The anatomical study of the pericardium in vibroacoustic disease (VAD) patients was prompted by the echo-imaging results obtained initially in aircraft technicians. With informed consent of VAD patients, submitted to cardiac surgery for other reasons, pericardial fragments were removed for study in order to determine the nature of this abnormal thickening.
The parietal pericardium fragments were removed during surgery. None had a record of any kind of pericarditis, nor of any type of diastolic problems, and there was no previous history of diabetes or repeated streptococcal infections. Fragments were removed at the beginning of the surgery, during the opening of the pericardial sac. Each fragment was divided in two and pinned in dentist wax in a Petry dish with the serosal surface facing up. The specimens for light microscopy were formalin-fixed, paraffin-embedded, hematoxylin, eosin and fuschsin-rhesorcin stained.
Normal pericardium has three layers: serosa, fibrosa and epipericardium. Five layers of tissue were identified, instead of the classical three: serosa, internal fibrosa, loose tissue layer, external fibrosa, and epipericardium. The external and internal fibrosa are composed of organized, wavy collagen bundles. Images of apoptotic (programmed) death were seen in the mesothelial layer, and non-apoptotic (mechanical) cell death was observed in all other layers. A large amount of cellular debris was present in all fields, however, not inflammatory process was present. Imaging frequently disclosed the presence of cell debris inside the small lymphatic vessels.
Given the large amount of cellular debris, auto-immune situations are certain to arise. Drainage of cellular debris seems to be a major function of the surrounding lymphatic vessels.
Pericardial thickening with no adiastole, and no inflammatory process is a VAD diagnosis, and can certainly be the cause of auto-immune situations.
José Fragata, None.