Contemporary biochemical analysis of normal pericardial fluid

Accumulation of Inflammatory Mediators in the Normal Pericardial Fluid

There is paucity of studies that focus on the composition of pericardial fluid under resting conditions. The purpose of this study is to determine the levels of inflammatory mediators in pericardial fluid and their correlation with plasma levels in patients undergoing elective cardiac surgery. We conducted a prospective cohort study on candidates for elective aortic valve replacement surgery. Pericardial fluid and peripheral venous blood samples were collected after opening the pericardium. Levels of interleukin 1α (IL-1α); interleukin 1β (IL-1β); interleukin 2 (IL-2) interleukin 4 (IL-4); interleukin 6 (IL-6); interleukin 8 (IL8); interleukin 10 (IL10); tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), vascular endothelial growth factor (VEGF), monocyte chemotactic protein-1 (MCP-1) epidermal growth factor (EGF), soluble E-selectin, L-selectin, P-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) were determined in both pericardial fluid and serum samples. A total of 45 patients with a mean age of 74 years were included of which 66% were males. Serum levels of all study mediators were within normal limits. Serum and pericardial levels of IL-1 α, IL-1 β, IL-2, IL-4, and IL-10 were similar. Levels of VEGF, EGF, VCAM-2, ICAM 1, E-selectin, P-selectin, and L-selectin were significantly lower in pericardial fluid than in serum. However, levels of IL-6, IL-8, TNF-α, IFN-γ, MCP-1, and MCP-1 were significantly higher in the pericardial fluid than in serum. Under normal conditions, the pattern of distribution of different inflammatory mediators in the pericardial fluid does not reflect serum levels. This may either reflect the condition of the underlying myocardium and epicardial fat or the activity of the mesothelial and mononuclear cells present in pericardial fluid.

Metabolomics investigation of post-mortem human pericardial fluid

INTRODUCTION

Due to its peculiar anatomy and physiology, the pericardial fluid is a biological matrix of particular interest in the forensic field. Despite this, the available literature has mainly focused on post-mortem biochemistry and forensic toxicology, while to the best of authors' knowledge post-mortem metabolomics has never been applied. Similarly, estimation of the time since death or post-mortem interval based on pericardial fluids has still rarely been attempted.

OBJECTIVES

We applied a metabolomic approach based on 1H nuclear magnetic resonance spectroscopy to ascertain the feasibility of monitoring post-mortem metabolite changes on human pericardial fluids with the aim of building a multivariate regression model for post-mortem interval estimation.

METHODS

Pericardial fluid samples were collected in 24 consecutive judicial autopsies, in a time frame ranging from 16 to 170 h after death. The only exclusion criterion was the quantitative and/or qualitative alteration of the sample. Two different extraction protocols were applied for low molecular weight metabolites selection, namely ultrafiltration and liquid-liquid extraction. Our metabolomic approach was based on the use of 1H nuclear magnetic resonance and multivariate statistical data analysis.

RESULTS

The pericardial fluid samples treated with the two experimental protocols did not show significant differences in the distribution of the metabolites detected. A post-mortem interval estimation model based on 18 pericardial fluid samples was validated with an independent set of 6 samples, giving a prediction error of 33-34 h depending on the experimental protocol used. By narrowing the window to post-mortem intervals below 100 h, the prediction power of the model was significantly improved with an error of 13-15 h depending on the extraction protocol. Choline, glycine, ethanolamine, and hypoxanthine were the most relevant metabolites in the prediction model.

CONCLUSION

The present study, although preliminary, shows that PF samples collected from a real forensic scenario represent a biofluid of interest for post-mortem metabolomics, with particular regard to the estimation of the time since death.

Chronic Pericardial Effusion: Causes and Management

Chronic pericardial effusion is a common pericardial syndrome whose approach has been well standardised in recent years. The main challenge associated with this condition is the progression (sometimes unheralded) to cardiac tamponade. Pericardial effusions may present either as an isolated finding or in the context of a specific etiology including autoimmune, neoplastic, or metabolic disease. Among investigations used during diagnostic work-up, echocardiography is of paramount importance for the diagnosis, sizing, and serial evaluation of the hemodynamic impact of effusions on heart diastolic function. In an individualised manner, advanced imaging including computed tomography and cardiac magnetic resonance imaging should be performed, especially if baseline tests are inconclusive. Triage of these patients according to the most recent 2015 European Society of Cardiology Guidelines for the diagnosis and management of pericardial diseases should take into account the presence of hemodynamic compromise as well as suspicion of malignant or purulent pericarditis as first step, C-reactive protein serum level measurement as second step, investigations for a specific condition known to be associated with pericardial effusion as third step, and finally the size and the duration of the effusion. Treatment depends on the evaluation of the above-mentioned parameters and should ideally be tailored to the individual patient. Prognosis of chronic pericardial effusions depends largely on the underlying etiology. According to novel data, the prognosis of individuals with idiopathic, chronic (> 3 months), large (> 2 cm), asymptomatic pericardial effusions is usually benign and a watchful waiting strategy seems more reasonable and cost-effective than routine drainage as previously recommended.

Causes of Polyserositis: A Systematic Review

At present, polyserositis (PS) remains a challenging entity, which resides both in the fact that there is confusion regarding the terminology, and that it is still understudied. We aimed to identify the etiologies of PS, reported in adult patients.

METHODS

We performed a systematic review of the literature on PubMed(MEDLINE) database, using the following (MESH) terms: pleurisy/etiology, pleural effusion/etiology, pericarditis/etiology, pericardial effusion/etiology, pericardial effusion chronic, ascites/etiology, ascitic fluid/etiology, polyserositis, serositis, and serositides.

RESULTS

A total of 1979 articles were identified, dating from 1973 onwards. After screening the articles, we included 114 patients from 23 articles (one case series including 92 patients and 22 case reports) in the final report. The most common diagnosis was neoplasia (30; 26.3%), followed by autoimmune diseases (19, 16.7%) and infections (16, 12.3%). Still, in 35 cases, the etiology of PS remained unkown.

CONCLUSION

PS is a challenging and understudied entity, which is associated with a wide range of diagnoses. However, prospective studies should be developed in order to have a clear understanding regarding its etiologies and their prevalences.

Metabolic signatures in pericardial fluid and serum are associated with new-onset atrial fibrillation after isolated coronary artery bypass grafting

Postoperative atrial fibrillation (POAF) is a common complication of coronary artery bypass grafting (CABG) procedures. However, the molecular mechanism of POAF remains poorly understood, hence the absence of effective prevention strategies. Here we used targeted metabolomics on pericardial fluid and serum samples from CABG patients to investigate POAF-associated metabolic alterations and related risk prediction of new-onset AF. Nine differential metabolites in various metabolic pathways were found in both pericardial fluid and serum samples from patients with POAF and without POAF. By using machine learning algorithms and regression models, a 4-metabolite (aceglutamide, ornithine, methionine, and arginine) risk prediction model was constructed and showed accurate performance in predicting POAF in both discovery and validation sets. This work extends the metabolic insights of the cardiac microenvironment and blood in patients with POAF and paves the way for the use of targeted metabolomics for predicting POAF in patients with CABG surgery.

Chronic pericardial effusion: current concepts and emerging trends

INTRODUCTION

Pericardial effusion (PEF) is a common and challenging pericardial syndrome with a variety of clinical manifestations ranging from asymptomatic, incidentally uncovered small PEFs, to life-threatening cardiac tamponade.

AREAS COVERED

: This review focuses on the pathophysiology, epidemiology, etiology, classification, clinical findings, diagnostic work-up, management and outcome of PEFs. Particular emphasis has been given on the most recent evidence concerning the contribution of imaging for the detection, differential diagnosis and evaluation of the hemodynamic impact of PEFs on the diastolic filling of the heart. Moreover, simplified algorithms for PEF triage and management have been included.

EXPERT OPINION

The management of patients with PEFs is mainly based on four parameters namely hemodynamic impact on diastolic function, elevation of inflammatory markers, presence of a specific underlying condition known to be associated with PEF and finally size and duration of the effusion. Novel data have contributed to change our view towards large, asymptomatic, "idiopathic" PEFs and dictated a rather conservative approach in most cases. It is also stressed that there is a compelling need for additional research, which is essential for tailored treatments aiming at the improvement of quality of life and containment of health care costs.

Recent advances in pericarditis

Pericardial diseases are an heterogeneous group of entities, ranging from acute pericarditis to asymptomatic pericardial effusions. New advances in understanding the processes underlying them have been made. In 2020 a prospective study defined the reference intervals of the component of normal pericardial fluid, that was found to be rich in nucleated cells, proteins, albumin and LDH, at levels compatible with the inflammatory exudates of other biological fluids such as pleural or peritoneal fluid; Light's criteria should not be used to evaluate it. Recently we also analyzed systematically large chronic idiopathic non-inflammatory pericardial effusions, observing that a non-invasive wait-and-see approach may be the best choice in clinical practice in oligosymptomatic cases. Concerning acute recurrent pericarditis (RP), an innovative interaction between cardiologists, internists and pediatric rheumatologists led to the intuition of a pivotal role of IL-1 in recurrent pericarditis characterized by an evident inflammatory recurrent phenotype, and recent data have shown the striking efficacy of anakinra and rilonacept in these patients. The proper selection of the patient is important; the ideal candidate for anti-IL-1 therapy is the patient with RP with high levels of serum C-reactive protein, high fever, neutrophil leukocitosis, pleuropulmonary involvement, frequent exacerbations and resistant to conventional therapy. On the contrary, anti-IL-1 drugs are not indicated in patients with pericardial effusion whose cause is not attributable to inflammatory phenomena. Finally, many patients with RP are women of childbearing age, and the possibility for these women to become pregnant must be addressed by multidisciplinary teams.

Upper Back Pain: A Rare Clinical Presentation in Pericardial Effusion

Pericardial effusion is an important cardiac condition seen in clinical practice with several known underlying etiologies. We are aware of the challenge that exists in diagnosing the effusion. An interesting challenge that has caught our attention is the highest chance of missing the diagnosis if there is an atypical clinical presentation of the patient. In this case report, our objective is to discuss a case that enhances the importance of careful and meticulous investigation of a patient with an atypical clinical picture. This is a case report of a 92-year-old woman who presented to the emergency department with a chief complaint of upper back pain for a few days. She was found to have cardiomegaly on further imaging. An echocardiogram showed a moderate size pericardial effusion. Pericardiocentesis was done and a drain was left in place. Of note, the patient reported remarkable resolution of the back pain after the fluid was taken out. The serial echocardiogram post pericardiocentesis showed minimal drainage, hence the drain was taken out, and the patient was observed for clinical monitoring 24 hours post drain removal. A timely diagnosis and treatment saved our patient from the most dreadful life-threatening condition along with a secure discharge from the hospital.

Pleural Fluid Analysis: Are Light's Criteria Still Relevant After Half a Century?

Fifty years from their initial description, Light's criteria are still unhesitatingly accepted as the default reference test for separating pleural transudates and exudates. Efforts should be focused not so much on trying to find an even more reliable technique for categorizing PEs but on improving the misclassification rate of transudates that characterize Light's criteria. Despite their shortcomings, Light's criteria may well continue their reign for another 50 years. Long live the Light's criteria!

Contemporary management of pericardial effusion

Pericardial effusion is a relatively common clinical condition with a variety of clinical manifestations ranging from incidentally discovered asymptomatic cases to life-threatening cardiac tamponade. The etiology encompasses idiopathic cases and forms secondary to different conditions, including autoimmune diseases, malignancies, metabolic disorders, etc. While medical therapy should be offered to patients with elevation of inflammatory markers, in specific forms treatment should be appropriate to the underlying disorder. In cases with hemodynamic compromise pericardial drainage either with pericardiocentesis or pericardial "window" is indicated for therapeutic and diagnostic purposes. In the remainder, factors like comorbidities, size and location of the pericardial effusion will influence the clinical decision making. In asymptomatic or minimally symptomatic chronic large idiopathic pericardial effusions, according to recent evidence, a conservative approach with watchful waiting seems the most reasonable option. The prognosis of pericardial effusions largely depends on the underlying etiologies. Metastatic spread to the pericardium has an ominous prognosis whereas large to moderate effusions have been often associated with known or newly discovered specific underlying causes. Chronic small idiopathic effusions have an excellent prognosis and do not require specific monitoring. Large chronic idiopathic effusions in clinically stable patients require a 3 to 6-month assessment ideally in a specialized unit.

What is the normal composition of pericardial fluid?

Objective

Biochemical and cytological pericardial fluid (PF) analysis is essentially based on the knowledge of pleural fluid composition. The aim of the present study is to identify reference intervals (RIs) for PF according to state-of-art methodological standards.

Methods

We prospectively collected and analysed the PF and venous blood of consecutive subjects undergoing elective open-heart surgery from July 2017 to October 2018. Exclusion criteria for study enrolment were evidence of pericardial diseases at preoperatory workup or at intraoperatory assessment, or any other condition that could affect PF analysis.

Results

The final study sample included 120 patients (median age 69 years, 83 men, 69.1%). The main findings were (1) High levels of proteins, albumin and lactate dehydrogenase (LDH), but not of glucose and cholesterol (2) High cellularity, mainly represented by mesothelial cells. RIs for pericardial biochemistry were: protein content 1.7–4.6 g/dL PF/serum protein ratio 0.29–0.83, albumin 1.19–3.06 g/dL, pericardium-to-serum albumin gradient 0.18–2.37 g/dL, LDH 141–2613 U/L, PF/serum LDH ratio 0.40–2.99, glucose 80–134 mg/dL, total cholesterol 12–69 mg/dL, PF/serum cholesterol ratio 0.07–0.51. RIs for pericardial cells by optic microscopy were: 278–5608 × 106 nucleated cells/L, 40–3790 × 106 mesothelial cells/L, 35–2210 × 106 leucocytes/L, 19–1634 × 106 lymphocytes/L.

Conclusions

PF is rich in nucleated cells, protein, albumin, LDH, at levels consistent with inflammatory exudates in other biological fluids. Physicians should stop to interpret PF as exudate or transudate according to tools not validated for this setting.