Nitric Oxide in Selective Cerebral Perfusion Could Enhance Neuroprotection During Aortic Arch Surgery

Neurodevelopmental Outcomes After Nitric Oxide During Cardiopulmonary Bypass for Open Heart Surgery: A Randomized Clinical Trial

Importance

Children with congenital heart defects who undergo cardiopulmonary bypass (CPB) surgery are at risk for delayed or impaired neurodevelopmental outcomes. Nitric oxide (NO) added to the CPB oxygenator may reduce systemic inflammation due to CPB and improve recovery from surgery, including improved neurodevelopmental outcomes.

Objective

To investigate neurodevelopment, health-related quality of life (HRQOL), and factors associated with impaired neurodevelopment at 12 months post surgery in infants who received CPB with NO or standard CPB.

Design, Setting, and Participants

This double-masked randomized clinical trial was conducted in 6 centers in Australia, New Zealand, and the Netherlands between July 19, 2017, and April 28, 2021, with a preplanned prospective follow-up 12 months postrandomization completed on August 5, 2022. The cohort included 1364 infants younger than 2 years who underwent open heart surgery with CPB for congenital heart disease.

Interventions

The intervention group received NO 20 ppm into the CPB oxygenator. The control group received standard CPB.

Main Outcomes and Measures

The primary outcome was neurodevelopment, defined as the Ages and Stages Questionnaire, Third Edition (ASQ-3) total score. Secondary outcomes were HRQOL and functional status as measured by Pediatric Quality of Life Inventory and modified Pediatric Overall Performance Category scores, respectively. Sensitivity analyses modeled the outcome for patients lost to follow-up.

Results

Of 1318 infants alive 12 months after randomization, follow-up was performed in 927, with 462 patients in the NO group and 465 in the standard care group (median [IQR] age at follow-up, 16.6 [13.7-19.8] months; median [IQR] time since randomization, 12.7 [12.1-13.9] months; 516 male [55.7%]). There were no differences between the NO and standard care groups in ASQ-3 total score (mean [SD], 196.6 [75.4] vs 198.7 [73.8], respectively; adjusted mean difference, -2.24; 95% CI, -11.84 to 7.36). There were no differences in secondary outcomes. Prematurity (gestational age <37 weeks), univentricular lesions, congenital syndromes, and longer intensive care unit length of stay were associated with lower ASQ-3 total scores in adjusted multivariable analyses.

Conclusions and Relevance

In this randomized clinical trial of infants with congenital heart disease, NO administered via the CPB oxygenator did not improve neurodevelopmental outcomes or HRQOL 12 months after open heart surgery. Further research should explore homogenous cohorts with higher surgical risk and higher-dose or alternative therapies.

Trial Registration

ANZCTR Identifier: ACTRN12617000821392.

The role of microglia in Neuroinflammation associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) are indispensable core techniques in cardiac surgery. Numerous studies have shown that cardiopulmonary bypass and deep hypothermic circulatory arrest are associated with the occurrence of neuroinflammation, accompanied by the activation of microglia. Microglia, as macrophages in the central nervous system, play an irreplaceable role in neuroinflammation. Current research on neuroinflammation induced by microglia activation mainly focuses on neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, neuropathic pain, acquired brain injury, and others. However, there is relatively limited research on microglia and neuroinflammation under conditions of cardiopulmonary bypass and deep hypothermic circulatory arrest. The close relationship between cardiopulmonary bypass, deep hypothermic circulatory arrest, and cardiac surgery underscores the importance of identifying targets for intervening in neuroinflammation through microglia. This could greatly benefit cardiac surgery patients during cardiopulmonary bypass and the perioperative period, significantly improving patient prognosis. This review article provides the first comprehensive discussion on the signaling pathways associated with neuroinflammation triggered by microglia activation, the impact of cardiopulmonary bypass on microglia, as well as the current status and advancements in cardiopulmonary bypass animal models. It provides new insights and methods for the treatment of neuroinflammation related to cardiopulmonary bypass and deep hypothermic circulatory arrest, holding significant importance for clinical treatment by cardiac surgeons, management strategies by cardiopulmonary bypass physicians, and the development of neurologically related medications.

Validation of a new model of selective antegrade cerebral perfusion with circulatory arrest in rats

BACKGROUND

Selective antegrade cerebral perfusion (SACP) is adopted as an alternative to deep hypothermic circulatory arrest (DHCA) during aortic arch surgery. However, there is still no preclinical evidence to support the use of SACP associated with moderate hypothermia (28-30°C) instead of DHCA (18-20°C). The present study aims to develop a reliable and reproducible preclinical model of cardiopulmonary bypass (CPB) with SACP applicable for assessing the best temperature management.

MATERIALS AND METHODS

A central cannulation through the right jugular vein and the left carotid artery was performed, and CPB was instituted.Animals were randomized into two groups: normothermic circulatory arrest without or with cerebral perfusion (NCA vs SACP). EEG monitoring was maintained during CPB. After 10 min of circulatory arrest, rats underwent 60 min of reperfusion. After that, animals were sacrificed, and brains were collected for histology and molecular biology analysis.

RESULTS

Power spectral analysis of the EEG signal showed decreased activity in both cortical regions and lateral thalamus in all rats during the circulatory arrest. Only SACP determined complete recovery of brain activity and higher power spectral signal compared to NCA (p < 0.05). Histological damage scores and western blot analysis of inflammatory and apoptotic proteins like caspase-3 and Poly-ADP ribose polymerase (PARP) were significantly lower in SACP compared to NCA. Vascular endothelial growth factor (VEGF) and RNA binding protein 3 (RBM3) involved in cell-protection mechanisms were higher in SACP, showing better neuroprotection (p < 0.05).

CONCLUSIONS

SACP by cannulation of the left carotid artery guarantees good perfusion of the whole brain in this rat model of CPB with circulatory arrest. The present model of SACP is reliable, repeatable, and not expensive, and it could be used in the future to achieve preclinical evidence for the best temperature management and to define the best cerebral protection strategy during circulatory arrest.

Cerebral Protection Strategies in Aortic Arch Surgery-Past Developments, Current Evidence, and Future Innovation

Surgery of the aortic arch remains a complex procedure, with neurological events such as stroke remaining its most dreaded complications. Changes in surgical technique and the continuous innovation in neuroprotective strategies have led to a significant decrease in cerebral and spinal events. Different modes of cerebral perfusion, varying grades of hypothermia, and a number of pharmacological strategies all aim to reduce hypoxic and ischemic cerebral injury, yet there is no evidence indicating the clear superiority of one method over another. While surgical results continue to improve, novel hybrid and interventional techniques are just entering the stage and the question of optimal neuroprotection remains up to date. Within this perspective statement, we want to shed light on the current evidence and controversies of cerebral protection in aortic arch surgery, as well as what is on the horizon in this fast-evolving field. We further present our institutional approach as a large tertiary aortic reference center.

Selective brain perfusion improves the neurological outcomes after extracorporeal cardiopulmonary resuscitation in a rat model

BACKGROUND

The major concern in patients who have suffered from cardiac arrest (CA) and undergone successful extracorporeal cardiopulmonary resuscitation (E-CPR) is poor neurological outcomes. In this study, we aimed to introduce a rat model of selective brain perfusion (SBP) during E-CPR to improve the neurological outcome after CA.

METHODS

The rats underwent 7 min of untreated asphyxial CA and then were resuscitated with E-CPR for 30 min. The right external jugular vein and right femoral artery were separately cannulated to the E-CPR outflow and inflow. The right common carotid artery was cannulated from the proximal to the distal side for SBP. Subsequently, rats were removed from E-CPR, wounds were closed, and 90 min of intensive care were provided. Neurological deficit scores were tested after 4 h of recovery when the rats were mechanical ventilation-free. S100 calcium-binding protein B (S100B) and glial fibrillary acidic protein (GFAP) were detected through immunohistochemistry (IHC) of brain tissue.

RESULTS

The rats that received SBP while resuscitated by E-CPR showed markedly better neurological performances after 4-h recovery than those resuscitated by E-CPR only. The IHC staining of GFAP and S100B in the hippocampus was low in the rats receiving SBP during E-CPR, but only GFAP showed significant differences.

CONCLUSIONS

We successfully developed a novel and reproducible rat model of SBP while resuscitated by E-CPR to ameliorate the neurological performances after CA. This achievement might have opportunities for studying how to improve the neurological outcome in the clinical condition.

S-Nitroso Human Serum Albumin Enhances Left Ventricle Hemodynamic Performance and Reduces Myocardial Damage after Local Ischemia-Reperfusion Injury

Endothelial nitric oxide (NO) production is crucial in maintaining vascular homeostasis. However, in the context of ischemia-reperfusion (I/R) injury, uncoupled endothelial nitric oxide synthase (eNOS) can exacerbate reactive oxygen species (ROS) generation. Supplementation with S-nitroso human serum albumin (S-NO-HSA) offers a potential solution by mitigating eNOS uncoupling, thereby enhancing NO bioavailability. In a study conducted at the University of Verona, male rats underwent thoracotomy followed by 30 min left anterior descendant coronary (LAD) occlusion and subsequent reperfusion. Hemodynamic parameters were meticulously assessed using a conductance catheter inserted via the carotid artery. The rats were stratified into two main groups based on reperfusion duration and the timing of drug infusion, with the effects of S-NO-HSA evaluated after 2 or 24 h. Remarkably, intravenous administration of S-NO-HSA, initiated before or during ischemia, exhibited notable benefits. It significantly improved left ventricular function, safeguarded energetic substrates such as phosphocreatine and ATP, and sustained glutathione levels akin to basal conditions, indicative of diminished oxidative stress. The data from this study strongly suggest a protective role for S-NO-HSA in mitigating I/R injury induced by LAD artery occlusion, a phenomenon observed at both 2 and 24 h post-reperfusion. These findings underscore the promising therapeutic potential of NO supplementation in alleviating myocardial damage subsequent to ischemic insult.