Introduction

Imagine a virus or bacteria silently overtaking and affecting the very core of your body- your heart. With this in mind, common symptoms such as a mild fever or fatigue can often be an indication of something much more severe: Endocarditis.

This hidden infection causes the endocardium, the inner lining of the heart, to become inflamed.¹ This illness can cause chaos in your heart, causing life-threatening damage and even an enlarged heart. But how does this happen? And why should you be concerned?

This article will cover what Endocarditis is in more detail, its symptoms, diagnosis, and treatments, together with how it can be prevented. In addition, the complex relationship between endocarditis and heart enlargement will be broken down, focusing on what you need to know to protect your health and, more importantly, your heart. Whether you just want to be proactive about your heart, want to make positive changes, or want to gain a better understanding of the potential warning signs of Endocarditis, this article is for you. Therefore, let’s dive into how such small infectious pathogens can cause such life-changing impacts on people. 

What is Endocarditis?

Endocarditis occurs when the endocardium, the inner lining of the heart cavities and valves, becomes infected by either bacteria or fungi.¹ The endocardium is the innermost layer of the heart, lining its chambers and extending over structures such as the valves. It plays several key roles in the overall functioning of the heart, which is why when it becomes inflamed it can be life-threatening.² 

Amongst other things, it provides a smooth surface, helping to lower blood flow resistance. Similarly, it acts as a protective barrier protecting the heart’s muscles from being exposed to pathogens or other agents in the bloodstream.³

This is a rare and potentially fatal infection, most commonly caused by bacteria entering the bloodstream and travelling to the heart, with the most common bacteria including Streptococcus and Staphylococcus.⁴ Although fungal infections are less common, representing only about 1% of cases,¹ they can nonetheless lead to Endocarditis.

Symptoms of Endocarditis

As with most infections, it is important to remember that symptoms may vary based on each individual, and not all symptoms might occur. Endocarditis can be fatal and difficult to diagnose because most patients present non-specific symptoms, which are symptoms that can correspond to several other dangerous illnesses. However, with this in mind, some of the most common symptoms of Endocarditis to look out for include: 

• Fever (high temperature)
• Fatigue and tiredness
• Headaches
• Night sweats (sweating)
• Chills

Additionally, some of the less common symptoms include: 

• Swelling in legs and feet
• Muscle and joint aches
• Skin rash
• Janeway lesions (red, painless skin spots)
• Splinter haemorrhage (Small areas of bleeding under the nails)

According to the British Heart Foundation, if you are thought to be at high risk for developing Endocarditis and you present flu-like symptoms for more than a week, you should see your general practitioner immediately.

Diagnosis and treatment of Endocarditis

Diagnosis

Endocarditis remains a diagnostic and treatment challenge, especially as during the early stages, the infection looks similar to other illnesses, making it hard to diagnose. Despite this, certain procedures can help diagnose it, which include:

• Blood test 

This is often performed to identify the type of bacteria or fungus causing the inflammation of the endocardium.⁴

• Diagnostic imaging 
  • Echocardiogram: a type of ultrasound scan that sends high-frequency sound waves, which echo when bouncing off the heart and nearby blood vessels. This is often the first diagnostic test carried out. It is used to look for an indication of damage to your heart^1,4 
  • Electrocardiogram (ECG): this is a test that records the electrical activity of your heart, including both its rhythm and pace. This diagnostic test is often carried out to look for abnormal heart rhythms and paces⁴ 
  • X-rays: chest X-rays are also used to check for buildup of fluids in your lungs
  • MRI scans: this is a relatively new imaging technique for diagnosing Endocarditis, that allows a clearer view of your heart.⁵ These types of scans use strong magnetic fields and radio waves to produce detailed images of the inside of the body, including those of the heart and its valves⁶

Due to the potential life-threatening effects of endocarditis, it is not uncommon for doctors to begin a form of treatment while steps are taken to confirm the diagnosis, as early detection, rapid diagnosis and timely management are essential for a positive outcome. 

Treatment

In terms of how Endocarditis is treated, in most cases, it can be managed with antibiotics. In the early stages of the infection, you'll be admitted to the hospital as the antibiotics need to be administered intravenously (into the vein) - via a drip in your arm. 

The choice of what antibiotic is given is dependent upon the cause of the infection (type of bacteria or fungus), and its antibiotic susceptibility.⁷ This is decided by your doctor taking a blood sample, before the antibiotics are prescribed, to ensure the most effective treatment is given. Regular blood samples will be taken during your time at the hospital to ensure the treatment is working and the infection is beginning to clear from the bloodstream. 

In more severe situations, you could be advised to take antibiotics as a preventative measure before learning the results of the blood test, to keep your symptoms from getting worse.

It is possible that once the severe symptoms have subsided and you no longer require monitoring, you may be able to leave the hospital and continue to receive antibiotics at home via an intravenous drip.

Similarly, when you are in hospital, you would need to have regular appointments with your GP to ensure the correct course of the treatment, and to check for any adverse effects. The course of antibiotics normally lasts between 2-6 weeks. If Endocarditis causes serious damage to your heart, such as heart failure, you may require surgery to repair the damage.

Antifungal medicines are administered when the blood sample shows that fungi are the cause of the infection. 

Prevention of Endocarditis

To prevent Endocarditis from taking place, certain measures need to be put in place to reduce the risk of infection. Therefore, preventative measures include:¹⁰

• Regular monitoring of heart conditions
• Maintaining good oral hygiene - this is to reduce the risk of bacteria and fungus entering the bloodstream
• Avoid body piercings and tattoos 
• Wash your hands regularly to prevent the spread of bacteria
• Avoid intravenous drugs

How Endocarditis leads to an enlarged heart

The heart is a muscular pump, generally the size of a clenched fist, that can become enlarged if it is forced to work harder than normal. Whilst an enlarged heart is not a condition itself, it is a symptom of an underlying problem. 

There are a range of different problems that can cause an enlarged heart, including both pathological and physiological. During endocarditis, when the inner lining of the heart becomes inflamed due to infection, it can lead to an enlarged heart (cardiomegaly) through a series of damaging processes.⁸ These include:

• Valve damage: Clumps of bacteria, fungi, or cellular debris, called vegetations, often form on the valves of the heart, which can cause erosions or holes, causing the valves to malfunction. Depending on where the vegetation occurs, damage can be caused to the conduction pathway or the sinus of the valve to rupture. Additionally, the inflammation from the infection can also affect the valves⁹ 
• Increased workload: Heart valve damage can result in stenosis, or narrowing of the heart valves, or regurgitation, or leakage of the valves, which makes the heart work harder to pump blood properly. With time, the extra strain on the muscle can cause these to become enlarged or thicken
• Weakened heart muscle: In some cases of endocarditis, the infection in the endocardium can spread to the myocardium (the muscle of the heart), weakening the muscle, impairing its ability to pump blood efficiently. Over time, due to the overcompensation, the heart has to pump more blood, causing the heart chambers to become enlarged or dilated⁹

Some patients with enlarged hearts present no symptoms (asymptomatic). However, some patients can develop a syndrome known as congestive heart failure, which occurs when the heart fails to pump blood effectively. Symptoms of this include:

• Shortness of breath
• Irregular heartbeat
• Fluid retention
• dizziness

In the most severe cases, if endocarditis is not diagnosed and treated quickly, the infection and damage caused by this can lead to heart failure, because the heart becomes too weak and enlarged to pump blood around the body in an efficient manner.⁹

Summary

Endocarditis is a serious infection of the endocardium, the inner lining of the heart's chambers and valves, typically caused by bacteria or fungi. Common symptoms include fever, fatigue, and chills, but diagnosing endocarditis can be challenging due to patients often presenting non-specific symptoms. 

If Endocarditis is left untreated, it can damage the heart valves, causing them to malfunction and forcing the heart to work harder. This strain can weaken the heart and cause an enlarged heart, especially if the infection spreads to the heart muscle. 

As the heart overcompensates for the valve damage, it may enlarge or thicken, eventually leading to heart failure in severe cases. ​​Preventive measures, antibiotic therapy, and early diagnosis are essential for controlling and lowering the risk of consequences such as an enlarged heart.