Pericardial fluid absorption into lymphatic vessels in sheep

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.

The ebb and flow of cardiac lymphatics: a tidal wave of new discoveries

The heart is imbued with a vast lymphatic network that is responsible for fluid homeostasis and immune cell trafficking. Disturbances in the forces that regulate microvascular fluid movement can result in myocardial edema, which has profibrotic and proinflammatory consequences and contributes to cardiovascular dysfunction. This review explores the complex relationship between cardiac lymphatics, myocardial edema, and cardiac disease. It covers the revised paradigm of microvascular forces and fluid movement around the capillary as well as the arsenal of preclinical tools and animal models used to model myocardial edema and cardiac disease. Clinical studies of myocardial edema and their prognostic significance are examined in parallel to the recent elegant animal studies discerning the pathophysiological role and therapeutic potential of cardiac lymphatics in different cardiovascular disease models. This review highlights the outstanding questions of interest to both basic scientists and clinicians regarding the roles of cardiac lymphatics in health and disease.

An overview of human pericardial space and pericardial fluid

The pericardium is a double-layered fibro-serous sac that envelops the majority of the surface of the heart as well as the great vessels. Pericardial fluid is also contained within the pericardial space. Together, the pericardium and pericardial fluid contribute to a homeostatic environment that facilitates normal cardiac function. Different diseases and procedural interventions may disrupt this homeostatic space causing an imbalance in the composition of immune mediators or by mechanical stress. Inflammatory cells, cytokines, and chemokines are present in the pericardial space. How these specific mediators contribute to different diseases is the subject of debate and research. With the advent of highly specialized assays that can identify and quantify various mediators we can potentially establish specific and sensitive biomarkers that can be used to differentiate pathologies, and aid clinicians in improving clinical outcomes for patients.

Different Expressions of Pericardial Fluid MicroRNAs in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy and Ischemic Heart Disease Undergoing Ventricular Tachycardia Ablation

Introduction: Pericardial fluid is enriched with biologically active molecules of cardiovascular origin including microRNAs. Investigation of the disease-specific extracellular microRNAs could shed light on the molecular processes underlying disease development. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart disease characterized by life-threatening arrhythmias and progressive heart failure development. The current data about the association between microRNAs and ARVC development are limited.

Methods and Results: We performed small RNA sequence analysis of microRNAs of pericardial fluid samples obtained during transcutaneous epicardial access for ventricular tachycardia (VT) ablation of six patients with definite ARVC and three post-infarction VT patients. Disease-associated microRNAs of pericardial fluid were identified. Five microRNAs (hsa-miR-1-3p, hsa-miR-21-5p, hsa-miR-122-5p, hsa-miR-206, and hsa-miR-3679-5p) were found to be differentially expressed between patients with ARVC and patients with post-infarction VT. Enrichment analysis of differentially expressed microRNAs revealed their close linkage to cardiac diseases.

Conclusion: Our data extend the knowledge of pericardial fluid microRNA composition and highlight five pericardial fluid microRNAs potentially linked to ARVC pathogenesis. Further studies are required to confirm the use of pericardial fluid RNA sequencing in differential diagnosis of ARVC.

Technologies for intrapericardial delivery of therapeutics and cells

The pericardium, which surrounds the heart, provides a unique enclosed volume and a site for the delivery of agents to the heart and coronary arteries. While strategies for targeting the delivery of therapeutics to the heart are lacking, various technologies and nanodelivery approaches are emerging as promising methods for site specific delivery to increase therapeutic myocardial retention, efficacy, and bioactivity, while decreasing undesired systemic effects. Here, we provide a literature review of various approaches for intrapericardial delivery of agents. Emphasis is given to sustained delivery approaches (pumps and catheters) and localized release (patches, drug eluting stents, and support devices and meshes). Further, minimally invasive access techniques, pericardial access devices, pericardial washout and fluid analysis, as well as therapeutic and cell delivery vehicles are presented. Finally, several promising new therapeutic targets to treat heart diseases are highlighted.

Malignant Pleural Mesothelioma presenting with Cardiac Tamponade- A Rare Case report and Review of the literature

Mesothelioma is a rare tumor of the pleura, peritoneum, pericardium or tunica vaginalis. About 2,500 cases are diagnosed annually in the United States. Mesothelioma often presents with pleuritic chest pain and dyspnea related to local invasion; distal metastasis and lymphadenopathy at the time of diagnosis is rare. Pericardial involvement in mesothelioma is related to direct invasion of the tumor. We here present a 71 year-old-male who presented with pleuritic chest pain and dyspnea, noted to have diffuse ST-segment elevation in EKG and cardiac tamponade physiology on 2D echocardiogram in who imaging subsequently revealed left upper lung mesothelioma. A pericardial window was created following which tamponade resolved. The pericardial biopsy did not show any mesothelioma cells or fibrous plaques. Computer tomography revealed regional lymphadenopathy in the chest. Disrupted cardiac lymphatic flow due to tumor mesothelioma induced lymphadenopathy is likely cause of the cardiac tamponade in this patient. This is the second ever reported case of pleural mesothelioma without a direct pericardial invasion that presented with cardiac tamponade.

Nanoparticles administered intrapericardially enhance payload myocardial distribution and retention

Pharmacological therapies for cardiovascular diseases are limited by short-term pharmacokinetics and extra-cardiac adverse effects. Improving delivery selectivity specifically to the heart, wherein therapeutic drug levels can be maintained over time, is highly desirable. Nanoparticle (NP)-based pericardial drug delivery could provide a strategy to concentrate therapeutics within a unique, cardiac-restricted compartment to allow sustained drug penetration into the myocardium. Our objective was to explore the kinetics of myocardial penetration and retention after pericardial NP drug delivery. Fluorescently-tagged poly(lactic-co-glycolic acid) (PLGA) NPs were loaded with BODIPY, a fluorophore, and percutaneously administered into the pericardium via subxiphoid puncture in rabbits. At distinct timepoints hearts were examined for presence of NPs and BODIPY. PLGA NPs were found non-uniformly distributed on the epicardium following pericardial administration, displaying a half-life of ~2.5days in the heart. While NPs were mostly confined to epicardial layers, BODIPY was capable of penetrating into the myocardium, resulting in a transmural gradient. The distinct architecture and physiology of the different regions of the heart influenced BODIPY distribution, with fluorophore penetrating more readily into atria than ventricles. BODIPY proved to have a long-term presence within the heart, with a half-life of ~7days. Our findings demonstrate the potential of utilizing the pericardial space as a sustained drug-eluting reservoir through the application of nanoparticle-based drug delivery, opening several exciting avenues for selective and prolonged cardiac therapeutics.

A case of diminished pericardial effusion after treatment of a giant hepatic cyst

A 75-year-old woman was discovered to have a pericardial effusion when she was admitted to our hospital because of a giant hepatic cyst. We could not detect the cause of the effusion and diagnosed idiopathic pericardial effusion. The patient underwent transcutaneous drainage of the hepatic cyst and an injection of antibiotics. There was no communication between the pericardial effusion and the hepatic cyst. Although the hepatic cyst was reduced in size, the pericardial effusion showed no remarkable change immediately after treatment; however, 5 months later, the pericardial effusion was found to be diminished. The pericardial effusion might have been caused by the physical pressure of the giant hepatic cyst and disturbance in the balance between the production and reabsorption of the pericardial fluid. When we experience a huge hepatic cyst, we should take into account its influence against the surrounding organs, including the intrapleural space.

Physiology of pericardial fluid production and drainage

The pericardium is one of the serosal cavities of the mammals. It consists of two anatomical structures closely connected, an external sac of fibrous connective tissue, that is called fibrous pericardium and an internal that is called serous pericardium coating the internal surface of the fibrous pericardium (parietal layer) and the heart (visceral layer) forming the pericardial space. Between these two layers a small amount of fluid exists that is called pericardial fluid. The pericardial fluid is a product of ultrafiltration and is considered to be drained by lymphatic capillary bed mainly. Under normal conditions it provides lubrication during heart beating while the mesothelial cells that line the membrane may also have a role in the absorption of the pericardial fluid along with the pericardial lymphatics. Here, we provide a review of the the current literature regarding the physiology of the pericardial space and the regulation of pericardial fluid turnover and highlight the areas that need to be further investigated.

Right side of heart failure

The function of the right ventricle (RV) in heart failure (HF) has been mostly ignored until recently. A 2006 report of the National Heart, Lung, and Blood Institute identified a gap between RV research efforts and its clinical importance compared with that of the left ventricle. This recent shift in paradigm is fueled by the prognostic value ascribed to RV failure in HF and morbidity/mortality after myocardial infarction and surgery. In this review, we examine the significance of RV failure in the HF setting, its clinical presentation and pathophysiology, and ways to evaluate RV function using echocardiographic measurements. Furthermore, we discuss the medical management of RV failure including traditional therapies like beta-blockers and newer options like nitric oxide, phosphodiesterase inhibitors, and calcium sensitizers. Mechanical support is also examined. Finally, this review places an emphasis on RV failure in the setting of left ventricular assist devices and heart transplantation.

Gene therapy for heart failure: where do we stand?

Advances in understanding of the molecular basis of myocardial dysfunction, together with the development of increasingly efficient gene transfer technology, has placed heart failure within reach of gene-based therapy. Multiple components of cardiac contractility, including the Beta-adrenergic system, the calcium channel cycling pathway, and cytokine mediated cell proliferation, have been identified as appropriate targets for gene therapy. The development of efficient and safe vectors such as adeno-associated viruses and polymer nanoparticles has provided an opportunity for clinical application for gene therapy. The recent successful and safe completion of a phase 2 trial targeting the sarcoplasmic reticulum calcium ATPase pump (SERCA2a) has the potential to open a new era for gene therapy in the treatment of heart failure.

Potential of gene therapy as a treatment for heart failure

Advances in understanding the molecular basis of myocardial dysfunction, together with the evolution of increasingly efficient gene transfer technology, make gene-based therapy a promising treatment option for heart conditions. Cardiovascular gene therapy has benefitted from recent advancements in vector technology, design, and delivery modalities. There is a critical need to explore new therapeutic approaches in heart failure, and gene therapy has emerged as a viable alternative. Advances in understanding of the molecular basis of myocardial dysfunction, together with the development of increasingly efficient gene transfer technology, has placed heart failure within reach of gene-based therapy. The recent successful and safe completion of a phase 2 trial targeting the cardiac sarcoplasmic/endoplasmic reticulum Ca2+ ATPase pump (SERCA2a) has the potential to open a new era for gene therapy for heart failure.

Percutaneous methods of vector delivery in preclinical models

Cardiovascular disease remains a leading cause of hospitalization and mortality worldwide. Conventional heart failure treatment is making steady and substantial progress to reduce the burden of disease. Nevertheless novel therapies and especially cardiac gene therapy have been emerging in the past and successfully made their way into first clinical trials. Gene therapy was initially a visionary treatment strategy for inherited, monogenetic diseases but has now developed to have potential for polygenic diseases as atherosclerosis, arrhythmias and heart failure. These novel therapeutic strategies require testing in clinically relevant animal models to transition from 'bench to bedside'. One of the major hurdles for effective cardiovascular gene therapy is the delivery of the viral vectors to the heart. In this review we present the currently available vector-mediated cardiac gene delivery methods in vivo considering the specific merits and deficiencies.

Delivery of gelfoam-enabled cells and vectors into the pericardial space using a percutaneous approach in a porcine model

Intrapericardial drug delivery is a promising procedure, with the ability to localize therapeutics with the heart. Gelfoam particles are nontoxic, inexpensive, nonimmunogenic and biodegradable compounds that can be used to deliver therapeutic agents. We developed a new percutaneous approach method for intrapericardial injection, puncturing the pericardial sac safely under fluoroscopy and intravascular ultrasound (IVUS) guidance. In a porcine model of myocardial infarction (MI), we deployed gelfoam particles carrying either (a) autologous mesenchymal stem cells (MSCs) or (b) an adenovirus encoding enhanced green fluorescent protein (eGFP) 48 h post-MI. The presence of MSCs and viral infection at the infarct zone was confirmed by immunoflourescence and PCR. Puncture was performed successfully in 16 animals. Using IVUS, we successfully determined the size of the pericardial space before the puncture, and safely accessed that space in setting of pericardial effusion and also adhesions induced by the MI. Intrapericardial injection of gelfoam was safe and reliable. Presence of the MSCs and eGFP expression from adenovirus in the myocardium were confirmed after delivery. Our novel percutaneous approach to deliver (stem-) cells or adenovirus was safe and efficient in this pre-clinical model. IVUS-guided delivery is a minimally invasive procedure that seems to be a promising new strategy to deliver therapeutic agents locally to the heart.

Four faces of a parapneumonic effusion: pathophysiology and varied radiographic presentations

We report a patient methicillin-resistant Staphylococcus aureus pneumonia who developed fluid collections in three spaces in the thorax, the pleural space, the pericardial space, and a pre-existing bulla, in addition to mediastinal oedema. We discuss the universal pathogenesis for the development of these fluid collections and the explanation for the most common presentation being a parapneumonic effusion.

Lymphatic transport of pericardial effusate in sheep

In this report, we quantified fluid loss from the pericardial cavity during simulated saline effusions and determined what proportion of this loss occurred through lymphatics. Fifty or 100 ml of Ringers lactate solution [containing 0.5% sheep albumin and (131)I-human serum albumin (HSA)] was injected into the pericardial cavity of sheep. Pericardial pressures, systemic arterial pressures, and plasma/pericardial fluid concentrations of the radioactive tracer were measured. Lymph transport of pericardial fluid was estimated from the plasma recovery of tracer using a mass balance equation. Plasma recoveries were corrected for tracer loss using a coefficient of elimination calculated from the plasma disappearance curve of intravenously administered (125)I-HSA. Over 4 h, 27.6 +/- 4.9 (+/-SE) and 36.7 +/- 4.2 ml were lost from the pericardial cavity in the 50- and 100-ml effusion series, respectively, of which 5.2 +/- 0.8 (20.2 +/- 3.8% of volume lost) and 7.7 +/- 1.6 ml (21.5 +/- 3.3% of volume lost) could be attributed to lymphatic transport. We conclude that lymphatic transport is one of the factors that contribute to pericardial "reserve" function by helping to restore pericardial fluid volume to resting levels.

Albumin transcytosis in mesothelium

Apparent permeability to albumin (P(alb)) was measured with (125)I-albumin in specimens of rabbit parietal pericardium from lumen to interstitium (L-I) and from interstitium to lumen (I-L). With albumin concentration (C(alb)) 0.5%, P(alb) (x 10(-5) cm/s) L-I at 37 degrees C was 0.172 +/- 0.019 SE; it decreased to 0.092 +/- 0.022 I-L at 37 degrees C, 0.089 +/- 0.021 L-I at 12 degrees C, and 0.084 +/- 0.018 I-L at 12 degrees C. These findings provide evidence for an active transport L-I, likely transcytosis. With C(alb) 2.5%, 0.05%, and 0.005%, P(alb) L-I at 37 degrees C was 0.188 +/- 0.023, 0.156 +/- 0.021, and 0.090 +/- 0.021, respectively; at 12 degrees C it was 0.089 +/- 0.017, 0.083 +/- 0.019, and 0.087 +/- 0.026, respectively. Hence, active albumin transport ceases with C(alb) 0.005%; P(alb) values I-L at 12 degrees C and with C(alb) 0.005% are similar and provide diffusional permeability. With physiological C(alb) (approximately 1%), active albumin flux was approximately 5 x 10(-4) micromol x h(-1) x cm(-2). Apparent permeability to FITC-dextran 70 (P(dx)) was also measured. P(dx) (x 10(-5) cm/s) L-I at 37 degrees C with C(alb) 0.5% was 0.095 +/- 0.018; it decreased to 0.026 +/- 0.004 I-L (37 degrees C, C(alb) 0.5%), 0.038 +/- 0.007 at 12 degrees C (L-I, C(alb) 0.5%), 0.030 +/- 0.009 with C(alb) 0.005% (L-I, 37 degrees C), and 0.032 +/- 0.011 with nocodazole (L-I, 37 degrees C, C(alb) 0.5%). These findings provide evidence for transcytosis and confirm conclusions drawn from P(alb). Vesicular liquid flow, computed from vesicular dextran flux (fluid-phase only), was approximately 3.5 microl x h(-1) x cm(-2). Transcytosis seems a relevant mechanism, removing protein and liquid from serous cavities.

High serum S100B levels for trauma patients without head injuries

OBJECTIVE

Studies of patients with head trauma have demonstrated a correlation between a serum marker of brain tissue damage, namely S100B, and neuroradiological findings. It was recently demonstrated that the increases in serum S100B levels after heart surgery have extracerebral origins, probably surgically traumatized fat, muscle, and bone marrow. The current study examined multitrauma patients without head trauma, to determine whether soft-tissue and bone damage might confound the interpretation of elevated serum S100B concentrations for patients after head trauma.

METHODS

A commercial assay was used to determine serum S100B concentrations for a normal population (n = 459) and multitrauma patients without head injury (n = 17). Concentrations of the two subtypes of S100B (S100A1B and S100BB) were determined using separate noncommercial assays.

RESULTS

The mean serum S100B concentration for a normal healthy population was 0.032 microg/L (median, 0.010 microg/L; standard deviation, 0.040 microg/L). The upper 97.5% and 95% reference limits were 0.13 and 0.10 microg/L, respectively. No major age or sex differences were observed. Among trauma patients, serum S100B levels were highest after bone fractures (range, 2-10 microg/L) and thoracic contusions without fractures (range, 0.5-4 microg/L). Burns (range, 0.8-5 microg/L) and minor bruises also produced increased S100B levels. S100A1B and S100BB were detected in all samples.

CONCLUSION

Trauma, even in the absence of head trauma, results in high serum concentrations of S100B. Interpretation of elevated S100B concentrations immediately after multitrauma may be difficult because of extracerebral contributions. S100B may have a negative predictive value to exclude brain tissue damage after trauma. Similarly, nonacute S100B measurements may be of greater prognostic value than acute measurements.

Increase in serum S100A1-B and S100BB during cardiac surgery arises from extracerebral sources

BACKGROUND

Elevated levels of serum S100B after coronary artery bypass grafting may arise from extracerebral contamination. Serum S100B content was analyzed in several tissues, and the two dimers S100A1-B and S100BB were analyzed separately in blood.

METHODS

Serum, shed blood, marrow, fat, and muscle were studied in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass using suction either to the cardiotomy reservoir (group 1, n = 10) or to a cell-saving device (group 2, n = 10), or operated on off-pump (group 3, n = 10).

RESULTS

Serum S100B was sixfold higher in group 1 than in groups 2 and 3, which were identical. The same ratio between S100A1-B and S100BB was found in all groups. When compared with serum, S100B was 10(2) to 10(4) times higher in marrow, fat, muscle tissue, and shed blood.

CONCLUSIONS

Separate analysis of S100A1-B and S100BB did not distinguish between S100B of cerebral and extracerebral origin. The concept that S100B only originates in astroglial and Schwann cells is wrong. Fat, muscle, and marrow in mediastinal blood contain high levels of S100B. Cardiopulmonary bypass caused no increase in S100B.

Relationship between pericardial pressure and lymphatic pericardial fluid transport in sheep

We investigated the relationship between pericardial pressure and the volumetric lymphatic clearance rate of pericardial fluid in sheep. A single catheter perfusion system was established to deliver tracer to the pericardial cavity and control pericardial pressure. In addition, catheters were placed into the thoracic duct and into the jugular vein at the base of the neck. (125)I-human serum albumin (HSA) was administered into the pericardial perfusate to serve as the lymph flow marker and its concentration monitored in the effluent from the outflow end of the perfusion system. (131)I-HSA was injected intravenously to permit calculation of plasma tracer loss and tracer recirculation into lymphatics. From mass balance equations, estimates of total pericardial clearance into lymphatics increased significantly as pericardial pressures were elevated in 2. 5 cm H(2)O increments from 2.5 to 12.5 cm H(2)O (P = 0.018). Pericardial lymph transport ranged from 0.89 +/- 0.10 to 3.09 +/- 0. 66 ml/h at 2.5 and 12.5 cm H(2)O pericardial pressure, respectively. The majority of transport occurred through mediastinal vessels with a small proportion (10.3 to 23.9%) being cleared into lymphatics leading to the thoracic duct. We conclude that lymphatic pericardial fluid transport increases approximately 3.5-fold over a pericardial pressure range that encompasses the transition between the shallow and steep portions of the pericardial pressure-volume relationship.