Endocarditis , Myocarditis, Pericarditis and Mitral valve endocarditis (MVE) in Lyme Disease

Valvular involvement and other cardiac manifestations are uncommon in Lyme disease. In a few cases in Europe and the United States, polymerase chain reaction (PCR) was used to confirm Borrelia species as the causal agent.

If a surgeon detects infective endocarditis during surgery, suitable specimens should be sent for histopathologic investigation, culture, and PCR assay. The most frequent tick-borne disease in the northern hemisphere is Lyme borreliosis. Lyme carditis (heart involvement) was first identified in 1980, and it affects 4%-10% of infected people who do not receive treatment. The most common presentation is conduction problems, evidenced by variable degrees of atrioventricular block. Pericarditis, pericardial effusion, myocarditis, and dilated cardiomyopathy are less common cardiac problems.

Understanding the heart's structure

The human heart is a four-chambered muscular organ with two-thirds of its mass to the left of midline, formed and sized roughly like a man's closed fist. A pericardial sac surrounds the heart and is lined by the parietal layers of a serous membrane. The epicardium is formed by the visceral layer of the serous membrane.

Layers of the heart wall

The heart wall is made up of three layers of tissue:

• The epicardium is the exterior layer.
• The myocardium is the middle layer.
• The endocardium is the inner layer.

The heart's chambers

The heart's interior cavity is divided into four chambers:

• Right atrium
• Right ventricle
• Left atrium
• Left ventricle

The two atria are hollow chambers with narrow walls that receive blood from veins. The two ventricles are hollow chambers with thick walls that drive blood out of the heart. The amount of myocardium tissue present, representing the amount of force required to be created by each chamber, directly indicates the thickness of the heart chamber walls.

Systemic veins deliver deoxygenated blood to the right atrium, whereas pulmonary veins deliver oxygenated blood to the left.

Valves of the heart

The heart, like all pumps, requires a system of valves to keep the fluid flowing in one direction. There are two types of valves in the heart that keep the blood flowing in the right direction. Atrioventricular valves (also known as cuspid valves) connect the atria and ventricles, and semilunar valves connect the bases of the major arteries leaving the ventricles.

The tricuspid valve is the right atrioventricular valve. The bicuspid or mitral valve is the left atrioventricular valve. The pulmonary semilunar valve connects the right ventricle to the pulmonary trunk. The aortic semilunar valve connects the left ventricle to the aorta.

Atrioventricular valves close when the ventricles contract, preventing the blood from flowing back into the atria. Semilunar valves close when the ventricles relax, preventing the blood from flowing back into the ventricles.

Endocarditis and Lyme Endocarditis

Infection of the inner lining of the heart frequently involves the heart valves.

Infections from other parts of the body migrate through the bloodstream and adhere to damaged regions of the heart, causing endocarditis. The people who are most at risk are those who have damaged or artificial heart valves and other cardiac diseases.

Fevers, chills, and exhaustion are some of the symptoms that can occur depending on the severity of the infection.

Antibiotics are the most common treatment. Occasionally, surgery is required.

Lyme endocarditis is a very uncommon symptom of Lyme disease. Because the clinical signs of Lyme endocarditis are nonspecific, diagnosing it when it is the only symptom of the disease might be difficult. Only a few cases have been recorded so far. In endemic locations, physicians should be aware of the likelihood of Borrelial endocarditis. A suitable valve tissue sample should be sent for histology, culture, and PCR, particularly in cases with unexplained endocarditis. PCR on heart valve samples is advised. Borrelia spp. may be more frequently found as a cause of infective endocarditis as PCR becomes more common.

Lyme carditis should be diagnosed and treated as soon as possible to avoid surgery and pacemaker placement. Lyme disease is becoming more common as a result of climate change and global warming. We predict an increase in the number of Lyme disease cases and Lyme endocarditis.

Lightheadedness, fainting, shortness of breath, heart palpitations, and chest pain are all signs that Lyme endocarditis may be present. Patients with Lyme carditis often experience various symptoms like fever and body aches, as well as more specific Lyme disease signs like the erythema migrans rash.

Myocarditis and Lyme myocarditis

Inflammation of the heart muscle (myocardium), which is in the middle of the heart, is known as myocarditis. The heart's ability to pump blood may be harmed as a result of the inflammation. Myocarditis can be caused by several other virus infections as well. Lyme disease can occasionally cause myocarditis.

A severe case of myocarditis can weaken the heart, resulting in cardiac failure, irregular heartbeats, and death.

Chest pain, an irregular heartbeat, and shortness of breath are all common symptoms of myocarditis.

Medication to control the heartbeat, improve heart function, and treat the underlying infection may be used as part of the treatment. In rare but severe cases, a device to aid cardiac function may be required.

Pericarditis and Lyme pericarditis

Pericarditis is when the thin, sac-like membrane (pericardium) that surrounds the heart swells and irritates.

A viral infection or a cardiac stroke can cause pericarditis. The reason for many of these cases is unknown. Rarely, Lyme disease can cause pericarditis.

• The most prevalent symptom is sharp, stabbing chest discomfort that may spread to the left shoulder and neck.
• Cough
• Fatigue, weakness, or being sick
• Swelling of the legs and/or abdomen
• Fever (usually low grade)
• Heart palpitations
• Breathlessness

Pericarditis usually develops rapidly and lasts only a few days.

The majority of instances are minor and resolve on their own. Medication and occasionally surgery may be used to treat more severe cases.

Lyme disease can cause heart block

The Lyme bacteria obstructs your heart's electrical system by entering the heart tissue and interfering with electrical signals, resulting in heart block. Moreover, your heart rate slows, and electrical messages between the upper and lower chambers of your heart have trouble travelling. This ailment is known as heart block.

Symptoms include dizziness, fainting, heart palpitations, chest aches, and shortness of breath.

Antibiotics and/or a temporary pacemaker are two treatment possibilities.

Heart block can occur in many forms. Heart blocks can be classified into three levels:

• First-degree heart block: Electrical signals reach the bottom chambers of the heart (ventricles) at a slower rate than typical in the first degree. This is considered mild.
• Second-degree heart block: Electrical signals do not fully reach the lower chambers of the heart in the second degree. This is considered moderate.
• Third-degree heart block: Electrical signals do not reach the lower chambers of the heart in the third degree. This is considered severe.

Mitral valve endocarditis: a rare manifestation of Lyme disease

Mitral valve endocarditis (MVE) is a condition in which one or both mitral valve leaflets become infected. It can be caused by various diseases, although the most frequent is bacterial. Lyme disease, which causes MVE, is a rare occurrence.

Infective endocarditis (IE) is one of the most common causes of acute mitral valve failure in developed countries. According to some reports, the annual prevalence of IE is three to nine instances per 100,000 people, with 40% of those cases involving the mitral valve and valve failure.

On the other hand, current evidence on the therapy and management strategy for MVE is mixed and frequently dependent on the personal experiences of doctors. As a result, clinicians have created a systematic approach to endocarditis care based on clinical, microbiological, and anatomopathological characteristics that have been shown to influence postoperative outcomes. The ultimate goal was to stratify the patients to aid in decision-making. Doctors recommend the systematic use of a coordinated multidisciplinary strategy in the diagnostic workup of MVE and emphasize the importance of early surgical referral, especially when conditions of high-risk embolization or clinical worsening are present despite effective antibiotic therapy.

For individuals with native valve endocarditis or pericardial valve endocarditis, the timing of surgical correction is critical. Delaying surgery raises the risk for complications, operational mortality, and morbidity. Unfortunately, most surgeons discover that patients with IE are only referred to cardiologists or other hospitals when medicinal therapy has failed, when patients have intractable heart failure, or when patients have had a severe stroke or multisystem organ failure. In some cases, there is a lack of understanding of the surgical challenges, the resulting complications, and the clinical course of these cases following the operation. This, combined with the difficulty in identifying the pathogen, leads to a delay in surgical referral, with patients being offered surgery at a late stage with significantly compromised clinical conditions and a higher intraoperative risk. As a result, early engagement of an expert cardiac surgeon is critical in determining the optimum surgical strategy and timing for patients with MVE. For example, during the first 2 weeks of antibiotic therapy and in those with left-sided IE, particularly in the mitral position, the risk for stroke is much increased. Furthermore, the option of repairing rather than replacing the mitral valve can only be considered after a thorough debate among expert surgeons and echocardiologists. Because mitral valve repair has a higher long-term survival and functional prognosis than valve replacement, a multidisciplinary approach to MVE treatment is critical to its effectiveness.

The goal of surgery is to restore mitral valve function while avoiding the danger of bacterial embolism during infection clearance.

Conservative surgery is possible if only one leaflet or scallop is involved. Mitral valve repair aims to eliminate vegetation, restore a normal line of coaptation on both leaflets, repair perforated leaflets, and retain the subvalvular apparatus. Excision of the vegetation, also known as vegetectomy, can be performed on the leaflet's cleavage plane. The use of a pericardial patch to reinforce leaflets is preferable to direct stitching of the lesion because it avoids stress on the suture line. The extent of tissue loss determines the viability of valve repair. The best candidates are those with a minimal current illness and no valve damage. The main challenges to mitral repair are extensive anterior leaflet damage, severe lesions involving the posterior leaflet or the mitral valve commissures, and annular abscesses.

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