Neurological complications of cardiac surgery

National Trends, Risk Factors, and Outcomes of Acute In-Hospital Stroke Following Lung Transplantation in the United States: Analysis of the United Network for Organ Sharing Registry

BACKGROUND

Lung transplantation (LTx) is the definitive treatment for end-stage lung failure. However, there have been no large, long-term studies on the impact of acute in-hospital stroke in this population.

RESEARCH QUESTION

What are the trends, risk factors, and outcomes of acute stroke in patients undergoing LTx in the United States?

STUDY DESIGN AND METHODS

We identified adult first-time isolated LTx recipients from the United Network for Organ Sharing database, which comprehensively captures every transplant in the United States, between May 2005 and December 2020. Stroke was defined as occurring at any time after LTx but prior to discharge. Multivariable logistic regression with stepwise feature elimination was used to identify risk factors for stroke. Freedom from death in patients with a stroke vs those without a stroke was evaluated with Kaplan-Meier analysis. Cox proportional hazards analysis was used to identify predictors of death at 24 months.

RESULTS

Of 28,564 patients (median age, 60 years; 60% male), 653 (2.3%) experienced an acute in-hospital stroke after LTx. Median follow-up was 1.2 (stroke) and 3.0 (non-stroke) years. Annual incidence of stroke increased (1.5% in 2005 to 2.4% in 2020; P for trend = .007), as did lung allocation score and utilization of post-LTx extracorporeal membrane oxygenation (P = .01 and P < .001, respectively). Compared with those without stroke, patients with stroke had lower survival at 1 month (84% vs 98%), 12 months (61% vs 88%), and 24 months (52% vs 80%) (log-rank test, P < .001 for all). In Cox analysis, acute stroke conferred a high hazard of mortality (hazard ratio, 3.01; 95% CI, 2.67-3.41). Post-LTx extracorporeal membrane oxygenation was the strongest risk factor for stroke (adjusted OR, 2.98; 95% CI, 2.19-4.06).

INTERPRETATION

Acute in-hospital stroke post-LTx has been increasing over time and is associated with markedly worse short- and long-term survival. As increasingly sicker patients undergo LTx as well as experience stroke, further research on stroke characteristics, prevention, and management strategies is warranted.

Early Postoperative Neurologic Events Are Associated With Worse Outcome and Fatal Midterm Survival After Adult Heart Transplantation

Background Neurologic events during primary stay in heart transplant (HTx) recipients may be associated with reduced outcome and survival, which we aim to explore with the current study. Methods and Results We screened and included all patients undergoing HTx in our center between September 2010 and December 2022 (n=268) and checked for the occurrence of neurologic events within their index stay. Neurologic events were defined as ischemic stroke, hemorrhage, hypoxic ischemic injury, or acute symptomatic neurologic dysfunction without central nervous system injury. The cohort was then divided into recipients with (n=33) and without (n=235) neurologic events after HTx. Using a multivariable Cox regression model, the association of neurologic events after HTx and survival was assessed. Recipients with neurologic events displayed a longer intensive care unit stay (30 versus 16 days; P=0.009), longer mechanical ventilation (192 versus 48 hours; P<0.001), and higher need for blood transfusion, and need for hemodialysis after HTx was substantially higher (81% versus 55%; P=0.01). Resternotomy (36% versus 26%; P=0.05) and mechanical life support (extracorporeal life support) after HTx (46% versus 24%; P=0.02) were also significantly higher in patients with neurologic events. Covariable-adjusted multivariable Cox regression analysis revealed a significant independent association of neurologic events and increased 30-day (hazard ratio [HR], 2.5 [95% CI, 1.0-6.0]; P=0.049), 1-year (HR, 2.2 [95% CI, 1.1-4.3]; P=0.019), and overall (HR, 2.5 [95% CI, 1.5-4.2]; P<0.001) mortality after HTx and reduced Kaplan-Meier survival up to 5 years after HTx (P<0.001). Conclusions Neurologic events after HTx were strongly and independently associated with worse postoperative outcome and reduced survival up to 5 years after HTx.

The role of peripheral inflammatory insults in Alzheimer's disease: a review and research roadmap

Peripheral inflammation, defined as inflammation that occurs outside the central nervous system, is an age-related phenomenon that has been identified as a risk factor for Alzheimer's disease. While the role of chronic peripheral inflammation has been well characterized in the context of dementia and other age-related conditions, less is known about the neurologic contribution of acute inflammatory insults that take place outside the central nervous system. Herein, we define acute inflammatory insults as an immune challenge in the form of pathogen exposure (e.g., viral infection) or tissue damage (e.g., surgery) that causes a large, yet time-limited, inflammatory response. We provide an overview of the clinical and translational research that has examined the connection between acute inflammatory insults and Alzheimer's disease, focusing on three categories of peripheral inflammatory insults that have received considerable attention in recent years: acute infection, critical illness, and surgery. Additionally, we review immune and neurobiological mechanisms which facilitate the neural response to acute inflammation and discuss the potential role of the blood-brain barrier and other components of the neuro-immune axis in Alzheimer's disease. After highlighting the knowledge gaps in this area of research, we propose a roadmap to address methodological challenges, suboptimal study design, and paucity of transdisciplinary research efforts that have thus far limited our understanding of how pathogen- and damage-mediated inflammatory insults may contribute to Alzheimer's disease. Finally, we discuss how therapeutic approaches designed to promote the resolution of inflammation may be used following acute inflammatory insults to preserve brain health and limit progression of neurodegenerative pathology.

Arrhythmic and thromboembolic outcomes in adults with coarctation of the aorta

BACKGROUND

Adults with congenital heart disease (ACHD) experience a high prevalence of atrial arrhythmia (AA) and thromboembolic cerebrovascular complications. However, data on AA and associated long-term outcomes are limited in ACHD patients with coarctation of the aorta (CoA).

OBJECTIVES

This study aimed to characterize the prevalence and risk factors for AA and thromboembolic complications in adults with CoA.

METHODS

We conducted a retrospective cohort study in a tertiary ACHD care center and included consecutive CoA patients older than 18 years old with more than one year of follow-up.

RESULTS

Two hundred seventy patients with CoA were followed for 7.2 ± 3.95 years. The mean age was 35.3 ± 11.1 and 55.2% were male. Patients had a mean of 2.1 ± 1.8 cardiovascular surgical or transcatheter procedures. Thirty-five patients (13%) had AA. Ten subjects (3.8%) had a thromboembolic cerebrovascular event, of which four (1.4%) had AA. In univariate analysis, age (p = 0.005) and total intracardiac interventions (p = 0.007) were associated with the presence of AA. Age (p = 0.021), history of heart failure (p = 0.022), and dyslipidemia (p = 0.019) were associated with thromboembolism. In multivariate analysis, age (p < 0.001) and intracardiac interventions (p = 0.007) were associated with AA.

CONCLUSIONS

The rate of AA is higher in adults with CoA than in the general population but lower than in other ACHD. Increasing age and intracardiac interventions were associated with AA. The rate of thromboembolic events was low. Some traditional risk factors for stroke may apply. Larger studies are needed to validate predictors for stroke in this population.

The effect of preoperative statins on postoperative mortality, renal, and neurological complications in patients undergoing cardiac surgeries: a retrospective cohort study

BACKGROUND

Cardiac surgery is performed worldwide to treat severe cases of cardiovascular diseases. Statins have shown controversial effects on complications after cardiac surgeries. We aimed to investigate the effect of preoperative statin therapy on the frequency of postoperative mortality, renal, and neurological complications.

METHODS

In a retrospective cohort study, the database of patients operated on in two hospitals in southern Iran during 2008-2019 was used to compare preoperative statin use with no use on the composite outcome of mortality, renal, and neurological complications as well as on each component of the composite, separately. Effects of low dose (<40 mg simvastatin equivalence) vs. high dose (≥40 mg) statins were also evaluated. Confounders that could affect the outcomes were considered in the logistic regression model, and multiple imputation techniques were used to categorize patients with unknown statin dose use as either high or low-dose users.

RESULTS

Of total 7329 patients, 17.6% of statin users and 17% of non-statin users developed the composite outcome (P=0.51). Statin use had no statistically significant association with the composite outcome (aRR 1.01 [95% CI: 0.88-1.16]). There was no significant association with mortality [aRR: 0.75 (95% CI: 0.34-1.69)], neurological [aRR: 1.25 (95% CI: 0.77-2.12)], or renal complications [aRR: 1.03 (95% CI 0.90-1.19)] after surgery. Neither low nor high doses had any statistically significant effect on the composite or any of its components.

CONCLUSIONS

In this large study, preoperative statin use, either high dose or low dose, did not affect short-term postoperative mortality, neurological, or renal complications.

Correlation and agreement of regional cerebral oxygen saturation measured from sensor sites at frontal and temporal areas in adult patients undergoing cardiovascular anesthesia

Background

The function and viability of the brain depend on adequate oxygen supply. A decrease in cerebral blood supply causing cerebral desaturation may lead to many neurological complications. Direct measurement of regional cerebral oxygen saturation (rScO₂) assists in early detection and management. Near-infrared spectroscopy (NIRS) has been introduced for measuring rScO₂. A pair of sensors are attached to the right and left forehead. However, there are some situations where the forehead of the patient is not accessible for sensor attachment (e.g., neurosurgery involving the frontal area; a bispectral index (BIS) sensor already attached, or a wound to the forehead); therefore, alternate sites for sensor attachment are required. The temporal area was proposed as an alternate site. The objective of this study was to assess the correlation and agreement of rScO₂ measured at the forehead vs. the temporal area.

Methods

Adult patients undergoing cardiothoracic or vascular surgery were monitored for rScO₂ using two pairs of ForeSight sensors. The first pair (A1 and A2) were attached to the right and left forehead, while the second pair (B1 and B2) were attached to the right and left temporal area. The rScO₂ values measured from A1 vs. B1 and A2 vs. B2 were assessed for correlation and agreement using the Bland-Altman analysis.

Results

Data from 19 patients with 14,364 sets of data were analyzed. The data from A1 vs. B1 and A2 vs. B2 showed moderate positive correlation (r = 0.627; P < 0.0001 and r = 0.548; P < 0.0001). The biases of A1 vs. B1 and A2 vs. B2 were -2.3% (95% CI [-2.5 to -2.2]; P < 0.0001) and 0.7% (95% CI [0.6-0.8]; P < 0.0001). The lower and upper limits of agreement of A1 vs. B1 were -17.5% (95% CI [-17.7 to -17.3]) and 12.8% (95% CI [12.6-13.0]). The lower and upper limits of agreement of A2 vs. B2 were -14.6% (95% CI [-14.8 to -14.4]) and 16.0% (95% [CI 15.8-16.3]).

Conclusions

The rScO₂ values measured from sensors at the frontal and temporal areas show a moderate correlation with sufficiently good agreement. The temporal area may be an alternative to the frontal area for cerebral oximetry monitoring.

Scoring of brain magnetic resonance imaging and neurodevelopmental outcomes in infants with congenital heart disease

BACKGROUND

Advances in surgical techniques to tackle critical congenital heart diseases (CHD) have enhanced the survival rates and life expectancy of children born with heart disease. Studies to better acknowledge their neurodevelopmental trajectory have paramount implications.

OBJECTIVE

The aim of this study is to examine the nature of brain MRI findings in infants born with critical congenital heart diseases needing intervention in the first 6 months of life, with the help of an MRI scoring system and correlation with long term neurodevelopmental outcomes.

METHODS

Brain MRI scans of eligible infants were extracted from database, reexamined to categorize, and score them into three main functional areas: cognitive/grey matter, motor/white matter, and visual. The scoring system also included stage of myelination and presence of punctate hemorrhages. The correlation of individual and total MRI scores with neurodevelopmental assessment using Bayley Scales for Infant and Toddler Development- version 3 (BSID III) were examined via logistic regression models while controlling for confounding variables.

RESULT

Median (IQR) MRI score was 6 (4-7) with grey matter score of 2 (1-4). Initial BSID III scores were 80 ± 15, 80 ± 18, and 81 ± 19 for cognitive, motor and language components, respectively. The MRI cognitive score had direct correlation with respiratory index prior to surgery (cc = 0.47, p = 0.03) and cross-clamping time (cc = 0.65, p = 0.001). It displayed a significant inverse correlation with language scores for BSID III at 9 months (R = -0.42, p = 0.04) which lost significance in subsequent visits.

CONCLUSION

This pilot study proved the feasibility of correlating structural brain abnormalities in MRI with later brain developmental deficits in infants with CHD. We envision establishing a standardized MRI scoring system to be performed on a large multi-center cohort that would help better predict and measure brain injury in infants with CHDs.

Neurocognitive, Quality of Life, and Behavioral Outcomes for Patients With Covert Stroke After Cardiac Surgery: Exploratory Analysis of Data From a Prospectively Randomized Trial

BACKGROUND

Asymptomatic brain ischemic injury detected with diffusion-weighted magnetic resonance imaging (DWI) is reported in more than one-half of patients after cardiac surgery. There are conflicting findings on whether DWI-detected covert stroke is associated with neurocognitive dysfunction after surgery, and it is unclear whether such ischemic injury affects quality of life or behavioral outcomes. The purpose of this study was to perform exploratory analysis on whether covert stroke after cardiac surgery is associated with delayed neurocognitive recovery 1 month after surgery, impaired quality of life, anxiety, or depression.

METHODS

Analysis of data collected in a prospectively randomized study in patients undergoing cardiac surgery testing whether basing mean arterial pressure (MAP) targets during cardiopulmonary bypass to be above the lower limit of cerebral autoregulation versus usual practices reduces the frequency of adverse neurological outcomes. A neuropsychological testing battery was administered before surgery and then 1 month later. Patients underwent brain magnetic resonance imaging (MRI) between postoperative days 3 and 5. The primary outcome was DWI-detected ischemic lesion; the primary end point was change from baseline in domain-specific neurocognitive Z scores 1 month after surgery. Secondary outcomes included a composite indicator of delayed neurocognitive recovery, quality of life measures, state and trait anxiety, and Beck Depression Inventory scores.

RESULTS

Of the 164 patients with postoperative MRI data, clinical stroke occurred in 10 patients. Of the remaining 154 patients, 85 (55.2%) had a covert stroke. There were no statistically significant differences for patients with or without covert stroke in the change from baseline in Z scores in any of the cognitive domains tested adjusted for sex, baseline cognitive score, and randomization treatment arm. The frequency of delayed neurocognitive recovery (no covert stroke, 15.1%; covert stroke, 17.6%; P = .392), self-reported quality of life measurements, anxiety rating, or depression scores were not different between those with or without DWI ischemic injury.

CONCLUSIONS

More than one-half of patients undergoing cardiac surgery demonstrated covert stroke. In this exploratory analysis, covert stroke was not found to be significantly associated with neurocognitive dysfunction 1 month after surgery; evidence of impaired quality of life, anxiety, or depression, albeit a type II error, cannot be excluded.

Minimally invasive versus conventional surgery of the ascending aorta and root: a systematic review and meta-analysis

Limited uptake of minimally invasive surgery (MIS) of the aorta hinders assessment of its efficacy compared to median sternotomy (MS). The objective of this systematic review is to compare operative and perioperative outcomes for MIS versus MS. Online databases Medline, EMBASE, Cochrane Library and Web of Science were searched from inception until July 2018. Both randomized and observational studies of patients undergoing aortic root, ascending aorta or aortic arch surgery by MIS versus MS were eligible for inclusion. Primary outcomes were 30-day mortality, reoperation for bleeding, perioperative renal impairment and neurological events. Intraoperative and postoperative timing measures were also evaluated. Thirteen observational studies were included comparing 1101 MIS and 1405 MS patients. The overall quality of evidence was very low for all outcomes. Mortality and the incidence of stroke were similar between the 2 cohorts. Meta-analysis demonstrated increased length of cardiopulmonary bypass (CPB) time for patients undergoing MS [standardized mean difference 0.36, 95% confidence interval (CI) 0.15-0.58; P = 0.001]. Patients receiving MS spent more time in hospital (standardized mean difference 0.30, 95% CI 0.17-0.43; P < 0.001) and intensive care (standardized mean difference 0.17, 95% CI 0.06-0.27; P < 0.001). Reoperation for bleeding (risk ratio 1.51, 95% CI 1.06-2.17; P = 0.024) and renal impairment (risk ratio 1.97, 95% CI 1.12-3.46; P = 0.019) were also greater for MS patients. There was substantial heterogeneity in meta-analyses for CPB and aortic cross-clamp timing outcomes. MIS may be associated with improved early clinical outcomes compared to MS, but the quality of the evidence is very low. Randomized evidence is needed to confirm these findings.

The Anaortic Technique with Bilateral Internal Thoracic Artery Grafting - Filling the Gap in Coronary Artery Bypass Surgery

Coronary artery bypass grafting (CABG) has consolidated its role as the most effective procedure for treating patients with advanced atherosclerotic coronary artery disease, reducing the long-term risk of myocardial infarction and death compared to other therapies and relieving angina. Despite the recognized benefits afforded by surgical myocardial revascularization, a subset of higher-risk patients bears a more elevated risk of perioperative stroke. Stroke remains the drawback of conventional CABG and has been strongly linked to aortic manipulation (cannulation, cross-clamping, and side-biting clamping for the performance of proximal aortic anastomoses) and the use of cardiopulmonary bypass. Adoption of off-pump CABG (OPCAB) is demonstrated to lower the risk of perioperative stroke, as well as reducing the risk of short-term mortality, renal failure, atrial fibrillation, bleeding, and length of intensive care unit stay. However, increased risk persists owing to the need for the tangential ascending aorta clamping to construct the proximal anastomosis. The concept of anaortic (aorta no-touch) OPCAB (anOPCAB) stems from eliminating ascending aorta manipulation, virtually abolishing the risk of embolism caused by aortic wall debris into the brain circulation. The adoption of anOPCAB has been shown to further decrease the risk of postoperative stroke, especially in higher-risk patients, entailing a step forward and a refinement of outcomes provided by the primeval OPCAB technique. Therefore, anOPCAB has been the recommended technique in patients with cerebrovascular disease and/or calcification or atheromatous plaque in the ascending aorta and should be preferred in patients with high-risk factors for neurological damage and stroke.

Inflammatory profile in a canine model of hypothermic circulatory arrest

BACKGROUND

Hypothermic circulatory arrest (HCA) is a technique used for complex repair of the aorta, but it can be associated with neurologic morbidity. To better understand the molecular changes that underlie ischemic brain injury, we assessed gene expression and cytokine/chemokine polypeptide concentration in brain tissue and cerebrospinal fluid (CSF) of canines that underwent two hours of HCA.

MATERIALS AND METHODS

Adult male canines were cannulated peripherally for cardiopulmonary bypass, cooled to 18°C, and arrested for two hours. Animals were euthanized two, eight, or 24 hours post-HCA (n = 8 per group), and their brains were compared to brains from eight normal canines, using gene expression microarray analysis, cytokine assay, and histopathology.

RESULTS

Two to eight hours after HCA, pro-inflammatory cytokine mRNAs increased markedly, and gene expression was enriched within signaling pathways related to neuroinflammation or ischemic injury. Concentrations of pro-inflammatory cytokine polypeptides IL-6, IL-8, IL-1β, and CCL2 were very low in normal canine brain, whereas anti-inflammatory IL-10 and TGF-β1 were expressed at moderate levels. Pro-inflammatory cytokine concentrations rose robustly in cerebral tissue and CSF after HCA. IL-6 and IL-8 peaked at eight hours and declined at 24 hours, while IL-1β and CCL2 remained elevated. Concentrations of anti-inflammatory IL-10 and TGF-β1 were maintained after HCA, with a significant increase in TGF-β1 at 24 hours.

CONCLUSIONS

These cytokines represent potential diagnostic markers for ischemic neurologic injury that could be used to assess neurologic injury in patients undergoing HCA. The cellular mechanisms underlying this pro-inflammatory, ischemic-induced injury represent potential targets for neuroprotection in the future.

Esmolol in Cardiac Surgery: A Randomized Controlled Trial

OBJECTIVE

To assess whether the administration of the ultra-short-acting β-blocker esmolol in cardiac surgery could have a cardioprotective effect that translates into improved postoperative outcomes.

DESIGN

Single-center, double-blinded, parallel-group randomized controlled trial.

SETTING

A tertiary care referral center.

PARTICIPANTS

Patients undergoing elective cardiac surgery with preoperative evidence of left ventricular end-diastolic diameter >60 mm and/or left ventricular ejection fraction <50%.

INTERVENTIONS

Patients were assigned randomly to receive either esmolol (1 mg/kg as a bolus before aortic cross-clamping and 2 mg/kg mixed in the cardioplegia solution) or placebo in a 1:1 allocation ratio.

MEASUREMENTS AND MAIN RESULTS

The primary composite endpoint of prolonged intensive care unit stay and/or in-hospital mortality occurred in 36/98 patients (36%) in the placebo group versus 27/102 patients (27%) in the esmolol group (p = 0.13). In the esmolol group, a reduction in the maximum inotropic score during the first 24 postoperative hours was observed (10 [interquartile range 5-15] v 7 [interquartile range 5-10.5]; p = 0.04), as well as a trend toward a reduction in postoperative low-cardiac-output syndrome (13/98 v 6/102; p = 0.08) and the rate of hospital admission at one year (26/95 v 16/96; p = 0.08). A trend toward an increase in the number of patients with ejection fraction ≥60% at hospital discharge also was observed (4/95 v 11/92; p = 0.06).

CONCLUSIONS

In the present trial, esmolol as a cardioplegia adjuvant enhanced postoperative cardiac performance but did not reduce a composite endpoint of prolonged intensive care unit stay and/or mortality.

Cardiopulmonary bypass duration is an independent predictor of adverse outcome in surgical repair for acute type A aortic dissection

OBJECTIVE

This study aimed to investigate the relationship between the duration of cardiopulmonary bypass (CPB) and stroke or early death in patients with acute type A aortic dissection (ATAAD) receiving total aortic arch replacement with the frozen elephant trunk procedure (TAR with FET).

METHODS

A retrospective cohort study of 258 consecutive patients was conducted at Beijing Anzhen Hospital from December 2014 to June 2016. Patients who received TAR with FET for ATAAD were included. An adverse outcome (AO) was defined as 30-day mortality or stroke. Additionally, an AO was compared using propensity score matching.

RESULTS

The incidence of AO was 13.6% (n = 35). The 30-day mortality rate was 10.8% and the stroke rate was 9.3%. Patients were aged 47.9 ± 10.6 years old. The duration of CPB was an independent predictor of occurrence of AO after adjusting for confounding factors by multivariable logistic regression analysis (odds ratio 1.101, 95% confidence interval 1.003-1.208). In matched analysis, CPB duration remained a risk factor of AO.

CONCLUSIONS

The duration of CPB is an independent predictor of AO in surgical repair for ATAAD. The underlying mechanisms of this association are important for developing improved prevention strategies.

The central nervous system and heart failure

The view that chronic heart failure was exclusively a disease of the heart dominated the cardiovascular literature until relatively recently. However, over the last 40 years it has increasingly come to be seen as a multisystem disease. Aside from changes in the sympathetic and parasympathetic nervous systems and the renin-angiotensin-aldosterone system, adaptations to the lungs, muscles and gastrointestinal tract have been clearly documented. It is clear that the brain and CNS are also affected in patients with heart failure, although this is often under recognized. The purpose of this review is to summarize the changes in the structure and biochemical function of the CNS in patients with chronic heart failure and to discuss their potential importance.

Total arterial off-pump coronary revascularization: The Holy Grail?

PURPOSE OF REVIEW

Coronary artery bypass grafting (CABG) remains the standard of care for patients with complex multivessel coronary artery disease. However, conventional CABG utilizing left internal mammary artery and supplemental vein grafts performed on cardiopulmonary bypass is marred by questionable long-term patency of vein grafts and risk of neurological injury. Total arterial off-pump CABG is a strategy associated with avoidance of neurological injury and vein graft failure. The aim of this review is to summarize recent evidence on safety and effectiveness of total arterial off-pump CABG.

RECENT FINDINGS

Two key studies have been published recently. One describes a dual inflow technique that achieves anaortic, off-pump complete revascularization using arterial grafts only. The other is single centre study that reports 10-year survival of 89.33%, rate of freedom from repeat revascularization of 91.33% and early stroke rate of 0.9% after total arterial off-pump CABG.

SUMMARY

Total arterial off-pump CABG with its advantages of improved survival, enhanced freedom from repeat revascularization and low stroke rate can be regarded as the Holy Grail of myocardial revascularization. However, the results of a large, multicenter, prospective trial are required to substantiate this status.

Ghrelin Pre-treatment Attenuates Local Oxidative Stress and End Organ Damage During Cardiopulmonary Bypass in Anesthetized Rats

Cardiopulmonary bypass (CPB) induced systemic inflammation significantly contributes to the development of postoperative complications, including respiratory failure, myocardial, renal and neurological dysfunction and ultimately can lead to failure of multiple organs. Ghrelin is a small endogenous peptide with wide ranging physiological effects on metabolism and cardiovascular regulation. Herein, we investigated the protective effects of ghrelin against CPB-induced inflammatory reactions, oxidative stress and acute organ damage. Adult male Sprague Dawley rats randomly received vehicle (n = 5) or a bolus of ghrelin (150 μg/kg, sc, n = 5) and were subjected to CPB for 4 h (protocol 1). In separate rats, ghrelin pre-treatment (protocol 2) was compared to two doses of ghrelin (protocol 3) before and after CPB for 2 h followed by recovery for 2 h. Blood samples were taken prior to CPB, and following CPB at 2 h and 4 h. Organ nitrosative stress (3-nitrotyrosine) was measured by Western blotting. CPB induced leukocytosis with increased plasma levels of tumor necrosis factor-α and interleukin-6 indicating a potent inflammatory response. Ghrelin treatment significantly reduced plasma organ damage markers (lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase) and protein levels of 3-nitrotyrosine, particularly in the brain, lung and liver, but only partly suppressed inflammatory cell invasion and did not reduce proinflammatory cytokine production. Ghrelin partially attenuated the CPB-induced elevation of epinephrine and to a lesser extent norepinephrine when compared to the CPB saline group, while dopamine levels were completely suppressed. Ghrelin treatment sustained plasma levels of reduced glutathione and decreased glutathione disulphide when compared to CPB saline rats. These results suggest that even though ghrelin only partially inhibited the large CPB induced increase in catecholamines and organ macrophage infiltration, it reduced oxidative stress and subsequent cell damage. Pre-treatment with ghrelin might provide an effective adjunct therapy for preventing widespread CPB induced organ injury.

Cerebral perfusion monitoring in adult patients following cardiac surgery: an observational study

BACKGROUND

Following adult cardiac surgery, often difficult to detect fluctuations in regional cerebral perfusion can contribute to strokes. Optimal cerebral perfusion remains elusive and traditional monitoring strategies do not consistently identify acute changes. Non-invasive cerebral oximetry may detect perfusion variations.

OBJECTIVE

To assess the feasibility of postoperative non-invasive cerebral oximetry monitoring.

METHODS

Non-invasive cerebral oximetry was performed on adult aortic valve surgery patients in a cardiac surgical intensive care unit. Monitoring feasibility was assessed using an investigator-developed, data extraction tool.

RESULTS

Non-invasive cerebral oximetry was completed in 94% of patients. Sixty percent had values that fell below pre-set ischemic threshold. Nurses reported monitoring was feasible, and they perceived identifying deleterious cerebral perfusion trends may improve patient care.

CONCLUSIONS

Prevalence of low cerebral oximetry values underscores the importance of increasing sensitivity of monitoring tools. Further evaluation is required to assess this modality and the role of nurses in optimizing neurocognitive outcomes. Impact statement: Cerebral oximetry monitoring may help identify adult patients at risk of neurological complications after cardiac surgery, and as a consequence initiate definitive therapeutic strategies.

Imaging Techniques for Diagnosis of Thoracic Aortic Atherosclerosis

The most severe complications after cardiac surgery are neurological complications including stroke which is often caused by emboli merging from atherosclerosis in the ascending aorta to the brain. Information about the thoracic aorta is crucial in reducing the embolization risk for both surgical open and closed chest procedures such as transaortic heart valve implantation. Several techniques are available to screen the ascending aorta, for example, transesophageal echocardiography (TEE), epiaortic ultrasound, TEE A-view method, manual palpation, computed tomography, and magnetic resonance imaging. This paper provides a description of the advantages and disadvantages of these imaging techniques.

Profiling of cell stress protein expression in cardiac tissue of cardiosurgical patients undergoing remote ischemic preconditioning: implications for thioredoxin in cardioprotection

Background

Transient episodes of ischemia in a remote organ (remote ischemic preconditioning, RIPC) can attenuate myocardial ischemia/reperfusion injury but the underlying mechanisms of RIPC in the target organ are still poorly understood. Recent animal studies suggested that the small redox protein thioredoxin may be a potential candidate for preconditioning-induced organprotection. Here we employed a human proteome profiler array to investigate the RIPC regulated expression of cell stress proteins and particularly of thioredoxin in heart tissue of cardiosurgical patients with cardiopulmonary bypass (CPB).

Methods

RIPC was induced by four 5 minute cycles of transient upper limb ischemia/reperfusion using a blood pressure cuff. Right atrial tissue was obtained from patients receiving RIPC (N = 19) and control patients (N = 19) before and after CPB. Cell stress proteome profiler arrays as well as Westernblotting and ELISA experiments for thioredoxin (Thio-1) were performed employing the respective tissue samples.

Results

Protein arrays revealed an up-regulation of 26.9% (7/26; CA IX, Cyt C, HSP-60, HSP-70, pJNK, SOD2, Thio-1) of cell stress associated proteins in RIPC tissue obtained before CPB, while 3.8% (1/26; SIRT2) of the proteins were down-regulated. Array results for thioredoxin were verified by semi-quantitative Westernblotting studies which showed a significant up-regulation of thioredoxin protein levels in cardiac tissue samples of RIPC patients taken before CPB (RIPC: 5.36 ± 0.85 a.u.; control: 3.23 ± 0.39 a.u.; P < 0.05). Quantification of thioredoxin levels in tissue of RIPC and control patients by ELISA experiments further confirmed the Westernblotting results (RIPC: 0.30 ± 0.02 ng/mg protein; control: 0.24 ± 0.02 ng/mg protein; P < 0.05).

Conclusion

We provide evidence for thioredoxin as a RIPC-induced factor in heart tissue of cardiosurgical patients and identified several cell stress associated proteins that are regulated by RIPC and may play a role in RIPC-mediated cardioprotection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0403-6) contains supplementary material, which is available to authorized users.

Activities of cardiac tissue matrix metalloproteinases 2 and 9 are reduced by remote ischemic preconditioning in cardiosurgical patients with cardiopulmonary bypass

Background

Transient episodes of ischemia in a remote organ or tissue (remote ischemic preconditioning, RIPC) can attenuate myocardial injury. Myocardial damage is associated with tissue remodeling and the matrix metalloproteinases 2 and 9 (MMP-2/9) are crucially involved in these events. Here we investigated the effects of RIPC on the activities of heart tissue MMP-2/9 and their correlation with serum concentrations of cardiac troponin T (cTnT), a marker for myocardial damage.

Methods

In cardiosurgical patients with cardiopulmonary bypass (CPB) RIPC was induced by four 5 minute cycles of upper limb ischemia/reperfusion. Cardiac tissue was obtained before as well as after CPB and serum cTnT concentrations were measured. Tissue derived from control patients (N = 17) with high cTnT concentrations (≥0.32 ng/ml) and RIPC patients (N = 18) with low cTnT (≤0.32 ng/ml) was subjected to gelatin zymography to quantify MMP-2/9 activities.

Results

In cardiac biopsies obtained before CPB, activities of MMP-2/9 were attenuated in the RIPC group (MMP-2: Control, 1.13 ± 0.13 a.u.; RIPC, 0.71 ± 0.12 a.u.; P < 0.05. MMP-9: Control, 1.50 ± 0.16 a.u.; RIPC, 0.87 ± 0.14 a.u.; P < 0.01), while activities of the pro-MMPs were not altered (P > 0.05). In cardiac biopsies taken after CPB activities of pro- and active MMP-2/9 were not different between the groups (P > 0.05). Spearman’s rank tests showed that MMP-2/9 activities in cardiac tissue obtained before CPB were positively correlated with postoperative cTnT serum levels (MMP-2, P = 0.016; MMP-9, P = 0.015).

Conclusions

Activities of MMP-2/9 in cardiac tissue obtained before CPB are attenuated by RIPC and are positively correlated with serum concentrations of cTnT. MMPs may represent potential targets for RIPC mediated cardioprotection.

Trial registration

ClinicalTrials.gov identifier NCT00877305.

Remote ischemic preconditioning regulates HIF-1α levels, apoptosis and inflammation in heart tissue of cardiosurgical patients: a pilot experimental study

Transient episodes of ischemia in a remote organ (remote ischemic preconditioning, RIPC) bears the potential to attenuate myocardial injury, but the underlying mechanisms are only poorly understood. In the pilot experimental study presented we investigated cellular and molecular effects of RIPC in heart tissue of cardiosurgical patients with cardiopulmonary bypass (CPB) and focussed on apoptotic events, local and systemic inflammation as well as the regulation of the hypoxia induced factor-1α (HIF-1α). RIPC was induced by four 5-min cycles of transient upper limb ischemia/reperfusion using a blood-pressure cuff. Right atrial tissue and serum were obtained from patients receiving RIPC (N = 32) and control patients (N = 29) before and after CPB. RIPC patients showed reduced troponin T serum concentrations in the first 48 h after surgery (P < 0.05 vs. control) indicating cardioprotective effects of RIPC. Samples from RIPC patients that were collected before CPB contained significantly increased amounts of HIF-1α and procaspase-3 (HIF-1α: P < 0.05 vs. control, procaspase-3: P < 0.05 vs. control), whereas activities of caspases 3 and 7 were by trend reduced. Samples from RIPC patients that were taken after CPB showed an increased activity of myeloperoxidase (P < 0.05 vs. control; P < 0.05 vs. RIPC before CPB) as well as elevated tissue concentrations of the interleukin (IL)-1β (P < 0.05 vs. RIPC before CPB). Serum levels of IL-8, IL-1β and TNFα were significantly increased in RIPC patients before CPB (P < 0.05 vs. control before CPB). In summary, RIPC regulates HIF-1α levels, apoptosis and inflammation in the myocardium of cardiosurgical patients and leads to increased concentrations of circulating cytokines.

[Acute neurological complications after pediatric cardiac surgery: still a long way to go]

INTRODUCTION

There has been an increasing concern over the neurological complications associated with congenital heart disease and cardiac surgery.

MATERIAL AND METHODS

We performed a retrospective, case-control, observational review of the postoperative period in the intensive care unit of patients undergoing cardiac surgery over the past 10 years. We selected 2 control patients for each case, matched for surgical complexity.

RESULTS

A total of 900 patients were reviewed. We found 38 neurological complications (4.2%), of which 21 (55.3%) were in the peripheral nervous system and 17 (44.7%) in the central nervous system. The complications involving the central nervous system (1.9% of total) consisted of 8 seizures, 4 cerebrovascular accidents, 4 hypoxic-ischemic encephalopathy events, and 1 reversible neurological deficit. At the time of discharge, 35.3% were symptomatic and 17.6% had died. Patients with neurological complications had a longer bypass time (P=.009), longer aortic cross time (P=.012), longer hospitalization in intensive care (P=.001), longer duration of mechanical ventilation (P=.004) and an increased number of days under inotropic support (P=.001).

CONCLUSIONS

Our incidence of neurological complications after cardiac surgery is similar to that previously described. Clinical seizures are the most common complication. Central nervous system complications are associated with a higher morbidity and hospitalization time. Units caring for patients with congenital heart disease must implement neurological monitoring during and after cardiac surgery to prevent and to detect these complications earlier.

Neurological biomarkers in the perioperative period

The rapid detection and evaluation of patients presenting with perioperative neurological dysfunction is of great clinical relevance. Biomarkers have been defined as biological molecules that can be used as an indicator of new onset or progression of a biological process or effect of treatment. Biomarkers have become increasingly important in this setting to supplement other modalities of diagnosis such as EEG, sensory- or motor-evoked potential, transcranial Doppler, near-infrared spectroscopy, or imaging methods. A number of neuro-proteins have been identified and are currently under investigation for potential to provide insights into injury severity, outcome, and the ability to monitor cellular damage and molecular events that occur during neurological injury. S100B is a protein released by glial cells and is considered a marker of blood-brain barrier dysfunction. Clinical studies in patients undergoing cardiac and non-cardiac surgery indicate that serum levels of S100B are increased intraoperatively and after operation. The neurone-specific enolase has also been extensively investigated as a potential marker of neuronal injury in the context of cardiac and non-cardiac surgery. A third biomarker of interest is the Tau protein, which has been linked to neurodegenerative disorders. Tau appears to be more specific than the previous two biomarkers since it is only found in the central nervous system. The metalloproteinase and ubiquitin C terminal hydroxylase-L1 (UCH-L1) are the most recently researched markers; however, their usefulness is still unclear. This review presents a comprehensive overview of S100B, neuronal-specific enolase, metalloproteinases, and UCH-L1 in the perioperative period.

Contralateral internal carotid artery occlusion impairs early but not 30-day stroke rate following carotid endarterectomy

Neurological complications and mortality within 30 days following carotid endarterectomy (CEA) alone or with concomitant cardiac surgery/cardiopulmonary bypass (CPB) were assessed in patients with or without contralateral occlusion of the internal carotid artery (CO-ICA).Of 335 patients undergoing CEA, 173 underwent concomitant cardiac surgery with CPB. Group A consisted of 260 patients without CO-ICA and group B of 75 patients with CO-ICA. The neurological complications (peripheral nerve damage, transient ischemic attack [TIA], prolonged reversible ischemic neurological deficit [PRIND], and stroke) and the Rankin index within 24 hours and 30 days postoperatively were compared. Strokes within 24 hours were significantly increased (P = .006) in group B (11%) compared with A (3.1%); TIA and PRIND did not differ (P = .33). The overall neurological complications and in particular for peripheral neurological damage, TIA/PRIND, and stroke did not differ within the 30-day-period postsurgery. A significantly higher stroke rate within 24 hours postsurgery occurred in patients with CO-ICA.