Biochemical Changes in Cardiopulmonary Bypass in Cardiac Surgery: New Insights

Differences in Plasma Extracellular Vesicles of Different Origin in On-Pump Versus Off-Pump Cardiac Surgery

Coronary artery bypass grafting (CABG) using cardiopulmonary bypass (CPB) causes a systemic inflammatory response that can worsen patient outcomes. Off-pump surgery has been associated with a reduced inflammatory response. The precise mechanisms and the role of extracellular vesicles (EVs) in this context are not fully understood. This study aimed to investigate the early immune response, including main T- and B-lymphocyte subsets, cytokine profiles, and plasma EVs, in patients undergoing off-pump (n = 18) and on-pump (n = 18) CABG. Thirty-six patients undergoing isolated CABG were enrolled in this randomized control study. Pre- and 24 h postoperative blood samples were analyzed for immune cell populations, cytokine levels, and plasma EV phenotyping. Off-pump CABG triggered a milder immune response than on-pump surgery. On-pump surgery led to greater changes in circulating EVs, particularly platelet- (CD62P+), endothelial- (CD31+), and B-cell-derived (CD19+), as well as platelet- and erythrocyte-derived aggregates (CD41+CD235a+). Levels of platelet-derived EVs, expressing both constitutional and activation markers (CD41+CD62P+) decreased in both groups of patients 24 h after surgery. On-pump cardiac procedures led to an increase in T-regulatory cell-derived EVs (CD73+CD39+), suggesting a potential mechanism for immune suppression compared to off-pump surgery. There were numerous correlations between EV levels and cytokine profiles following on-pump surgery, hinting at a close relationship. Leucocyte-derived EVs exhibited positive correlations with each other and with GRO but showed negative correlations with endothelial-derived EVs (CD90+ and CD31+). Additionally, CD73+ EVs demonstrated positive correlations with platelet counts and with erythrocyte-derived CD235a+ EVs. EV changes were significantly greater after on-pump surgery, highlighting a more pronounced response to this type of surgery and emphasizing the role of EVs as regulators of post-surgical inflammation.

The Effects of Corticosteroids on Survival in Pediatric and Nonelderly Adult Patients Undergoing Cardiac Surgery: A Meta-analysis of Randomized Studies

OBJECTIVE

Cardiac surgery can be complicated by the development of a systemic inflammatory response syndrome related to cardiopulmonary bypass. This potentially contributes to the occurrence of postoperative morbidity and mortality. Corticosteroids can be used to reduce such inflammation, but the overall balance between potential harm and benefit is unknown and may be age-dependent. The present meta-analysis aims to evaluate the effects of prophylactic corticosteroids in pediatric and non-elderly adult cardiac surgery patients.

DESIGN

Systematic review and meta-analysis of randomized trials.

SETTING

Cardiac surgery with cardiopulmonary bypass.

PARTICIPANTS

Patients younger than 65 years old (pediatric and non-elderly adults).

INTERVENTIONS

Perioperative use of corticosteroids versus placebo or standard care.

MEASUREMENTS AND MAIN RESULTS

Two independent investigators searched PubMed, EMBASE and the Cochrane Library from inception to January 20, 2024. The primary outcome was mortality at the longest follow-up available. Secondary outcomes included acute kidney injury, atrial fibrillation, myocardial injury, cerebrovascular events, and infections. Our search strategy identified a total of 17 randomized trials involving 6,598 patients. Mortality was significantly reduced in the corticosteroid group (78/3321 [2.3%] vs. 116/3277 [3.5%]; risk ratio = 0.69; 95% confidence interval, 0.52 to 0.92; P = 0.01; I2 = 0%; NNT = 91). Moreover, the highest postoperative vasoactive inotropic score (VIS) was significantly lower in corticosteroid group (MD: -2.07, 95% CI -3.69 to -0.45, P = 0.01, I2 = 0%). No significant differences in secondary outcomes between the two treatment groups were recorded.

CONCLUSIONS

This meta-analysis of randomized trials highlights the potential benefits of corticosteroids on survival in cardiac surgery for patients younger than 65 years old.

Review of Interleukin-6 and Cardiopulmonary Bypass-Related End-Organ Injury Along With the Potential for Mitigation With Tocilizumab

Cardiopulmonary bypass (CPB) is essential for the conduct of open-heart procedures. While lifesaving, CPB can be associated with significant end-organ injuries believed to result from inflammatory responses triggered by the extracorporeal surfaces encountering cellular elements in the blood stream. In this review, we discuss the role of interleukin-6 (IL-6) and the potential for Tocilizumab, an anti-IL-6 receptor antibody, in mitigating these effects. We compare the inflammatory responses in CPB and cytokine storm, a clinical condition in which Tocilizumab has been effectively implemented. Finally, we examine why corticosteroids, used to reduce the morbidity of CPB, may not effectively reduce IL-6 levels.

The Value of Biomarkers in Major Cardiovascular Surgery Necessitating Cardiopulmonary Bypass

The use of biomarkers in cardiovascular surgery is an evolving field with promising potential; however, current research remains largely limited, requiring further validation for routine clinical application. This review explores the application of biomarkers in cardiovascular surgery, focusing on heart failure, cardiac ischemia, and organ dysfunction, including renal, cerebral, pulmonary, and splanchnic impairments. Additionally, it examines the significance of biomarkers in assessing the inflammatory state and oxidative stress during the perioperative period, particularly in the context of major surgical trauma and cardiopulmonary bypass (CPB). From January 2018 to June 2024, we reviewed 133 studies and four systematic reviews and meta-analyses using the Medline, Embase, and Central databases, screening for pre- or postoperative biomarker levels in patients undergoing cardiac surgery. Outcomes of interest were postoperative mortality, nonfatal myocardial infarction, stroke, congestive heart failure, and major adverse cardiovascular events (MACEs). Studies reporting multivariable-adjusted risk estimates were included. The findings revealed that cardiac troponins (cTns) and creatine kinase isoenzyme MB (CK-MB) remain the most widely utilized biomarkers for assessing myocardial injury post-surgery. These elevated biomarker levels were consistently associated with an increased risk of postoperative complications, including low cardiac output syndrome, prolonged ventilation, and mortality. Emerging biomarkers, such as heart-type fatty acid-binding protein (h-FABP) and high-sensitivity C-reactive protein (hs-CRP), demonstrated promising early detection and risk stratification results. In particular, h-FABP increased rapidly within one hour of myocardial injury, peaking at 4-6 hours and returning to baseline within 24 hours. This rapid clearance makes h-FABP a valuable tool for early myocardial injury detection, potentially allowing for timely interventions. Inflammatory biomarkers, including hs-CRP and pentraxin 3 (PTX3), were found to be associated with poor outcomes, such as increased morbidity and mortality. Elevated preoperative levels of these markers were indicative of a heightened inflammatory response, correlating with worse postoperative recovery and higher rates of complications. Furthermore, the neutrophil-to-lymphocyte ratio (NLR) emerged as a cost-effective and easily accessible predictor of postoperative outcomes. Elevated NLR values were linked to an increased risk of adverse events, including prolonged ventilation, low cardiac output syndrome, and overall mortality. Further, the practicality of measuring NLR through routine blood tests makes it viable for widespread clinical use. In conclusion, integrating biomarkers in cardiovascular surgery significantly advances predicting postoperative outcomes for cardiac surgery patients. Therefore, it is essential to categorize these biomarkers into two distinct groups in the future, inflammatory and non-inflammatory (related to organ damage), to improve understanding and enhance their clinical applicability. Future research should focus on standardizing the use of these biomarkers and exploring their combined predictive power to enhance risk stratification and improve patient prognosis.

Acute type A aortic dissection in patients with non-prior cardiac surgery vs. prior cardiac surgery: a systematic review and meta-analysis

Background

Patients with prior cardiac surgery undergoing acute type A aortic dissection (ATAAD) are thought to have worse clinical outcomes as compared to the patients without prior cardiac surgery.

Aim

To compare the safety and efficacy of ATAAD in patients with prior cardiac surgery.

Methods

We systematically searched PubMed, Cochrane Library and Google Scholar from database inception until April 2024. We included nine studies which consisted of a population of 524 in the prior surgery group and 5,249 in the non-prior surgery group. Our primary outcome was mortality. Secondary outcomes included reoperation for bleeding, myocardial infarction, stroke, renal failure, sternal wound infection, cardiopulmonary bypass (CPB) time, cross-clamp time, hospital stay, and ICU stay.

Results

Our pooled estimate shows a significantly lower rate of mortality in the non-prior cardiac surgery group compared to the prior cardiac surgery group (RR = 0.60, 95% CI = 0.48-0.74). Among the secondary outcomes, the rate of reoperation for bleeding was significantly lower in the non-prior cardiac surgery group (RR = 0.66, 95% CI = 0.50-0.88). Additionally, the non-prior cardiac surgery group had significantly shorter CPB time (MD = -31.06, 95% CI = -52.20 to -9.93) and cross-clamp time (MD = -21.95, 95% CI = -42.65 to -1.24). All other secondary outcomes were statistically insignificant.

Conclusion

Patients with prior cardiac surgery have a higher mortality rate as compared to patients who have not undergone cardiac surgery previously. Patients with prior cardiac surgery have higher mortality and longer CPB and cross-clamp times. Tailored strategies are needed to improve outcomes in this high-risk group.

Predictors of length of hospital stay after pediatric Ebstein anomaly corrective surgery: a retrospective cohort study

BACKGROUND

The remarkable advancements in surgical techniques over recent years have shifted the clinical focus from merely reducing mortality to enhancing the quality of postoperative recovery. The duration of a patient's hospital stay serves as a crucial indicator in evaluating postoperative recovery and surgical outcomes. This study aims to identify predictors of the length of hospital stay for children who have undergone corrective surgery for Ebstein Anomaly (EA).

METHODS

We conducted a retrospective cohort study on children (under 18 years of age) diagnosed with EA who were admitted for corrective surgery between January 2009 and November 2021 at Fuwai Hospital. The primary outcome was the Time to Hospital Discharge (THD). Cox proportional hazard models were utilized to identify predictors of THD. In the context of time-to-event analysis, discharge was considered an event. In cases where death occurred before discharge, it was defined as an extended THD, input as 100 days (exceeding the longest observed THD), and considered as a non-event.

RESULTS

A total of 270 children were included in this study, out of which three died in the hospital. Following the Cox proportional hazard analysis, six predictors of THD were identified. The hazard ratios and corresponding 95% confidence intervals were as follows: age, 1.030(1.005,1.055); C/R > 0.65, 0.507(0.364,0.707); Carpentier type C or D, 0.578(0.429,0.779); CPB time, 0.995(0.991,0.998); dexamethasone, 1.373(1.051,1.795); and transfusion, 0.680(0.529,0.875). The children were categorized into three groups based on the quartile of THD. Compared to children in the ≤ 6 days group, those in the ≥ 11 days group were associated with a higher incidence of adverse outcomes. Additionally, the duration of mechanical ventilation and ICU stay, as well as hospital costs, were significantly higher in this group.

CONCLUSION

We identified six predictors of THD for children undergoing corrective surgery for EA. Clinicians can utilize these variables to optimize perioperative management strategies, reduce adverse complications, improve postoperative recovery, and reduce unnecessary medical expenses.

Postoperative C-reactive protein levels correlate with reduced spinal column mobility after median sternotomy: a prospective cohort study

Background

The sternum is connected to the spinal column via the ribs, forming the thorax. Therefore, it is necessary to consider the effect of a midline sternotomy on the spinal column, but no in vivo studies have been conducted to date. We investigated the changes in the range of motion of the spinal column before and after midline sternotomy and the perioperative factors that have the greatest influence.

Methods

The participants were patients who had undergone cardiac surgery through a standby midline sternotomy. Spinal range of motion in forward flexion was measured before and after surgery. The following perioperative factors were investigated: operating time, days to postoperative measurement, C-reactive protein (CRP) measurement on the third postoperative day, the day of the start of bed release, and the stage of bed release progression on the second postoperative day. Statistics were compared between the two groups before and after surgery for each factor. Multiple regression analysis (forced entry method) was then performed with the change in spinal range of motion, which showed statistical differences between the preoperative and postoperative groups, as the dependent variable and each perioperative factor as the independent variable.

Results

The study included 93 patients. Postoperatively, there was a significant decrease in thoracic spine range of motion. Multiple regression analysis showed that an increase in CRP on the third postoperative day was responsible for the decrease in thoracic range of motion (β=-0.30, P<0.01).

Conclusions

After median sternotomy, thoracic spine range of motion was decreased and correlated with postoperative inflammation.