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 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 (polymerase chain reaction 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% to 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.

The Heart Wall's Layers

• The heart wall is made up of three layers of tissue.
• The epicardium is the exterior layer of the heart wall
• 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 accept blood from veins. The two ventricles are hollow chambers with thick walls that drive blood out of the heart. Variations in the quantity of myocardium present, which represents the amount of force each chamber is required to create, cause differences in 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.

The 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 blood flowing in the right way. Atrioventricular valves (also known as cuspid valves) connect the atria and ventricles, whereas 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 blood from flowing back into the atria. Semilunar valves close when the ventricles relax, preventing blood from flowing back into the ventricles.

Endocarditis and Lyme Endocarditis

Infection of the inner lining of the heart, frequently involving the heart valves.

Infection 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 danger are those who have damaged or artificial heart valves, as well as those who have 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 non-specific, 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 found as a cause of infective endocarditis more frequently 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 should predict an increase in the number of Lyme disease cases as well as Lyme endocarditis.

Light-headedness, fainting, shortness of breath, heart palpitations, or 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 which is the middle of the heart is known as myocarditis (myocardium). The heart's ability to pump blood may be harmed as a result of the inflammation. Myocarditis can be caused by several 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 and improve heart function, as well as medication to 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

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

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

• Sharp, stabbing chest discomfort that may spread to the left shoulder and neck is the most prevalent symptom.
• Cough.
• Fatigue or 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.  Your heart rate slows, and electrical messages between the upper and lower chambers of your heart have problems 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 take many forms. Heart block 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 (MVE): A Rare Manifestation in Lyme Disease

Mitral valve endocarditis (MVE) is a condition in which one or both mitral valve leaflets become infected. It can be caused by a variety of diseases, although the most frequent is bacterial. Lyme Disease causing Mitral Valve Endocarditis 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 3 to 9 instances per 100,000 people, with 40% of those cases involving the mitral valve and valve failure.

Current evidence on the therapy and management strategy for MVE, on the other hand, is mixed and frequently dependent on 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 in order to aid decision-making. Doctors recommend a systematic use of a coordinated multidisciplinary strategy in the diagnostic workup of MVE and emphasise the importance of early surgical referral, especially when conditions of high-risk of embolization or clinical worsening are present despite effective antibiotic therapy.

For individuals with native valve endocarditis (NVE) or pericardial valve endocarditis (PVE), the timing of surgical correction is critical. Delaying surgery raises the risk of complications as well as the risk of 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 offered surgery at a late stage in 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 two weeks of antibiotic therapy and in those with left-sided IE, particularly in the mitral position, the risk of 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 while restoring 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 done 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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