Physiopathology of Infections in Patients with Permanently Implanted Heart Care Devices

In recent decades there has been a rapid increase in the use of implantable cardiac assist devices in patients with advanced heart failure, as data in the literature have recently demonstrated that their use lead to survival advantage over maximal medical therapy. Nowadays, the increasing use of cardiac implantable devices has been accompanied by a significant increase in different complications. Infections are one of the major medical complications associated with permanence cardiac devices, not only because of the "invasive" nature required for implantation but also because of the dysregulation of the immune system and the chronic inflammatory state associated with the underlying heart failure. The major sources of infection are contamination by the skin flora during the placement of the device. In the alterative, at the skin level, the exit point of the DLI, i.e. the cable connecting the device to an external generator, is often the entry point of microorganisms that, following the course of the generator cables, can reach the device, causing infections in the skin and soft tissues or alternatively gain access to the bloodstream causing bacteremia, sepsis, endocarditis, and distant metastatic localizations. Also, the ability of pathogens to form a biofilm, a matrix that is difficult to penetrate by antibiotics, plays a central role in making the infectious process chronic linked to implantable devices. Normally, the skin surface is colonized by a resident microbial population, stable over time with different characteristics concerning the anatomical site explored, while infections are largely sustained by Gram-positive bacteria such as Staphylococcus, followed by Gram-negative bacteria such as Enterobacteriaceae and Pseudomonas. It can, therefore, be hypothesized that malnutrition, comorbidities, and frequent hospitalizations to which these patients are subject are elements of vulnerability, able to determine the dysbiosis of the resident skin flora, reducing the diversity of the skin microbiota and finally encouraging colonization and/or infection by pathogenic species.