What Is Endocarditis?

A fever that keeps coming back, night after night, when you otherwise feel only vaguely unwell — that is often how endocarditis first announces itself. Endocarditis is an infection of the inner lining of the heart, the endocardium, and it usually involves one or more of the heart valves. Germs — most often bacteria — reach the heart through the bloodstream, settle on a valve or lining surface, and grow there. Because the infection sits inside the heart itself, it is treated seriously and usually in hospital, even when the early symptoms feel mild.

The short video at the top of this page, "Endocarditis" (about a minute and a half), introduces the condition in plain terms. Its description puts the starting point clearly: germs from another part of the body, such as the mouth, spread through the bloodstream and attach to the heart's lining. Everything that follows in this guide — the tests, the treatment, the follow-up — flows from that one journey the germs have taken.

Who tends to be at risk?

Most healthy hearts shrug off the brief trickle of bacteria that enters the blood during everyday life, such as chewing or brushing your teeth. Endocarditis is more likely when a valve gives germs somewhere to grip: a valve that was already damaged or diseased, a replacement (prosthetic) valve, a heart defect present from birth, or a previous episode of endocarditis. Risk also rises when bacteria get repeated or direct access to the bloodstream, for example through medical lines placed in veins, or through infected skin. Knowing your own situation matters, because people in the higher-risk groups are sometimes advised to take extra precautions around dental and medical procedures — a conversation to have with your own doctor, who knows your heart history, rather than something to decide from an article.

What the illness can feel like

Expect a slow burn rather than a sudden collapse, in most cases. A persistent or recurring fever, chills and night sweats are the classic pattern, along with tiredness, aching muscles and joints, and sometimes weight loss that you can't explain. Some people notice new breathlessness, a new heart murmur picked up at an examination, tiny painless or painful spots on the skin or under the nails, or blood in the urine. Others deteriorate faster, with high fever and feeling very unwell — that pattern is an emergency, not a wait-and-see. A fever that will not settle, especially if you know you have a valve problem or a replacement valve, deserves prompt medical assessment in its own right.

Complications are the reason doctors act quickly once endocarditis is suspected. Infected material on a valve can damage the valve until it leaks, pushing the heart toward the strain described in our guide to what heart failure is. Fragments can also break away in the bloodstream and seed infection elsewhere; one recorded example you can watch is "Mycotic Aneurysms" (about five minutes), a case in which infection from endocarditis weakened an artery wall — a reminder that this is a whole-body infection, not just a heart one. When bloodstream infection escalates, it can also tip into the emergency covered in our guide to what sepsis is.

How the diagnosis is pinned down

Two kinds of evidence, gathered together, usually make the picture. The first is blood cultures: samples of blood drawn — ideally before antibiotics start — and watched in the laboratory to see whether germs are growing, and which ones. Repeated sets matter, because a germ found again and again in the blood is very different from a single contaminated sample. The second is imaging of the valves, and that means an echocardiogram, an ultrasound scan of the heart that can show clumps of infection, called vegetations, sitting on a valve and how well the valve is working. Our guide to what an echocardiogram shows walks through that scan in detail, including the closer-up version passed down the gullet when the first pictures are not clear enough. Blood tests for inflammation, kidney checks, urine tests and sometimes scans of other organs complete the search for where the infection came from and where it may have travelled.

What treatment in hospital looks like

Plan on intravenous antibiotics — antibiotics given into a vein — as the backbone of treatment, chosen once the blood cultures name the germ, and continued for a course measured in weeks rather than days. The first days usually involve close monitoring, repeat blood cultures to confirm the infection is clearing, and repeat echocardiograms to watch the valve. If a valve is badly damaged, leaking severely, or the infection is not coming under control, the team may discuss heart-valve surgery to remove infected tissue and repair or replace the valve; that decision rests with a combined team of cardiology, infection and surgical specialists. Once you are stable and the plan is set, some people complete the later part of the antibiotic course at home with visiting support, if their team judges that safe.

Settling back into everyday life

Recovery is gradual. Follow-up typically includes clinic reviews, blood tests and sometimes a further echocardiogram to check the valve has settled. Dental health deserves real attention afterwards: the mouth is the everyday source doctors worry about most, so regular dental care and telling your dentist about the episode are sensible habits. And if fever returns after treatment, treat it as information your team needs promptly — mention the previous endocarditis episode to whoever sees you, before any antibiotic is started, so blood cultures can be taken first.

References & further reading

• MedlinePlus — Endocarditis: https://medlineplus.gov/endocarditis.html
• Cleveland Clinic — Endocarditis: https://my.clevelandclinic.org/health/diseases/16957-endocarditis
• NHS — Endocarditis: https://www.nhs.uk/conditions/endocarditis/

Frequently Asked Questions

Is endocarditis the same as a heart attack?

No. A heart attack is a blocked artery starving heart muscle of blood. Endocarditis is an infection of the heart's inner lining and valves, caused by germs travelling in the bloodstream. The two are different conditions with different tests and treatment.

How long does treatment for endocarditis take?

Antibiotic treatment is usually measured in weeks, not days, because the infection sits in tissue the bloodstream reaches slowly. Part of the course is in hospital, and some people finish it at home under supervision if their team agrees. Your own team's plan depends on the germ and the valve involved.

Can endocarditis come back?

It can, which is why follow-up matters and why a previous episode is itself a risk factor for a future one. Keeping up dental care, telling your dentist and doctors about the episode, and getting a returning fever checked promptly — with blood cultures before antibiotics — all help protect you.

When should a fever be checked urgently?

A fever that keeps returning or will not settle always deserves medical review. Seek urgent help the same day if you feel very unwell, develop breathlessness, chest pain, confusion, or a rash that does not fade under pressure — and sooner still if you have a replacement valve or a previous episode of endocarditis.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician-scientist.

Educational only — this article is general information about endocarditis, not medical advice and not a diagnosis. Decisions about testing and treatment for a heart infection belong with your own cardiology and infection team, who know your blood cultures and scans.