Associations between mean arterial pressure during cardiopulmonary bypass and biomarkers of cerebral injury in patients undergoing cardiac surgery: secondary results from a randomized controlled trial

Standard versus High Cardiopulmonary Bypass Flow Rate: A Randomized Controlled Subtrial Comparing Brain Injury Biomarker Release

OBJECTIVES

To compare brain injury biomarker release levels between two different cardiopulmonary bypass (CPB) flow rates in elective cardiac surgery and to explore differences in postoperative delirium between groups and associations between age, sex, CPB time, oxygen levels, and near-infrared spectroscopy, and biomarker levels.

DESIGN

A randomized controlled substudy trial SETTING: Sahlgrenska University Hospital, Sweden PARTICIPANTS: Forty patients undergoing elective cardiac surgery with CPB INTERVENTION: Patients were assigned at random to either a standard (2.4 L/min/m2) or a high (2.9 L/min/m2) CPB flow rate.

MEASUREMENTS AND MAIN RESULTS

Glial fibrillary acidic protein, neurofilament light chain, total-tau, and phosphorylated-tau217 were sampled in plasma before anesthesia induction, after 60 minutes on CPB, and at 30 minutes, 24 hours, and 72 hours post-CPB. Mixed models for repeated measures were used to analyze differences in biomarker levels between groups and to assess relationships, which showed no differences between the 2 flow rate groups. There also was no difference in the occurrence of delirium between the 2 groups. Associations were found between age and increased neurofilament light chain levels. Female sex, oxygen delivery >330 mL/min/m2, and near-infrared spectroscopy level >60% were associated with lower biomarker levels.

CONCLUSIONS

An increased flow rate did not have any significant effects on biomarker levels compared to a standard flow rate. Several associations were identified between treatment characteristics and biomarker levels. No difference in delirium was seen.

Analysis and prevention strategies of risk factors for postoperative stroke complications in cardiac surgery

OBJECTIVE

To analyze the risk factors associated with postoperative stroke complications in cardiac surgery.

METHODS

A retrospective analysis was conducted on the clinical data of 549 patients who underwent cardiac surgery. Among these patients, 501 did not experience a stroke postoperatively (non-stroke group), while 48 developed a postoperative stroke (stroke group). Patients who experienced a stroke postoperatively were divided into two groups based on the type of surgery: those who underwent surgery with cardiopulmonary bypass (18 patients) and those without cardiopulmonary bypass (30 patients). The clinical characteristics of the two groups of patients with postoperative strokes were compared, and the risk factors influencing the occurrence of postoperative stroke complications in cardiac surgery were analyzed.

RESULTS

① Clinical findings: Cardiopulmonary bypass group had lower cortical infarction rates but higher large-area and bilateral infarction rates compared to the non-cardiopulmonary bypass group (p < 0.05). No significant gender, age, or infarction type differences were observed (p > 0.05). ② Univariate analysis: No significant differences were found in gender, smoking, alcohol, lipids, or glucose levels (p > 0.05). However, age, education, hypertension, diabetes, hypotension, and atrial fibrillation showed significant differences (p < 0.05). ③ Multivariate Logistic regression: Age, education, hypertension, diabetes, hypotension, and atrial fibrillation were independent risk factors for postoperative stroke complications (p < 0.05).

CONCLUSION

Cardiopulmonary bypass increases risk of large-area and bilateral strokes; non-bypass surgery associates with cortical strokes. Age, educational level, hypertension, diabetes, postoperative hypotension, and atrial fibrillation are all factors independently associated with the occurrence of postoperative cerebral infarctions in cardiac surgery. Early interventions may reduce postoperative strokes.

A Set of Possible Markers for Monitoring Heart Failure and Cognitive Impairment Associated: A Review of Literature from the Past 5 Years

BACKGROUND

Heart failure is an epidemiologically relevant disease because of the aging population and widespread lifestyles that promote it. In addition to the acute event, it is possible for the disease to become chronic with periodic flare-ups. It is essential to study pathology from a diagnostic and prognostic point of view and to identify parameters for effective monitoring. In addition, heart failure is associated with multiple comorbidities, including cognitive impairment, which is monitored clinically but not through specific biomarkers in these patients. The purpose of this review is to gather the most recent scientific evidence on a few possible biomarkers previously identified for monitoring heart failure and associated cognitive impairment.

METHODS

We surveyed studies inherent to a set of previously identified markers, evaluating English-language articles from the past five years conducted in adult heart failure patient populations. We used the databases PubMed, Web of Sciences, and Cochrane Library for search studies, and we considered articles published in journals with an impact factor greater than five in the publication year.

RESULTS

Among the biomarkers evaluated, a concordant indication for serial measurements for heart failure monitoring emerged only for interleukin-6. For the other markers, there is still little evidence available, which is interesting but sometimes conflicting. Interesting studies have also emerged for biomarkers of cognitive decline assessed in patients with heart failure, confirming the hypotheses of the increasingly studied heart-brain correlation.

CONCLUSION

Certainly, further studies in large populations are needed to identify effective biomarkers for monitoring heart failure and associated cognitive impairment.

Hypotension during transsphenoidal pituitary surgery associated with increase in plasma levels of brain injury markers

BACKGROUND

Patients undergoing pituitary surgery may experience short- and long-term postoperative morbidity. Intraoperative factors such as hypotension might be a contributing factor. Our aim was to investigate the association between intraoperative hypotension and postoperative plasma levels of tau, neurofilament light (NfL), and glial fibrillary acidic protein (GFAP) as markers of perioperative brain injury.

METHODS

Between June 2016 and October 2017, 35 patients from the Gothenburg Pituitary Tumor Study were included. For tau, NfL, and GFAP, concentrations were measured in plasma samples collected before and immediately following surgery, and on postoperative days 1 and 5. The difference between the highest postoperative value and the value before surgery was used for analysis (∆taupeak , ∆NfLpeak , ∆GFAPpeak ). Intraoperative hypotension was defined as the area under the curve of an absolute threshold below 70 mmHg (AUC70) and a relative threshold below 20% (AUC20%) of the baseline mean arterial blood pressure.

RESULTS

Plasma tau and GFAP were highest immediately following surgery and on day 1, while NfL was highest on day 5. There was a positive correlation between AUC20% and both ∆taupeak (r2  = .20, p < .001) and ∆NfLpeak (r2  = .26, p < .001). No association was found between AUC20% and GFAP or between AUC70 and ∆taupeak , ∆NfLpeak or ∆GFAPpeak .

CONCLUSION

Intraoperative relative, but not absolute, hypotension was associated with increased postoperative plasma tau and NfL concentrations. Patients undergoing pituitary surgery may be vulnerable to relative hypotension, but this needs to be validated in future prospective studies.

Postoperative Delirium and Dementia in Patients Undergoing Cardiac Surgery: A Review of Randomized Controlled Trials

Delirium and dementia are considered to be the most significant postoperative neurocognitive complications in patients undergoing cardiac surgery, particularly those aged 60 years and older, which reduces the post-surgery quality of life, prolongs hospitalization, increases costs, and elevated the rates of mortality. Nevertheless, the etiology, risk factors, and predictive biomarkers, have not been well elucidated particularly, in patients with unmanifested underline cognitive impairments. The present study aimed to review the findings on the etiology, factors increasing the risk of incidence, and predictive biomarkers of postoperative delirium and dementia after cardiac surgery, and to describe the suggested pharmacological and non-pharmacological interventions.

Perioperative brain injury marker concentrations in neonatal open-heart surgery: a prospective observational study

Neonates with critical congenital heart defects undergoing open-heart surgery on cardiopulmonary bypass circulation are at risk for white matter brain injury. This article reports on pre- and postoperative plasma concentrations of brain injury markers glial fibrillary acidic protein (GFAP), neurofilament light (NfL) and Tau, and their respective associations with white matter lesions detected on postoperatively performed brain MRI. Forty term newborns with isolated critical congenital heart defects were included in a prospective observational study. Brain injury marker plasma concentrations were determined prior to surgery and at postoperative days 1, 2 and 3. Brain magnetic resonance imaging was performed pre- and postoperatively. Concentrations of brain injury markers were analysed using ultrasensitive single molecule array technology. Absolute pre- and postoperative plasma biomarker concentrations, and postoperative concentrations adjusted for preoperative concentrations were used for subsequent analysis. Plasma concentrations of GFAP, NfL and Tau displayed a well-defined temporal trajectory after neonatal cardiopulmonary bypass circulation. GFAP and Tau reached peak concentrations at postoperative day 2 (median concentrations 170.5 and 67.2 pg/ml, respectively), whereas NfL continued to increase throughout the study period (median concentration at postoperative day 3 191.5 pg/ml). Adjusted Tau at postoperative day 2 was significantly higher in infants presenting with white matter lesions on postoperative MRI compared to infants without white matter injury.

The multifaceted role of neurofilament light chain protein in non-primary neurological diseases

The advancing validation and exploitation of CSF and blood neurofilament light chain protein as a biomarker of neuroaxonal damage has deeply changed the current diagnostic and prognostic approach to neurological diseases. Further, recent studies have provided evidence of potential new applications of this biomarker also in non-primary neurological diseases. In the present review we summarize the state of the art, future perspectives, but also limitations, of neurofilament light chain protein as a CSF and blood biomarker in several medical fields, including intensive care medicine, surgery, internal medicine and psychiatry. In particular, neurofilament light chain protein is associated with the degree of neurological impairment and outcome in patients admitted to intensive care units or in the perioperative phase and it seems to be highly interconnected with cardiovascular risk factors. Beyond that, interesting diagnostic and prognostic insights have been provided by the investigation of neurofilament light chain protein in psychiatric disorders as well as in the current coronavirus disease-19 pandemic and in normal ageing. Altogether, current data outline a multifaceted applicability of CSF and blood neurofilament light chain protein ranging from the critical clinical setting to the development of precision medicine models suggesting a strict interplay between the nervous system pathophysiology and the health-illness continuum.

High versus low blood pressure targets for cardiac surgery while on cardiopulmonary bypass

BACKGROUND

Cardiac surgery is performed worldwide. Most types of cardiac surgery are performed using cardiopulmonary bypass (CPB). Cardiac surgery performed with CPB is associated with morbidities. CPB needs an extracorporeal circulation that replaces the heart and lungs, and performs circulation, ventilation, and oxygenation of the blood. The lower limit of mean blood pressure to maintain blood flow to vital organs increases in people with chronic hypertension. Because people undergoing cardiac surgery commonly have chronic hypertension, we hypothesised that maintaining a relatively high blood pressure improves desirable outcomes among the people undergoing cardiac surgery with CPB.

OBJECTIVES

To evaluate the benefits and harms of higher versus lower blood pressure targets during cardiac surgery with CPB.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search of databases was November 2021 and trials registries in January 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing a higher blood pressure target (mean arterial pressure 65 mmHg or greater) with a lower blood pressure target (mean arterial pressure less than 65 mmHg) in adults undergoing cardiac surgery with CPB.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Primary outcomes were 1. acute kidney injury, 2. cognitive deterioration, and 3. all-cause mortality. Secondary outcomes were 4. quality of life, 5. acute ischaemic stroke, 6. haemorrhagic stroke, 7. length of hospital stay, 8. renal replacement therapy, 9. delirium, 10. perioperative transfusion of blood products, and 11. perioperative myocardial infarction. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included three RCTs with 737 people compared a higher blood pressure target with a lower blood pressure target during cardiac surgery with CPB. A high blood pressure target may result in little to no difference in acute kidney injury (risk ratio (RR) 1.30, 95% confidence interval (CI) 0.81 to 2.08; I² = 72%; 2 studies, 487 participants; low-certainty evidence), cognitive deterioration (RR 0.82, 95% CI 0.45 to 1.50; I² = 0%; 2 studies, 389 participants; low-certainty evidence), and all-cause mortality (RR 1.33, 95% CI 0.30 to 5.90; I² = 49%; 3 studies, 737 participants; low-certainty evidence). No study reported haemorrhagic stroke. Although a high blood pressure target may increase the length of hospital stay slightly, we found no differences between a higher and a lower blood pressure target for the other secondary outcomes. We also identified one ongoing RCT which is comparing a higher versus a lower blood pressure target among the people who undergo cardiac surgery with CPB.

AUTHORS' CONCLUSIONS

A high blood pressure target may result in little to no difference in patient outcomes including acute kidney injury and mortality. Given the wide CIs, further studies are needed to confirm the efficacy of a higher blood pressure target among those who undergo cardiac surgery with CPB.

The 2022 Lady Estelle Wolfson lectureship on neurofilaments

Neurofilament proteins (Nf) have been validated and established as a reliable body fluid biomarker for neurodegenerative pathology. This review covers seven Nf isoforms, Nf light (NfL), two splicing variants of Nf medium (NfM), two splicing variants of Nf heavy (NfH),α -internexin (INA) and peripherin (PRPH). The genetic and epigenetic aspects of Nf are discussed as relevant for neurodegenerative diseases and oncology. The comprehensive list of mutations for all Nf isoforms covers Amyotrophic Lateral Sclerosis, Charcot-Marie Tooth disease, Spinal muscular atrophy, Parkinson Disease and Lewy Body Dementia. Next, emphasis is given to the expanding field of post-translational modifications (PTM) of the Nf amino acid residues. Protein structural aspects are reviewed alongside PTMs causing neurodegenerative pathology and human autoimmunity. Molecular visualisations of NF PTMs, assembly and stoichiometry make use of Alphafold2 modelling. The implications for Nf function on the cellular level and axonal transport are discussed. Neurofilament aggregate formation and proteolytic breakdown are reviewed as relevant for biomarker tests and disease. Likewise, Nf stoichiometry is reviewed with regard to in vitro experiments and as a compensatory mechanism in neurodegeneration. The review of Nf across a spectrum of 87 diseases from all parts of medicine is followed by a critical appraisal of 33 meta-analyses on Nf body fluid levels. The review concludes with considerations for clinical trial design and an outlook for future research.

Neurofilament light: a possible prognostic biomarker for treatment of vascular contributions to cognitive impairment and dementia

Background

Decreased cerebral blood flow and systemic inflammation during heart failure (HF) increase the risk for vascular contributions to cognitive impairment and dementia (VCID) and Alzheimer disease-related dementias (ADRD). We previously demonstrated that PNA5, a novel glycosylated angiotensin 1–7 (Ang-(1–7)) Mas receptor (MasR) agonist peptide, is an effective therapy to rescue cognitive impairment in our preclinical model of VCID. Neurofilament light (NfL) protein concentration is correlated with cognitive impairment and elevated in neurodegenerative diseases, hypoxic brain injury, and cardiac disease. The goal of the present study was to determine (1) if treatment with Ang-(1–7)/MasR agonists can rescue cognitive impairment and decrease VCID-induced increases in NfL levels as compared to HF-saline treated mice and, (2) if NfL levels correlate with measures of cognitive function and brain cytokines in our VCID model.

Methods

VCID was induced in C57BL/6 male mice via myocardial infarction (MI). At 5 weeks post-MI, mice were treated with daily subcutaneous injections for 24 days, 5 weeks after MI, with PNA5 or angiotensin 1–7 (500 microg/kg/day or 50 microg/kg/day) or saline (n = 15/group). Following the 24-day treatment protocol, cognitive function was assessed using the Novel Object Recognition (NOR) test. Cardiac function was measured by echocardiography and plasma concentrations of NfL were quantified using a Quanterix Simoa assay. Brain and circulating cytokine levels were determined with a MILLIPLEX MAP Mouse High Sensitivity Multiplex Immunoassay. Treatment groups were compared via ANOVA, significance was set at p < 0.05.

Results

Treatment with Ang-(1–7)/MasR agonists reversed VCID-induced cognitive impairment and significantly decreased NfL levels in our mouse model of VCID as compared to HF-saline treated mice. Further, NfL levels were significantly negatively correlated with cognitive scores and the concentrations of multiple pleiotropic cytokines in the brain.

Conclusions

These data show that treatment with Ang-(1–7)/MasR agonists rescues cognitive impairment and decreases plasma NfL relative to HF-saline-treated animals in our VCID mouse model. Further, levels of NfL are significantly negatively correlated with cognitive function and with several brain cytokine concentrations. Based on these preclinical findings, we propose that circulating NfL might be a candidate for a prognostic biomarker for VCID and may also serve as a pharmacodynamic/response biomarker for therapeutic target engagement.

Serum Neurofilament Light is elevated in COVID-19 Positive Adults in the ICU and is associated with Co-Morbid Cardiovascular Disease, Neurological Complications, and Acuity of Illness

In critically ill COVID-19 patients, the risk of long-term neurological consequences is just beginning to be appreciated. While recent studies have identified that there is an increase in structural injury to the nervous system in critically ill COVID-19 patients, there is little known about the relationship of COVID-19 neurological damage to the systemic inflammatory diseases also observed in COVID-19 patients. The purpose of this pilot observational study was to examine the relationships between serum neurofilament light protein (NfL, a measure of neuronal injury) and co-morbid cardiovascular disease (CVD) and neurological complications in COVID-19 positive patients admitted to the intensive care unit (ICU). In this observational study of one-hundred patients who were admitted to the ICU in Tucson, Arizona between April and August 2020, 89 were positive for COVID-19 (COVID-pos) and 11 was COVID-negative (COVID-neg). A healthy control group (n=8) was examined for comparison. The primary outcomes and measures were subject demographics, serum NfL, presence and extent of CVD, diabetes, sequential organ failure assessment score (SOFA), presence of neurological complications, and blood chemistry panel data. COVID-pos patients in the ICU had significantly higher mean levels of Nfl (229.6 ± 163 pg/ml) compared to COVID-neg ICU patients (19.3 ± 5.6 pg/ml), Welch's t-test, p =.01 and healthy controls (12.3 ± 3.1 pg/ml), Welch's t-test p =.005. Levels of Nfl in COVID-pos ICU patients were significantly higher in patients with concomitant CVD and diabetes (n=35, log Nfl 1.6±.09), and correlated with higher SOFA scores (r=.5, p =.001). These findings suggest that in severe COVID-19 disease, the central neuronal and axonal damage in these patients may be driven, in part, by the level of systemic cardiovascular disease and peripheral inflammation. Understanding the contributions of systemic inflammatory disease to central neurological degeneration in these COVID-19 survivors will be important to the design of interventional therapies to prevent long-term neurological and cognitive dysfunction.

Biomarkers of Cerebral Injury for Prediction of Postoperative Cognitive Dysfunction in Patients Undergoing Cardiac Surgery

OBJECTIVES

To assess the ability of the biomarkers neuron-specific enolase (NSE), tau, neurofilament light chain (NFL), and glial fibrillary acidic protein (GFAP) to predict postoperative cognitive dysfunction (POCD) at discharge in patients who underwent cardiac surgery.

DESIGN

Post hoc analyses (with tests being prespecified before data analyses) from a randomized clinical trial.

SETTING

Single-center study from a primary heart center in Denmark.

PARTICIPANTS

Adult patients undergoing elective or subacute on-pump coronary artery bypass grafting and/or aortic valve replacement.

INTERVENTIONS

Blood was collected before induction of anesthesia, after 24 hours, after 48 hours, and at discharge from the surgical ward. The International Study of Postoperative Cognitive Dysfunction test battery was applied to diagnose POCD at discharge and after three months. Linear mixed models of covariance were used to assess whether repeated measurements of biomarker levels were associated with POCD. Receiver operating characteristic (ROC) curves were applied to assess the predictive value of each biomarker measurement for POCD.

MEASUREMENTS AND MAIN RESULTS

A total of 168 patients had biomarkers measured at baseline, and 47 (28%) fulfilled the POCD criteria at discharge. Patients with POCD at discharge had significantly higher levels of tau (p = 0.02) and GFAP (p = 0.01) from baseline to discharge. The biomarker measurements achieving the highest area under the ROC curve for prediction of POCD at discharge were NFL measured at discharge (AUC, 0.64; 95% confidence interval [CI], 0.54-0.73), GFAP measured 48 hours after induction (AUC, 0.64; 95% CI, 0.55-0.73), and GFAP measured at discharge (AUC, 0.64; 95% CI, 0.54-0.74), corresponding to a moderate predictive ability.

CONCLUSIONS

Postoperative serum levels of tau and GFAP were elevated significantly in patients with POCD who underwent cardiac surgery at discharge; however, the biomarkers achieved only modest predictive abilities for POCD at discharge. Postoperative levels of NSE were not associated with POCD at discharge.