How is inflammation of the hearth muscle (myocarditis) diagnosed? What are typical symptoms? What is it commonly mixed up with? How do you differentiate reliably?
Diagnosis of myocarditis
To diagnose myocarditis, your doctor may conduct a physical examination, and discuss your medical history and any signs or symptoms you may have. If your doctor suspects myocarditis, he or she might order one or more tests to confirm the diagnosis and determine the severity of your condition, including:
MRI. Cardiac magnetic resonance imaging (MRI) will show your heart's size, shape and structure. This test can show signs of inflammation of the heart muscle and help make or confirm a diagnosis of myocarditis.
Echocardiogram. Sound waves, or ultrasound, can create moving images of the beating heart. An echocardiogram might detect enlargement of your heart, poor pumping function, valve problems or fluid around your heart.
Cardiac catheterization and endomyocardial biopsy. In this test, a small tube (catheter) is inserted into a vein in your leg or neck and then is threaded into your heart. In some cases, doctors use a special instrument to remove a tiny sample of heart muscle tissue (biopsy) for analysis in the lab to see if there are signs of inflammation or infection.
Symptoms of myocarditis
The most common symptom of myocarditis is shortness of breath during exercise or exertion.
Other symptoms may include fatigue, heart palpitations and chest pain or pressure. The legs also may swell. Rarely, myocarditis causes a sudden loss of consciousness that may be due to abnormal heart rhythms. In summary, patients may experience some, all or none of the following symptoms: shortness of breath, chest pain, lightheadedness, irregular heartbeat, sudden loss of consciousness.
Can myocarditis be confused with other heart diseases?
Yes. For example, the symptoms of heart failure, including shortness of breath, fatigue, inability to tolerate exercise, and associated with difficulty breathing while laying down/sleeping are common to many heart diseases besides myocarditis. One feature that distinguishes myocarditis from other causes of heart failure is that it often follows an upper respiratory or gastrointestinal infection and is due to a specific immune response against the heart itself.
Acute Myocarditis isn't exactly what a doctor sees in his daily practice.
Just like many other disorders and diseases, and depending on etiology, the clinical picture may vary between extremes: a relatively asymptomatic patient or a severe case of acute hear failure, arrhythmias and conduction disturbances. Sometimes the clinical picture may be misleading and mimic an acute MI.
The main symptoms are usually shortness of breath, palpitations, dizziness. Usual clinical signs are those of acute heart failure, arrhythmias, hypotension, etc.
Electrocardiograms are inevitably abnormal and may show ischemic changes similar to those found in coronary heart disease, tachycardia, all sorts of cardiac arrhythmias, conduction disturbances (electrical blocks).
Echocardiograms will show, among other things, left ventricular dysfunction of any degree. Labs will always be useful and depending on etiology (rheumatic myocarditis, viral myocarditis, etc) may even help determine the etiologic diagnosis.
Myocardial biopsy is reserved for a few selected cases where the etiologic factor couldn't be determined.
Each patient is unique in that the severity of the disease varies a lot. Some may recover completely, some may have a sequelae with limited heart function and others may die.
Acute Myocarditis can be easier to diagnose when it affects children or young adults before the age of thirty, as coronary heart disease is very rare in that age group.