionally, a multitude of studies confirmed genetic associations between the analyzed genes and autoimmune diseases, underlining the versatile immune consequences of these variants. Based on confirmed associations it is highly plausible that the SNPs affecting viral entry and innate immunity might confer altered susceptibility to SARS-CoV-2 infection and its complex clinical consequences. Anticipating several COVID-19 genomic susceptibility loci based on the ongoing genome wide association studies, our review also proposes that a well-established polygenic risk score would be able to clinically leverage the acquired knowledge.

Temperature management on cardiopulmonary bypass: Is it standardised across Great Britain and Ireland?

Temperature management is an essential element of cardiopulmonary bypass (CPB), as indicated in the Guide to Good Practice in Clinical Perfusion, 'The safe conduct of CPB requires the clinical perfusionist to measure and control. . . blood temperature. . . during the period of bypass'. To review current practice, we have conducted a research survey into the management of temperature on CPB. Surveys were distributed to each centre in Great Britain and the Republic of Ireland, investigating numerous temperature management practices, to elucidate current practice and assess if recent research into temperature management marry routine clinical practice. Our results demonstrate that nasopharyngeal temperature is the most common (52%) temperature site used across the many centres, which correlates with previous research as a routine site for cerebral temperature management. The arterial outlet of the oxygenator temperature was used in 33% of centres, however, all centres lacked the knowledge to maintain this temperature below 37°C. There was significant variation between all centres, especially regarding rewarming times (20-40 minutes), demonstrating a lack of uniformity among perfusion centres. Interestingly, most centres have been using the same protocol that has been in place over the previous 10 years.To conclude, the practice of temperature management is changing with the awareness of new research. Lower target temperatures are recommended for rewarming, ensuring a lower temperature gradient and a longer mean rewarming time.

Arterial Hypertension and Interleukins: Potential Therapeutic Target or Future Diagnostic Marker?

Hypertension as a multifactorial pathology is one of the most important cardiovascular risk factors, affecting up to 30-40% of the general population. Complex immune responses are involved in the inflammatory mechanism of hypertension, with evidence pointing to increased inflammatory mediators even in prehypertensive patients. Increased vascular permeability, thrombogenesis, and fibrosis, effects that are associated with sustained hypertension, could be attributed to chronic inflammation. Chronic inflammation triggers endothelial dysfunction via increased production of ROS through proinflammatory cytokines. Increased serum level of proinflammatory cytokines such as IL-1β, IL-6, IL-8, IL-17, IL-23, TGFβ, and TNFα in hypertensive patients has been associated with either increased blood pressure values and/or end-organ damage. Moreover, some cytokines (i.e., IL-6) seem to determine a hypertensive response to angiotensin II, regardless of blood pressure values. Understanding hypertension as an inflammatory-based pathology gives way to new therapeutic targets. As such, conventional cardiovascular drugs (statins, calcium channels blockers, and ACEIs/ARBs) have shown additional anti-inflammatory effects that could be linked to their blood pressure lowering properties. Moreover, anti-inflammatory drugs (mycophenolate mofetil) have been shown to decrease blood pressure in hypertensive patients or prevent its development in normotensive individuals. Further research is needed to evaluate whether drugs targeting hypertensive-linked proinflammatory cytokines, such as monoclonal antibodies, could become a new therapeutic option in treating arterial hypertension.

Genetic Influences on Cerebral Outcome After Cardiac Surgery

Just as the influence of genetic variation on patient outcomes is being discussed in many other areas of medicine, so too are its effects on cerebral outcome after cardiac surgery now being described. Whereas early studies focused on neurocognitive outcome, where the single nucleotide polymorphisms of APOE4 and PLA2 were the first investigated genetic targets, stroke is now being elaborated on with related single and multi-gene single nucleotide polymorphisms having been identified. Our work has established key links between post-cardiac surgery stroke and C-reactive protein (3’UTR 1846C/T) and interleukin-6 (-174 G/C) single nucleotide polymorphisms.

Adrenergic receptor genotype influences heart failure severity and β-blocker response in children with dilated cardiomyopathy

BACKGROUND

Adrenergic receptor (ADR) genotypes are associated with heart failure (HF) and β-blocker response in adults. We assessed the influence of ADR genotypes in children with dilated cardiomyopathy (DCM).

METHODS

Ninety-one children with advanced DCM and 44 with stable DCM were genotyped for three ADR genotypes associated with HF risk in adults: α2cdel322-325, β1Arg389, and β2Arg16. Data were analyzed by genotype and β-blocker use. Mean age at enrollment was 8.5 y.

RESULTS

One-year event-free survival was 51% in advanced and 80% in stable DCM. High-risk genotypes were associated with higher left ventricular (LV) filling pressures, higher systemic and pulmonary vascular resistance, greater decline in LV ejection fraction (P < 0.05), and a higher frequency of mechanical circulatory support while awaiting transplant (P = 0.05). While β-blockers did not reduce HF severity in the overall cohort, in the subset with multiple high-risk genotypes, those receiving β-blockers showed better preservation of cardiac function and hemodynamics compared with those not receiving β-blockers (interaction P < 0.05).

CONCLUSION

Our study identifies genetic risk markers that may help in the identification of patients at risk for developing decompensated HF and who may benefit from early institution of β-blocker therapy before progression to decompensated HF.

Association between APOE epsilon 4 allele and postoperative cognitive dysfunction: a meta-analysis

BACKGROUND

Carriers of the apolipoprotein E epsilon 4 allele (APOEε4) may be at increased risk of postoperative cognitive dysfunction (POCD), but this association has not been reported consistently. We conducted a meta-analysis to derive a more precise conclusion.

METHODS

The PubMed, EBSCO and EMBASE databases were searched for eligible studies published in English before March 2013. The association between APOEε4 and POCD was expressed by the odds ratio (OR) with 95% confidence interval (CI). Funnel plots were constructed and publication bias assessed by Egger's test.

RESULTS

Nine studies encompassing 1063 APOEε4 carriers and 2983 noncarriers were included. At about 1-week postsurgery, a significant association between APOEε4 and POCD was found (OR 1.83, 95% CI: 1.18-2.85), but the association was no longer significant after removing one large study (OR 1.35, 95% CI: 0.92-1.97). Stratified analysis of cardiac/vascular surgery patients also yielded no significant correlation (OR 1.62, 95% CI: 0.80-3.28). One to three months postsurgery, neither the overall analysis (OR 1.56, 95% CI: 0.87-2.81) nor the stratified analysis of cardiac/vascular surgery patients (OR 3.33, 95% CI: 0.55-20.22) indicated a significant correlation. APOEε4 was also not correlated with POCD at 1-year postsurgery (OR 1.15, 95% CI: 0.71-1.86). No evidence of publication bias was revealed by Egger's test.

CONCLUSIONS

The APOEε4 allele was associated with a significantly increased POCD risk about 1-week postsurgery, but the association depended on one large study. No association was found 1-3 months and 1-year postsurgery.

Association between CRP gene polymorphism 717A/G, C-reactive protein and neurological deficit in ischemic stroke

Inflammatory components play an important role in the pathogenesis of arteriosclerosis, one of the main causes of stroke. Blood C-reactive protein (CRP) level is connected with the severity of neurological deficit and disability after stroke. Production of CRP depends on CRP gene polymorphism. This study enrolled 125 patients with ischemic stroke. CRP 717A/G polymorphism was tested in all patients along with an assay of CRP levels measured on the first and tenth day after stroke onset. Neurological deficit on admission and before discharge from hospital was evaluated according to National Institutes of Health Stroke Scale (NIHSS), and then associated with CRP levels and the CRP polymorphism. The CRP 717AA genotype was the most frequent, observed in 53.6% of patients; AG genotype in 40%, and GG genotype in 6.4%. Carriers of the 717GG genotype had a significantly higher CRP level on the first day after stroke versus heterozygotes (p=0.023). The improvement in neurological state evaluated with the NIHSS was significantly better in CRP 717AA patients in comparison with other CRP 717 genotypes (p=0.035). A higher level of CRP on the first day after ischemic stroke was slightly associated with the CRP 717AG genotype. The CRP 717AA genotype promotes improvement of neurological state in patients with ischemic stroke.

COMT-Val158Met-polymorphism is not a risk factor for acute kidney injury after cardiac surgery

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) depicts a major complication after cardiac surgery using cardiopulmonary bypass (CPB).

OBJECTIVE

CSA-AKI has clearly been linked to increased perioperative morbidity and mortality. Dysregulations of vasomotor tone are assumed to be causal for CSA-AKI. While catechol-O-methyltransferase (COMT) is involved in metabolizing catecholamines, a single-nucleotide polymorphism (SNP) in the COMT gene leads to different enzyme activities according to genotype. Pilot studies found associations between those COMT genotypes and CSA-AKI.

METHODS

We prospectively included 1741 patients undergoing elective cardiac surgery using cardiopulmonary bypass (CPB). Patients were genotyped for COMT-Val158Met-(G/A) polymorphism (rs4680).

RESULTS

Demographic characteristics and procedural data revealed no significant differences between genotypes. No association between COMT genotypes and the RIFLE criteria could be detected. A multiple linear regression analysis for postoperative creatinine increase revealed highly significant associations for aortic cross-clamp time (P < 0.001), CPB time (P < 0.001), norepinephrine (P < 0.001), and age (P < 0.001). No associations were found for COMT genotypes or baseline creatinine. With an R (2) = 0.39 and a sample size of 1741, the observed power of the regression analysis was >99%.

CONCLUSIONS

Based on our results, we can rule out an association between the COMT-Val158Met-(G/A) polymorphism and the appearance of CSA-AKI.

Neurocognitive outcomes after cardiac surgery

PURPOSE OF REVIEW

To summarize recent studies of neurocognitive dysfunction after cardiac surgery, as well as to outline efforts and approaches toward advancing the field.

RECENT FINDINGS

Observational studies have improved our understanding of the incidence and the trajectory of cognitive decline after cardiac surgery; however, the magnitude of this neurocognitive change remains controversial because of the inconsistent definitions and the lack of a gold-standard diagnostic modality. Nonetheless, physicians commonly see patients with functional and cognitive impairments after cardiac surgery, which utilize healthcare resources and impact quality of life. Novel approaches have utilized advanced neuroimaging techniques as well as innovative monitoring modalities to improve the efficiency of neuroprotective strategies during cardiac surgery.

SUMMARY

Adverse cognitive and neurologic outcomes following cardiac surgery range from discrete neurocognitive deficits to severe neurologic injury such as stroke and even death. The elderly are at higher risk of suffering these outcomes and the public health dimension of this problem is expected to accelerate. Future studies should combine advanced neuroimaging with genomic, transcriptional, proteomic, and metabolomic profiling to improve our understanding of the pathophysiologic mechanisms and optimize the diagnosis, prevention, and treatment of neurocognitive injury.

Preoperative Stroke and Outcomes after Coronary Artery Bypass Graft Surgery

Background:

Data are lacking on the optimal scheduling of coronary artery bypass grafting (CABG) surgery after stroke. The authors investigated the preoperative predictors of adverse outcomes in patients undergoing CABG, with a focus on the importance of the time interval between prior stroke and CABG.

Methods:

The Hospital Episode Statistics database (April 2006–March 2010) was analyzed for elective admissions for CABG. Independent preoperative patient factors influencing length of stay, postoperative stroke, and mortality, were identified by logistic regression and presented as adjusted odds ratios (OR).

Results:

In all, 62,104 patients underwent CABG (1.8% mortality). Prior stroke influenced mortality (OR 2.20 [95% CI 1.47–3.29]), postoperative stroke (OR 1.99 [1.39–2.85]), and prolonged length of stay (OR 1.31 [1.11–1.56]). The time interval between stroke and CABG did not influence mortality or prolonged length of stay. However, a longer time interval between stroke and CABG surgery was associated with a small increase in risk of postoperative stroke (OR per month elapsed 1.02 [1.00–1.04]; P = 0.047). An interaction was evident between prior stroke and myocardial infarction for death (OR 5.50 [2.84–10.8], indicating the importance of the combination of comorbidities. Prominent effects on mortality were also exerted by liver disease (OR 20.8 [15.18–28.51]) and renal failure (OR 4.59 [3.85–5.46]).

Conclusions:

The authors found no evidence that more recent preoperative stroke predisposed patients undergoing CABG surgery to suffer postoperative stroke, death, or prolonged length of stay. The combination of prior stroke and myocardial infarction substantially increased perioperative risk.

Genetics and epigenetics in perioperative medicine

PURPOSE OF REVIEW

To summarize is to review recent progress in 'genomic' science and how this may be applied to the perioperative environment. Although investigations that relate genetic variation to perioperative outcomes continue, it is increasingly apparent that epigenetic mechanisms may contribute to much of the observed variation in complex outcomes not otherwise explained by differences in genetic sequence.

RECENT FINDINGS

Examples of recent findings relating to the role of epigenetic modifications in complex disease and outcomes are derived from research into type 1 diabetes, pain, and the hypoxic response. These studies provide models for future cohort study design, potential perioperative drug targets, and hypothesis development. Genetic and epigenetic factors combine to alter both gene expression and drug responses at both pharmacokinetic and pharmacodynamic levels. These factors impact on the efficacy and safety of multiple drug classes used in perioperative medicine.

SUMMARY

Enhancing our understanding of the way in which patients as genomic organisms interact with the perioperative environment requires a more sophisticated appreciation of the factors governing gene expression than has been the case to date. Epigenetic mechanisms are sure to play a pivotal role in what is essentially an acquired phenotype.

Fibrinogen beta-chain -C148T polymorphism is associated with increased fibrinogen, C-reactive protein, and interleukin-6 in patients undergoing coronary artery bypass grafting

The fibrinogen beta-chain (FGB) -C148T polymorphism is linked with plasma fibrinogen concentration in the general population. We examined whether the -C148T polymorphism is associated with pre- and early postoperative levels of fibrinogen, C-reactive protein (CRP), and interleukin-6 (IL-6) in 243 consecutive patients undergoing coronary artery bypass grafting (CABG) surgery. Plasma inflammatory markers were measured prior to and 5-7 days after surgery. The -C148T polymorphism was analyzed with the restriction fragment-length polymorphism method. The genotype distribution was as follows: CC-142 (58%), CT-85 (35%), and TT-16 (7%). Carriers of the -148T allele had higher preoperative plasma fibrinogen (4.42 ± 0.14 vs. 4.07 ± 0.11 mg/L, p = 0.04) and CRP levels (7.49 ± 1.2 vs. 4.26 ± 1.0 mg/L, p = 0.04) compared with non-carriers; 5 to 7 days after CABG, patients carrying -148T allele had increased CRP (70.4 ± 5.0 vs. 51.6 ± 4.25 mg/L, p = 0.005) and IL-6 levels (22.34 ± 2.64 vs. 15.53 ± 2.28 pg/L, p = 0.05), but not fibrinogen, compared with the remaining subjects. In-hospital nonfatal stroke occurred more frequently in -148T allele carriers (4% vs. 0%, p = 0.02). No genotype-associated differences were found in the occurrence of postoperative myocardial infarction and death. Presence of the -148T allele has also been associated with longer intensive care stay and intubation time (p = 0.01). Multivariate analysis identified the CT+TT genotype as an independent predictor of pre- and postoperative CRP levels. The results indicate that the presence of the -148T FGB allele determines higher pre- and postoperative levels of inflammatory markers, which might be associated with in-hospital clinical outcomes.

Brain damage in cardiac surgery patients

Neuropsychological disorders and brain injury are still a serious problem in cardiac surgery patients. Owing to multifactorial mechanism of brain injury during extracorporeal circulation, the effective and safe protection is extremely difficult. Despite several studies, the ideal neuroprotective treatment has not been found. Based on literature we analysed the main mechanisms of brain injury and new methods of brain protection.

Understanding the transition to acute illness: the promise of perioperative genomics

Over the last decades, tremendous advances have been made in understanding the genomic basis of a large number of chronic human diseases. Such advances were made possible by studying large numbers of patients over relatively long periods of time. It is increasingly recognized that acute robust stress stimulates pathways activated in chronic disease, facilitating mechanistic studies in much shorter time frames. A new field of molecular medicine, called perioperative genomics, uses robust surgical stress as a perturbation designed to explore such mechanisms. This new field is described briefly below.

Carotid plaque, stroke pathogenesis, and CRP: treatment of ischemic stroke

Inflammation is receiving increased attention as a cause of atherosclerosis and stroke. Several inflammatory biomarkers, and particularly high-sensitivity C-reactive protein (hsCRP), have been identified as likely predictors of the risk of a future stroke. In clinical settings, it has been consistently observed that higher concentrations of CRP are associated with larger brain infarcts, stroke severity, neurologic disability, and future vascular events. However, there is still controversy over the degree of risk conferred by elevated CRP concentrations. Some studies reported that the predictive value of CRP is moderate compared with classical risk factors and is only weakly related to cardiovascular damage after adjustment for traditional cardiovascular risk factors. CRP like many other hemostatic factors is an acute-phase protein and, therefore, it is not always clear whether its association with cerebrovascular disease reflects its contribution to atherothrombosis, its acute-phase condition, or both. Furthermore, the value of single measurements of CRP in patients with concurrent infection or other inflammatory conditions has not been established and reported data should be interpreted cautiously. Several drugs, especially hydroxymethylglutaryl coenzyme A reductase inhibitors (statins), have been demonstrated to reduce hsCRP levels independently of their effects on plasma cholesterol. Recently, emerging therapies have been aimed at the control of blood pressure and inflammation in stroke patients. Whether a reduction of hsCRP levels could be beneficial to stroke patients remains to be clarified, and it is also unclear whether other drugs may be useful to lower hsCRP levels. More studies are needed before hsCRP becomes a routine part of the evaluation of stroke patients. This should also prompt the search for new agents directly blocking CRP actions.

Metabolic syndrome is an independent risk factor for stroke and acute renal failure after coronary artery bypass grafting

OBJECTIVES

Metabolic syndrome is common among patients having coronary artery bypass grafting. However, it remains unclear whether it has a significant impact on postoperative complications. We aimed to determine whether metabolic syndrome negatively influences the postoperative outcomes of coronary artery bypass grafting.

METHODS

We enrolled 1183 patients who had coronary artery bypass grafting at Juntendo University Hospital between 1984 and 1992. Patients were categorized by the presence or absence of metabolic syndrome using the modified National Cholesterol Education Program Adult Treatment Panel III definition with body mass index in the place of waist circumference. Multivariate analysis was performed to assess the relationships between preoperative presence of metabolic syndrome and postoperative outcomes.

RESULTS

Metabolic syndrome was present in 551 (46.6%) patients and absent in 632 (53.4%). Postoperative stroke occurred in 4.7% of patients with metabolic syndrome and 2.1% of patients without metabolic syndrome (P < .0001). Postoperative acute renal failure occurred in 3.8% of patients with metabolic syndrome and 1.1% of patients without metabolic syndrome. On multivariate analysis, metabolic syndrome had odds ratios of 2.47 (95% confidence interval 1.22-4.99; P = .012) for postoperative stroke and 3.81 (95% confidence interval 1.42-10.3; P = .008) for postoperative acute renal failure.

CONCLUSIONS

This study showed the clinical importance of metabolic syndrome with respect to postoperative stroke and acute renal failure in patients having coronary artery bypass grafting. Like many established risk factors for postoperative complications, metabolic syndrome should be recognized as a novel risk factor for adverse events.

Ambivalent aspects of interleukin-6 in cerebral ischemia: inflammatory versus neurotrophic aspects

Interleukin-6 (IL-6) is pleiotropic cytokine involved in many central nervous system disorders including stroke, and elevated serum IL-6 has been found in acute stroke patients. IL-6 is implicated in the inflammation, which contributes to both injury and repair process after cerebral ischemia. However, IL-6 is one of the neurotrophic cytokines sharing a common receptor subunit, gp130, with other neurotrophic cytokines, such as leukemia inhibitory factor (LIF) and ciliary neurotrophic factor. The expression of IL-6 is most prominently identified in neurons in the peri-ischemic regions, and LIF expression shows a similar pattern. The direct injection of these cytokines into the brain after ischemia can reduce ischemic brain injury. The cytokine receptors are localized on the neuron surface, suggesting that neurons are the cytokine target. The major IL-6 downstream signaling pathway is JAK-STAT, and Stat3 activation occurs mainly in neurons during postischemic reperfusion. Further investigation is necessary to clarify the exact role of Stat3 signaling in neuroprotection. Taken together, the information suggests that IL-6 plays a double role in cerebral ischemia, as an inflammatory mediator during the acute phase and as a neurotrophic mediator between the subacute and prolonged phases.

Neurological complications of cardiac surgery

Neurological injury resulting from cardiac surgery has a range of manifestations from focal neurological deficit to encephalopathy or coma. As the safety of drug-eluting stents comes into question, more patients will likely undergo coronary artery bypass graft surgery. These projections, along with the growing proportions of elderly patients and those with comorbidities, portend the potential for rising rates of perioperative neurological complications. The risk for neurological injury may be determined by the type of procedure, by patient-specific characteristics, and by the extent of cerebral embolization and hypoperfusion during and after surgery. Changes in surgical techniques, including the use of off-pump surgery, have not decreased rates of brain injury from cardiac surgery. When appropriate, modern neuroimaging techniques should be used in postoperative patients to confirm diagnosis, to provide information on potential etiology, to direct appropriate therapy, and to help in prognostication. Management of postoperative medications and early use of rehabilitation services is a recommended strategy to optimize the recovery for individuals with neurological injury after cardiac surgery.

Brain protection in cardiac surgery

Brain injury is a major source of patient morbidity after cardiac surgery, and is associated with prolonged hospitalization, excessive operative mortality, high hospital costs, and altered quality of life. Frequency and the clinical manifestations depend on multiple factors, including the completeness and timing of neurologic testing. Ischemic brain infarctions may or may not be associated with stroke or postoperative neurocognitive dysfunction, but the long-term implications of these lesions on neurologic function have not yet been extensively evaluated. This article reviews the current views on the pathophysiologic basis of cerebral injury after cardiac surgery and provides a summary of measures aimed at reducing its occurrence.

The effect of NQO1 polymorphism on the inflammatory response in cardiopulmonary bypass

Cardiopulmonary bypass (CPB) has been associated with systemic inflammatory response syndrome (SIRS). Endothelial dysfunction related to non-laminar flow during CPB is known to play a key role in this complex pathology. Antioxidant response element (ARE) dependent NAD(P)H:quinone oxidoreductase 1 (NQO1) promoter is a regulatory element involved in the anti-inflammatory mechanism in vasculature exposed to non-laminar flow. Mutation of the NQO1 could represent a novel anti-inflammatory effect in CPB. The goal of this study was to demonstrate whether genetic variants of NQO1 affect cytokine release after CPB. Eighteen patients who underwent standard coronary artery bypass grafting (CABG) operation were included in the study. Genotyping for NQO1 was performed. Serum Interleukin-6 (IL-6) levels were measured before induction, during CPB after declamping the aorta, and 24 h after operation. Clinical data were collected respectively. Seven patients were NQO1 T carriers and 11 patients were NQO1 T non-carriers. During CPB, IL-6 concentrations were increased in NQO1 T carriers compared to T non-carriers (p = 0.038). Although ventilation times and blood loss were higher in T carriers these were not statistically significant. Patients with NQO1 T carriers showed significantly higher IL-6 levels during CPB. Non-laminar flow during CPB may diminish the transcriptional activation of the NQO1 in T carriers. Preoperative determination of this novel anti-inflammatory mechanism could be useful to improve operative outcome in CPB.

Carotid plaque, stroke pathogenesis, and CRP: treatment of ischemic stroke

C-reactive protein (CRP), an inflammatory marker, has been identified as a likely predictor of the risk of a future stroke. In clinical settings, it has been consistently observed that higher concentrations of CRP are associated with larger brain infarcts and worst neurologic outcome. However, there is still controversy over the degree of risk conferred by elevated CRP concentrations. CRP, like many other hemostatic factors, is an acute-phase protein and, therefore, it is not always clear whether its association with cerebrovascular disease reflects its contribution to atherothrombosis, its acute-phase condition, or both. Whether a reduction of CRP levels could be beneficial to stroke patients remains to be clarified. More studies are needed before CRP becomes a routine part of the evaluation of stroke patients.

Neuroprotection during cardiac surgery

Cardiac surgery continues to be associated with significant adverse cerebral outcomes, ranging from stroke to cognitive decline. The underlying mechanism of the associated cerebral injury is incompletely understood but is believed to be primarily caused by cerebral embolism and hypoperfusion, exacerbated by ischemia/reperfusion injury. Extensive research has been undertaken in an attempt to minimize the incidence of perioperative cerebral injury, and both pharmacological and nonpharmacological strategies have been investigated. Although many agents demonstrated promise in preclinical studies, there is currently insufficient evidence from clinical trials to recommend the routine administration of any pharmacological agents for neuroprotection during cardiac surgery. The nonpharmacological strategies that can be recommended on the basis of evidence include transesophageal echocardiography and epiaortic ultrasound-guided assessment of the atheromatous ascending aorta with appropriate modification of cannulation, clamping or anastomotic technique and optimal temperature management. Large-scale randomized controlled trials are still required to address further the issues of optimal pH management, glycemic control, blood pressure management and hematocrit during cardiopulmonary bypass. Past, present and future directions in the field of neuroprotection in cardiac surgery will be discussed.

Mechanisms of cerebral injury from cardiac surgery

Cerebral injury is a frequent complication of cardiac surgery, and it has been associated with high mortality, morbidity, hospital costs; an increased likelihood of admission to a secondary care facility after hospital discharge; and impaired quality of life. This article examines postulated mechanisms for cerebral injury from cardiac surgery. Most emphasis has been placed in the past on the intraoperative interval as being the period of highest cerebral vulnerability. Many clinical cerebral events, however, occur in the postoperative period.

Pharmacogenomics and end-organ susceptibility to injury in the perioperative period

Genomic medicine has provided new mechanistic understanding for many complex diseases over the last 5-10 years. More recently genomic approaches have been applied to the perioperative paradigm, facilitating identification of patients at high risk for adverse events, as well as those who will respond better/worse to specific pharmacologic therapies. The consistent biological theme emerging is that while inflammation is important in healing from surgical trauma, patients who are too robustly proinflammatory appear to be at higher risk for adverse perioperative events. Precise predictors of each adverse event are being elucidated so that corrective therapeutics can be instituted to improve outcomes in high-risk patients. While the field of perioperative genomics could be considered in its infancy, such approaches are the wave of the future.

Drugs for the perioperative control of hypertension: current issues and future directions

The management of hypertension continues to pose important challenges. Recent developments have established the importance of more rigorous blood pressure control in the community. In the perioperative setting, hypertension has long been recognised as undesirable, although the adverse impact of high blood pressure on the acute risks of elective surgery may have been previously overstated.A number of agents and techniques are available to control blood pressure perioperatively. These include principally general and regional anaesthetics, alpha(2)-adrenoceptor agonists, peripheral alpha(1)- and beta-adrenoceptor antagonists, dihydropyridine calcium channel antagonists, dopamine D(1A)-receptor agonists (fenoldopam), and nitric oxide donors. Recent years have seen important developments in the receptor selectivity of new compounds and in pharmacokinetics, particularly esterase metabolism. The future study of genomics may enable us to identify patients at risk for hypertension-related adverse events and target therapies most effectively to these high-risk groups.

Association of interleukin-6, interleukin-12, and interleukin-10 gene polymorphisms with essential hypertension in Tatars from Russia

Essential hypertension is a common disease with fatal clinical complications. Epidemiological and family studies have confirmed the role of genetic predisposition in its development. Hypertensive patients have been shown to have an altered profile of pro- and anti-inflammatory cytokines. The aim of our investigation was to reveal the association of interleukin-6, interleukin-12, and interleukin-10 gene polymorphisms with essential hypertension and its clinical complications in a Tatar ethnic group from Bashkortostan, Russia. The study involved 362 hypertensive patients and 244 healthy subjects from this Tatar ethnic group (Bashkortostan, Russia). DNA was isolated from whole venous blood using phenol-chloroform extraction by the standard method. IL6 -572 G/C, IL12B 1159 C/A, and IL10 -627 C/A genotypes were typed using polymerase chain reaction followed by restriction enzyme digestion. We found that the IL10 -627 *C/*C genotype was associated with decreased risk of hypertension (OR = 0.64, P = 0.035). IL6 genotypes and allele distribution did not differ significantly between subjects with and without hypertension, but the IL6 -572 *G/*G genotype frequency was found to be significantly higher among those patients who had stroke, compared with normotensive control subjects (P = 0.036). Carriers of the IL12B 1159 *A/*A genotype had a lower risk of stroke (OR = 0.38, P = 0.028). Our study has shown the association between IL10 -627 C/A polymorphism and essential hypertension in the Tatar ethnic group from Bashkortostan, Russia. The IL10 -627*C/*C genotype was found to be protective against hypertension. We also demonstrated that hypertensive patients with the IL12B *A/*A and IL6 *G/*G genotypes had increased risk of stroke. Our results suggest a role for cytokines in cardiovascular disease development in the Tatar ethnic group, but further investigation is needed.

Interleukin-6 −174G/C Polymorphism and Ischemic Stroke

Background and Purpose— Interleukin-6 (IL-6) is associated with atherosclerotic disease and is also a key mediator in the inflammatory response to cerebral ischemia. Although the IL-6 −174G/C promoter polymorphism has been associated with carotid artery atherosclerosis and coronary heart disease, its relation to ischemic stroke is unclear. This review summarizes the current literature and discusses methodological considerations for future studies.

Methods— Electronic searches were conducted in the PubMed MEDLINE, Scopus, and ISI Web of Science databases. Two investigators independently reviewed all abstracts to identify studies examining the association between the IL-6 −174G/C polymorphism and ischemic cerebrovascular events.

Results— Twelve relevant publications were identified. Three reported on a subset of patients from a later publication, leaving 9 independent studies. Two studies found an association between ischemic stroke and the G allele or GG genotype, whereas 4 found an association with the C allele or CC genotype. One study found the CC genotype to be significantly less frequent in retinal artery occlusion patients. Two studies found no association between the −174G/C polymorphism and stroke.

Conclusions— Studies investigating stroke and the −174G/C polymorphism report conflicting results, which may reflect the complex physiology of IL-6 and true differences between stroke subtypes and populations. However, interpretation of published results is hindered by methodological limitations, and greater rigor and consistency in future studies will help unravel the relationship between the −174G/C polymorphism and stroke.

Neuroprotection during cardiac surgery

Cerebral injury following cardiac surgery continues to be a significant source of morbidity and mortality after cardiac surgery. A spectrum of injuries ranging from subtle neurocognitive dysfunction to fatal strokes are caused by a complex series of multifactorial mechanisms. Protecting the brain from these injuries has focused on intervening on each of the various etiologic factors. Although numerous studies have focused on a pharmacologic solution, more success has been found with nonpharmacologic strategies, including optimal temperature management and reducing emboli generation.

Genetics of postoperative complications following thoracic surgery

The field of complex trait-gene interaction research has expanded exponentially in recent years, and new insights into the ways patients respond to surgical stimuli have arisen from this body of work. From a physiological systems perspective, thoracic surgical procedures (thoracotomy in particular) represent a massive input stimulus, and it is, therefore, not surprising that approximately 30% of these patients experience an adverse postoperative event. The best risk prediction models have typically explained about 60% to 70% of the risk, leaving a large residual component unaccounted for. It is quite possible that there is a genetic (heritable) component to this residual risk. This article explores some of the concepts underlying gene-disease interactions, the preliminary work that has been done to date in this area, and finally discusses some of the more important methodological issues involved in complex trait association study design.

Genomics and the cardiac surgeon

Until recently, genetics was a course relegated to Saturdays in medical school, and molecular biology was a subject you could only discuss while smoking a pipe. Now, some gene polymorphisms may predict perioperative trouble more precisely than a 10% ejection fraction. Gene chips will soon permit designer therapy and a micro-array "signature" will soon become fundamental to pre-operative risk stratification. It is time for the cardiac surgical community to come aboard.

Applying pharmacogenomics to enhance the use of biomarkers for drug effect and drug safety

Pharmacogenomics is used to improve patient outcome by maximizing the likelihood of desired effects and minimizing the risk of adverse events using an individual's genetic profile. As such, pharmacogenomics can be used to improve current risk-management strategies (improving the risk-benefit balance). Two areas of great promise for pharmacogenomics in this regard are emerging: (i) the pharmacogenomics of modulating disease biomarkers (to provide insight into novel mechanisms of drug response and to identify the patients most likely to respond to a drug in a favorable way); and (ii) using pharmacogenomics to enhance drug safety. Given that novel biomarkers could enable the earlier detection of many diseases and more-widespread therapies for primary prevention, pharmacogenomics provides the opportunity to identify the patients most likely to respond to these therapies, thereby preserving valuable health-care resources. The use of pharmacogenomics in pharmacovigilance could also be useful for risk-stratifying patients and for helping to identify the mechanisms involved in adverse events.

Cardiopulmonary bypass management and neurologic outcomes: an evidence-based appraisal of current practices

Neurologic complications after cardiac surgery are of growing importance for an aging surgical population. In this review, we provide a critical appraisal of the impact of current cardiopulmonary bypass (CPB) management strategies on neurologic complications. Other than the use of 20-40 microm arterial line filters and membrane oxygenators, newer modifications of the basic CPB apparatus or the use of specialized equipment or procedures (including hypothermia and "tight" glucose control) have unproven benefit on neurologic outcomes. Epiaortic ultrasound can be considered for ascending aorta manipulations to avoid atheroma, although available clinical trials assessing this maneuver are limited. Current approaches for managing flow, arterial blood pressure, and pH during CPB are supported by data from clinical investigations, but these studies included few elderly or high-risk patients and predated many other contemporary practices. Although there are promising data on the benefits of some drugs blocking excitatory amino acid signaling pathways and inflammation, there are currently no drugs that can be recommended for neuroprotection during CPB. Together, the reviewed data highlight the deficiencies of the current knowledge base that physicians are dependent on to guide patient care during CPB. Multicenter clinical trials assessing measures to reduce the frequency of neurologic complications are needed to develop evidence-based strategies to avoid increasing patient morbidity and mortality.

Long-term Outcome After Anesthesia and Surgery: Remarks on the Biology of a Newly Emerging Principle in Perioperative Care

There is a strong possibility that the risk from anesthesia and surgery carries over from the immediate perioperative period to more remote time points. This extended risk seems to influence the progression, severity, and complication rate of certain chronic illnesses, such as vascular heart disease and some of the malignancies, although other disease processes might be affected as well. With the recognition that the perioperative process could be responsible for later adverse events comes the need to reassess existing patient safety models, because some of the risk could be preventable. To confront these challenges, it is necessary to understand the underlying biology of this association, and immunology should be particularly helpful in this pursuit. It will be of special importance to integrate our knowledge of the host immune response to anesthesia and surgery with the recent revelations on the role of immunity in the progression of many of the chronic diseases. Additionally, we need to examine how genetic diversity or acquired defects alter the immune response to tissue injury and infection so that we can improve risk stratification and preemptive therapies. In the meantime, we must strive to improve short- and long-term outcomes by expanding our efforts to reduce disease activity preoperatively, to control the surgical stress response and infection rate, and to use tissue-preserving surgical techniques. Long-term patient safety after anesthesia and surgery is not a specialty-by-specialty endeavor; it requires a highly collaborative, institutional, and national effort to foster innovative research and health care process improvements.

Prospective health care: the second transformation of medicine

Emerging scientific technologies provide rich sources of predictive biomarkers, which will enable the development of tools to quantify risk and anticipate disease, so health care can become rational, preventive and personalized.

Emerging scientific technologies provide rich sources of predictive biomarkers, which could transform health care. Identification of causal biomarkers will enable the development of tools to quantify risk and anticipate disease. Accurate health risk analysis is rapidly becoming feasible, so health care can become rational, preventive and personalized.

New Paradigms in Cardiovascular Medicine

Considerable progress has been made in understanding the pathophysiology of perioperative stress responses and their impact on the cardiovascular system; however, researchers are just beginning to unravel genetic and molecular determinants that predispose to increased risk for postoperative cardiovascular adverse events. A new field, coined perioperative genomics, aims to apply functional genomic approaches to uncover the biological reasons why similar patients can have dramatically different clinical outcomes after surgery. For the perioperative physician, such findings may soon translate into prospective risk assessment incorporating genomic profiling of markers important in inflammatory, thrombotic, vascular, and neurologic responses to perioperative stress, with implications ranging from individualized additional pre-operative testing and physiological optimization, to perioperative decision-making, choice of monitoring strategies, and critical care resource utilization. We review current knowledge regarding genomic technologies in perioperative cardiovascular disease characterization and outcome prediction, as well as discuss future trends/challenges for translating integrated "omic" information into daily clinical management of the surgical patient.