Brain-Heart Axis and the Inflammatory Response: Connecting Stroke and Cardiac Dysfunction

BACKGROUND

In recent years, the mechanistic interaction between the brain and heart has been explored in detail, which explains the effects of brain injuries on the heart and those of cardiac dysfunction on the brain. Brain injuries are the predominant cause of post-stroke deaths, and cardiac dysfunction is the second leading cause of mortality after stroke onset.

SUMMARY

Several studies have reported the association between brain injuries and cardiac dysfunction. Therefore, it is necessary to study the influence on the heart post-stroke to understand the underlying mechanisms of stroke and cardiac dysfunction. This review focuses on the mechanisms and the effects of cardiac dysfunction after the onset of stroke (ischemic or hemorrhagic stroke).

KEY MESSAGES

The role of the site of stroke and the underlying mechanisms of the brain-heart axis after stroke onset, including the hypothalamic-pituitary-adrenal axis, inflammatory and immune responses, brain-multi-organ axis, are discussed.

Emergency Medical Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is a medical emergency that necessitates direct transfer to a tertiary referral center specialized in the diagnosis and treatment of this condition. The initial hours after aneurysmal rupture are critical for patients with aneurysmal subarachnoid hemorrhage, both in terms of rebleeding and combating the effect of early brain injury. No good treatment options are available to reduce the risk of rebleeding before aneurysm occlusion. Lowering the blood pressure may reduce the risk of rebleeding but carries a risk of inducing delayed cerebral ischemia or aggravating the consequences of early brain injury. Early brain injury after aneurysmal rupture has an important effect on final clinical outcome. Proper cerebral perfusion is pivotal in these initial hours after aneurysmal rupture but threatened by complications such as neurogenic pulmonary edema and cardiac stunning, or by acute hydrocephalus, which may necessitate early drainage of cerebrospinal fluid.

Sex-specific extracerebral complications in patients with aneurysmal subarachnoid hemorrhage

Background

Extracerebral complications in patients with aneurysmal subarachnoid hemorrhage (aSAH) often occur during their stay at the neurocritical care unit (NCCU). Their influence on outcomes is poorly studied. The identification of sex-specific extracerebral complications in patients with aSAH and their impact on outcomes might aid more personalized monitoring and therapy strategies, aiming to improve outcomes.

Methods

Consecutive patients with aSAH admitted to the NCCU over a 6-year period were evaluated for the occurrence of extracerebral complications (according to prespecified criteria). Outcomes were assessed with the Glasgow Outcome Scale Extended (GOSE) at 3 months and dichotomized as favorable (GOSE 5-8) and unfavorable (GOSE 1-4). Sex-specific extracerebral complications and their impact on outcomes were investigated. Based on the results of the univariate analysis, a multivariate analysis with unfavorable outcomes or the occurrence of certain complications as dependent variables was performed.

Results

Overall, 343 patients were included. Most of them were women (63.6%), and they were older than men. Demographics, presence of comorbidities, radiological findings, severity of bleeding, and aneurysm-securing strategies were compared among the sexes. More women than men suffered from cardiac complications (p = 0.013) and infection (p = 0.048). Patients with unfavorable outcomes were more likely to suffer from cardiac (p < 0.001), respiratory (p < 0.001), hepatic/gastrointestinal (p = 0.023), and hematological (p = 0.021) complications. In the multivariable analysis, known factors including age, female sex, increasing number of comorbidities, increasing World Federation of Neurosurgical Societies (WFNS), and Fisher grading were expectedly associated with unfavorable outcomes. When adding complications to these models, these factors remained significant. However, when considering the complications, only pulmonary and cardiac complications remained independently associated with unfavorable outcomes.

Conclusion

Extracerebral complications after aSAH are frequent. Cardiac and pulmonary complications are independent predictors of unfavorable outcomes. Sex-specific extracerebral complications in patients with aSAH exist. Women suffered more frequently from cardiac and infectious complications potentially explaining the worse outcomes.

Cardiac dysfunction in patients affected by subarachnoid haemorrhage affects in-hospital mortality: A systematic review and metanalysis

BACKGROUND

Subarachnoid haemorrhage (SAH) is a life-threatening condition with associated brain damage. Moreover, SAH is associated with a massive release of catecholamines, which may promote cardiac injury and dysfunction, possibly leading to haemodynamic instability, which in turn may influence a patient's outcome.

OBJECTIVES

To study the prevalence of cardiac dysfunction (as assessed by echocardiography) in patients with SAH and its effect on clinical outcomes.

DESIGN

Systematic review of observational studies.

DATA SOURCES

We performed a systematic search over the last 20 years on MEDLINE and EMBASE databases.

ELIGIBILITY CRITERIA

Studies reporting echocardiography findings in adult patients with SAH admitted to intensive care. Primary outcomes were in-hospital mortality and poor neurological outcome according to the presence or absence of cardiac dysfunction.

RESULTS

We included a total of 23 studies (4 retrospective) enrolling 3511 patients. The cumulative frequency of cardiac dysfunction was 21% (725 patients), reported as regional wall motion abnormality in the vast majority of studies (63%). Due to the heterogeneity of clinical outcome data reporting, a quantitative analysis was carried out only for in-hospital mortality. Cardiac dysfunction was associated with a higher in-hospital mortality [odds ratio 2.69 (1.64 to 4.41); P < 0.001; I2 = 63%]. The GRADE of evidence assessment resulted in very low certainty of evidence.

CONCLUSION

About one in five patients with SAH develops cardiac dysfunction, which seems to be associated with higher in-hospital mortality. The consistency of cardiac and neurological data reporting is lacking, reducing the comparability of the studies in this field.

Neuroinflammatory Mechanisms in Ischemic Stroke: Focus on Cardioembolic Stroke, Background, and Therapeutic Approaches

One of the most important causes of neurological morbidity and mortality in the world is ischemic stroke. It can be a result of multiple events such as embolism with a cardiac origin, occlusion of small vessels in the brain, and atherosclerosis affecting the cerebral circulation. Increasing evidence shows the intricate function played by the immune system in the pathophysiological variations that take place after cerebral ischemic injury. Following the ischemic cerebral harm, we can observe consequent neuroinflammation that causes additional damage provoking the death of the cells; on the other hand, it also plays a beneficial role in stimulating remedial action. Immune mediators are the origin of signals with a proinflammatory position that can boost the cells in the brain and promote the penetration of numerous inflammatory cytotypes (various subtypes of T cells, monocytes/macrophages, neutrophils, and different inflammatory cells) within the area affected by ischemia; this process is responsible for further ischemic damage of the brain. This inflammatory process seems to involve both the cerebral tissue and the whole organism in cardioembolic stroke, the stroke subtype that is associated with more severe brain damage and a consequent worse outcome (more disability, higher mortality). In this review, the authors want to present an overview of the present learning of the mechanisms of inflammation that takes place in the cerebral tissue and the role of the immune system involved in ischemic stroke, focusing on cardioembolic stroke and its potential treatment strategies.

Aerobic Training and Mobilization Early Post-stroke: Cautions and Considerations

Knowledge gaps exist in how we implement aerobic exercise programs during the early phases post-stroke. Therefore, the objective of this review was to provide evidence-based guidelines for pre-participation screening, mobilization, and aerobic exercise training in the hyper-acute and acute phases post-stroke. In reviewing the literature to determine safe timelines of when to initiate exercise and mobilization we considered the following factors: arterial blood pressure dysregulation, cardiac complications, blood-brain barrier disruption, hemorrhagic stroke transformation, and ischemic penumbra viability. These stroke-related impairments could intensify with inappropriate mobilization/aerobic exercise, hence we deemed the integrity of cerebral autoregulation to be an essential physiological consideration to protect the brain when progressing exercise intensity. Pre-participation screening criteria are proposed and countermeasures to protect the brain from potentially adverse circulatory effects before, during, and following mobilization/exercise sessions are introduced. For example, prolonged periods of standing and static postures before and after mobilization/aerobic exercise may elicit blood pooling and/or trigger coagulation cascades and/or cerebral hypoperfusion. Countermeasures such as avoiding prolonged standing or incorporating periodic lower limb movement to activate the venous muscle pump could counteract blood pooling after an exercise session, minimize activation of the coagulation cascade, and mitigate potential cerebral hypoperfusion. We discuss patient safety in light of the complex nature of stroke presentations (i.e., type, severity, and etiology), medical history, comorbidities such as diabetes, cardiac manifestations, medications, and complications such as anemia and dehydration. The guidelines are easily incorporated into the care model, are low-risk, and use minimal resources. These and other strategies represent opportunities for improving the safety of the activity regimen offered to those in the early phases post-stroke. The timeline for initiating and progressing exercise/mobilization parameters are contingent on recovery stages both from neurobiological and cardiovascular perspectives, which to this point have not been specifically considered in practice. This review includes tailored exercise and mobilization prescription strategies and precautions that are not resource intensive and prioritize safety in stroke recovery.

Immune response mediates the cardiac damage after subarachnoid hemorrhage

Cardiac dysfunction is a common adverse effect of subarachnoid hemorrhage (SAH). Autopsy of SAH patients shows immunocyte infiltration into the heart. In this study, a SAH model of endovascular perforation was performed in adult male mice in order to test whether SAH causes cardiac dysfunction in non-primary cardiac disease young adult male mice and whether immune response mediates SAH induced cardiac and neurological deficit. Splenectomy was performed on a subpopulation of mice one week prior to induction of the SAH. Neurological functional tests, transthoracic Doppler echocardiography, immunofluorescent staining, and flow cytometry were performed to investigate neurological and cardiac function and immune/inflammatory effects of SAH in mice with or without splenectomy. We found that SAH significantly induces ventricular fibrillation and cardiac dysfunction identified by significantly reduced left ventricular ejection fraction, left ventricular fractional shortening, decreased heart rate, as well as increased macrophage and neutrophil infiltration into heart and inflammatory factor expression in the heart compared to sham control mice. SAH also induces neurological deficit, increases astrocyte and microglial activity, and inflammatory cell infiltration into brain as well as up-regulates inflammatory factor expression in the brain tissue. Splenectomy not only significantly improves neurological function, but also reduces cardiac dysfunction compared to SAH alone mice. Splenectomy in SAH mice significantly reduces inflammatory cell infiltration, and decreases NADPH oxidase-2 and macrophage chemokine protein-1 expression in heart and brain when compared to non-splenectomy SAH mice. Our data suggest that, SAH induces acute cardiac dysfunction in non-primary cardiac disease mice. Secondary immune response may play an important role in mediating brain-heart damage after SAH.

Evaluation of the Effect of Aneurysmal Clipping on Electrocardiography and Echocardiographic Changes in Patients With Subarachnoid Hemorrhage: A Prospective Observational Study

BACKGROUND

Electrocardiographic (ECG) and echocardiographic changes that are subsequent to aneurysmal subarachnoid hemorrhage (a-SAH) are commonly observed with a prevalence varying from 27% to 100% and 13% to 18%, respectively. There are sparse data in the literature about the pattern of ECG and echocardiographic changes in patients with SAH after clipping of the aneurysm. Hence, we observed the effect of aneurysmal clipping on ECG and echocardiographic changes during the first week after surgery, and the impact of these changes on outcome at the end of 1 year.

MATERIALS AND METHODS

This prospective, observational study was conducted in 100 consecutive patients with a-SAH undergoing clipping of ruptured aneurysm. ECG and echocardiographic changes were recorded preoperatively and every day after surgery until 7 days. Outcome was evaluated using the Glasgow outcome scale at the end of 1 year.

RESULTS

Of 100 patients, 75 had ECG changes and 17 had echocardiographic changes preoperatively. The ECG changes observed were QTc prolongation, conduction defects, ST-wave and T-wave abnormalities, tachyarrhythmias, and bradyarrhythmias. The echocardiography changes included global hypokinesia and regional wall motion abnormalities. Both echocardiographic and ECG changes showed significant recovery on the first postoperative day. Patients presenting with both echocardiographic and ECG changes were found to require higher ionotropic support to maintain the desired blood pressure, and were associated with poor outcome (Glasgow outcome scale, 1 to 2) at 1 year after surgery. There was no association of ECG and echocardiographic changes with mortality (both in-hospital or at 1 year).

CONCLUSIONS

The ECG changes, such as QTc prolongation, bradycardia, conduction abnormality, and echocardiographic changes, recover on postoperative day-1, in most of the cases after clipping. Patients with combined ECG and echocardiographic changes tend to have poor neurological outcome at the end of 1 year.

The Extracranial Consequences of Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is managed across the full spectrum of healthcare, from clinical diagnosis to management of the hemorrhage and associated complications. Knowledge of the pathogenesis and pathophysiology of SAH is widely known; however, a full understanding of the underlying molecular, cellular, and circulatory dynamics has still to be achieved. Intracranial complications including delayed ischemic neurologic deficit (vasospasm), rebleed, and hydrocephalus form the targets for initial management. However, the extracranial consequences including hypertension, hyponatremia, and cardiopulmonary abnormalities can frequently arise during the management phase and have shown to directly affect clinical outcome. This review will provide an update on the pathophysiology of SAH, including the intra- and extracranial consequences, with a particular focus on the extracranial consequences of SAH.

METHODS

We review the literature and provide a comprehensive update on the extracranial consequences of SAH that we hope will help the management of these cohort of patients.

RESULTS

In addition to the pathophysiology of SAH, the following complications were examined and discussed: vasospasm, seizures, rebleed, hydrocephalus, fever, anemia, hypertension, hypotension, hyperglycemia, hyponatremia, hypernatremia, cardiac abnormalities, pulmonary edema, venous thromboembolism, gastric ulceration, nosocomial infection, bloodstream infection/sepsis, and iatrogenic complications.

CONCLUSIONS

Although the intracranial complications of SAH can take priority in the initial management, the extracranial complications should be monitored for and recognized as early as possible because these complications can develop at varying times throughout the course of the condition. Therefore, a variety of investigations, as described by this article, should be undertaken on admission to maximize early recognition of any of the extracranial consequences. Furthermore, because the extracranial complications have a direct effect on clinical outcome and can lead to and exacerbate the intracranial complications, monitoring, recognizing, and managing these complications in parallel with the intracranial complications is important and would allow optimization of the patient's management and thus help improve their overall outcome.

Brain-Heart Interaction: Cardiac Complications After Stroke

Neurocardiology is an emerging specialty that addresses the interaction between the brain and the heart, that is, the effects of cardiac injury on the brain and the effects of brain injury on the heart. This review article focuses on cardiac dysfunction in the setting of stroke such as ischemic stroke, brain hemorrhage, and subarachnoid hemorrhage. The majority of post-stroke deaths are attributed to neurological damage, and cardiovascular complications are the second leading cause of post-stroke mortality. Accumulating clinical and experimental evidence suggests a causal relationship between brain damage and heart dysfunction. Thus, it is important to determine whether cardiac dysfunction is triggered by stroke, is an unrelated complication, or is the underlying cause of stroke. Stroke-induced cardiac damage may lead to fatality or potentially lifelong cardiac problems (such as heart failure), or to mild and recoverable damage such as neurogenic stress cardiomyopathy and Takotsubo cardiomyopathy. The role of location and lateralization of brain lesions after stroke in brain-heart interaction; clinical biomarkers and manifestations of cardiac complications; and underlying mechanisms of brain-heart interaction after stroke, such as the hypothalamic-pituitary-adrenal axis; catecholamine surge; sympathetic and parasympathetic regulation; microvesicles; microRNAs; gut microbiome, immunoresponse, and systemic inflammation, are discussed.

Clinical Presentation to the Emergency Department Predicts Subarachnoid Hemorrhage-Associated Myocardial Injury

INTRODUCTION

Aneurysmal subarachnoid hemorrhage (aSAH) is frequently seen in emergency departments. Secondary injury, such as subarachnoid hemorrhage-associated myocardial injury (SAHMI), affects one third of survivors and contributes to poor outcomes. SAHMI is not attributed to ischemia from myocardial disease but can result in hypotension and arrhythmias. It is important that emergency nurses recognize which clinical presentation characteristics are predictive of SAHMI to initiate proper interventions. The aim of this study was to determine whether patients who present to the emergency department with clinical aSAH are likely to develop SAHMI, as defined by troponin I ≥0.3 ng/mL.

METHODS

This was a prospective descriptive study. SAHMI was defined as troponin I ≥0.3 ng/mL. Predictors included demographics and clinical characteristics, severity of injury, admission 12-lead electrogardiogram (ECG), initial emergency department vital signs, and pre-hospital symptoms at time of aneurysm rupture.

RESULTS

Of 449 patients, 126 (28%) had SAHMI. Patients with SAHMI were more likely to report seizures and unresponsiveness with significantly lower Glasgow coma score and higher proportion of Hunt and Hess grades 3 to 5 and Fisher grades III and IV (all P < .05). Patients with SAHMI had higher atrial and ventricular rates and longer QTc intervals on initial ECG (P < .05). On multivariable logistic regression, poor Hunt and Hess grade, report of prehospital unresponsiveness, lower admission Glasgow coma score, and longer QTc interval were significantly and independently predictive of SAHMI (P < .05).

DISCUSSION

Components of the clinical presentation of subarachnoid hemorrhage to the emergency department predict SAHMI. Identifying patients with SAHMI in the emergency department can be helpful in determining surveillance and care needs and informing transfer unit care. Contribution to Emergency Nursing Practice.

Coronary fat embolism following subarachnoid hemorrhage: an experimental study

BACKGROUND

Subarachnoid hemorrhage (SAH) can lead to neurogenic pulmonary edema (NPE), and chylomicron metabolism may be altered unfavorably in acute lung injury. This study aimed to investigate the possible effect of NPE on the development of coronary fat embolism.

METHODS

This study was conducted on 27 rabbits, 5 of which were used as the control (n=5). Experimental SAH was induced in 15 of the animals by injecting homologous blood into the cisterna magna, and the remaining 7 animals were administered only isotonic saline solution (Sham, n=7) in the same manner under general anesthesia. After 21 days, all the animals were euthanized, and their hearts, lungs, and brains underwent histopathological examination.

RESULTS

Six animals died of SAH during the experiment, and foamy hemorrhagic parenchymal lesions and intra-alveolar hemorrhage were observed in their lungs. The histopathologic findings revealed minimal changes in the lungs, heart, and brains of the surviving animals; however, an abundant amount of fat globules was found in the coronary arteries of the six nonsurviving animals. There was a meaningful difference between the number of occluded coronary arteries with fatty globules in the surviving and nonsurviving animals (P<.001). However, the difference between the survivors and the isotonic-saline-injected group was not meaningful (P>.05). Coronary fat embolism was an important mortality factor following SAH (P<.005).

CONCLUSIONS

In SAH-induced NPE, the leakage of chylomicrons into the systemic circulation may lead to coronary fat embolism, which has not yet been reported in the literature.