http://www.imim.cat/noticies Programa de recerca: Processos inflamatoris i cardiovasculars http://www.imim.cat/noticies/view.php?ID=743 <p>One of the symptoms associated with long COVID is<strong> chronic fatigue</strong>. Until now, its origin was unclear. A study conducted by the Pneumology, Pathology, and Intensive Care Services at Hospital del Mar, along with researchers from the Hospital del Mar Research Institute, points to a potential cause: <strong>fibrosis in the walls of blood vessels triggered by the infection</strong>. The study has been published in the journal Ultrastructural Pathology.</p> <p>The research is based on muscle biopsies taken from the quadriceps of 35 patients admitted to Hospital del Mar during the pandemic. Eight of these samples were analyzed using <strong>electron microscopy</strong> to assess the state of the tissue. <strong>Significant fibrosis was found in the walls of the capillaries supplying blood to the muscle fibers</strong>, a finding consistent with observations in other organs from patients who died from COVID-19.</p> 29/07/2025