Neurological Damage Related to Cardiac Surgery: Pathophysiology, Diagnostic Tools and Prevention Strategies. Using Actual Knowledge for Planning the Future

Coronary heart disease increases the risk of perioperative ischemic stroke after noncardiac surgery: A retrospective cohort study

OBJECTIVE

To investigate the association between coronary heart disease (CHD) and the risk of perioperative ischemic stroke in patients undergoing noncardiac surgery.

METHODS

This retrospective study evaluated the incidence of ischemic stroke within 30 days after a noncardiac surgery. A cohort of 221,541 patients who underwent noncardiac surgery between January 2008 and August 2019 was segregated according to whether they were diagnosed with CHD. Primary, sensitivity, and subgroup logistic regression analyses were conducted to confirm that CHD is an independent risk factor for perioperative ischemic stroke. Propensity score matching analysis was used to account for the potential residual confounding effect of covariates.

RESULTS

Among the 221,541 included patients undergoing noncardiac surgery, 484 patients (0.22%) experienced perioperative ischemic stroke. The risk of perioperative ischemic stroke was higher in patients with CHD (0.7%) compared to patients without CHD (0.2%), and multivariate logistic regression analysis showed that CHD was associated with a significantly increased risk of perioperative ischemic stroke (odds ratio (OR), 3.7943; 95% confidence interval (CI) 2.865-4.934; p < 0.001). In a subset of patients selected by propensity score matching (PSM) in which all covariates between the two groups were well balanced, the association between CHD and increased risk of perioperative ischemic stroke remained significantly significant (OR 1.8150; 95% CI, 1.254-2.619; p = 0.001). In the subgroup analysis stratified by age, preoperative β-blockers, and fibrinogen-to-albumin ratio (FAR), the association between CHD and perioperative ischemic stroke was stable (p for interaction >0.05). Subgroup analyses also showed that CHD was significantly increased the risk of perioperative ischemic stroke in the preoperative mean arterial pressure (MAP) ≥94.2 mmHg subgroups (p for interaction <0.001).

CONCLUSION

CHD is significantly associated with an increased risk of perioperative ischemic stroke and is an independent risk factor for perioperative ischemic stroke after noncardiac surgery. Strict control of preoperative blood pressure may reduce the risk of perioperative ischemic stroke for patients with CHD undergoing noncardiac surgery.

Epilepsy in patients undergoing cardiac surgery with ExtraCorporeal Circulation: case series and description of a peculiar clinical phenotype

BACKGROUND

Extracorporeal circulation (ECC) is now being increasingly used in critical care settings. Epileptic seizures are a recognized but under reported complication in patients receiving this care. Acute symptomatic post-operative seizures have been described, as well as remote seizure, mostly in the form of convulsive seizures. Epilepsy has also been reported, although with lower frequency and mainly with convulsive seizures, while different seizure semiology is rarely described.

CASE PRESENTATION

We report a case series of four patients developing epilepsy with homogeneous features following heart surgery with ECC. We present neurophysiological and neuroradiological data and we describe the peculiar characteristics of epilepsies in terms of seizure semiology, frequency, and drug response. The main features are: an insulo-temporal or parieto-occipital semiology, often multifocal and without loss of consciousness or motor manifestations, a high frequency of seizures but with low impact on daily life, and a good response to anti-epileptic therapy.

CONCLUSIONS

We hypothesize a pathogenetic mechanism and we discuss the clinical implications of identifying these forms of epilepsy which tend to be often under-recognized.

Postoperative cognitive decline: the nurse's role in identifying this underestimated and misinterpreted condition

BACKGROUND

postoperative cognitive changes can increase morbidity and mortality, demand for postoperative care and social and health costs, and can lead to dementia.

AIM

this article discusses perioperative variables that can be used to identify patients who are more vulnerable to experiencing cognitive decline after surgery. It also highlights some screening tools that could be useful for early detection and for planning nursing care.

METHOD

a literature search was conducted using the Medline, CINAHL, PsychINFO and Cochrane Library databases from 2010 to 2018. Google Scholar was also consulted. The reference lists of relevant articles covering postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) were reviewed for further relevant papers.

CONCLUSION

assessment and evaluation of a patient's cognitive resources before and after surgery can lead to clinical interventions to support the person's coping mechanisms; health professionals can reduce the short- and long-term effects of cognitive decline. Screening tools could be used as part of a strategy to minimise postoperative cognitive changes.

The value of a cross-discipline team-based approach for resection of renal cell carcinoma with IVC tumor thrombus: A report of a large, contemporary, single-institution experience

INTRODUCTION

We report the evolution of the largest, contemporary, single-institution experience with this complex procedure to highlight the value of a cross-discipline, team-based approach.

METHODS

Patients from a prospectively maintained database who underwent resection of renal cell carcinoma (RCC) with inferior vena cava (IVC) tumor thrombus from 2005 to 2016 at a single-institution were included for analysis.

RESULTS

Of 140 patients, 102 (73%) had tumor thrombus below the level of the hepatic vein confluence, and 96 (69%) were performed for curative-intent, while 43 (31%) were cytoreductive procedures for clinical trial consideration. Median overall survival (OS) of the entire cohort was 43.8 months (5-year OS:43%), and 73.6 months (5-year OS:59%) for those without metastatic disease. Fifty-one patients underwent resection from 2005 to 2010 and 89 from 2011 to 2016. All procedures since 2011 were performed by the same cross-discipline dedicated team of two surgeons, composed of a surgical and urological oncologist. When comparing the two time-periods, the team-approach after 2011 had shorter operative-times (5.3 vs 6.7 hours; P = 0.009), decreased ICU-utilization (25% vs 72%; P < 0.001), and decreased ICU length-of-stay (0.4 vs 2.2 days; P = 0.001). This group also trended towards less blood loss (1.2 vs 1.8 L), shorter average hospital length-of-stay (10 vs 11 days), and decreased 90-day mortality (6% vs 10%).

CONCLUSION

Resection of RCC with IVC tumor thrombus yields long-term survival. A dedicated, cross-discipline, and team-based approach optimizes patient outcomes and may improve value of care by reducing utilization of expensive hospital resources.

Soft robotic ventricular assist device with septal bracing for therapy of heart failure

Previous soft robotic ventricular assist devices have generally targeted biventricular heart failure and have not engaged the interventricular septum that plays a critical role in blood ejection from the ventricle. We propose implantable soft robotic devices to augment cardiac function in isolated left or right heart failure by applying rhythmic loading to either ventricle. Our devices anchor to the interventricular septum and apply forces to the free wall of the ventricle to cause approximation of the septum and free wall in systole and assist with recoil in diastole. Physiological sensing of the native hemodynamics enables organ-in-the-loop control of these robotic implants for fully autonomous augmentation of heart function. The devices are implanted on the beating heart under echocardiography guidance. We demonstrate the concept on both the right and the left ventricles through in vivo studies in a porcine model. Different heart failure models were used to demonstrate device function across a spectrum of hemodynamic conditions associated with right and left heart failure. These acute in vivo studies demonstrate recovery of blood flow and pressure from the baseline heart failure conditions. Significant reductions in diastolic ventricle pressure were also observed, demonstrating improved filling of the ventricles during diastole, which enables sustainable cardiac output.

Hemoglobin Concentration Affects Electroencephalogram During Cardiopulmonary Bypass: An Indication for Neuro-Protective Values

Hemodilution during cardiopulmonary bypass (CPB) is widely used to decrease transfusion and improve microcirculation but has drawbacks, such as diminished hemoglobin levels. Among others, reduced brain oxygenation accounts for neurological adverse outcomes after CPB. The aim of the present study was to ascertain if and how continuous electroencephalogram (EEG) during CPB is affected by hematocrit level and what should be the minimum value to avoid significant frequency band shifts on the EEG. A comparative study design was used with 16 subjects undergoing elective mitral valve repair/replacement. EEG was continuously recorded during the surgical procedure (from anesthesia induction to 20 min after CPB end). Data were marked at relevant time points (T0: before CPB start; T1: after 30 min from CPB beginning; T2: at CPB end), and the following 2 min EEG analyzed with a fast Fourier transform to obtain relative power for delta, theta, alpha, and beta bands. A general linear model for repeated measure was used to study interactions of time (T0, T1, and T2, EEG frequency band, and topographical distribution. The relative powers for each electrode were calculated and represented using topographic maps. Power spectrum differences between time points (T2-T1; T2-T0; T1-T0) were calculated for each electrode, and differences >10%, considered indicative of neuronal sufferance, were included in further analysis. Cutoff hemoglobin values that maximize the proportion of correctly classified EEG band shifts were obtained by previous definition were obtained. At T2, diffuse EEG slowing in delta and theta bands was detected; a minor slowing over anterior regions was evident at T1 for the theta band. Decrements in EEG power greater than 10% were detected only for the delta band at T2. Hemoglobin concentration levels at which no slowing increase was evident were 9.4 mg/dL (Ht: 28.2%) at T1 and 9.2 mg/dL (Ht: 27.6%) at T2. EEG burst-suppression pattern related to a lesser degree of slowing at T2. In conclusion, we propose hemoglobin cutoff levels that prevent EEG slowing indicative of neuronal sufferance. In addition, burst-suppression EEG patterns offer higher central nervous system protection as measured on EEG.

Stroke after coronary artery surgery: a single center report

Stroke or cerebrovascular accident (CVA) is a devastating complication of coronary surgery. In this report, the incidence, and correlates of CVA following isolated coronary artery bypass grafting (CABG) surgery were evaluated. Data were collected retrospectively. Between 2006 and 2009, 855 patients underwent isolated CABG surgery. CVA was defined as any new neurological deficit lasting more than 24 hours. Univariate and multivariate analyses were utilized as appropriate. The incidence of CVA was 1.4% (n = 12). Age, previous CVA, and emergency surgery were correlated by univariate analysis. Multivariate analysis revealed age, previous CVA, and chronic renal impairment as predictors of CVA. Ten (83.3%) of the 12 patients were diagnosed to have CVA in the first 24 hours. Length of hospital stay was 20.9 ± 20.34 days for CVA patients and 9.2 ± 5.17 days for non-CVA patients (p ≤ 0.001). There were 4 (33.3%) deaths in CVA group and 27 (3.2%) for non-CVA patients (p = 0.001). Postoperative CVA is a major contributor to mortality, prolonged hospitalization, and other adverse postoperative complications. Further studies are needed to develop better strategies to minimize the occurrence of CVA among patients undergoing CABG.

Sleep-disordered breathing is a risk factor for delirium after cardiac surgery: a prospective cohort study

Introduction

Delirium is a frequent complication after cardiac surgery. Although various risk factors for postoperative delirium have been identified, the relationship between nocturnal breathing disorders and delirium has not yet been elucidated. This study evaluated the relationship between sleep-disordered breathing (SDB) and postoperative delirium in cardiac surgery patients without a previous diagnosis of obstructive sleep apnea.

Methods

In this prospective cohort study, 92 patients undergoing elective cardiac surgery with extracorporeal circulation were evaluated for both SDB and postoperative delirium. Polygraphic recordings were used to calculate the apnea-hypopnea index (AHI; mean number of apneas and hypopneas per hour recorded) of all patients preoperatively. Delirium was assessed during the first four postoperative days using the Confusion Assessment Method. Clinical differences between individuals with and without postoperative delirium were determined with univariate analysis. The relationship between postoperative delirium and those covariates that were associated with delirium in univariate analysis was determined by a multivariate logistic regression model.

Results

The median overall preoperative AHI was 18.3 (interquartile range, 8.7 to 32.8). Delirium was diagnosed in 44 patients. The median AHI differed significantly between patients with and without postoperative delirium (28 versus 13; P = 0.001). A preoperative AHI of 19 or higher was associated with an almost sixfold increased risk of postoperative delirium (odds ratio, 6.4; 95% confidence interval, 2.6 to 15.4; P <0.001). Multivariate logistic regression analysis showed that preoperative AHI, age, smoking, and blood transfusion were independently associated with postoperative delirium.

Conclusions

Preoperative SDB (for example, undiagnosed obstructive sleep apnea) were strongly associated with postoperative delirium, and may be a risk factor for postoperative delirium.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0477-1) contains supplementary material, which is available to authorized users.

Detection of cerebral arterial gas embolism using regional cerebral oxygen saturation, quantitative electroencephalography, and brain oxygen tension in the swine

BACKGROUND

Cerebral air emboli occur as a complication of invasive medical procedures. The sensitivity of cerebral monitoring methods for the detection of air emboli is not known. This study investigates the utility of electroencephalography and non-invasively measured cerebral oxygen saturation in the detection of intracerebrovascular air.

NEW METHOD

In 12 pigs oxygen saturation was continuously measured using transcranial near-infrared spectroscopy and oxygen tension was continuously measured using intraparenchymal probes. Additionally, quantitative electroencephalography and microdialysis were performed. Doses of 0.2, 0.4, 0.8, and 1.6 ml of air were injected into the cerebral arterial vasculature through a catheter.

RESULTS

Oxygen saturation and electroencephalography both reacted almost instantaneously on the air emboli, but were less sensitive than the intraparenchymal oxygen tension. There was reasonable correlation (ρ ranging from 0.417 to 0.898) between oxygen saturation, oxygen tension, electroencephalography and microdialysis values.

COMPARISON WITH EXISTING METHODS

Our study is the first to demonstrate the effects of cerebral air emboli using multimodal monitoring, specifically on oxygen saturation as measured using near-infrared spectroscopy.

CONCLUSIONS

Our results show that non-invasively measured oxygen saturation and quantitative electroencephalography can detect the local effects of air emboli on cerebral oxygenation, but with reduced sensitivity as compared to intraparenchymal oxygen tension. Prospective human studies using multimodal monitoring incorporating electroencephalography and oxygen saturation should be performed.

Postoperative stroke related to cardiac surgery in octogenarians

OBJECTIVES

Demographics of cardiac surgery patients are changing, with an increase in aged patients. We aim to identify risk factors, mortality, morbidity and increasing postoperative costs due to postoperative stroke in octogenarians following cardiopulmonary bypass (CPB).

METHODS

A total of 418 consecutive patients older than 80 years (Group A) who underwent cardiac surgery with CPB between 2000 and 2012 were matched according to gender, surgical procedure and comorbidities with 426 younger patients (Group B). Risk factors for postoperative stroke were retrospectively evaluated.

RESULTS

We identified postoperative stroke in 4.1% of patients in Group A and in 3.5% in Group B (P = 0.65). Early stroke was diagnosed in 13 patients in Group A (76.5%) and 10 patients in Group B (66.7%) (P = 0.53). In multivariate analysis, preoperative anaemia (P = 0.033; odds ratio [OR]: 3.84; 95% CI: 1.11-13.28) was the only risk factor associated with postoperative stroke in Group A. In Group B, preoperative peripheral vascular disease (P = 0.0003; OR: 7.30; 95% CI: 2.47-21.55) and postoperative atrial fibrillation (P = 0.0134; OR: 4.05; 95% CI: 1.33-12.31) were identified as risk factors.

CONCLUSIONS

Incidence of postoperative stroke after CPB was not significantly higher in our octogenarian population. Although in younger patients peripheral vascular disease and cardiac rhythm disturbances were significant risk factors, it seems that factors related to intraoperative brain oxygenation (secondary to preoperative anaemia) are the most critical determinant of stroke in the elderly.

Repair of posterior mitral valve prolapse with a novel leaflet plication clip in an animal model

OBJECTIVE

Recently, there has been increased interest in minimally invasive mitral valve prolapse repair techniques; however, these techniques have limitations. A new technique was developed for treating mitral valve prolapse that uses a novel leaflet plication clip to selectively plicate the prolapsed leaflet segment. The clip's efficacy was tested in an animal model.

METHODS

Yorkshire pigs (n = 7) were placed on cardiopulmonary bypass (CPB), and mitral valve prolapse was created by cutting chordae supporting the P2 segment of the posterior leaflet. Animals were weaned off CPB and mitral regurgitation (MR) was assessed echocardiographically. CPB was reinitiated and the plication clip was applied under direct vision to the P2 segment to eliminate the prolapse. The animals survived for 2 hours. Epicardial echocardiography was obtained before and after prolapse creation and 2 hours after clip placement to quantify MR grade and vena contracta area. Posterior leaflet mobility and coaptation height were analyzed before and after clip placement.

RESULTS

There were no cases of clip embolization. Median MR grade increased from trivial (0-1.5) to moderate-severe after MR creation (2.5-4+) (P < .05), and decreased to mild after clip placement (0-3+) (P < .05). Vena contracta area tended to increase after cutting the chordae and decrease after clip placement: 0.08 ± 0.10 cm(2) versus 0.21 ± 0.15 cm(2) versus 0.16 ± 0.16 cm(2) (P = .21). The plication clip did not impair leaflet mobility. Coaptation height was restored to baseline: 0.51 ± 0.07 cm versus 0.44 ± 0.18 cm (P = 1.0).

CONCLUSIONS

The leaflet plication clip can treat mitral valve prolapse in an animal model, restoring coaptation height without affecting leaflet mobility. This approach is a simple technique that may improve the effectiveness of beating-heart and minimally invasive valve surgery.

Use of EuroSCORE as a predictor of morbidity after cardiac surgery

OBJECTIVE

To evaluate the use of the EuroSCORE as a predictor of postoperative morbidity after cardiac surgery.

METHODS

We retrospectively analyzed the charts of 900 patients operated on and admitted to the intensive care unit postoperatively at the Royal Portuguese Hospital of Recife. We included all patients with complete medical records, excluding those who died during surgery, underwent transplantation or correction of congenital heart disease. We evaluated the development of respiratory infection, cerebrovascular accident, and dialysis-dependent renal failure, and the EuroSCORE was compared in terms of the three complications using the Mann-Whitney test. The calibration model for predicting the morbidities being studied was evaluated using the test set of Homer-Lemeshow goodness. The accuracy of the model was assessed using the area under the ROC curve (AUROC).

RESULTS

The model showed good calibration in predicting respiratory infection, acute renal failure and stroke (P=0.285, P=0.789, P=0.45, respectively), with good accuracy for respiratory infection (AUROC=0.710 and P<0.001) and dialysis-dependent renal failure (AUROC=0.834 and P<0.001), but no accuracy to predict stroke (AUROC=0.519). The high-risk patients were more likely to develop respiratory infection (OR=9.05, P<0.001) and dialysis-dependent renal failure (OR=39.6, P<0.001). The probability of developing respiratory infection and dialysis-dependent renal failure was less than 10% with EuroSCORE up to 7 and more than 70% with EuroSCORE greater than 15.

CONCLUSION

EuroSCORE proved to be a good predictor of major postoperative morbidity in cardiac surgery: respiratory and dialysis-dependent renal failure.

Challenges of cardiopulmonary bypass-a review of the veterinary literature

Cardiopulmonary bypass (CPB) has been used in veterinary medicine in experimental surgery and to address congenital and acquired diseases. We review the veterinary literature and expose common challenges of CPB in dogs and cats. Specifically, we describe the most specific elements of this technique in veterinary patients. The variety in animal size has made it difficult to standardize cannulation techniques, oxygenators, and priming volumes and solutions. The fact that one of the most common cardiovascular disorders, mitral valve disease, occurs predominantly in small dogs has limited the use of bypass in these patients because of the need for small, low prime oxygenators and pumps that have been unavailable until recently. Coagulation, hemostasis, and blood product availability have also represented important factors in the way CPB has developed over the years. The cost and the challenges in operating the bypass machine have represented substantial limitations in its broader use.

Studies of isolated global brain ischaemia: I. A new large animal model of global brain ischaemia and its baseline perfusion studies

OBJECTIVES

Neurological injury after global brain ischaemia (i.e. sudden death) remains problematic, despite improving cardiac survival. Unfortunately, sudden death models introduce unwanted variables for studying the brain because of multiple organ injury. To circumvent this, a new minimally invasive large animal model of isolated global brain ischaemia, together with baseline perfusion studies is described.

METHODS

The model employs neck and small (3-4 inches) supra-sternal incisions to block inflow from carotid and vertebral arteries for 30 min of normothermic ischaemia. Neurological changes after 24 h in six pigs was compared with six Sham pigs assessing neurological deficit score (NDS, 0 = normal, 500 = brain death), brain oedema and cerebral infarction by 2,3,5-triphenyltetrazolium chloride (TTC) stain. Six other pigs had baseline perfusion characteristics in this new model evaluated at carotid flows of 750, 550 and 450 cc/min, with cerebral perfusion pressure, cerebral oximeter saturation [IN Vivo Optical Spectroscopy (INVOS)] and transcranial O(2) uptake measurements.

RESULTS

The model never altered cardiac or pulmonary function, and six Sham pigs had normal (NDS = 0) neurological recovery without brain injury. Conversely, 24 h analysis showed that 30 min of global normothermic brain ischaemia caused multiple post-reperfusion seizures (P < 0.001 versus Sham), raised NDS (231 ± 16; P < 0.001 versus Sham) in four of six survivors and caused marked post-brain oedema (P < 0.001 versus Sham) and extensive cerebral infarctions (TTC stain; P < 0.001 versus Sham). Baseline perfusion showed 750 cc/min flow rate produced normal INVOS levels and O(2) consumption at mean 90-100 mmHg carotid pressure. Carotid pressure and INVOS fell at mid- and low-flow rates. Although INVOS did not change, 450 cc/min flow lowered global O(2) consumption, which further decreased after transient ischaemia (30 s) and 5 min of reperfusion.

CONCLUSIONS

This new isolated global brain model consistently caused anatomic, biochemical and functional neurological damage in pigs after 30 min of ischaemia. Flows of 750 cc/min maintained normal mean systemic arterial (90-100 mmHg) pressure, INVOS levels and O(2) consumption. Cerebral pressure and INVOS fell in mid- and low-flow studies. A disparity existed between INVOS oxygen saturation and global O(2) consumption at lower flow rates of 450 cc/min following transient ischaemia, indicating that surface oxygen saturation measurement does not reflect global brain O(2) consumption.

Use of blood products and risk of stroke after coronary artery bypass surgery

BACKGROUND

The impact of blood transfusion on the development of post-operative stroke after coronary artery bypass grafting (CABG) is not well established. We, therefore, investigated this issue.

MATERIALS AND METHODS

Complete data on peri-operative blood transfusion were available for 2,226 patients who underwent CABG in three Finnish hospitals.

RESULTS

Stroke occurred post-operatively in 53 patients (2.4%). Logistic regression showed that pre-operative creatinine (OR 1.003, 95% CI 1.000-1.006), extracardiac arteriopathy (OR 2.344, 95% CI 1.133-4.847), pre-operative atrial fibrillation (OR 2.409, 95% CI 1.149-5.052), and the number of packed red blood cell units transfused (OR 1.121, 95% CI 1.065-1.180) were significantly associated with post-operative stroke. When the various blood product transfusions instead of transfused units were included in the multivariable analysis, solvent/detergent treated plasma (Octaplas) transfusion (OR 2.149, 95% CI 1.141-4.047), but not red blood cell transfusion, was significantly associated with postoperative stroke. Use of blood products ranging from no transfusion (stroke rate 1.6%) to combined transfusion of red blood cells, platelets and Octaplas was associated with a significant increase in post-operative stroke incidence (6.6%, adjusted analysis: OR 1.727, 95% 1.350-2.209). Patients who received >2 units of red blood cells, >4 units of Octaplas units and >8 units of platelets had the highest stroke rate of 21%. CART analysis showed that increasing amount of transfused Octaplas, platelets and history of extracardiac arteriopathy were significantly associated with post-operative stroke.

CONCLUSIONS

Transfusion of blood products after CABG has a strong, dose-dependent association with the risk of stroke. The use of Octaplas and platelet transfusions seem to have an even larger impact on the development of stroke than red blood cell transfusions.

Brain damage in cardiac surgery patients

Neuropsychological disorders and brain injury are still a serious problem in cardiac surgery patients. Owing to multifactorial mechanism of brain injury during extracorporeal circulation, the effective and safe protection is extremely difficult. Despite several studies, the ideal neuroprotective treatment has not been found. Based on literature we analysed the main mechanisms of brain injury and new methods of brain protection.

Neurologic complications of cardiac surgery and interventional cardiac procedures

Neurologic complications of cardiac surgery and interventional cardiac procedures may affect the central nervous system or the peripheral nervous system. The most common central nervous system complications are strokes and seizures. This article provides a succinct neuroanatomic and pathophysiologic approach to a wide array of neurologic complications associated with cardiac procedures.