Delayed cardiogenic shock and acute lung injury after aneurysmal subarachnoid hemorrhage

Neurocardiology

Neurocardiology refers to the interplay between the nervous system and the cardiovascular system. Stress-related cardiomyopathy exemplifies the brain-heart connection and occurs in several conditions with acute brain injury that share oversympathetic activation. The brain's influences on the heart can include elevated cardiac markers, arrhythmias, repolarization abnormalities on electrocardiogram, myocardial necrosis, and autonomic dysfunction. The neurogenic stunned myocardium in aneurysmal subarachnoid hemorrhage represents one end of the spectrum, and is associated with an explosive rise in intracranial pressure that results in excess catecholamine state and possibly CBN. A brain-heart link is more known to cardiologists than neurologists. This chapter provides some insight into the pathophysiology of these pathologic neurocardiac states and their most appropriate management relevant to neurologists.

H7N9 and other pathogenic avian influenza viruses elicit a three-pronged transcriptomic signature that is reminiscent of 1918 influenza virus and is associated with lethal outcome in mice

Modulating the host response is a promising approach to treating influenza, caused by a virus whose pathogenesis is determined in part by the reaction it elicits within the host. Though the pathogenicity of emerging H7N9 influenza virus in several animal models has been reported, these studies have not included a detailed characterization of the host response following infection. Therefore, we characterized the transcriptomic response of BALB/c mice infected with H7N9 (A/Anhui/01/2013) virus and compared it to the responses induced by H5N1 (A/Vietnam/1203/2004), H7N7 (A/Netherlands/219/2003), and pandemic 2009 H1N1 (A/Mexico/4482/2009) influenza viruses. We found that responses to the H7 subtype viruses were intermediate to those elicited by H5N1 and pdm09H1N1 early in infection but that they evolved to resemble the H5N1 response as infection progressed. H5N1, H7N7, and H7N9 viruses were pathogenic in mice, and this pathogenicity correlated with increased transcription of cytokine response genes and decreased transcription of lipid metabolism and coagulation signaling genes. This three-pronged transcriptomic signature was observed in mice infected with pathogenic H1N1 strains such as the 1918 virus, indicating that it may be predictive of pathogenicity across multiple influenza virus strains. Finally, we used host transcriptomic profiling to computationally predict drugs that reverse the host response to H7N9 infection, and we identified six FDA-approved drugs that could potentially be repurposed to treat H7N9 and other pathogenic influenza viruses.

IMPORTANCE

Emerging avian influenza viruses are of global concern because the human population is immunologically naive to them. Current influenza drugs target viral molecules, but the high mutation rate of influenza viruses eventually leads to the development of antiviral resistance. As the host evolves far more slowly than the virus, and influenza pathogenesis is determined in part by the host response, targeting the host response is a promising approach to treating influenza. Here we characterize the host transcriptomic response to emerging H7N9 influenza virus and compare it with the responses to H7N7, H5N1, and pdm09H1N1. All three avian viruses were pathogenic in mice and elicited a transcriptomic signature that also occurs in response to the legendary 1918 influenza virus. Our work identifies host responses that could be targeted to treat severe H7N9 influenza and identifies six FDA-approved drugs that could potentially be repurposed as H7N9 influenza therapeutics.

Neurogenic Stunned Myocardium Following Acute Subarachnoid Hemorrhage

Neurogenic stunned myocardium (NSM) is a triad of transient left ventricular dysfunction, electrocardiogram changes, and elevation in cardiac enzymes, often mimicking a myocardial infarction. It has been described following acute brain injury. The purported mechanism is catecholamine excess resulting in cardiac dysfunction. From the clinical standpoint, the most frequently encountered electrocardiographic changes are QTc prolongation and ST-T changes, with modest elevations in troponin levels. Basal and mid-ventricular segments of the left ventricle are most commonly involved. NSM poses therapeutic challenges when it occurs secondary to aneurysmal subarachnoid hemorrhage, particularly in the setting of coexisting vasospasm. Overall, NSM carries good prognosis if recognized early, with appropriate management of hemodynamic and cardiopulmonary parameters.

Prolonged paroxysmal sympathetic storming associated with spontaneous subarachnoid hemorrhage

Paroxysmal sympathetic storming (PSS) is a rare disorder characterized by acute onset of nonstimulated tachycardia, hypertension, tachypnea, hyperthermia, external posturing, and diaphoresis. It is most frequently associated with severe traumatic brain injuries and has been reported in intracranial tumors, hydrocephalous, severe hypoxic brain injury, and intracerebral hemorrhage. Although excessive release of catecholamine and therefore increased sympathetic activities have been reported in subarachnoid hemorrhage (SAH), there is no descriptive report of PSS primarily caused by spontaneous SAH up to date. Here, we report a case of prolonged PSS in a patient with spontaneous subarachnoid hemorrhage and consequent vasospasm. The sympathetic storming started shortly after patient was rewarmed from hypothermia protocol and symptoms responded to Labetalol, but intermittent recurrence did not resolve until 3 weeks later with treatment involving Midazolam, Fentanyl, Dexmedetomidine, Propofol, Bromocriptine, and minimizing frequency of neurological and vital checks. In conclusion, prolonged sympathetic storming can also be caused by spontaneous SAH. In this case, vasospasm might be a precipitating factor. Paralytics and hypothermia could mask the manifestations of PSS. The treatment of the refractory case will need both timely adjustment of medications and minimization of exogenous stressors or stimuli.

Cardiac troponin I and acute lung injury after subarachnoid hemorrhage

INTRODUCTION

There are few predictors of acute lung injury (ALI) or the acute respiratory distress syndrome (ARDS) after subarachnoid hemorrhage (SAH). We hypothesized that cardiac troponin I, which is associated with cardiovascular morbidity, would also predict ALI.

METHODS

We prospectively enrolled 171 consecutive patients with SAH. Troponin was routinely measured on admission and the next day and subsequently if abnormal. We prospectively recorded the maximum troponin, in-hospital events, and clinical endpoints. ALI and ARDS were defined by standard criteria.

RESULTS

Acute lung injury was found in 10 patients (6%), ARDS in an additional 14 (8%), and pulmonary edema without lung injury in 9 (5%). Maximum troponin was different in patients without lung injury or pulmonary edema (0.03 [0.02-0.12] mcg/l), ALI (0.17 [0.04-1.4]), or ARDS (0.31 [0.9-1.8], P < 0.001). In ROC analysis, a cutoff of 0.04 mcg/l had 91% sensitivity and 42% specificity for ALI or ARDS (AUC = 0.75, P < 0.001). Troponin was associated with ALI or ARDS after accounting for neurologic grade in multivariate models without further contribution from pneumonia, packed red cell transfusion, gender, tobacco use, coronary artery disease, vasospasm, depressed ejection fraction on echocardiography, or CT grade. Lung injury was associated with worse functional outcome at 14 days, but not at 28 days or 3 months.

CONCLUSION

Troponin I is associated with the development of ALI after SAH.

Integrating echocardiography into human patient simulator training of anesthesiology residents using a severe pulmonary embolism scenario

INTRODUCTION

Echocardiographic images were integrated into patient simulation (PS)-based resident training with a goal of highlighting the applicability and limitations of pure pressure-based measurements in the management of different disease states.

METHODS

Relevant echocardiographic images were selected, categorized, and sequenced to best represent specific hemodynamic changes and incorporated into a Powerpoint slideshow. Appropriate PS scenarios were then created to represent the hemodynamic changes seen with the selected pathophysiologic states. Instructors then displayed the visual images along with PS scenarios during lecture and testing sessions at the PS bedside during standard didactic sessions with small groups of anesthesiology residents and informal resident testing sessions.

CONCLUSIONS

The use of echo images to demonstrate, in real time, the hemodynamic consequences of changes in myocardial contractility, cardiac chamber volume, and valvular function is possible during PS in anesthesiology residency training. Echo imaging as a teaching tool during anesthesiology residency may yield a greater understanding of the pathophysiology of certain disease states, ultimately leading to faster diagnosis and more appropriate intervention by anesthesiologists.

Myocardial contrast echocardiography in subarachnoid hemorrhage-induced cardiac dysfunction: case report

OBJECTIVE

Cardiac dysfunction is a well-known complication of aneurysmal subarachnoid hemorrhage (SAH) that is generally regarded as secondary to catecholamine excess rather than overt ischemia. Myocardial contrast echocardiography (MCE) is a novel method of evaluating cardiac function and perfusion. We report the use of MCE in a patient with SAH and correlate the results to coronary angiography.

METHODS

Bedside MCE using Definity contrast agent (Bristol-Myers Squibb/Sanofi Pharmaceuticals, New York, NY) was performed at the onset of SAH and at the 1-week and 4-month follow-up evaluations.

RESULTS

A 64-year-old woman presented with aneurysmal SAH. She developed transient ST elevation on lateral electrocardiographic leads and elevated cardiac enzymes with creatine-kinase MB isoenzyme of 44.3 ng/ml and troponin of 0.62 ng/ml. An emergent coronary angiogram performed at the outside facility revealed normal coronary anatomy, ejection fraction of 30%, and midventricular akinesis. On transfer to our facility, MCE demonstrated an ejection fraction of 45% with normal coronary perfusion in the akinetic midventricular segments and normally contracting basal and apical segments. At the 4-month follow-up examination, her ejection fraction normalized to 67% and regional wall motion had improved.

CONCLUSION

To our knowledge, our case represents the first reported use of MCE in a patient with SAH. MCE demonstrating normal myocardium perfusion in the setting of normal coronary arteries on coronary angiogram and midventricular akinetic segments is compatible with nonischemic injury, which further supports the "catecholamine hypothesis" of neurogenic cardiac stunning. MCE may be a feasible noninvasive method to evaluate myocardial perfusion in the SAH population.

The systemic implications of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is analogous to a pathophysiological watershed, disrupting brain integrity and function and precipitating an array of systemic derangements including cardiovascular, respiratory, endocrine, hematological, and immune dysfunction. Extracerebral organ dysfunction is closely linked to the magnitude of the primary neurological insult, suggesting neurogenic, neuroendocrine and neuroimmunomodulatory mechanisms. Systemic organ involvement is associated with increased mortality and neurological impairment, even after adjustment for other outcome predictors such as the severity of the initial neurological injury. This may be a reflection of secondary brain injury precipitated by hypoxemia, circulatory failure, fever, or hyperglycemia, all of which have been linked to adverse clinical outcomes. Interventions to avert or reverse these and other perturbations need to be tested in clinical trials as they represent opportunities to improve survival and neurological recovery in patients with SAH.

Mechanisms in neurogenic stress cardiomyopathy after aneurysmal subarachnoid hemorrhage

Cardiac dysfunction after aneurysmal subarachnoid hemorrhage (SAH) is often referred to as "neurogenic stunned myocardium," which does not accurately reflect the suspected pathophysiology. We propose an alternative terminology, "neurogenic stress cardiomyopathy," as a more appropriate label based on our review of the current literature. This article will review the distinctive characteristics of SAH-induced cardiac dysfunction, hypotheses to explain the pathophysiology, and the supporting clinical and animal studies. Recognition of the unique features associated with SAH-induced cardiac complications allows optimal management of patients with SAH. We will also discuss the clinical and theoretical overlap of SAH-induced cardiac dysfunction with a syndrome known as tako-tsubo cardiomyopathy and explore therapeutic opportunities.

Tako-tsubo cardiomyopathy in aneurysmal subarachnoid hemorrhage: an underappreciated ventricular dysfunction

OBJECT

Neurogenic stunned myocardium in aneurysmal subarachnoid hemorrhage (SAH) is associated with a wide spectrum of reversible left ventricular wall motion abnormalities and includes a subset of patients with a pattern of apical akinesia and concomitant sparing of basal segments called "tako-tsubo cardiomyopathy".

METHODS

After obtaining institutional review board approval, the authors retrospectively identified among all patients admitted to the Mayo Clinic's Neurological Intensive Care Unit between January 1990 and January 2005 those with aneurysmal SAH who had met the echocardiographic criteria for tako-tsubo cardiomyopathy. Among 24 patients with SAH-induced reversible cardiac dysfunction, the authors identified eight with SAH-induced tako-tsubo cardiomyopathy. All eight patients were women with a mean age of 55.5 years (range 38.6-71.1). Seven patients presented with a poor-grade SAH, reflected by a Hunt and Hess grade of III or IV. Four patients underwent aneurysm clip application, and four underwent endovascular coil occlusion. The initial mean ejection fraction (EF) was 38% (range 25-55%), and the mean EF at recovery was 55% (range 40-68%). Cerebral vasospasm developed in six patients, but cerebral infarction developed in only three patients.

CONCLUSIONS

The authors describe the largest cohort with aneurysmal SAH-induced tako-tsubo cardiomyopathy. In the SAH population, tako-tsubo cardiomyopathy predominates in postmenopausal women and is often associated with pulmonary edema, prolonged intubation, and cerebral vasospasm. Additional studies are warranted to understand the complex mechanism involved in tako-tsubo cardiomyopathy and its intriguing relationship to neurogenic stunned myocardium.

Management of physiological variables in neuroanaesthesia: maintaining homeostasis during intracranial surgery

PURPOSE OF REVIEW

The recent literature on the perioperative maintenance of cerebral homeostasis was reviewed.

RECENT FINDINGS

Several studies focused on the regulation of cerebral blood flow in patients without intracranial disease; therefore, further studies in neurosurgical patients are needed. High intracranial pressure and brain swelling can be controlled by the choice of anaesthetic agents, and also by optimal positioning of the patient. The use of positive end-expiratory pressure may impair cerebral blood flow, but the effects of positive end-expiratory pressure seem to depend on the respiratory system compliance. The international multicenter study failed to show any benefit from intraoperative hypothermia in patients with subarachnoid hemorrhage; similarly, the results on corticosteroid therapy in head-injured patients are discouraging. Corticosteroid therapy has prompted studies on the control of blood glucose levels. While tight glycemic control has been recommended, it can have untoward effects manifested as cerebral metabolic stress.

SUMMARY

From the clinical point of view, the recent research has added only little to the knowledge on the management of physiological parameters in neurosurgery. More adequately powered studies focusing in specific problems, and having a meaningful aim relative to outcome, are needed also in neuroanaesthesia.

Detection of bleeding in injured femoral arteries with contrast-enhanced sonography

OBJECTIVE

The purpose of this study was to investigate the feasibility of detecting acute arterial bleeding by means of contrast-enhanced sonography.

METHODS

Puncture injury was produced transcutaneously with an 18-gauge needle in 26 femoral arteries (13 in the control group and 13 in the contrast-enhanced group) of rabbits. A sonographic contrast agent (Optison; Mallinckrodt Inc, St Louis, MO) was administered intravenously at a dose of 0.06 to 0.07 mL/kg. Sonography of the femoral arteries was performed before and after injury, both before and after injection of Optison, with B-mode imaging, color Doppler imaging, and pulse inversion harmonic imaging (PIHI).

RESULTS

The specific location of active bleeding could not be visualized in B-mode and PIHI scans in the control group (no Optison injection). After administration of Optison, the bleeding site was visualized because of the increased echogenicity of the extravasated blood at the puncture site in both B-mode imaging and PIHI. In color Doppler images, bleeding sites were localized successfully in 84.6% of the cases in the presence of Optison and in 30.8% of the cases without Optison. Histologic examination (light microscopy) of the hematoma confirmed the presence of contrast agent microbubbles in the extravascular space surrounding the artery.

CONCLUSIONS

Contrast-enhanced sonography may provide an effective method for detecting arterial bleeding.

Neurogenic Pulmonary Edema Due to Traumatic Brain Injury: Evidence of Cardiac Dysfunction

• Background Acute neurogenic pulmonary edema, a common and underdiagnosed clinical entity, can occur after virtually any form of injury of the central nervous system and is a potential early contributor to pulmonary dysfunction in patients with head injuries.

• Objective To explore myocardial function in patients with evident neurogenic pulmonary edema after traumatic head injury.

• Methods During a 1-year period in a university hospital in Sfax, Tunisia, information was collected prospectively on patients admitted to the 22-bed intensive care unit because of isolated traumatic head injury who had neurogenic pulmonary edema. Data included demographic information, vital signs, neurological status, physiological status, and laboratory findings. All of the patients had computed tomography and plain radiography of the neck and determination of cardiac function.

• Results All 7 patients in the sample had cardiac dysfunction. Evidence of myocardial damage was confirmed by echocardiography in 3 patients, pulmonary artery catheterization in 3 patients, and/or postmortem myocardial biopsy in 4 patients. Echocardiography studies, repeated 7 days after the initial study in one patient and 90 days afterward in another, showed complete improvement in wall motion, with a left ventricular ejection fraction of 0.65.

• Conclusion All patients who had neurogenic pulmonary edema due to traumatic head injury had myocardial dysfunction. The mechanisms of the dysfunction were multiple. The great improvement in wall motion seen in 2 patients indicated the presence of a stunned myocardium. Further studies are needed to understand the mechanisms of this cardiac dysfunction.