Myocarditis
Caused by viruses, protozoa, bacteria, fungi, toxins, drugs, metabolic derangement, and autoimmune disease. Most common is viral etiology (50%). Common viral causes are enterovirus, parvovirus, and Human Herpes Simplex 6. Other emerging causes are adenovirus, Epstein-Barr virus, influenza, and parainfluenza.
Signs and symptoms are often vague and/or subtle initially. They can start as a viral syndrome, and progress, or simply be misinterpreted.
To add to the difficulty in diagnosis, patients present differently by age group.
Respiratory and/or GI symptoms predominate in the < 10 year old population. Children older than 10 years of age tend to have more cardiac symptoms.
Neonates have a fever or are fussy for no apparent reason. They may present listless with poor feeding. Signs on a neonate may include diaphoresis, cyanosis, or apnea.
The diagnosis is clinical. Testing cannot definitively rule in or rule out. Be your patient’s advocate.
Tests are not conclusive except for biopsy, which is rarely done, risky, and often unnecessary.
When considering the diagnosis of myocarditis, you may order:
EKG – most will be abnormal. Sinus tachycardia (46%); ST/T wave changes (60%); axis deviation (53%). Other findings include decreased voltage and infarction pattern.
CXR – only 60% will show cardiomegaly for age, but 90% will have some abnormality (venous congestion, effusion, etc).
LFTs – AST is the most sensitive laboratory test (congestion)
Troponin – may be elevated, but a negative troponin does not rule out disease
BNP – like troponin, an elevation is consistent with myocarditis (congestion), but a normal troponin does not rule out inflammation, only risk-stratifies congestion
ESR, CRP – may be elevated, but very non-specific (viral syndrome, bacterial pneumonia, etc.)
Sensitivities for lab testing
Goals of Management
Stabilize, gain good vascular access, and support cardiac output
Types of Shock
Goals for types of Cardiogenic Shock
“Septic Shock – the Remix”: Start vasopressors before endotracheal intubation (ETI) and/or fluids in this case. Use dobutamine, together with norepinephrine.
No evidence to prefer non-invasive positive pressure ventilation (NIPPV) over ETI
ETI is a respiratory holiday (metabolic and cardiac output improvement)
Often overloaded, so peripheral IV ok; can also use IO
Nitroglycerin can cause more harm than good in decompensated pediatric heart failure. Poorly compliant ventricles need some preload to generate adequate stroke volume. The issue is not so much of relieving the heart of too much preload; it is more about increasing contractility and supporting afterload.
Varying results with IV Ig, in small studies.
More
Intra-aortic balloon pump (IABP) – placed in descending aorta, below left subclavian. Deflated with aortic valve opening during systole; inflated with aortic valve closure in diastole.
Extracorporeal membrane oxygenation (ECMO) – venous-arterial (VA) ECMO is used primarily for cardiac failure. VA ECMO targets a flow rate that is “just enough” pressure to perfuse tissues and support venous oxyhemoglobin saturation, but low enough to allow for sufficient preload to maintain left ventricular output. Venous-venous (VV) ECMO is used primarily for respiratory failure; VV ECMO requires near-maximum flow rates in order to oxygenate properly.
Comparison of the modalities of mechanical support in children
| Parameter | IABP | ECMO | VAD |
| Ventricle supported | Left ventricle | Both ventricles | Mainly left ventricle |
| Complexity of equipment | Low | High | Moderate |
| Ease of use | Easy | Low | Moderate |
| Anticoagulation needed | Low | High | High |
| Complication rate | Moderate | High | Least |
| Duration of support | Days | Weeks | Weeks to months |
| Survival (%) | 56 | 40 | 40 |
ECMO, extracorporeal membrane oxygenation; IABP, intra‐aortic balloon pump; VAD, ventricular assist devices.
Selected References
Auerbach SR et al. BNP Levels Predict Outcome in Pediatric Heart Failure Patients, Post Hoc Analysis of the Pediatric Carvedilol Trial. Circ Heart Fail. 2010 Sep;3(5):606-11.
Bozkurt B et al on behalf of American Heart Association Committee on Heart Failure. Current Diagnostic and Treatment Strategies for Specific Dilated Cardiomyopathies. Circulation. 2016; 134:579-646.
Brissaud O et al. Experts’ recommendations for the management of cardiogenic shock in children. Ann Intensive Care. 2016; 6:14.
Caforio ALP et al. Current state of knowledge on aetiology, diagnosis, management, and therapy of myocarditis: a position statement of the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases. 2013; 34:2636-2648.
Canter CE et al. Diagnosis and Treatment of Myocarditis in Children in the Current Era. Circultion. 2014; 129:115-128.
Caughey RW et al. High-Degree Atrioventricular Block in a Child with Acute Myocarditis. Ochsner Journal. 2014; 14:244-247.
Drucker NA et al. Gamma-globulin treatment of acute myocarditis in the pediatric population. Circulation. 1994;89:252–257.
Eisenberg MA et al. Cardiac troponin T as a screening test for myocarditis in children. Pediatr Emerg Care. 2012 Nov;28(11):1173-8.
Farinha IT et al. Myocarditis in Paediatric Patients: Unveiling the Progression to Dilated Cardiomyopathy and Heart Failure. J Cardiovasc Dev Dis. 2016; 3(31):1-18.
Freedman SB et al. Pediatric Myocarditis: Emergency Department Clinical Findings and Diagnostic Evaluation. Pediatrics. 2007; 120(6):1278-1285.
Gandolfo F et al. Mechanical circulatory support in pediatrics. Ann Cardiothorac Surg. 2014 Sep; 3(5): 507–512.
Howlett JG et al. Canadian Cardiovascular Society Consensus Conference guidelines on heart failure, update 2009: Diagnosis and management of right-sided heart failure, myocarditis, device therapy and recent important clinical trials. Can J Cardiol. 2009; 25(2):85-105.
Levine MC et al. Update on myocarditis in children. Curr Opin Pediatr. 2010; 22:278-283.
Nosaka N et al. Effects of the elective introduction of extracorporeal membrane oxygenation on outcomes in pediatric myocarditis cases. Acute Med Surg. 2015; 2:92-97.
Ramachandra G et al. The challenges of prompt identification and resuscitation in children with acute fulminant myocarditis: case series and review of the literature. J Pediatr Child Health. 2010; 579-582.
This post and podcast are dedicated to Roger Harris, Chris Nickson, and Oli Flower — and all of the #SMACC community. Thank you for sharing of yourselves with the #FOAMed community.
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