Normothermia versus Hypothermia during Cardiopulmonary Bypass in Cases of Repair of Atrioventricular Septal Defect

Ferroptosis Exists in Ischemia Reperfusion Injury after Cardiac Surgery with Cardiopulmonary Bypass

Ischemia-reperfusion (IR) injury commonly arises during cardiac surgery involving Cardiopulmonary Bypass (CPB), and it has relationship with ferroptosis in mice. However, the exact role of ferroptosis in the human cardiac damage caused by cardiac surgery remains unclear. Basic patient data and perioperative period information were collected, and clinic indicators related to cardiac function were detected to assess the extent of cardiac injury. Cardiac tissue samples were collected to determine histopathological changes, ultrastructure of mitochondrial and hallmarks of ferroptosis. 25 patients were involved in this study. In the present study, we observed a significant increase in the clinical indicator hs-cTnT, with levels rising more than 1393 ± 242 folds (P < 0.0001) following the cardiac surgery. Masson staining revealed a notable increase in fibrosis levels by 2.282 ± 0.259% (P = 0.0009). Furthermore, there was a significant elevation in lipid peroxidation, as evidenced by a 61.42 ± 17.33% increase in MDA (P = 0.0006). Additionally, we observed notable swelling, decreased mitochondrial crista, and even fragmented mitochondria. Notably, changes in the marker gene of ferroptosis were observed, with PTGS2 showing a 6.437 ± 0.81 folds increase (P < 0.0001). Furthermore, key regulators such as SLC7A11 and GPX4 proteins exhibited a reduction of 97.33 ± 25.78% (P = 0.0068) and 60.59 ± 14.93% (P = 0.0071), respectively, indicating the occurrence of ferroptosis following the surgery. Ferroptosis exists in myocardial IR injury caused by cardiac surgery with CPB, indicating that targeting ferroptosis could serve as a potential strategy for myocardial protection against CPB-induced IR injury. The trial has been registered in Chinese Clinical Trial Registry (ChiCTR, No. ChiCTR2200061995) on July 16th, 2022.

Neurological Impact of Slower Rewarming during Bypass Surgery in Infants

BACKGROUND

 Hypothermia is a neuroprotective strategy during cardiopulmonary bypass. Rewarming entailing a rapid rise in cerebral metabolism might lead to secondary neurological sequelae. In this pilot study, we aimed to validate the hypothesis that a slower rewarming rate would lower the risk of cerebral hypoxia and seizures in infants.

METHODS

 This is a prospective, clinical, single-center study. Infants undergoing cardiac surgery in hypothermia were rewarmed either according to the standard (+1°C in < 5 minutes) or a slow (+1°C in > 5-8 minutes) rewarming strategy. We monitored electrocortical activity via amplitude-integrated electroencephalography (aEEG) and cerebral oxygenation by near-infrared spectroscopy during and after surgery.

RESULTS

 Fifteen children in the standard rewarming group (age: 13 days [5-251]) were cooled down to 26.6°C (17.2-29.8) and compared with 17 children in the slow-rewarming group (age: 9 days [4-365]) with a minimal temperature of 25.7°C (20.1-31.4). All neonates in both groups (n = 19) exhibited suppressed patterns compared with 28% of the infants > 28 days (p < 0.05). During rewarming, only 26% of the children in the slow-rewarming group revealed suppressed aEEG traces (vs. 41%; p = 0.28). Cerebral oxygenation increased by a median of 3.5% in the slow-rewarming group versus 1.5% in the standard group (p = 0.9). Our slow-rewarming group revealed no aEEG evidence of any postoperative seizures (0 vs. 20%).

CONCLUSION

 These results might indicate that a slower rewarming rate after hypothermia causes less suppression of electrocortical activity and higher cerebral oxygenation during rewarming, which may imply a reduced risk of postoperative seizures.

Novel cfDNA Methylation Biomarkers Reveal Delayed Cardiac Cell Death after Open-heart Surgery

The use of cardiopulmonary bypass (CPB) is thought to cause delayed cardiac damage. DNA methylation-based liquid biopsies are novel biomarkers for monitoring acute cardiac cell death. We assessed cell-free DNA molecules as markers for cardiac damage after open-heart surgery. Novel cardiomyocyte-specific DNA methylation markers were applied to measure cardiac cfDNA in the plasma of 42 infants who underwent open-heart surgery. Cardiac cfDNA was elevated following surgery, reflecting direct surgery-related tissue damage, and declined thereafter in most patients. The concentration of cardiac cfDNA post-surgery correlated with the duration of CPB and aortic cross clamping. Strikingly, cardiac cfDNA at 6 h predicted duration of mechanical ventilation and maximal vasoactive-inotropic score better than did maximal troponin levels. Cardiac cfDNA reveals heart damage associated with CPB, and can be used to monitor cardiac cell death, to predict clinical outcome of surgery and to assess performance of cardioprotective interventions.

Effectiveness of Mild to Moderate Hypothermic Cardiopulmonary Bypass on Early Clinical Outcomes

Background: Intraoperative hypothermia is an integral part of cardiopulmonary bypass (CPB), and a precise degree of hypothermia may improve the early clinical outcomes of cardiac surgery. Presently, there is no agreement on an accurate, advantageous temperature range for routine use in CPB. To address this issue, we conducted a retrospective observational study to compare the effects of different hypothermic temperature ranges on primary (inotropic support, blood loss, and platelet count) and secondary (ventilation support and in-hospital stay) outcomes in patients undergoing elective cardiac surgery. Methods: Data were retrieved from the medical database of the Cardiovascular Surgery Department, King Edward Medical University, Lahore-Pakistan (a tertiary care hospital), dating from February 2015 to December 2017. Patients were divided into mild (34 °C to 36 °C), intermediate (31 °C to 33 °C), or moderate (28 °C to 30 °C) hypothermic groups. Results: Out of 275 patients, 245 (89.09%) fit the inclusion criteria. The cohort with mild hypothermic CPB temperatures presented better clinical outcomes in terms of requiring less inotropic support, less blood loss, fewer blood transfusions, improved platelet counts, shorter in-hospital stays, and required less ventilation support, when compared with other hypothermic groups. Conclusions: Mild hypothermic CPB (34 °C to 36 °C) may produce better clinical outcomes for cardiac surgery and improve the quality of health of cardiac patients.

Safety of Normothermic Cardiopulmonary Bypass in Pediatric Cardiac Surgery: A System Review and Meta-Analysis

Objectives: Hypothermic cardiopulmonary bypass (HCPB) has been used successfully in cardiac surgery for more than half a century, although adverse effects have been reported with its use. Many studies on temperature management during CPB published to date have shown that normothermic CPB (NCPB) provides more benefits to children undergoing cardiac surgery. The present meta-analysis investigated the effect of NCPB on clinical outcomes based on results of randomized controlled trials and observational studies on pediatric cardiac surgery. Methods: Databases such as PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and Clinical Trials.gov were searched from inception to May 2021 to identify relevant studies published in English. Results: The present meta-analysis included 13 studies characterizing a total of 837 pediatric patients. The random effects model exhibited that the NCPB group had reduced revision for postoperative bleeding [odds ratio (OR): 0.11; 95% confidence interval (CI): 0.01-0.89; I ² = 0%, P = 0.04], serum lactate 2-4 h after CPB (mean difference: -0.60; 95% CI: -1.09 to -0.11; I ² = 82%, P = 0.02), serum creatinemia 24 h after CPB (mean difference: -2.73; 95% CI: -5.06 to -0.39; I ² = 83%, P = 0.02), serum creatinemia 48 h after CPB (mean difference: -2.08; 95% CI: -2.78 to -1.39; I ² = 0%, P < 0.05), CPB time (mean difference: -19.10, 95% CI: -32.03 to -6.18; I ² = 96%, P = 0.04), and major adverse events (OR: 0.37; 95% CI: 0.15-0.93; Z = 2.12, P = 0.03) after simple congenital surgery compared with the HCPB group. Conclusion: NCPB is as safe as HCPB in pediatric congenital heart surgery. Moreover, NCPB provides more advantages than HCPB in simple congenital heart surgery.