Changes in pericardial calcification due to antiplatelet agents: in vitro studies

Oral Use of Phenytoin to Reduce Calcification in Bovine Pericardium and Porcine Aortic Leaflets Implants in Rats

Introduction:

This study aims to test the effect of phenytoin as an inhibitor of the process of dystrophic calcification in bovine pericardium and porcine leaflets implanted in the subcutaneous tissue of rats.

Methods:

Isolated segments of biomaterials were implanted subcutaneously in young rats. The study groups received 500 mg phenytoin per kilogram of diet per day. After 90 days, samples were collected and quantitative calcification assessment by optical microscopy, radiological studies with mammography, and atomic emission spectrometry were performed.

Results:

Inflammatory reaction was a frequent finding in all groups when analyzed by optical microscopy. The calcium level assessed by atomic absorption spectrophotometry was significantly lower in the study groups using phenytoin compared to the control groups (control bovine pericardium group X=0.254±0.280 µg/mg; study bovine pericardium group X=0.063±0.025 µg/mg; control porcine aortic leaflets group X=0.640±0.226 µg/mg; study porcine aortic leaflets group X=0.056±0.021 µg/mg; P<0.05). Radiologic studies revealed a statistically significant difference between the groups treated with and without phenytoin (not only regarding the bovine pericardium but also the porcine leaflets).

Conclusion:

The results obtained suggest that phenytoin reduces the calcification process of bovine pericardium segments and porcine aortic leaflets in subdermal implants in rats; also, the incidence of calcification in bovine pericardium grafts was similar to that of porcine aortic leaflets.

Surface-Immobilized Biomolecules on Albumin Modified Porcine Pericardium for Preventing Thrombosis and Calcification

The search for a noncalcifying tissue material to be used for valve replacement application continues to be a field of extensive investigation. A series of porcine pericardial membranes was prepared by modifying the glutaraldehyde - treated tissues with albumin and subsequently immobilizing bioactive molecules like PGE1, PGI2 or heparin via the carbodiimide functionalities. The in vitro calcification and collagenase degradation of these modified tissues were studied as a function of exposure time. Furthermore, the biocompatibility aspects of such novel interfaces were established by platelet adhesion and fibrinogen adsorption.

The results reported in this article propose that the treatment with antiplatelet agents such as albumin, heparin and prostaglandins (PGE1 or PGI2) change the surface conditioning of pericardial tissues, suggesting a possible role of deposited serum components in affecting mineralization process on bioprosthesis. Therefore, it is worthy to hypothesize that besides inhibiting the accumulation of calcium in the devitalized cells, the early formation of a conditioning layer on the bioprosthesis surface may affect salt precipitations, determining the propensity of the implant to calcify. More detailed studies are needed to understand the involvement of plasma proteins and cellular components of the recipient blood in tissue-associated calcification.

Cardiac calcification in acute intermittent porphyria

Aetiology of pericardial calcifications can be multifactorial. Tuberculosis has been reported as the most common cause. Other known causes include uraemia, asbestosis, post-traumatic or postoperative. We report a rare case of pericardial calcification seen in a patient with established acute intermittent porphyria. A direct causal relationship cannot be established between porphyria and pericardial calcification, but it may be due to deposition of the porphyrin in the pericardium.