Editorial
Shining a new light on pericardial fluid Table 1 Comparison of normal reference
intervals of pericardial fluid to transudative Heart: first published as 10.1136/heartjnl-2021-319929 on 7 July 2021. Downloaded from Erin A Fender ,1 Chad J Zack2 pleural fluid Pericardial Pleural fluid fluid transudate 7 In a healthy individual, there is 15–50 mL for pericardial fluid analysis. This Biochemical of fluid between the visceral and parietal study examined a final sample of 120 components layers of the fibroelastic pericardium. The adult subjects undergoing elective open- Total protein (g/dL) 2.8 (1.7– <3.0 normal composition of pericardial fluid is heart surgery. The study population was 4.6) currently ill-defined. In the USA, pericar- predominantly male (68.1 %) with a Total protein ratio 0.5 (0.29– ≤0.5 diocentesis is performed in patients with median age of 67 years and included those 0.83) pericardial disease approximately 1000 that underwent surgical revascularisa- Albumin gradient 1.4 (0.18– ≥1.2 times per month.1 2 During pericardiocen- tion, valve repair/replacement, myomec- (g/dL) 2.37) tesis fluid is almost uniformly sent for tomy and ascending aortic replacement. LDH (U/L) 357 (141– ≤147* laboratory analysis per guideline recom- Subjects with active pericardial disease, 2613) mendations to quantify general chemistry heart failure, liver disease, renal disease, LDH ratio 1.1 (0.40– ≤0.6 and cellular composition.3 To date, there recent malignancy, haematological disor- 2.99) is no established methodology to assess ders, hypoproteinaemia, pregnancy and Glucose (mg/dL) 95 (80–134) 65-139† pericardial fluid composition nor are there diabetes were excluded. At the time of Total cholesterol 27 (12–69) ≤45 recognised reference values for the normal surgery, the pericardial space was opened (mg/dL) constituents of pericardial fluid. Interpre- using an electric scalpel to minimise Cellular counts tation of pericardial fluid composition is Leucocytes 503 (35–2210) 125 (83– traumatic bleeding, and two separate 6 commonly performed by extending the 2 mL samples were obtained for analysis. (10 cells/L) 214) Mesothelial cells 1283 (40– 1 (0–2) Light’s criteria validated on pleural fluid Samples with evidence of haemolysis 6 3 4 (10 cells/L) 3790) analysis to pericardial fluid. The accu- were discarded. The samples underwent Lymphocytes 304 (19–1634) 23 (16–31) racy of this approach to establish if peri- biochemical analyses, automated cell 6 (10 cells/L) cardial fluid is transudative or exudative is count and optical microscopy. unknown. Polymorphonucleated 2 (0–116) 1 (0–2) The authors found that physiological cells, (106 cells/L) Available data regarding the biochem- pericardial fluid is rich in protein, albumin, Macrophages, 1 (0–207) 75 (64–81) ical and cellular composition of physi- LDH and nucleated cells with low levels (106 cells/L) ological pericardial fluid are sparse. In a of glucose and cholesterol. They derived *Value is two-thirds of the upper limit of normal for study of 30 consecutive patients without normal reference values for total protein those aged 18 years or older (222 IU/L). pericardial disease undergoing coronary (1.7–4.6 g/dL), pericardial fluid/serum †Similar to blood glucose concentration. artery bypass grafting or valvular replace-
protein ratio (0.29–0.83), LDH (141– http://heart.bmj.com/ ment that underwent pericardial fluid 2613 U/L), pericardial fluid/serum LDH physiological samples would be routinely analysis, mean fluid lactate dehydrogenase ratio (0.40–2.99), albumin (1.19–3.06 g/ misclassified as exudates due to the rich (LDH) was 2.4 times higher and mean dL) and pericardium to serum albumin cellularity and biochemical composition protein was 0.6 times lower than serum gradient (0.18–2.37 g/dL). Normal refer- of pericardial fluid. Similar misclassifica- levels. LDH and protein fluid-serum ratio ence intervals were also determined by tion would likely occur with pathological values of these normal specimens would optical microscopy for nucleated cells specimens. More work remains to deter- be classified as exudative per the Light’s (278–5608 × 106 cells/L), mesothelial 5 mine an adequate schema able to differen- on October 2, 2021 by guest. Protected copyright. criteria. A more recent study performed cells (40–3790 × 106 cells/L), leucocytes tiate between transudative and exudative on 50 patients undergoing cardiac surgery (19–2210 × 106 cells/L) and lympho- pericardial fluid. However, the efforts put without pericardial disease found that cytes (19–1634 × 106 cells/L). While the forth by the authors to first define the mean fluid LDH levels were 1.1 times study’s modest sample size likely contrib- higher and total protein in pericardial normal composition of pericardial fluid utes to wide reference intervals, the results is crucial and should be commended. This fluid was 0.5 times lower than plasma imply normal physiological pericardial levels.6 All 50 samples of normal physio- study is a step forward in the management fluid would meet traditional criteria for an of pericardial disease and provides a new logical pericardial fluid would be classified exudate. The authors hypothesise that the by the Light’s criteria as exudates. These standard in interpreting pathological peri- unique composition of pericardial fluid cardial fluid specimens. studies appear to suggest that the compo- may be due to increased pericardial vascu- sition of pericardial fluid is distinct from lature permeability, pericardial mechan- pleural fluid and methods for classifying Contributors EAF and CJZ: Drafting and critical ical stress due to cardiac contractility, or revision of the manuscript. pleural effusions may not apply to pericar- related to the abundant cell types found dial effusions. Funding The authors have not declared a specific within the pericardial space. grant for this research from any funding agency in the In Heart, Sabrina Buoro and colleagues The findings of the study highlight the public, commercial or not-for-profit sectors. sought to define specific reference values potential for diagnostic errors when inter- Competing interests None declared. pretive tools are used outside of their vali- 1Cardiology, Christiana Care, Newark, Delaware, USA Patient and public involvement Patients and/or 2Cardiology, Penn State College of Medicine, Hershey, dated purpose. The Light’s criteria were the public were not involved in the design, or conduct, Pennsylvania, USA derived on fluid samples from a different or reporting, or dissemination plans of this research. physiological space with a composition Patient consent for publication Not required. Correspondence to Dr Erin A Fender, Cardiology, Christiana Care, Newark, Delaware 19713, USA; distinct from pericardial fluid (table 1). Provenance and peer review Commissioned; erinfender@ gmail.com Based on the current study, normal internally peer reviewed.
Fender EA, Zack CJ. Heart Month 2021 Vol 0 No 0 1 Editorial
To cite Fender EA, Zack CJ. Heart Epub ahead of 2 Gad MM, Elgendy IY, Mahmoud AN, et al. Temporal print: [please include Day Month Year]. doi:10.1136/ trends, outcomes, and predictors of mortality after
heartjnl-2021-319929 pericardiocentesis in the United States. Catheter Heart: first published as 10.1136/heartjnl-2021-319929 on 7 July 2021. Downloaded from Cardiovasc Interv 2020;95:375–86. 3 Adler Y, The CP. ESC guidelines on the diagnosis and management of pericardial diseases. Eur Heart J Open access This is an open access article distributed 2015;2015:2873–4. in accordance with the Creative Commons Attribution 4 Light RW, Macgregor MI, Luchsinger PC, et al. Pleural ►► http://dx. doi. org/ 10. 1136/ heartjnl- 2020- 317966 Non Commercial (CC BY-NC 4.0) license, which permits effusions: the diagnostic separation of transudates and others to distribute, remix, adapt, build upon this work Heart 2021;0:1–2. exudates. Ann Intern Med 1972;77:507–13. non-commercially, and license their derivative works on doi:10.1136/heartjnl-2021-319929 5 Ben-Horin S, Shinfeld A, Kachel E, et al. The composition different terms, provided the original work is properly of normal pericardial fluid and its implications cited, appropriate credit is given, any changes made ORCID iD for diagnosing pericardial effusions. Am J Med indicated, and the use is non-commercial. See: http:// Erin A Fender http://orcid. org/0000- 0003-1513- 0169 2005;118:636–40. creativecommons.org/ licenses/by- nc/4. 0/. 6 Imazio M, Biondo A, Ricci D, et al. Contemporary © Author(s) (or their employer(s)) 2021. Re-use REFERENCES biochemical analysis of normal pericardial fluid. Heart permitted under CC BY-NC. No commercial re-use. See 1 Imazio M, Cecchi E, Demichelis B, et al. Myopericarditis 2020;106:541–4. rights and permissions. Published by BMJ. versus viral or idiopathic acute pericarditis. Heart 7 Buoro S, Tombetti E, Ceriotti F, et al. What is the 2008;94:498–501. normal composition of pericardial fluid? Heart 2020. doi:10.1136/heartjnl-2020-317966. [Epub ahead of print: 11 Nov 2020]. http://heart.bmj.com/ on October 2, 2021 by guest. Protected copyright.
2 Fender EA, Zack CJ. Heart Month 2021 Vol 0 No 0