The characteristic lesion of infectious endocarditis is endocardial vegetation. It is made up of the completely abnormal presence of an aggregate of platelets, fibrin, bacteria and inflammatory cells that adhere to the internal surface of the heart, usually on the surface of a cardiac valve, and which is susceptible to breaking off, causing an infectious embolism at a distance in another organ (skin, nervous system, limb).
It is considered a serious illness and although in most cases it is cured, it also has significant complications and mortality despite treatment. In many cases, patients must be subjected to surgical intervention in order for it to be definitively cured, eliminating the affected tissue and inserting a new artificial heart valve.
In its most acute form infectious endocarditis can produce high fever, chills, prostration and severally affect the patient's general condition in a short time period (hours-days). In subacute forms it may evolve over weeks or months, with a clinical presentation of tiredness, lack of appetite and low-grade fever. In these cases, infectious skin manifestations may also occur as nodules or characteristic spots, which do not always appear.
In patients with severe cardiac valve involvement, the valves themselves may not function correctly, which may result in symptoms of heart failure such as severe shortness of breath and swelling of the lower limbs
How is afeccted by the condition
Infectious endocarditis has a global incidence of 2-3 cases per 100,000 population per year, and so it is estimated that in Catalonia around 200 cases are diagnosed every year. Its incidence increases greatly with age, reaching 15-30 cases/per 100,000 population/year in over 65s, or 10 times higher than that of the younger population.
The cause of infectious endocarditis has changed a lot in recent decades. In recent years the most frequent causal bacterium has been streptococcus, especially a species called viridans. There is currently a great variety of causal agents, although staphylococci are the most frequent, followed by streptococci and enterococci. It is, however, advisable to note that any microorganism that circulates through the blood can adhere to a heart valve, especially if it has previous injuries or is an artificial valve.
The diagnosis of endocarditis is based essentially on:
- blood cultures to identify the bacterium that causes the infection and allow the most suitable specific antibiotic treatment to be chosen.
- echocardiogram that allows the endocardial vegetations typical of the disease to be located. It also informs doctors about the function of the valve affected and contributes significantly to assessing the need for surgical treatment in some patients.
- in some cases it is necessary to carry out other explorations (such as CAT or scintigraphy) to rule out the existence of peripheral embolisms, which are very common at the time of diagnosis or during the course of treatment of the disease.
The treatment of infectious endocarditis is antibiotic, but specifically targeting the microorganism that causes it. The doses are high and prolonged over time because the vegetations typical of the disease are not very vascularised and antibiotics must penetrate through diffusion from circulating blood. In patients who do not respond adequately to this antibiotic treatment or who have major valve damage as a consequence of the infection, it is necessary to assess the need for valve replacement surgery.
Blood cultures and echocardiogram, both at the time of diagnosis and to monitor the evolution of the illness.
When an alteration of a person's heart valve is recognised, antibiotic prevention must be administered before any dental or gum treatment is given, following specialised consultation.
Preventive measures must also be taken in the case of endoscopes, especially of the upper gastrointestinal tract (gastroscopy), with the antibiotic and guidelines indicated by the doctor.
This prevention is very important because the presence of bacteria in the blood, as a result of the intervention or exploration, carries a significant risk of infectious endocarditis.
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Guillén del Castillo