Myocarditis, Emergency Medicine

Basics

Description

An inflammatory change in the heart muscle characterized by myocyte necrosis and subsequent myocardial destruction
Direct cytotoxic effect of causative agent followed by a secondary immune response
True incidence is unknown because many cases are asymptomatic.
Autopsy studies have demonstrated evidence of myocarditis in 1 " 7% of cases and >50% in HIV patients.
Male > female (1.5:1)
Average age of patients with myocarditis is 42 yr.
Major cause of unexpected sudden death (15 " 20% of cases) <40 yr old

Etiology

Viral:
- Enteroviruses (coxsackie B)
- Adenovirus
- Herpesvirus (including cytomegalovirus [CMV])
- Hepatitis C
- Influenza
- Echovirus
- Herpes simplex virus
- Varicella-zoster
- Epstein " Barr virus
- Cytomegalovirus
- Mumps
- Rubeola
- Variola/vaccinia
- Yellow fever
- Rabies
- HIV
Bacteria:
- Diphtheria
- Tuberculosis
- Brucellosis
- Psittacosis
- Meningococcus
- Mycoplasma
- Group A streptococcus
Protozoa:
- Leishmaniasis
- Malaria
- Toxoplasmosis in the immunocompromised host
- Treponema cruzi (Chagas disease):
  - Most common cause of heart failure and myocarditis worldwide
  - 20 million persons infected in Central and South America
- Trichinosis
- Trypanosomiasis
Spirochetes:
- Borrelia burgdorferi, the spirochete agent in Lyme disease
- Syphilis
Rickettsial:
- Scrub typhus
- Rocky Mountain spotted fever
- Q fever
Fungal:
- Candidiasis
- Aspergillosis
- Cryptococcosis
- Histoplasmosis
- Actinomycosis
- Helminthic
- Trichinosis
- Echinococcosis
- Schistosomiasis
- Cysticercosis
Drugs:
- Acetaminophen
- Ampicillin
- Chemotherapeutic agents (anthracyclines)
- Cocaine
- Hydrochlorothiazide
- Lithium
- Methyldopa
- Penicillin
- Sulfamethoxazole
- Sulfonamides
- Zidovudine
- Radiation
- Hypersensitivity
- Heavy metals
- Hydrocarbons
- Carbon monoxide
- Arsenic
Autoimmune disorders:
- Systemic lupus erythematosus (SLE)
- Wegener granulomatosis
- Kawasaki disease
- Giant cell arteritis
- Sarcoidosis
Peripartum cardiomyopathy
Bites/stings:
- Scorpion
- Snake
- Black widow venom

Diagnosis

Signs and Symptoms

Arrhythmias (18%), dyspnea (72%), and chest pain (35%)
History

Fatigue
Myalgias/arthralgias
Malaise
Fever
Chest pain:
- Reported in 35%
- Most commonly pleuritic, sharp, stabbing, precordial
Dyspnea on exertion is common.
Orthopnea and shortness of breath if congestive heart failure (CHF) is present
Palpitations are common
Acute coronary syndrome due to local spasm & inflammation
Syncope:
- May signal high-grade aortic valve block or risk for sudden death from VT/VF

Physical Exam

Fever
Tachypnea
Tachycardia:
- Often out of proportion to fever
Cyanosis
Hypotension:
- Due to left ventricular dysfunction
- Uncommon in the acute setting and indicates a poor prognosis when present
Bibasilar crackles
Rales
Jugular venous distention (JVD)
Peripheral edema
Hepatomegaly
Ascites
S3 or a summation gallop if significant biventricular involvement
Intensity of S1 may be diminished
Murmurs of mitral or tricuspid regurgitation
Pericardial friction rub if associated with pericarditis

Most common cause of heart failure in previously healthy children
Particularly infants, present with nonspecific symptoms:
- Fever
- Respiratory distress
- Poor feeding or, in cases with CHF, sweating while feeding
- New onset murmur
- Cyanosis in severe cases

Essential Workup

Physical exam
EKG
CXR

Diagnosis Tests & Interpretation

Lab

Cardiac enzymes
- Troponin T: Low levels can be used to exclude myocarditis
- Troponin I specificity is 89%; sensitivity is 34%
- Creatinine kinase (elevated MB) may be elevated from myocardial necrosis
Erythrocyte sedimentation rate (ESR) is elevated in 60% during the acute phase.
Leukocytosis is present in 25%.
Viral titers; cultures rarely positive
Mycoplasma, antistreptolysin titers, cold agglutinin titer
Hepatitis panels
Lyme titer
Monospot testing
CMV serology
Blood cultures

Imaging

EKG:
- Sinus tachycardia most frequent finding
- Transient, nonspecific ST- and T-wave changes
- Atrial and ventricular dysrhythmias
- Heart block and conduction defects:
  - 20% have a conduction delay.
  - 20% have a left bundle branch block.
CXR:
- Normal cardiac silhouette
- Pulmonary edema
- Pleural effusion
Echocardiogram:
- Impairment of left ventricular systolic and diastolic function
- Segmental wall motion abnormalities
- Impaired ejection fraction
- Pericardial effusion
- Ventricular thrombus has been identified in 15% of patients
Gallium67 and Indium111-labeled antimyosin antibody scans
Gadolinium-enhanced MRI:
- Indicate cardiac inflammation and myocyte necrosis
Cardiac MRI:
- Abnormal signal areas correlate with regions of myocarditis
- Reported 76% sensitivity, 96% specificity, and 85% diagnostic accuracy
- Considered in patients in whom the diagnosis is unclear and endocardial biopsy is planned

Diagnostic Procedures/Surgery

Right ventricular endomyocardial biopsy:
- Appropriate in heart transplant recipients
- Polymerase chain reaction (PCR) amplification of viral genome in endomyocardial tissue
PCR identification of a viral infection from pericardial fluid, or other body fluid sites

Differential Diagnosis

Acute MI
Acute and chronic pulmonary embolus
Aortic dissection
Adrenal insufficiency
Environmental challenges
Esophageal perforation/rupture/tear
Hyperpyrexia
Hypothermia
Kawasaki disease
Pericarditis
Pneumonia
Viral
Bacterial
Sepsis
Severe hypothyroidism and hyperthyroidism
Toxin-mediated disease

Treatment

Avoid sympathomimetic and ²-blocker drugs.
Patients presenting with Mobitz II or complete heart block require pacemaker placement.

Initial Stabilization/Therapy

ABCs
Supplemental oxygen
Cardiac monitor
Pulse oximetry
IV access

Ed Treatment/Procedures

Treat dysrhythmias.
Transthoracic or transvenous pacing for symptomatic heart block
Supplemental oxygen
ACE inhibitors (captopril):
- Reduce afterload and inflammation.
Digoxin:
- CHF or atrial fibrillation
Diuretics (furosemide, bumetanide)
Hyperimmunoglobulin therapy in CMV-associated myopericarditis.
NSAIDs contraindicated in early and acute-phase myocarditis
Heparin and warfarin for patients with depressed LV function or intracardiac thrombus

IV immunoglobulin is an effective treatment option in pediatric viral myocarditis.
Improved LV function and trend toward better survival

Medication

Captopril:
- Adult dose: Initial dose 6.25 mg; can titrate to 50 mg/dose
- Pediatric dose:
  - Infants: 0.15 " 0.3 mg/kg/dose (max. 6 mg/kg)
  - Children: 0.5 " 1 mg/kg/24h
Digoxin:
- Adult dose: Load: 0.4 " 0.6 mg IV, then 0.1 " 0.3 mg q6 " 8h. Maintain: 0.125 " 0.5 mg/d IV/PO
- Pediatric dose:
  - <2 yr: 15 " 20 Όg/kg IV
  - 2 " 10 yr: 10 " 15 Όg/kg IV
  - >10 yr: 4 " 5 Όg/kg IV
Furosemide:
- Adult dose: 20 " 80 mg/d PO/IV/IM; titrate up to 600 mg/d for severe edematous states
- Pediatric dose: 1 " 2 mg/kg PO; not to exceed 6 mg/kg; do not administer >q6h 1 mg/kg IV/IM slowly under close supervision; not to exceed 6 mg/kg
Immunoglobulin IV (Gamimune, Gammagard, Gammar-P, Sandoglobulin):
- Adult dose: 2 g/kg IV over 2 " 5 days

Follow-Up

Disposition

Admission Criteria
Symptomatic patients with myocarditis:

New-onset
CHF
Dysrhythmia
Mobitz II or complete heart block
Embolic events
Cardiogenic shock

Discharge Criteria
Asymptomatic patient with no evidence of dysrhythmia or cardiac dysfunction
Issues for Referral
Cardiac transplant for patients with intractable CHF:

Approximately 50% of patients die within 5 yr of diagnosis.
Best prognosis for lymphocytic myocarditis

Pearls and Pitfalls

Careful physical exam for signs of CHF and pericarditis is paramount.
EKG should be obtained when considering the diagnosis and is especially sensitive for pediatric cases.
Patients with evidence of dysrhythmia, CHF, or thromboembolism must be admitted.

Additional Reading

Brady WJ, Ferguson JD, Ullman EA, et al. Myocarditis: Emergency department recognition and management. Emerg Med Clin North Am. 2004;22(4):865 " 885.
Cooper LT. Myocarditis. N Engl J Med. 2009;360:1526 " 1538.
Durani Y. Pediatric myocarditis: Presenting clinical characteristics. Am J Emerg Med. 2009;27(8):942 " 947.
Magnani JW, Dec GW. Myocarditis: Current trends in diagnosis and treatment. Circulation. 2006;113:876 " 890.
Monney PA, Sekhri N, Burchell T, et al. Acute myocarditis presenting as acute coronary syndrome: Role of early cardiac magnetic resonance in its diagnosis. Heart. 2011;97(16):1312 " 1318.

Codes

ICD9

074.23 Coxsackie myocarditis
422.91 Idiopathic myocarditis
429.0 Myocarditis, unspecified
036.43 Meningococcal myocarditis
422.0 Acute myocarditis in diseases classified elsewhere

ICD10

B33.22 Viral myocarditis
I40.0 Infective myocarditis
I51.4 Myocarditis, unspecified
A39.52 Meningococcal myocarditis
A18.84 Tuberculosis of heart
D86.85 Sarcoid myocarditis

SNOMED

50920009 Myocarditis (disorder)
89141000 viral myocarditis (disorder)
91025000 Idiopathic myocarditis (disorder)
91468009 Meningococcal myocarditis (disorder)
195033009 Sarcoid heart muscle disease (disorder)
233868005 Fungal myocarditis (disorder)
37217002 coxsackie myocarditis (disorder)
64043005 Bacterial myocarditis (disorder)

Home

Erectile Dysfunction

Doctor123.org