Introduction

Blood flow in and out of the heart is controlled by valves in the heart. These valves must function correctly for the heart to work properly and supply blood to the rest of the body. Each valve has flaps that open and close (like doors) with each heartbeat and hence regulate the blood flow to and from the heart in the right direction. A normal healthy heart has 4 valves:¹

• Aortic valve: Located between the left ventricle (lower chamber of the heart) and the aorta (a large artery that delivers oxygenated blood to the body)
• Mitral valve: Located between the left atrium (upper chamber of the heart) and the left ventricle
• Pulmonary valve: Located between the right ventricle and the pulmonary artery which is the artery that carries deoxygenated blood from the heart to the lungs for oxygenation
• Tricuspid valve: Located between the right atrium and the right ventricle

Sometimes a valve may have one or more problems. These problems can make the heart work harder and affect its ability to pump blood. If a valve condition is left untreated, it can get worse over time, putting one at risk for serious problems such as heart failure or stroke.¹

Infectious endocarditis is when harmful microorganisms (mostly bacteria) infect the inner lining of the heart and the heart valves.² Infective endocarditis is most frequently seen to affect the mitral valve, followed by the aortic valve, the mitral and aortic valves in combination, the tricuspid valve, and the pulmonary valve.³ Although infective endocarditis is rare, it can cause serious health problems and even death if not quickly diagnosed and treated.² This article gives an overview of mitral valve disease and infective endocarditis.

Overview of mitral valve disease

There are two main types of mitral valve diseases: regurgitation and stenosis:¹

1. Regurgitation (backflow or insufficiency)

Occurs when a valve does not close tightly allowing the blood to leak backward instead of flowing forward. Since some of the blood flows in the wrong direction, it reduces the efficiency of the heart. Regurgitation can be caused by valve flaps that may not be the right size or shape, or if the valve opening is stretched. Regurgitation often affects the mitral valve. However, mitral valve regurgitation does not always cause backflow but when backflow occurs, it can lead to complications such as infection and increased pressure in the heart and lungs.

2. Stenosis

Occurs when the valve opening is too small. The valve may become too narrow, or the flaps may have incorrectly formed. This condition makes it difficult for blood to pass through the valve, so the heart has to work harder to pump blood to the body.

Causes

The main causes of valve diseases include:⁴

• Congenital abnormalities i.e., being born with an abnormal valve
• Rheumatic fever
• Cardiomyopathy (a disease of the heart muscle)
• Damage to the heart muscle e.g because of a heart attack
• Ageing
• Endocarditis (infection of the heart)

Symptoms

Some people do no show symptoms, while others may exhibit one or more of the following symptoms which can be mild or severe:⁴

• Shortness of breath
• Chest pain
• Feeling weak or dizzy
• Discomfort in the chest
• Swelling in legs and feet
• Fatigue
• A fluttering or pounding sensation in the chest or neck (palpitations)

Diagnosis

Doctors might detect a heart murmur when listening to the heart with a stethoscope, which could indicate a heart valve problem. The most common test to diagnose heart valve disease is an echocardiogram. Additional tests or scans may also be recommended, including:⁴

• Chest x-ray 
• Electrocardiogram (ECG)
• Blood tests 
• Cardiac CT scan 
• Cardiac MRI 
• Angiogram 

If the tests show valvular heart disease, the patient is usually referred to a cardiology team for a specialist assessment.

Treatment

Most cases of valve diseases are mild with no symptoms and may not require specific treatment except follow-up with  regular echocardiograms (every 3 to 5 years). Some people with mild symptoms might need to be on medication (such as beta blockers) to reduce the load on the heart which can improve the symptoms and reduce the damage on the heart.^4,5

However, if the valve disease is moderate or severe, in addition to medication more frequent follow-up, surgery may be recommended to repair or replace a part or all of the heart valve.⁴

Overview of infective endocarditis

Infective endocarditis (bacterial endocarditis) is caused by bacteria (like Streptococcus, Staphylococcus) that enter the bloodstream and settle in the heart lining, a heart valve or a blood vessel. Though uncommon, people with heart conditions (damaged heart valves, artificial heart valves or other heart defects) have a greater risk of developing it. Bacteria can grow on the heart valves and it is difficult to fight this infection through the body’s immune system and it leads to damage to the valves.⁶ Small clumps of bacteria may develop and can act like blood clots travelling away from the heart and blocking blood supply to the organs. This can cause organ failure or trigger a stroke.⁸ Despite progress in diagnosing and treating infective endocarditis, its mortality rate remains high and appears to be rising. The reported mortality rates in the literature vary from 8% to 40%.¹⁰

Causes

The bacterial infection can result from many sources including:⁶

1. Poor dental hygiene
2. Tooth brushing that causes minor injuries to the mouth or gums
3. Dental procedures
4. Implanted cardiovascular medical devices (e.g pacemaker)
5. Chronic skin disorders and infections
6. Burns
7. Infectious diseases
8. Intravenous drug use

Symptoms

The symptoms of infective endocarditis include:⁶

1. Flu-like symptoms including fever, chills, persistent cough, fatigue
2. Increased heart rate
3. Night sweats
4. Aching joints and muscles
5. Swelling in the feet, legs or abdomen
6. Unexplained weight loss
7. Anaemia (low red blood cell count) is seen in chronic cases

Other, rarer symptoms include:⁷

1. Small, dark-coloured spots on the skin
2. Unusual dark lines under the fingernails
3. Painful red lumps on the fingers or toes

Diagnosis

Infective endocarditis can often resemble other illnesses, making it difficult to diagnose. The following procedures can help in the diagnosis:⁹

1. Blood tests to identify the type of bacteria causing the inflammation
2. An echocardiogram to check for heart damage
3. An electrocardiogram (ECG) to check for abnormal heart rhythms
4. A chest X-ray to check for fluid buildup in the lungs
5. An MRI scan to obtain clearer views of the heart

Treatment

Treatment typically involves antibiotics, with the choice and duration depending on the type of infection causing the endocarditis. Surgery to either repair or replace the valve may be required for mechanical complications or infections caused by resistant organisms.⁶

Relationship between mitral valve disease and infective endocarditis

As endocarditis progresses, it can cause ulcers that erode or perforate the valve flaps leading to valve failure. About 60% of patients with endocarditis are known to have a pre-existing heart condition. Endocarditis can affect both native and prosthetic valves. The infection usually forms on the left side of the heart, commonly due to mitral valve prolapse or degenerative mitral regurgitation.⁹

FAQs

What lifestyle choices can help with living better with a valve disease?⁴

Healthy lifestyle choices like maintaining a healthy weight, exercising, eating a healthy balanced diet, quitting smoking, and limiting alcohol intake can help better live with a heart valve disease.

What kind of exercises can one include in their routine?⁴

Adding simple movements, like walking or light gardening, in the day can keep the heart healthier for longer. Sometimes activities that cause strain or need breath holding, like heavy lifting, weight training, or swimming, may need to be avoided and should be checked with a healthcare professional.

Can one get pregnant with a heart valve disease?⁴

Most people with heart valve disease can have a complication-free pregnancy but it is important to consult with a doctor.

Summary

Mitral valve disease and infective endocarditis are serious heart conditions that can have a major impact on one's health. Proper functioning of heart valves is crucial for maintaining effective blood circulation, and any malfunction can lead to severe complications. Mitral valve disease primarily involves issues like regurgitation and stenosis, while infective endocarditis is an infection of the heart’s inner lining, often affecting the mitral valve. Early diagnosis and treatment are essential to manage these conditions and prevent serious outcomes like heart failure or stroke. Regular medical check-ups, maintaining a healthy lifestyle, and being vigilant about symptoms are key to managing heart valve disease and preventing complications from infective endocarditis. If diagnosed, following the recommended treatment plan and working closely with healthcare providers can greatly improve the prognosis and quality of life for affected individuals.