Cerebral injury after cardiac surgery: identification of a group at extraordinary risk. Multicenter Study of Perioperative Ischemia Research Group (McSPI) and the Ischemia Research Education Foundation (IREF) Investigators

Benefits of prophylactic carotid revascularization in patients with asymptomatic carotid artery stenosis undergoing coronary artery bypass surgery: A narrative review

Patients undergoing coronary artery bypass grafting (CABG) are at increased risk of perioperative stroke. Carotid atherosclerosis has been identified as an independent risk factor for stroke during and in the early postoperative period of cardiac surgery. However, the pathogenesis of peri-CABG stroke is multifactorial and frequently involves other noncarotid causes, such as cardiac emboli and aortic atheroma. Therefore, routine population-wide screening of carotid stenosis is not recommended, but target screening of patients at high risk of carotid-related perioperative stroke can have benefits. Carotid duplex sonography is recommended as an initial screening tool. Elimination of carotid stenosis before cardiac surgery is indicated in patients in whom carotid atherosclerosis is suspected to be the primary contributor to perioperative stroke. In patients with advanced carotid atherosclerosis, an individualized revascularization approach, including simultaneous or staged procedures, is advocated. The prevailing consensus is that synchronous surgery is safer than staged procedures. Carotid artery stenting represents a less invasive alternative, but its role in high-risk patients requires further investigation. In conclusion, the risk of perioperative stroke in patients undergoing CABG involves different factors, and carotid artery stenosis is involved in its pathogenesis only in some patients. Therefore, individualized approaches and careful consideration of patient risk factors are essential in determining the need for carotid screening and revascularization before CABG.

Impact of an enhanced recovery after surgery program integrating cardiopulmonary rehabilitation on post-operative prognosis of patients treated with CABG: protocol of the ERAS-CaRe randomized controlled trial

BACKGROUND

Coronary artery bypass grafting is associated with a high occurrence of postoperative cardiopulmonary complications. Preliminary evidence suggested that enhanced recovery after surgery can effectively reduce the occurrence of postoperative cardiopulmonary complications. However, enhanced recovery after surgery with systematic integration of cardiopulmonary rehabilitation (ERAS-CaRe) into for Coronary artery bypass grafting has not been evaluated so far. We thus design the ERAS-CaRe randomized-controlled trial to evaluate possible superiority of embedding cardiopulmonary rehabilitation in ERAS over ERAS alone as well as to investigate effects of differential timing of cardiopulmonary rehabilitation within enhanced recovery after surgery (pre-, post-, perio-operative) on post-operative cardiopulmonary complications following Coronary artery bypass grafting surgery.

METHODS

ERAS-CaRe is a pragmatic, randomized-controlled, parallel four-arm, clinical trial. Three hundred sixty patients scheduled for Coronary artery bypass grafting in two Chinese hospitals will be grouped randomly into (i) Standard enhanced recovery after surgery or (ii) pre-operative ERAS-CaRe or (iii) post-operative ERAS-CaRe or (iv) perio-operative ERAS-CaRe. Primary outcome is the occurrence of cardiopulmonary complications at 10 days after Coronary artery bypass grafting. Secondary outcomes include the occurrence of other individual complications including cardiac, pulmonary, stroke, acute kidney injury, gastrointestinal event, ICU delirium rate, reintubation rate, early drainage tube removal rate, unplanned revascularization rate, all-cause mortality, ICU readmission rate, plasma concentration of myocardial infarction-related key biomarkers etc. DISCUSSION: The trial is designed to evaluate the hypothesis that a cardiopulmonary rehabilitation based enhanced recovery after surgery program reduces the occurrence of cardiopulmonary complications following Coronary artery bypass grafting and to determine optimal timing of cardiopulmonary rehabilitation within enhanced recovery after surgery. The project will contribute to increasing the currently limited knowledge base in the field as well as devising clinical recommendations.

TRIAL REGISTRATION

The trial was registered at the Chinese Clinical Trials Registry on 25 August 2023 (ChiCTR2300075125; date recorded: 25/8/2023, https://www.chictr.org.cn/ ).

Neurologic complications after cardiopulmonary bypass - A narrative review

Neurologic complications, associated with cardiac surgery and cardiopulmonary bypass (CPB) in adults, are common and can be devastating in some cases. This comprehensive review will not only consider the broad categories of stroke and neurocognitive dysfunction, but it also summarises other neurological complications associated with CPB, and it provides an update about risks, prevention and treatment. Where appropriate, we consider the impact of off-pump techniques upon our understanding of the contribution of CPB to adverse outcomes.

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.

Milrinone is better choice for controlled low central venous pressure during hepatectomy: A randomized, controlled trial comparing with nitroglycerin

BACKGROUND

To explore the feasibility and effectiveness of controlled low central venous pressure(CLCVP)induced by milrinone during hepatectomy, and its influence on perioperative hemodynamics, blood loss and patients' recovery, comparing with the traditional method by nitroglycerin.

METHODS

52 patients who underwent elective open hepatectomy were enrolled in the study and randomly divided into two groups: milrinone (M) group and nitroglycerin (NG) group. Milrinone was infused with the rate of 0.5 μg/kg/min in group M, while nitroglycerin was given 0.2-0.5 μg/kg/min in group NG to maintain CVP≤ 5 mmHg during liver resection. The demographic variables, data of the operative procedure and intraoperative hemodynamics were recorded. The postoperative recovery profiles and pre- and post-operative haematological markers of vital organs were also collected and compared.

RESULTS

1. The blood loss of group M, no matter during liver resection or in the whole procedure, was both less than that of group NG (P < 0.05), so did the hemoglobin detected by blood gas analysis (P < 0.05). Meanwhile, time of hepatectomy and hepatic hilum occlusion were shorter in group M (P < 0.05). 2. Compared with the NG group, cardiac index (CI) and stroke volume index (SVR) were higher in group M in the operation. The norepinephrine dosage necessary in the operation was of no difference in two groups (P > 0.05). 3. Drainage indwelling time and postoperative hospital stay of group M were shorter than that of group NG (P < 0.05). Most of the blood biomarkers increased on postoperative day (POD)-1, and returned to the preoperative level on POD-7 without inter-group difference (P > 0.05). Brain natriuretic peptide precursor (Pro-BNP) in group M was higher than NG group on POD-1 (P < 0.05), and the statistical difference disappeared on POD-7.

CONCLUSION

Milrinone can effectively maintain a controlled low central venous pressure during hepatectomy. Compared with nitroglycerin, milrinone can reduce the amount of blood loss, with the benefit of better manifestation of hemodynamics and enhanced postoperative recovery.

Hypoxic postconditioning-induced neuroprotection increases neuronal autophagy via activation of the SIRT1/FoxO1 signaling pathway in rats with global cerebral ischemia

Hypoxic postconditioning (HPC) has been reported to be a beneficial and promising treatment for global cerebral ischemia (GCI). However, its neuroprotective mechanism remains unclear. The aim of the present study was to determine whether the protective effects of HPC in a rat model of GCI were due to the upregulation of autophagy via the silent information regulator transcript-1 (SIRT1)/Forkhead box protein 1 (FoxO1) pathway. Morris water maze test revealed that HPC attenuated cognitive damage in GCI rats. HPC also significantly increased the levels of the autophagy-related protein LC3-II, SIRT1 and FoxO1 compared with those in the GCI group. However, the HPC-induced LC3-II upregulation was blocked by the SIRT1 inhibitor EX527. These results suggested that the beneficial effects of HPC on GCI rats were due to the upregulation of ischemiainduced autophagy and involved the SIRT1/FoxO1 signaling pathway.

Use of carotid artery cannulation during redo sternotomy in congenital cardiac surgery: a single-centre experience

 

OBJECTIVES

Management of resternotomy is often a difficult challenge in patients with congenital diseases who have undergone multiple sternotomies. Our goal was to report our single-centre experience with carotid cannulation using a graft interposed during redo sternotomy in complex cardiac reintervention procedures.

METHODS

We performed a retrospective review of all patients who had undergone complex redo sternotomies between January 2019 and May 2020 utilizing a cervical cannulation technique with a Gore-Tex graft interposed on the carotid artery. We classified our population study on the basis of the primary diagnosis and the type of surgery. The primary outcomes of our analysis were the evaluation of the safety of the procedure in terms of survival and freedom from neurological events.

RESULTS

We analysed 22 patients who had undergone previous complex operations. The median age and weight at the time of reintervention were 130.35 (range 0.46-435) months and 31.5 (range 2.2-85) kg, respectively. Composite graft carotid cannulation provided adequate arterial flow in all patients with a median arterial flow of 3.5 l/min/m2 (range 0.6-6). One major cardiac injury occurred during sternotomy when emergency cardiopulmonary bypass (CPB) was initiated. Moreover, during their hospital stays, all patients had an uneventful recovery without neurological or vascular complications and no cervical wound infections.

CONCLUSIONS

Carotid cannulation using interposition of a side graft on the common carotid artery for arterial inflow is a reliable and safe method for initiation of CPB in complex redo surgeries in patients with congenital disease. Complications directly associated with this type of cannulation are uncommon and allow surgical re-entry with overall low risks.

A rare complication of cerebral venous thrombosis during simple percutaneous coronary intervention: A case report

RATIONALE

Cerebrovascular accidents (CVAs) after percutaneous coronary intervention (PCI), although rare, are associated with high in-hospital morbidity and mortality rates. Cerebral venous thrombosis (CVT) is an uncommon cause of CVAs compared with arterial disease but is associated with favorable outcomes in most cases. We present a rare case of CVT following a simple PCI procedure with stent implantation, which has not been previously reported in the literature.

PATIENT CONCERNS

A 78-year-old woman with hypertension, hyperlipidemia, and coronary artery disease received simple PCI with stent implantation. After PCI, she developed a throbbing headache with nausea and vomiting, with her blood pressure increasing to 190/100 mmHg. Drowsiness, disorientation, and neck stiffness were noted. Neurological complication due to the PCI procedure was highly suspected.

DIAGNOSIS

Noncontrast brain computed tomography was performed along with emergency neurological consultation, and the patient was diagnosed as having acute CVT.

INTERVENTIONS

The patient was treated with anti-intracranial pressure therapy and anticoagulation therapy through low-molecular-weight heparin and was subsequently treated with warfarin.

OUTCOMES

After treatment, the patient's symptoms and signs gradually subsided, and her clinical condition improved. She was discharged with full recovery thereafter.

LESSONS

A case of acute CVT, a rare, and atypical manifestation of venous thromboembolism and CVA, complicated simple PCI with stent implantation. During PCI, identifying patients with a high risk of a CVA is critical, and special care should be taken to prevent this devastating complication.

Perioperative covert stroke in patients undergoing coronary artery bypass graft surgery

Objectives

Covert stroke is a complication of coronary artery bypass graft surgery that is increasingly recognized as a serious problem. In noncardiac surgery settings, covert stroke is associated with the development of delirium, long-term cognitive decline, and future clinical stroke. Therefore, we sought to determine the feasibility of conducting a large, prospective cohort study of the influence of covert stroke on neurocognitive outcomes in patients undergoing coronary artery bypass graft surgery.

Methods

NeuroVISION Cardiac pilot was a prospective cohort study enrolling patients aged ≥21 years undergoing isolated coronary artery bypass graft surgery to receive diffusion-weighted magnetic resonance imaging of the brain after surgery to identify patients with covert stroke. Patients were screened for postoperative delirium in-hospital and were administered questionnaires of cognitive and global function (once before and twice after surgery). Regional cerebral oxygen saturation was recorded during surgery using near-infrared spectroscopy.

Results

Between March 27, 2017, and February 11, 2018, 50 of 66 patients enrolled (76%) completed the brain magnetic resonance imaging (1 patient per week). Among the 49 patients included in the analysis, 19 (39%; 95% confidence interval, 26%-53%) experienced perioperative covert stroke and 3 (6%) had a clinical stroke within 30 days of surgery. Postoperative delirium occurred in 5 (26%) patients with covert stroke and in 3 (10%) patients who did not experience covert stroke.

Conclusions

The NeuroVISION Cardiac pilot study established the feasibility of conducting a large, prospective cohort study of the determinants and consequences of covert stroke in patients undergoing coronary artery bypass graft surgery.

A randomized trial comparing axillary versus innominate artery cannulation for aortic arch surgery

BACKGROUND

Cerebral protection remains the cornerstone of successful aortic surgery; however, there is no consensus as to the optimal strategy.

OBJECTIVE

To compare the safety and efficacy of innominate to axillary artery cannulation for delivering antegrade cerebral protection during proximal aortic arch surgery.

METHODS

This randomized controlled trial (The Aortic Surgery Cerebral Protection Evaluation CardioLink-3 Trial, ClinicalTrials.gov Identifier: NCT02554032), conducted across 6 Canadian centers between January 2015 and June 2018, allocated 111 individuals to innominate or axillary artery cannulation. The primary safety outcome was neuroprotection per the appearance of new severe ischemic lesions on the postoperative diffusion-weighted-magnetic resonance imaging. The primary efficacy outcome was the difference in total operative time. Secondary outcomes included 30-day all-cause mortality and postoperative stroke.

RESULTS

One hundred two individuals (mean age, 63 ± 11 years) were in the primary safety per-protocol analysis. Baseline characteristics between the groups were similar. New severe ischemic lesions occurred in 19 participants (38.8%) in the axillary versus 18 (34%) in the innominate group (P for noninferiority = .0009). Total operative times were comparable (median, 293 minutes; interquartile range, 222-411 minutes) for axillary versus (298 minutes; interquartile range, 231-368 minutes) for innominate (P for superiority = .47). Stroke/transient ischemic attack occurred in 4 (7.1%) participants in the axillary versus 2 (3.6%) in the innominate group (P = .43). Thirty-day mortality, seizures, delirium, and duration of mechanical ventilation were similar in both groups.

CONCLUSIONS

diffusion-weighted magnetic resonance imaging assessments indicate that antegrade cerebral protection with innominate cannulation is safe and affords similar neuroprotection to axillary cannulation during aortic surgery, although the burden of new neurological lesions is high in both groups.

Feasibility of studying the association between intraoperative regional cerebral oxygen saturation and postoperative functional decline (ReFUNCTION): a pilot sub-study of NeuroVISION-Cardiac Surgery

PURPOSE

Function describes an individual's ability to perform everyday activities. In the context of cardiac surgery, functional changes quantify the effect of surgery on one's day-to-day life. Decreases in regional cerebral oxygen saturation (rScO₂) measured using near-infrared spectroscopy (NIRS) has been associated with postoperative cognitive decline but its relationship with function has not been studied. We sought to determine the feasibility of conducting a large observational study examining the relationship between decreases in rScO₂ during cardiac surgery and postoperative functional decline.

METHODS

We undertook a single-centre, pilot sub-study of the NeuroVISION-Cardiac Surgery pilot study, which included adults undergoing isolated coronary artery bypass grafting on cardiopulmonary bypass; all patients enrolled in NeuroVISION-Cardiac Surgery were included. Function was evaluated at baseline, 30 days, and three months using the Standardized Assessment of Global activities in the Elderly (SAGE) scale. Blinded NIRS monitors were affixed for the duration of surgery. Our feasibility outcomes were to recruit one patient per week, obtain complete NIRS data in ≥ 90%, obtain SAGE at all time-points in ≥ 90%, and determine the time required for NIRS data to be transcribed into case report forms.

RESULTS

49/50 patients enrolled in NeuroVISION-Cardiac Surgery were recruited over 48 weeks (1.02 patients/week). Of the 49 included patients, 49 (100%) had complete NIRS data and 44 (90%) had complete SAGE data. The time required for NIRS data collection was a mean (standard deviation) of 5.5 (1.8) min per patient.

CONCLUSION

This pilot study shows the feasibility of conducting a large observational study examining the relationship between decreases in cerebral saturation during cardiac surgery and postoperative functional decline.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04241289); registered 27 January 2020.

Photobiomodulation for Global Cerebral Ischemia: Targeting Mitochondrial Dynamics and Functions

Hypothermia is currently the only approved therapy for global cerebral ischemia (GCI) after cardiac arrest; however, it unfortunately has multiple adverse effects. As a noninvasive procedure, photobiomodulation (PBM) therapy has emerged as a potential novel treatment for brain injury. PBM involves the use of low-level laser light therapy to influence cell behavior. In this study, we evaluated the therapeutic effects of PBM treatment with an 808-nm diode laser initiated 6 h after GCI. It was noted that PBM dose-dependently protected against GCI-induced neuronal death in the vulnerable hippocampal CA1 subregion. Functional assessments demonstrated that PBM markedly preserved both short-term (a week) and long-term (6 months) spatial learning and memory function following GCI. Further mechanistic studies revealed that PBM post-treatment (a) preserved healthy mitochondrial dynamics and suppressed substantial mitochondrial fragmentation of CA1 neurons, by reducing the detrimental Drp1 GTPase activity and its interactions with adaptor proteins Mff and Fis1 and by balancing mitochondrial targeting fission and fusion protein levels; (b) reduced mitochondrial oxidative damage and excessive mitophagy and restored mitochondrial overall health status and preserved mitochondrial function; and (c) suppressed mitochondria-dependent apoptosome formation/caspase-3/9 apoptosis-processing activities. Additionally, we validated, in an in vitro ischemia model, that cytochrome c oxidase served as a key PBM target for mitochondrial function preservation and neuroprotection. Our findings suggest that PBM serves as a promising therapeutic strategy for the functional recovery after GCI, with mechanisms involving PBM's preservation on mitochondrial dynamics and functions and the inhibition of delayed apoptotic neuronal death in GCI.

Neurological complications after cardiac surgery: a retrospective case-control study of risk factors and outcome

Background

To evaluate incidence, risk factors, and outcomes of postoperative neurological complications in patients undergoing cardiac surgery.

Methods

A total of 2121 patients underwent cardiac surgery between August, 2008 and December, 2013; 91/2121 (4.3%) underwent brain computed tomography (70/91, 77%) or magnetic resonance imaging (21/91, 23%) scan because of major stroke (37/2121, 1.7%) and a spectrum of transient neurological episodes as well as transient ischemic attacks and delirium /psychosis/seizures (54/2121, 2.5%). The mean age was 65.3 ± 12.1 years and 60 (65.9%) were male. Variables were compared among study- and matched-patients (n = 113) without neurological deficits.

Results

A total of 37/2121 (1.7%) patients had imaging evidence of stroke. Radiological examinations were done 5.72 ± 3.6 days after surgery. Patients with and without imaging evidence of stroke had longer intensive care unit length of stay (LOS) (13.8 ± 14.7 and 12.9 ± 15 days vs. 5.7 ± 12.1 days, respectively (p < 0.001) and hospital LOS (53 ± 72.8 and 35.5 ± 29.8 days vs. 18.4 ± 29.2 days, respectively (p < 0.001) than the control group. The hospital mortality of patients with and without imaging evidence of stroke was higher than the control group (7/37 patients [19%], and 12/54 patients [22%] vs. 4/115 patients [3%], respectively (p < 0.001). Multivariate analysis showed that bilateral internal carotid artery stenosis of any grade (p < .001), and re-do operations (p = .013) increased the risk of postoperative neurological complications.

Conclusions

Neurological complications after cardiac surgery increase hospitalization and mortality even in patients without radiologic evidence of stroke. Bilateral internal carotid artery stenosis of any grade, suggesting a diffuse patient propensity toward atherosclerosis, and re-do operations increase the risk of postoperative neurological complications.

Coronary artery bypass graft surgery complications: A review for emergency clinicians

INTRODUCTION

Coronary artery bypass graft (CABG) surgery remains a high-risk procedure, and many patients require emergency department (ED) management for complications after surgery.

OBJECTIVE

This narrative review provides an evidence-based summary of the current data for the emergency medicine evaluation and management of post-CABG surgery complications.

DISCUSSION

While there has been a recent decline in all cardiac revascularization procedures, there remains over 200,000 CABG surgeries performed in the United States annually, with up to 14% of these patients presenting to the ED within 30 days of discharge with post-operative complications. Risk factors for perioperative mortality and morbidity after CABG surgery can be divided into three categories: patient characteristics, clinician characteristics, and postoperative factors. Emergency physicians will be faced with several postoperative complications, including sternal wound infections, pneumonia, thromboembolic phenomena, graft failure, atrial fibrillation, pulmonary hypertension, pericardial effusion, strokes, renal injury, gastrointestinal insults, and hemodynamic instability. Critical patients should be evaluated in the resuscitation bay, and consultation with the primary surgical team is needed, which improves patient outcomes. This review provides several guiding principles for management of acute complications. Understanding these complications and an approach to the management of hemodynamic instability is essential to optimizing patient care.

CONCLUSIONS

Postoperative complications of CABG surgery can result in significant morbidity and mortality. Physicians must rapidly diagnose these conditions while evaluating for other diseases. Early surgical consultation is imperative, as is optimizing the patient's hemodynamics, including preload, heart rate, cardiac rhythm, contractility, and afterload.

Contemporary Management of Patients with Concomitant Coronary and Carotid Artery Disease

The ideal management of concomitant carotid and coronary artery occlusive disease remains elusive. Although researchers have advocated the potential benefits of varying treatment strategies based on either concomitant or staged surgical treatment, there is no consensus in treatment guidelines among national or international clinical societies. Clinical studies show that coronary artery bypass grafting (CABG) with either staged or synchronous carotid endarterectomy (CEA) is associated with a high procedural stroke or death rate. Recent clinical studies have found carotid artery stenting (CAS) prior to CABG can lead to superior treatment outcomes in asymptomatic patients who are deemed high risk of CEA. With emerging data suggesting favorable outcome of CAS compared to CEA in patients with critical coronary artery disease, physicians must consider these diverging therapeutic options when treating patients with concurrent carotid and coronary disease. This review examines the available clinical data on therapeutic strategies in patients with concomitant carotid and coronary artery disease. A treatment paradigm for considering CAS or CEA as well as CABG and percutaneous coronary intervention is discussed.

Neuroprotective Strategies in Repair and Replacement of the Aortic Arch

Aortic arch surgery is a technical challenge, and cerebral protection during distal anastomosis is a continued topic of controversy and discussion. The physiologic effects of hypothermic arrest and adjunctive cerebral perfusion have yet to be fully defined, and the optimal strategies are still undetermined. This review highlights the historical context, physiological rationale, and clinical efficacy of various neuroprotective strategies during arch operations.

Coronary artery bypass grafting and paraparesis; is there a correlation?

Adult cardiac surgery is associated with significant perioperative morbidity and mortality rates, mainly in elderly patients with co-morbidities. A series of postoperative complications may arise and delay the recovery of patients undergoing cardiac surgery. Such complications also increase the burden of resource use and may affect late survival rates. Neurological complications appear mainly as stroke of varying degrees, with impairment of mobility and ability of the patient. We describe a rare case of progressive paraparesis after on-pump coronary artery bypass grafting, and review its aetiology, diagnosis and management.

Effects of Dexmedetomidine-Isoflurane versus Isoflurane Anesthesia on Brain Injury After Cardiac Valve Replacement Surgery

OBJECTIVES

To compare dexmedetomidine combined with isoflurane versus isoflurane anesthesia on brain injury after cardiac surgery.

DESIGN

A prospective, randomized, single-blind study.

SETTING

University hospital.

PARTICIPANTS

Adult patients undergoing elective valve replacement surgery.

INTERVENTIONS

Ninety-seven patients scheduled for valve replacement surgery were randomly divided into 2 groups: dexmedetomidine and isoflurane (Dex-Iso, n = 50) and isoflurane alone (Iso, n = 47). Dexemedetomidine was infused at 0.6 μg/kg as a bolus, followed with 0.2 μg/kg/h until the end of surgery.

MEASUREMENTS AND MAIN RESULTS

Jugular blood samples were drawn for analysis of matrix metalloproteinase-9 (MMP-9) and glial fibrillary acidic protein (GFAP) levels on time points of: T1 (before induction); T2 (5 minutes after cardiopulmonary bypass [CPB] onset); T3 (after CPB off); T4 (the first day after operation); T5 (the second day after operation). Plasma lactate levels in arterial and jugular venous blood also were quantified. The difference between arterial and jugular bulb venous blood lactate levels (AVDL) was calculated. An antisaccadic eye movement (ASEM) test was carried out on the day before the operation and the seventh day postoperatively. In both groups, serum MMP-9 and GFAP concentrations increased after CPB, with the peak values occurring after CPB. At time point T5, MMP-9 and GFAP levels were close to those at T1. MMP-9 concentrations in the Dex-Iso group were lower than the Iso group at T3 and T4. GFAP concentrations in the Dex-Iso group were lower at T3 but were higher than the Iso group at T2. No significant differences were found in AVDL between the 2 groups perioperatively except at T2. The ASEM scores decreased significantly postoperatively. There was no significant difference in the ASEM scores between the 2 treatment groups before and after the operation.

CONCLUSIONS

The use of dexmedetomidine decreased the biochemical markers of brain injury but did not improve the neuropsychological test result after cardiac surgery.

Risk Factors for Peri-Procedural Arterial Ischaemic Stroke in Children with Cardiac Disease

Improved survival of children with congenital heart disease has led to increasing focus on neurodevelopmental outcome, as close to half of the infants undergoing cardiac surgery are affected by neurodevelopmental disability. Stroke is particularly important as it frequently results in permanent neurologic sequelae. The aim of this study was to investigate risk factors for peri-procedural arterial ischaemic stroke (AIS) in children with cardiac disease. A retrospective case-control analysis of children aged <18 years with radiologically confirmed AIS following a cardiac procedure admitted to the Royal Children's Hospital Melbourne between 1993 and 2010. Each case was matched with two controls with similar cardiac diagnosis, procedure type, age and date of procedure. Demographics and peri-procedural data were collected from medical records and departmental database. Fifty-two cases were identified. Multivariable analysis identified post-procedural infection (OR 6.1, CI 1.3-27, p = 0.017) and length of ICU stay (OR 4.0, CI 1.4-11, p = 0.009) as risk factors for AIS. Although the study is limited to a single-centre cohort, length of ICU stay and post-procedural infection were identified as risk factors for AIS. These findings demonstrate these factors to be important areas to focus attention for stroke prevention in children with cardiac disease.

Axillary versus innominate artery cannulation for antegrade cerebral perfusion in aortic surgery: design of the Aortic Surgery Cerebral Protection Evaluation (ACE) CardioLink-3 randomised trial

INTRODUCTION

Neurological injury remains the major cause of morbidity and mortality following open aortic arch repair. Systemic hypothermia along with antegrade cerebral perfusion (ACP) is the accepted cerebral protection approach, with axillary artery cannulation being the most common technique used to establish ACP. More recently, innominate artery cannulation has been shown to be a safe and efficacious method for establishing ACP. Inasmuch as there is a lack of high-quality data comparing axillary and innominate artery ACP, we have designed a randomised, multi-centre clinical trial to compare both cerebral perfusion strategies with regards to brain morphological injury using diffusion-weighted MRI (DW-MRI).

METHODS AND ANALYSIS

110 patients undergoing elective aortic surgery with repair of the proximal arch requiring an open distal anastamosis will be randomised to either the innominate artery or the axillary artery cannulation strategy for establishing unilateral ACP during systemic circulatory arrest with moderate levels of hypothermia. The primary safety endpoint of this trial is the proportion of patients with new radiologically significant ischaemic lesions found on postoperative DW-MRI compared with preoperative DW-MRI. The primary efficacy endpoint of this trial is the difference in total operative time between the innominate artery and the axillary artery cannulation group.

ETHICS AND DISSEMINATION

The study protocol and consent forms have been approved by the participating local research ethics boards. Publication of the study results is anticipated in 2018 or 2019. If this study shows that the innominate artery cannulation technique is non-inferior to the axillary artery cannulation technique with regards to brain morphological injury, it will establish the innominate artery cannulation technique as a safe and potentially more efficient method of antegrade cerebral perfusion in aortic surgery.

TRIAL REGISTRATION NUMBER

NCT02554032.

Hypertension and Risk of Post-Operative Cognitive Dysfunction (POCD): A Systematic Review and Meta-Analysis

Background:

Post-operative cognitive dysfunction (POCD) occurs frequently after major surgery. Hypertension is well-established as a risk factor for age-related cognitive impairment, but it is unclear whether or not it also increases the risk of POCD.

Objective:

To evaluate the role of hypertension in POCD risk in a systematic review and meta-analysis.

Method:

PubMed, Ovid SP and the Cochrane Database of Systematic Reviews were searched for longitudinal studies of adults undergoing surgery with reporting of hypertension, blood pressure and/or anti-hypertensive treatment associations with POCD as relative risks or odds ratios. Fixed-effects meta-analyses were performed using Review Manager (version 5.3).

Results:

Twenty-four studies on 4317 patients (mean age 63 years) were included. None of the studies had set out to assess hypertension as a risk factor for POCD. Hypertension was used as a categorical predictor throughout and only 2 studies adjusted for potential confounders. Across all 24 studies, hypertension was not significantly associated with POCD risk (RR 1.01; 95% CI 0.93, 1.09; p=0.82), though among 8 studies with >75% males, we found hypertension associations with a 27% increased risk of POCD (RR 1.27, 95% CI 1.07, 1.49; p=0.005).

Conclusion:

Our findings do not support the hypothesis that hypertension is a risk factor for POCD. However, since none of the studies included in our analysis were hypothesis-driven and most did not adjust for potential confounders, further systematic investigations are needed to evaluate the role of hypertension in the epidemiology of POCD.

Carotid artery disease and perioperative stroke risk after surgical aortic valve replacement: A nationwide inpatient sample analysis

To study the role of carotid stenosis (CS) and cerebrovascular disease as independent risk factors for perioperative stroke following surgical aortic valve replacement (SAVR). The National Inpatient Sample (NIS) database was used for our study. All patients who underwent SAVR from 1999 to 2011 were identified using ICD-9 codes. Univariate and multivariate analysis of baseline characteristics, Elixhauser comorbidities and other covariates were examined to identify independent predictors of perioperative strokes following SAVR. Data on 50,979 patients who underwent SAVR from 1999 to 2011 was obtained. The mean age of the study cohort was 60.5. The study patients were predominantly Caucasian (79.3%) and males (60.01%). The incidence of perioperative stroke was 2.48%. CS (OR 1.8, 95%CI 1.1-2.8, p=0.009) and cerebral arterial occlusion (OR 3.4, 95% CI 1.3-8.9) significantly increased perioperative stroke risk following SAVR. Infective endocarditis (OR 4.6, 95%CI 3.8-5.6, p=0.00) and neurological disorders (OR 4.8, 95% CI 4-5.8, p=0.00) appeared to be the strongest risk factors for strokes. Other risk factors found to be significant predictors of perioperative strokes (p<0.05) were - age, higher VWR scores, CS, cerebral arterial occlusion, infective endocarditis, DM, HTN, renal failure, neurological disorders, coagulopathy and hypothyroidsm. In conclusion, perioperative stroke risk has remained more or less constant despite advancements in surgical techniques with risk having gone up in patients <65years of age. CS and cerebral arterial occlusion significantly increase stroke risk following SAVR. Improved patient selection with pre-operative risk stratification and institution of preventive strategies are necessary to improve operative outcomes following SAVR.

Combination Treatment with Methylene Blue and Hypothermia in Global Cerebral Ischemia

Therapeutic hypothermia (TH) is the most potent therapeutic strategy for global cerebral ischemia (GCI), usually induced by cardiac arrest. TH has been shown both to suppress the delayed neuronal cell death in the vulnerable hippocampal CA1 subregion and to improve neurological outcomes in experimental animals after GCI. However, given the multiple adverse effects resulting from TH, application of such a therapy is typically limited. In recent years, methylene blue (MB) has emerged as a potential therapeutic drug for the treatment of neurodegenerative diseases. In this study, we investigated the beneficial effects of mild TH combined with MB treatment after GCI. We report that both the neuronal survival in the hippocampal CA1 region and the hippocampus-dependent spatial learning and memory in the combined treatment animals were enhanced compared to those in the single treatment animals. Mechanistic studies revealed that combined TH and MB treatment significantly attenuated mitochondrial dysfunction induced by GCI in the hippocampus CA1 region. The combined treatment also markedly suppressed GCI-induced reactive gliosis and inflammation and reduced oxidative stress while enhancing the antioxidant capacity of hippocampal CA1 neurons. Finally, combining TH and MB synergistically attenuated the intrinsic cytochrome c/caspase-3 apoptotic pathway induced by GCI. Our results suggest that TH and MB act synergistically to protect the ischemic brain and suppress cognitive impairment caused by GCI.

Blood Flow Quantitation by Positron Emission Tomography During Selective Antegrade Cerebral Perfusion

BACKGROUND

Perfusion strategies during aortic surgery usually comprise hypothermic circulatory arrest (HCA), often combined with selective antegrade cerebral perfusion (SACP) or retrograde cerebral perfusion. Cerebral blood flow (CBF) is a fundamental parameter for which the optimal level has not been clearly defined. We sought to determine the CBF at a pump flow level of 6 mL/kg/min, previously shown likely to provide adequate SACP at 20°C in pigs.

METHODS

Repeated positron emission tomography (PET) scans were used to quantify the CBF and glucose metabolism throughout HCA and SACP including cooling and rewarming. Eight pigs on cardiopulmonary bypass were assigned to either HCA alone (n = 4) or HCA+SACP (n = 4). The CBF was measured by repeated [¹⁵O]water PET scans from baseline to rewarming. The cerebral glucose metabolism was examined by [¹⁸F]fluorodeoxyglucose PET scans after rewarming to 37°C.

RESULTS

Cooling to 20°C decreased the cortical CBF from 0.31 ± 0.06 at baseline to 0.10 ± 0.02 mL/cm³/min (p = 0.008). The CBF was maintained stable by SACP of 6 mL/kg/min during 45 minutes. After rewarming to 37°C, the mean CBF increased to 0.24 ± 0.07 mL/cm³/min, without significant differences between the groups at any time-point exclusive of the HCA period. The net cortical uptake (K_i) of [¹⁸F]fluorodeoxyglucose after rewarming showed no significant difference between the groups.

CONCLUSIONS

Cooling autoregulated the CBF to 0.10 mL/cm³/min, and 45 minutes of SACP at 6 mL/kg/min maintained the CBF in the present model. Cerebral glucose metabolism after rewarming was similar in the study groups.

Reducing Cerebral Emboli During Cardiopulmonary Bypass

Neurologic injury is a common complication of cardiac surgery and is associated with significant morbidity, mortality, and resource utilization. The incidence varies widely according to the definition used, patient age, and complexity of surgery. The manifestations of neurologic injury are broad, ranging from subtle neurocognitive dysfunction to frank stroke. An increasing amount of evidence points to cerebral embolization during cardiopulmonary bypass (CPB) as the principal etiologic factor of these neurologic complications. Cerebral emboli may be composed of atherosclerotic debris, calcium, air, fat, platelet thrombi, or CPB tubing. Advancements in perfusion technology, CPB techniques and surgical strategies may lead to a reduction in neurologic injury during cardiac surgery. In the current paper, we discuss the pathophysiology of neurologic injury after cardiac surgery and methods of reducing cerebral embolization. Reducing emboli and neurologic injury during CPB requires a multidisciplinary approach that includes several simple diagnostic and therapeutic strategies. Reducing cerebral emboli should be a major goal for future research in the fields of cardiac anesthesia, surgery and perfusion.

Absence of association between whole blood viscosity and delirium after cardiac surgery: a case-controlled study

Background

Delirium after cardiothoracic surgery is common and associated with impaired outcomes. Although several mechanisms have been proposed (including changes in cerebral perfusion), the pathophysiology of postoperative delirium remains unclear. Blood viscosity is related to cerebral perfusion and thereby might contribute to the development of delirium after cardiothoracic surgery. The aim of this study was to investigate whether whole blood viscosity differs between cardiothoracic surgery patients with and without delirium.

Methods

In this observational study postoperative whole blood viscosity of patients that developed delirium (cases) were compared with non-delirious cardiothoracic surgery patients (controls). Cases were matched with the controls, yielding a 1:4 case–control study. Serial hematocrit, fibrinogen, and whole blood viscosity were determined pre-operatively and at each postoperative day. Delirium was assessed using the validated Confusion Assessment Method for the Intensive Care Unit or Delirium Screening Observation scale.

Results

In total 80 cardiothoracic surgery patients were screened of whom 12 delirious and 48 matched non-delirious patients were included. No significant difference was found between both groups in fibrinogen (p = 0.36), hematocrit (p = 0.23) and the area under curve of the whole blood viscosity between shear rates 0.02 and 50 s^-1 (p = 0.80) or between shear rates 0.02 and 5 s^-1 (p = 0.78).

Conclusion

In this case control study in cardiothoracic surgery patients changes in whole blood viscosity were not associated with the development of delirium.

Upper gastrointestinal bleeding following transcatheter aortic valve replacement: A retrospective analysis

OBJECTIVES

The aim of this study was to identify the incidence of upper gastrointestinal bleeding (UGIB) in the postprocedural period following transcatheter aortic valve replacement (TAVR).

BACKGROUND

As TAVR moves into intermediate- and low-risk patients, it has become increasingly important to understand its extracardiac complications. The patient population undergoing TAVR have clinical and demographic characteristics that place them at significant risk of UGIB. Practical aspects of TAVR, including use of antithrombotic therapy, further increase risk of UGIB.

METHODS

A retrospective single-center evaluation of 841 patients who underwent TAVR between January 2005 and August 2014 was performed in conjunction with analysis of referral patterns to the gastroenterology service for UGIB at the same site.

RESULTS

The overall risk of UGIB following TAVR was found to be 2.0% (n = 17/841). Additionally, the risk of UGIB in patients receiving triple antithrombotic therapy was found to be 10-fold greater than patients not receiving triple antithrombotic therapy (11.8% vs 1.0%). Endoscopy findings demonstrated five high-risk esophageal lesions including erosive esophageal ulcers, visible vessels at the GE junction, erosions at distal esophagus, and an actively bleeding esophageal ring that had been intubated through by the transesophageal echocardiography (TEE) probe.

CONCLUSIONS

This large cohort study demonstrates that TAVR is associated with a moderate risk of severe UGIB. The results of this study suggest that patients on triple antithrombotic therapy are at highest risk for severe UGIB. © 2016 Wiley Periodicals, Inc.

Routine postoperative care of patients undergoing coronary artery bypass grafting on cardiopulmonary bypass

The postoperative course of a patient undergoing cardiac surgery (CS) is dictated by a largely predictable set of interactions between disease-specific and therapeutic factors. ICU personnel need to quickly develop a detailed understanding of the patient's current status and how critical care resources can be used to promote further recovery and eventual independence from external support. The goal of this article is to describe a typical operative and postoperative course, with emphasis on the latter, and the diagnostic and therapeutic options necessary for the proper care of these patients. This paper will focus on coronary artery bypass grafting as a model for understanding the course of CS patients; however, many of the principles discussed are applicable to most cardiac surgery patients.

Cell-Permeable Peptide Targeting the Nrf2-Keap1 Interaction: A Potential Novel Therapy for Global Cerebral Ischemia

The current study examined efficacy of a small Tat (trans-activator of transcription)-conjugated peptide activator of the Nrf2 (nuclear factor-E2-related factor-2) antioxidant/cell-defense pathway as a potential injury-specific, novel neuroprotectant against global cerebral ischemia (GCI). A competitive peptide, DEETGE-CAL-Tat, was designed to facilitate Nrf2 activation by disrupting interaction of Nrf2 with Keap1 (kelch-like ECH-associated protein 1), a protein that sequesters Nrf2 in the cytoplasm and thereby inactivates it. The DEETGE-CAL-Tat peptide contained the critical sequence DEETGE for the Nrf2-Keap1 interaction, the cell transduction domain of the HIV-Tat protein, and the cleavage sequence of calpain, which is sensitive to Ca(2+) increase and allows injury-specific activation of Nrf2. Using an animal model of GCI, we demonstrated that pretreatment with the DEETGE-CAL-Tat peptide markedly decreased Nrf2 interaction with Keap1 in the rat hippocampal CA1 region after GCI, and enhanced Nrf2 nuclear translocation and DNA binding. The DEETGE-CAL-Tat peptide also induced Nrf2 antioxidant/cytoprotective target genes, reduced oxidative stress, and induced strong neuroprotection and marked preservation of hippocampal-dependent cognitive function after GCI. These effects were specific as control peptides lacked neuroprotective ability. Intriguingly, the DEETGE-CAL-Tat peptide effects were also injury specific, as it had no effect upon neuronal survival or cognitive performance in sham nonischemic animals. Of significant interest, peripheral, postischemia administration of the DEETGE-CAL-Tat peptide from days 1-9 after GCI also induced robust neuroprotection and strongly preserved hippocampal-dependent cognitive function. Based on its robust neuroprotective and cognitive-preserving effects, and its unique injury-specific activation properties, the DEETGE-CAL-Tat peptide represents a novel, and potentially promising new therapeutic modality for the treatment of GCI.

SIGNIFICANCE STATEMENT

The current study demonstrates that DEETGE-CAL-Tat, a novel peptide activator of a key antioxidant gene transcription pathway in the hippocampus after global cerebral ischemia, can exert robust neuroprotection and preservation of cognitive function. A unique feature of the peptide is that its beneficial effects are injury specific. This feature is attractive as it targets drug activation specifically in the site of injury, and likely would lead to a reduction of undesirable side effects if translatable to the clinic. Due to its injury-specific activation, robust neuroprotection, and cognitive-preserving effects, this novel peptide may represent a much-needed therapeutic advance that could have efficacy in the treatment of global cerebral ischemia.

Neurologic aspects of cardiac emergencies

In this review, cardiac arrest is discussed, with a focus on neuroprognostication and the emerging data, with regard to identifying more accurate predictors of neurologic outcomes in the era of therapeutic hypothermia. Topics discussed include recent controversies with regard to targeted temperature management in comatose survivors of cardiac arrest; neurologic complications associated with surgical disease and procedures, namely aortic dissection, infective endocarditis, left ventricular assist devices, and coronary artery bypass grafting; and the cause, pathogenesis, and management of neurogenic stunned myocardium.

Prosurvival NMDA 2A receptor signaling mediates postconditioning neuroprotection in the hippocampus

Ischemic postconditioning (Post C), which involves administration of a brief ischemia after the initial ischemic event, has been demonstrated to be strongly neuroprotective against global cerebral ischemia (GCI) and to improve cognitive outcome. To enhance understanding of the underlying mechanisms, the current study examined the role of NMDA receptors in mediating the beneficial effects of Post C (3 min ischemia) administered 2 days after GCI in adult male rats. The results revealed that Post C was strongly neuroprotective against GCI, and that this effect was blocked by administration of the NMDA receptor antagonist MK-801. Further work revealed that the NR2A-type NMDA receptors mediate the Post C beneficial effects as administration of a NR2A-preferring antagonist (NVP-A) blocked Post C neuroprotection and cognitive enhancement, while administration of a NR2B-preferring antagonist (Ro25) was without effect. Post C significantly up-regulated NR2A levels and phosphorylation of NR2A in the hippocampal CA1 region after Post C. Post C also increased Ca(2+) influx and activation/phosphorylation of CamKIIα at Thr(286), effects that were NR2A mediated as they were blocked by NVP-A. Phosphorylation of ERK and CREB was also increased by Post C, as were two downstream CREB-dependent prosurvival factors, brain derived neurotropic factor (BDNF) and Bcl2, effects that were blocked by the NR2A antagonist, NVP-A. Taken as a whole, the current study provides evidence that NR2A-activation and downstream prosurvival signaling is a critical mediator of Post C-induced neuroprotection and cognitive enhancement following GCI.

Impact of perioperative acute ischemic stroke on the outcomes of noncardiac and nonvascular surgery: a single centre prospective study

BACKGROUND

Although ischemic stroke is a well-known complication of cardiovascular surgery it has not been extensively studied in patients undergoing noncardiac surgery. The aim of this study was to assess the predictors and outcomes of perioperative acute ischemic stroke (PAIS) in patients undergoing noncardiothoracic, nonvascular surgery (NCS).

METHODS

We prospectively evaluated patients undergoing NCS and enrolled patients older than 18 years who underwent an elective, non-daytime, open surgical procedure. Electrocardiography and cardiac biomarkers were obtained 1 day before surgery, and on postoperative days 1, 3 and 7.

RESULTS

Of the 1340 patients undergoing NCS, 31 (2.3%) experienced PAIS. Only age (odds ratio [OR] 2.5, 95% confidence interval [CI] 1.01-3.2, p < 0.001) and preoperative history of stroke (OR 3.6, 95% CI 1.2-4.8, p < 0.001) were independent predictors of PAIS according to multivariate analysis. Patients with PAIS had more cardiovascular (51.6% v. 10.6%, p < 0.001) and noncardiovascular complications (67.7% v. 28.3%, p < 0.001). In-hospital mortality was 19.3% for the PAIS group and 1% for those without PAIS (p < 0.001).

CONCLUSION

Age and preoperative history of stroke were strong risk factors for PAIS in patients undergoing NCS. Patients with PAIS carry an elevated risk of perioperative morbidity and mortality.

Neurologic complications of cardiac surgery and interventional cardiology

A wide array of neurologic complications can occur in relation to cardiac surgical procedures, most of which are transient and do not result in permanent sequelae. Specific neurologic insults can occur depending on the type of cardiac procedure and are an important cause of morbidity and mortality. Neurologists practicing in the hospital setting as well as outpatient neurologists should be familiar with the cardiac surgical procedures currently available. Prompt identification of neurologic deficits is important in order to plan an appropriate systematic evaluation and initiate possible treatments in a timely manner. This chapter provides a comprehensive overview of all facets of neurologic complications after cardiac surgical procedures.