Myocarditis - causes, symptoms, diagnosis, treatment, pathology

Summary

Myocarditis is an inflammation of the heart's muscular layer, often caused by viral infections like Coxsackie virus in North America or Chagas disease in South America. It impairs the heart's ability to pump blood, potentially leading to heart failure. Symptoms include chest pain, arrhythmias, fatigue, and shortness of breath. Diagnosis is confirmed via biopsy, but treatment depends on the underlying cause and may involve medication or even a heart transplant in severe cases. While viral myocarditis usually improves over time, other causes like drug reactions or autoimmune diseases require specific treatments.

Takeaways

• 😀 Myocarditis is inflammation of the myocardium, the middle layer of the heart wall, which can impair the heart's ability to pump blood effectively.
• 😀 Viral infections, especially Coxsackie virus B, are the leading cause of myocarditis in North America.
• 😀 Myocarditis can cause swelling in the heart muscle, leading to reduced blood flow and potential heart failure if severe.
• 😀 In severe cases of myocarditis, fibrosis (scar tissue) can form in the heart muscle, leading to long-term contraction issues.
• 😀 Other infectious causes of myocarditis include Trypanosoma cruzi (Chagas disease), Trichinella (roundworm), Lyme disease, and Toxoplasma gondii (parasite).
• 😀 Non-infectious causes of myocarditis include autoimmune diseases like lupus, polymyositis, and drug reactions.
• 😀 Symptoms of myocarditis include positional chest pain, arrhythmias (irregular heartbeats), fatigue, fever, and shortness of breath.
• 😀 In severe cases, myocarditis can progress to heart failure, leading to fluid retention in the feet and ankles.
• 😀 Blood tests may show elevated troponin and creatine kinase levels, indicating heart muscle damage.
• 😀 Diagnosis of myocarditis often involves a biopsy of the heart muscle, though it is risky and not always performed.
• 😀 Treatment for myocarditis depends on the cause, with viral myocarditis improving over time, while bacterial infections may be treated with antibiotics. Severe cases may require a heart transplant.

Q & A

What is myocarditis?

Myocarditis is the inflammation of the myocardium, the muscular middle layer of the heart wall that helps the heart pump blood throughout the body.

What causes myocarditis?

Myocarditis can be caused by viral infections, including Coxsackie virus B, and other pathogens like Trypanosoma cruzi, Trichinella, and Toxoplasma gondii. Non-infectious causes include autoimmune conditions like lupus and polymyositis, as well as adverse drug reactions and giant cell myocarditis.

How does myocarditis affect the heart?

Inflammation in the myocardium leads to swelling, which damages heart muscle cells and reduces the heart's ability to contract, decreasing the amount of blood pumped with each heartbeat. Severe cases can lead to heart failure.

What are the symptoms of myocarditis?

Symptoms of myocarditis include chest pain (sometimes positional), arrhythmias (irregular heartbeats), fatigue, fever, shortness of breath, and in severe cases, fluid retention in the feet and ankles.

How is myocarditis diagnosed?

Myocarditis is typically diagnosed based on blood tests showing elevated levels of troponin and creatine kinase, an ECG showing sinus tachycardia, T-wave inversions, and saddle-shaped ST segment elevations, and imaging tests like chest x-rays and echocardiograms. A biopsy of the heart muscle is the most definitive test, but it comes with risks.

What is the treatment for myocarditis?

Treatment depends on the underlying cause. Viral myocarditis usually improves over time, while bacterial infections are treated with antibiotics. If heart failure or arrhythmias occur, medications and fluid management are used. Severe cases may require a heart transplant.

What is the significance of the 'saddle-shaped' ST segment elevation seen in an ECG?

The 'saddle-shaped' ST segment elevation on an ECG is a characteristic finding in myocarditis, indicating inflammation of the heart muscle. It resembles the shape of a horse saddle and is a key diagnostic feature.

Can myocarditis lead to long-term complications?

Yes, if the inflammation is severe enough, it can lead to fibrosis (scar tissue) in the heart muscle, which can impair heart function and lead to long-term problems with heart contraction.

What are some viral causes of myocarditis in North America?

In North America, the most common viral cause of myocarditis is Coxsackie virus B, which can trigger inflammation in the heart muscle.

How does Chagas disease contribute to myocarditis?

Chagas disease, caused by the Trypanosoma cruzi parasite, can lead to myocarditis by causing groups of trypanosomes to invade heart muscle cells, damaging them and contributing to heart muscle failure.