00:00 / 00:00









0 / 10 complete

USMLE® Step 1 questions

0 / 1 complete

High Yield Notes

10 pages



of complete


USMLE® Step 1 style questions USMLE

of complete

A 30-year-old man comes to the physician for evaluation of fever, headache, and swelling in the right eye. The patient’s symptoms started a few days after he returned from a trip to South America. During the trip, he spent much time hiking outdoors and visiting rural towns. His temperature is 38.5°C (101.3°F), blood pressure is 120/75 mmHg, and pulse is 100/minute. Physical examination reveals swelling in the right orbital region and redness in the conjunctiva. A blood smear is obtained and shown below. If untreated, this patient is at risk of developing which of the following complications?
Image reproduced from

Memory Anchors and Partner Content

External References

First Aid








Autoimmune diseases

myocarditis p. 481

Myocarditis p. 481

adenovirus p. 161

Corynebacterium diphtheriae p. , 137

coxsackievirus p. 164

diptheria p. 137

picornaviruses p. 164

Toxocara canis p. , 156


with myocarditis p. 481


With myocarditis, myo- means muscle, card- means heart, and -itis means inflammation. So, myocarditis is inflammation of the myocardium, which is the muscular middle layer of the heart wall, which contracts and relaxes so the heart can pump blood all around the body.

Inflammation in the myocardium layer causes swelling, which damages the heart muscle cells’ ability to contract. That means that less blood gets pumped out of the heart with each heartbeat. If myocarditis is severe enough, it can lead to heart failure, which is when the heart can’t keep up with the demands of the body. Once the inflammation resolves, the heart contraction typically returns to normal, but occasionally, when the inflammation is really severe, it can cause fibrosis, or scar tissue, in the myocardium. Scar tissue doesn’t contract normally, so if that happens, it can cause long term problems with heart contraction.

In North America, viral infections, specifically Coxsackievirus B infections, are the main cause of myocarditis. Viral infections can trigger lymphocytic myocarditis, which is when lymphocytes - the B and T cells of the immune system - and water make their way into the interstitial space - the space in between heart muscle cells. There are plenty of other infectious causes as well, though. One of these is trypanosoma cruzi, a single-cell protozoan that causes Chagas disease throughout South America. In Chagas disease, under a microscope, it’s possible to see groups of amastigotes within the heart muscle cells, which are trypanosomes that are in the intracellular stage. As a result, the heart muscle cells necrose or die. There’s also Trichinella, a roundworm that moves from the intestines into various parts of the body, causing a variety of problems, including myocarditis. Myocarditis can also be seen in Lyme disease which is caused by the bacteria Borrelia burgdorferi, which is spread by deer ticks. Finally, in immunocompromised individuals, there’s Toxoplasma gondii, a single-cell parasite harbored by cats, that can cause myocarditis.


Myocarditis is an inflammation of the heart muscle, also known as the myocardium. It can be caused by a variety of different infections, including viruses, bacteria, fungi, and parasites. It can also be caused by autoimmune diseases, such as lupus, or by drugs and toxins. Symptoms of myocarditis include chest pain, palpitations, shortness of breath, and fluid retention which might be an indication of heart failure. Treatment for myocarditis involves medications to reduce inflammation, and antibiotics to treat any underlying infections. In some cases, a heart transplant may be necessary.


  1. "Pediatric nonviral myocarditis" undefined (2015)
  2. "Myocarditis overview" undefined (2017)
  3. "Treatment and prognosis of myocarditis in adults" undefined (2017)
  4. "Robbins Basic Pathology (10 edition)" Elsevier (2017)
  5. "First Aid for the USMLE Step 1 2017 (27 edition)" McGraw-Hill Education / Medical (2017)
  6. "Beta blockers and heart failure." undefined (2003)
  7. "Myocarditis" undefined (2017)
  8. "Myocarditis" undefined (undefined)
  9. "Fundamentals of Pathology: Medical Course and Step 1 Review" Pathoma LLC (2017)
  10. "Myocarditis: practice essentials" undefined (2016)
  11. "Myocarditis pathology" undefined (2015)

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.