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Myocarditis

Myocarditis
Histopathological image of myocarditis at autopsy in a patient with acute onset of congestive heart failure
Classification and external resources
Specialty Cardiology
ICD-10 I09.0, I51.4
ICD-9-CM 391.2, 422, 429.0
DiseasesDB 8716
MedlinePlus 000149
eMedicine article/156330 article/890740 article/1612533
MeSH D009205

Myocarditis or inflammatory cardiomyopathy is inflammation of heart muscle. The consequences of myocarditis vary widely. It can cause a mild disease without any symptoms that resolves itself, or it may cause chest pain, heart failure, or sudden death. An acute myocardial infarction-like syndrome with normal coronary arteries has a good prognosis. Heart failure, even with a dilated left ventricle, may have a good prognosis. Ventricular arrhythmias and high-degree heart block have a poor prognosis. Loss of right ventricular function is a strong predictor of death.[1] Myocarditis is most often due to infection by common viruses, such as parvovirus B19, less commonly nonviral pathogens such as Borrelia burgdorferi (Lyme disease) or Trypanosoma cruzi, or as a hypersensitivity response to drugs.[1] Myocarditis can sometimes be an autoimmune disease. Streptococcal M protein and coxsackievirus B have regions that are similar to the myosin protein found in the heart muscle. During and after the infection, the immune system may attack cardiac myosin.[1] Myocarditis may or may not include death (necrosis) of heart tissue. It may include dilated cardiomyopathy.[1] A definitive diagnosis requires a heart biopsy.[1] Cardiomyopathy, including myocarditis, resulted in 443,000 deaths in 2013 up from 294,000 in 1990.[2]

Contents

  • Definition 1
  • Signs and symptoms 2
  • Causes 3
    • Infections 3.1
    • Toxins 3.2
    • Immunologic 3.3
    • Physical agents 3.4
  • Diagnosis 4
  • Treatment 5
  • Epidemiology 6
  • History 7
  • References 8
  • External links 9

Definition

The definition of myocarditis varies, but the central feature is an infection of the heart, with an inflammatory infiltrate, and damage to the heart muscle, without the blockage of coronary arteries that define a heart attack (myocardial infarction) or other common noninfectious causes.[3]

Signs and symptoms

The signs and symptoms associated with myocarditis are varied, and relate either to the actual inflammation of the myocardium or to the weakness of the heart muscle that is secondary to the inflammation. Signs and symptoms of myocarditis include the following:[4]

Since myocarditis is often due to a viral illness, many patients give a history of symptoms consistent with a recent viral infection, including fever, rash, diarrhea, joint pains, and easily becoming tired.

Myocarditis is often associated with pericarditis, and many people with myocarditis present with signs and symptoms that suggest myocarditis and pericarditis at the same time.

Causes

A large number of causes of myocarditis have been identified, but often a cause cannot be found. In Europe and North America, viruses are common culprits. Worldwide, however, the most common cause is Chagas' disease, an illness endemic to Central and South America that is due to infection by the protozoan Trypanosoma cruzi.[4]

Infections

Bacterial myocarditis is rare in patients without immunodeficiency.

Toxins

Immunologic

Physical agents

Diagnosis

Endomyocardial biopsy specimen with extensive eosinophilic infiltrate involving the endocardium and myocardium (hematoxylin and eosin stain)

Myocarditis refers to an underlying process that causes inflammation and injury of the heart. It does not refer to inflammation of the heart as a consequence of some other insult. Many secondary causes, such as a heart attack, can lead to inflammation of the myocardium and therefore the diagnosis of myocarditis cannot be made by evidence of inflammation of the myocardium alone.[7]

Myocardial inflammation can be suspected on the basis of electrocardiographic (ECG) results, elevated C-reactive protein (CRP) and/or Erythrocyte sedimentation rate (ESR), and increased IgM (serology) against viruses known to affect the myocardium. Markers of myocardial damage (troponin or creatine kinase cardiac isoenzymes) are elevated.[4]

The ECG findings most commonly seen in myocarditis are diffuse T wave inversions; saddle-shaped ST-segment elevations may be present (these are also seen in pericarditis).[4]

The gold standard is still biopsy of the myocardium, in general done in the setting of angiography. A small tissue sample of the endocardium and myocardium is taken, and investigated by a pathologist by light microscopy and—if necessary—immunochemistry and special staining methods. Histopathological features are myocardial interstitium with abundant edema and inflammatory infiltrate, rich in lymphocytes and macrophages. Focal destruction of myocytes explains the myocardial pump failure.[4]

Cardiac magnetic resonance imaging (cMRI or CMR) has been shown to be very useful in diagnosing myocarditis by visualizing markers for inflammation of the myocardium.[8] Recently, consensus criteria for the diagnosis of myocarditis by CMR have been published.[9]

Treatment

As most viral infections cannot be treated with directed therapy, symptomatic treatment is the only form of therapy for those forms of myocarditis.[10] In the acute phase, supportive therapy, including bed rest, is indicated. For symptomatic patients, digoxin and diuretics provide clinical improvement. For patients with moderate to severe dysfunction, cardiac function can be supported by use of inotropes such as Milrinone in the acute phase, followed by oral therapy with ACE inhibitors (Captopril, Lisinopril) when tolerated. People who do not respond to conventional therapy are candidates for bridge therapy with left ventricular assist devices. Heart transplantation is reserved for patients who fail to improve with conventional therapy.[11]

In several small case series and randomized control trials, systemic corticosteroids have shown to have beneficial effects in people with proven myocarditis.[11] However, data on the usefulness of corticosteroids should be interpreted with caution, since 58% of adults recover spontaneously, while most studies on children lack control groups.[10] Studies have shown no benefit for the use of herbal medicine on all cause mortality in viral myocarditis.[12]

A 2015 Cochrane review found no evidence of benefit of using intravenous immunoglobulin (IVIG) in adults and tentative benefit in certain children.[13] It is not recommended routinely until there is better evidence.[13]

Epidemiology

The exact incidence of myocarditis is unknown. However, in series of routine autopsies, 1–9% of all patients had evidence of myocardial inflammation. In young adults, up to 20% of all cases of sudden death are due to myocarditis.[4]

Among patients with HIV, myocarditis is the most common cardiac pathological finding at autopsy, with a prevalence of 50% or more.[1]

History

Cases of myocarditis have been documented as early as the 1600s,[14] but the term "myocarditis", implying an inflammatory process of the myocardium, was introduced by German physician Joseph Friedrich Sobernheim in 1837.[15] However, the term has been conflated with other cardiovascular conditions, such as hypertension and ischemic heart disease.[16] Following admonition regarding the indiscriminate use of myocarditis as a diagnosis from authorities such as British cardiologist Sir Thomas Lewis and American cardiologist and a co-founder of the American Heart Association Paul White, myocarditis was under-diagnosed.[16]

Although myocarditis is clinically and pathologically clearly defined as "inflammation of the myocardium", its definition, classification, diagnosis, and treatment are subject to continued controversy, but endomyocardial biopsy has helped define the natural history of myocarditis and clarify clinicopathological correlations.[17]

References

  1. ^ a b c d e f Cooper LT (April 2009). "Myocarditis". N. Engl. J. Med. 360 (15): 1526–35.  
  2. ^ GBD 2013 Mortality and Causes of Death, Collaborators (17 December 2014). "Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013.". Lancet.  
  3. ^ Kenneth L. Baughman, Special Report: Diagnosis of Myocarditis; Death of Dallas Criteria. Circulation. 2006;113:593-595 Free full text
  4. ^ a b c d e f Feldman AM, McNamara D (November 2000). "Myocarditis". N. Engl. J. Med. 343 (19): 1388–98.  
  5. ^ Eckart RE, Scoville SL, Campbell CL, et al. (December 2004). "Sudden death in young adults: a 25-year review of autopsies in military recruits". Ann. Intern. Med. 141 (11): 829–34.  
  6. ^ Nicholson PJ, Quinn MJ, Dodd JD (December 2010). "Headshop heartache: acute mephedrone 'meow' myocarditis". Heart (British Cardiac Society) 96 (24): 2051–2.  
  7. ^ Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; & Mitchell, Richard N. (2007). Robbins Basic Pathology (8th ed.). Saunders Elsevier. pp. 414-416 ISBN 978-1-4160-2973-1
  8. ^ Skouri HN, Dec GW, Friedrich MG, Cooper LT (2006). "Noninvasive imaging in myocarditis". J. Am. Coll. Cardiol. 48 (10): 2085–93.  
  9. ^ Friedrich MG, Sechtem U, Schulz-Menger J, Holmvang G, Alakija P, Cooper LT, White JA, Abdel-Aty H, Gutberlet M, Prasad S, Aletras AH, Laissy JP, Paterson I, Filipchuk NG, Kumar A, Pauschinger M, Liu P (2009). "Cardiovascular Magnetic Resonance in Myocarditis: A JACC White Paper". J. Am. Coll. Cardiol. 53 (17): 1475–87.  
  10. ^ a b Hia, CP; Yip, WC; Tai, BC; Quek, SC (June 2004). "Immunosuppressive therapy in acute myocarditis: an 18 year systematic review". Archives of Disease in Childhood 89 (6): 580–4.  
  11. ^ a b Aziz, KU; Patel, N; Sadullah, T; Tasneem, H; Thawerani, H; Talpur, S (October 2010). "Acute viral myocarditis: role of immunosuppression: a prospective randomised study". Cardiology in the young 20 (5): 509–15.  
  12. ^ Liu, ZL; Liu, ZJ; Liu, JP; Kwong, JS (28 August 2013). "Herbal medicines for viral myocarditis.". The Cochrane database of systematic reviews 8: CD003711.  
  13. ^ a b Robinson, J; Hartling, L; Vandermeer, B; Klassen, TP (20 May 2015). "Intravenous immunoglobulin for presumed viral myocarditis in children and adults.". The Cochrane database of systematic reviews 5: CD004370.  
  14. ^ P. Schölmerich. (1983.) "Myocarditis — Cardiomyopathy Historic Survey and Definition", International Boehringer Mannheim Symposia, 1:5.
  15. ^ Joseph Friedrich Sobernheim. (1837.) Praktische Diagnostik der inneren Krankheiten mit vorzueglicher Ruecksicht auf pathologische Anatomic. Hirschwald, Berlin, 117.
  16. ^ a b Eckhardt G. J. Olsen. (1985.) "What is myocarditis?", Heart and Vessels, 1(1):S1-3.
  17. ^ Jared W. Magnani; G. William Dec. (2006.) "Myocarditis", Circulation, 113:876-890.

External links

  • Myocarditis on emedicine
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