Physiology of pericardial fluid production and drainage

BNP and NT-proBNP as Diagnostic Biomarkers for Cardiac Dysfunction in Both Clinical and Forensic Medicine

Currently, brain natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are widely used as diagnostic biomarkers for heart failure (HF) and cardiac dysfunction in clinical medicine. They are also used as postmortem biomarkers reflecting cardiac function of the deceased before death in forensic medicine. Several previous studies have reviewed BNP and NT-proBNP in clinical medicine, however, few articles have reviewed their application in forensic medicine. The present article reviews the biological features, the research and application status, and the future research prospects of BNP and NT-proBNP in both clinical medicine and forensic medicine, thereby providing valuable assistance for clinicians and forensic pathologists.

Pericardial diseases in patients with hypothyroidism

Hypothyroidism is a well-known cause of pericardial effusion (with an incidence of 3%-37%) and can cause cardiac tamponade in severe cases. In this review, we present the current knowledge on the epidemiology of hypothyroid-induced pericardial diseases, the mechanism through which low thyroid hormone levels affect the pericardium, the associated clinical manifestations, diagnostic tests and management options. Hypothyroidism causes pericardial effusion through increased permeability of the epicardial vessels and decreased lymphatic drainage of albumin, resulting in accumulation of fluid in the pericardial space. Interestingly, autoimmunity does not seem to play a major role in the pathophysiology, and a majority of effusions are asymptomatic due to slow fluid accumulation. The diagnosis is generally made when the pericardial disease is associated with an elevated thyroid-stimulating hormone level, and other secondary causes are excluded. Management consists of thyroid replacement therapy, along with pericardial drainage in case of tamponade.In conclusion, hypothyroidism-induced pericardial diseases are underdiagnosed. Initiating treatment early in the disease process and preventing complications relies on early diagnosis through systematic screening per guidelines.

Biochemical investigations performed in pericardial fluid in forensic cases that underwent postmortem angiography

Postmortem biochemical investigations in vitreous humor samples collected before and after performing multiphase postmortem computed tomography angiography were performed in the past and demonstrated that specific contrast material injection allowed perfusion and radiological identification of the main vessels of the eye to be obtained without any changes in vitreous humor composition. In the study presented herein, we aimed to test whether the injection of the same contrast material using the same postmortem angiography protocol might influence pericardial fluid composition. Postmortem biochemical investigations were performed on pericardial fluid samples collected from bodies that underwent postmortem angiography (n = 16) prior to and post angiography. Two pericardial fluid samples were analyzed. No statistically significant differences were noticed among levels of any tested markers (urea nitrogen, creatinine, uric acid, C-reactive protein, procalcitonin, beta-hydroxybutyrate, and total IgE levels) in pericardial fluid samples collected prior to and post angiography, leading to the conclusion that pericardial fluid sampling can be delayed until after postmortem angiography when a specific contrast material injection is used.

Established and novel pathophysiological mechanisms of pericardial injury and constrictive pericarditis

This review article aims to: (1) discern from the literature the immune and inflammatory processes occurring in the pericardium following injury; and (2) to delve into the molecular mechanisms which may play a role in the progression to constrictive pericarditis. Pericarditis arises as a result of a wide spectrum of pathologies of both infectious and non-infectious aetiology, which lead to various degrees of fibrogenesis. Current understanding of the sequence of molecular events leading to pathological manifestations of constrictive pericarditis is poor. The identification of key mechanisms and pathways common to most fibrotic events in the pericardium can aid in the design and development of novel interventions for the prevention and management of constriction. We have identified through this review various cellular events and signalling cascades which are likely to contribute to the pathological fibrotic phenotype. An initial classical pattern of inflammation arises as a result of insult to the pericardium and can exacerbate into an exaggerated or prolonged inflammatory state. Whilst the implication of major drivers of inflammation and fibrosis such as tumour necrosis factor and transforming growth factor β were foreseeable, the identification of pericardial deregulation of other mediators (basic fibroblast growth factor, galectin-3 and the tetrapeptide Ac-SDKP) provides important avenues for further research.

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.

A fractionation approach applying chelating magnetic nanoparticles to characterize pericardial fluid's proteome

Owing to their close proximity, pericardial fluid (PF)'s proteome may mirror the pathophysiological status of the heart. Despite this diagnosis potential, the knowledge of PF's proteome is scarce. Large amounts of albumin hamper the characterization of the least abundant proteins in PF. Aiming to expand PF's proteome and to validate the technique for future applications, we have fractionated and characterized the PF, using N-(trimethoxysilylpropyl)ethylenediamine triacetic acid (EDTA)-functionalized magnetic nanoparticles (NPs@EDTA) followed by a GeLC-MS/MS approach. Similarly to an albumin-depletion kit, NPs@EDTA-based fractionation was efficient in removing albumin. Both methods displayed comparable inter-individual variability, but NPs@EDTA outperformed the former with regard to the protein dynamic range as well as to the monitoring of biological processes. Overall, 565 proteins were identified, of which 297 (>50%) have never been assigned to PF. Moreover, owing to this method's good proteome reproducibility, affordability, rapid automation and high binding ability of NP@EDTA, it bears a great potential towards future clinical application.

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.

A four-compartment PBPK heart model accounting for cardiac metabolism - model development and application

In the field of cardiac drug efficacy and safety assessment, information on drug concentration in heart tissue is desirable. Because measuring drug concentrations in human cardiac tissue is challenging in healthy volunteers, mathematical models are used to cope with such limitations. With a goal of predicting drug concentration in cardiac tissue, we have developed a whole-body PBPK model consisting of seventeen perfusion-limited compartments. The proposed PBPK heart model consisted of four compartments: the epicardium, midmyocardium, endocardium, and pericardial fluid, and accounted for cardiac metabolism using CYP450. The model was written in R. The plasma:tissues partition coefficients (Kp) were calculated in Simcyp Simulator. The model was fitted to the concentrations of amitriptyline in plasma and the heart. The estimated parameters were as follows: 0.80 for the absorption rate [h⁻¹], 52.6 for Kp_rest, 0.01 for the blood flow through the pericardial fluid [L/h], and 0.78 for the P-parameter describing the diffusion between the pericardial fluid and epicardium [L/h]. The total cardiac clearance of amitriptyline was calculated as 0.316 L/h. Although the model needs further improvement, the results support its feasibility, and it is a first attempt to provide an active drug concentration in various locations within heart tissue using a PBPK approach.

Adipokine Imbalance in the Pericardial Cavity of Cardiac and Vascular Disease Patients

Aim

Obesity and especially hypertrophy of epicardial adipose tissue accelerate coronary atherogenesis. We aimed at comparing levels of inflammatory and atherogenic hormones from adipose tissue in the pericardial fluid and circulation of cardiovascular disease patients.

Methods and Results

Venous plasma (P) and pericardial fluid (PF) were obtained from elective cardiothoracic surgery patients (n = 37). Concentrations of leptin, adipocyte fatty acid-binding protein (A-FABP) and adiponectin (APN) were determined by enzyme-linked immunosorbent assays (ELISA). The median concentration of leptin in PF (4.3 (interquartile range: 2.8–9.1) μg/L) was comparable to that in P (5.9 (2.2–11) μg/L) and these were significantly correlated to most of the same patient characteristics. The concentration of A-FABP was markedly higher (73 (28–124) versus 8.4 (5.2–14) μg/L) and that of APN was markedly lower (2.8 (1.7–4.2) versus 13 (7.2–19) mg/L) in PF compared to P. APN in PF was unlike in P not significantly related to age, body mass index, plasma triglycerides or coronary artery disease. PF levels of APN, but not A-FABP, were related to the size of paracardial adipocytes. PF levels of APN and A-FABP were not related to the immunoreactivity of paracardial adipocytes for these proteins.

Conclusion

In cardiac and vascular disease patients, PF is enriched in A-FABP and poor in APN. This adipokine microenvironment is more likely determined by the heart than by the circulation or paracardial adipose tissue.