Cardiomyopathy
Cardiomyopathy: Excerpt from The 5-Minute Pediatric Consult
Nelangi Pinto, MD
Cardiomyopathy - BASICS
Cardiomyopathy - description
Cardiomyopathy is defined as a disease of the heart muscle which results in impaired function (systolic, diastolic, or both). It is divided into 3 main classifications based on structural and functional abnormalities:
- Dilated cardiomyopathy (DCM): The key finding in DCM is impairment of biventricular systolic function with predominant involvement of the left ventricle (LV), which manifests as CHF.
- Hypertrophic cardiomyopathy (HCM): Excessive thickening of the LV that is not secondary to load conditions such as aortic stenosis or hypertension. Up to 20–25% of the patients exhibit LV outflow tract obstruction.
- Restrictive cardiomyopathy (RCM): A myocardial disease in which there is impairment of ventricular diastolic function (or relaxation) from an increased stiffness of the ventricle. This results in decreased ventricular filling while systolic function is generally preserved.
Cardiomyopathy - general prevention
There is no specific prevention; however, a physician should evaluate individuals with a familial history of cardiomyopathy even if they are asymptomatic.
Cardiomyopathy - epidemiology
Cardiomyopathy - incidence
- Overall incidence of cardiomyopathy is 1–2 cases per 100,000 people. There is a peak incidence during the 1st year of life and a 2nd peak in adolescence.
- DCM: Studies have reported the incidence to range from 0.3–2.6 cases per 100,000 people.
- HCM: Reported incidence is 0.3–0.5 cases per 100,000 people.
Cardiomyopathy - prevalence
- DCM: 36 cases per 100,000 people
- HCM: Estimated to be 10–20 cases per 100,000 people
- RCM: Least common form of cardiomyopathy
Cardiomyopathy - risk factors
Cardiomyopathy - genetics
- DCM: Familial DCM accounts for ~20% of cases.
- Autosomal dominant inheritance remains the most common pattern. Although no specific gene has been identified as the cause of familial DCM, 6 genes have been localized in different family cohorts.
- DCM has also been seen in association with diseases of X-linked inheritance, such as Duchenne and Becker muscular dystrophy, and Barth syndrome.
- May also be inherited via mitochondrial DNA, with differing penetrance
- HCM: ~60% of reported cases are thought to be inherited. Traditionally, HCM is inherited in an autosomal dominant pattern with incomplete penetrance.
- RCM: Idiopathic cases may have a familial occurrence and may be associated with a skeletal myopathy. An autosomal dominant form of the disease with variable penetrance has been associated with Noonan syndrome.
Cardiomyopathy - pathophysiology
- DCM: Depressed systolic function and abnormally dilated chambers are the common features of all forms of DCM. On a cellular level, there is often fibrosis of the myocardium.
- HCM: Thickened LV (and sometimes right ventricle) can cause impaired filling. Systolic function is usually hyperdynamic. Can have outflow obstruction and asymmetric hypertrophy. At the cellular level, myocytes are hypertrophied and disorganized.
- RCM: This disease is manifest by increased stiffness of the myocardium leading to impairment of ventricular filling. Can see myocardial fibrosis and/or infiltration on a cellular level.
Cardiomyopathy - etiology
- DCM: There are many etiologies for DCM.
Of known causes the most common is myocarditis (coxsackievirus B, echovirus, adenovirus). DCM can also occur from toxin exposure (anthracyclines), ischemic coronary artery disease (anomalous left coronary artery from the pulmonary artery, coronary aneurysms), and chronic tachyarrhythmias.
- Can occur as a finding associated with another disease or syndrome. These include inborn errors of fatty-acid oxidation, disorders of mitochondrial oxidative phosphorylation, nutritional deficiencies, primary and secondary carnitine deficiency, and X-linked muscular dystrophies.
- It may be familial and genetically inherited.
- DCM is most commonly idiopathic (with no etiology identified).
- RCM: Most commonly idiopathic, although known causes include:
- Systemic disease such as lupus erythematosis, sarcoidosis, amyloidosis, infiltrative diseases (Gaucher disease, Hurler syndrome), storage diseases (Fabry disease), carcinoid syndrome, and radiation-induced fibrosis
- Familial forms of RCM
Cardiomyopathy - DIAGNOSIS
Cardiomyopathy - signs & symptoms
In the early stages of all 3 forms of cardiomyopathy, the symptoms are nonspecific and can mimic other disease processes. The cardiac examination can be completely normal. Therefore, those patients who raise suspicion for this disease either by family history or clinical presentation should be carefully evaluated.
Cardiomyopathy - history
- DCM: Symptoms usually develop slowly although they may also be of sudden onset.
- Irritability
- Respiratory distress
- Dyspnea with exertion
- Anorexia, abdominal pain, nausea
- Failure to thrive
- Exercise intolerance
- Syncope
- Palpitations
- HCM: Often children are asymptomatic and are first referred for evaluation based on family history or for murmur evaluation. Of those with symptoms the following may be present:
- Chest pain with exertion
- Dizziness
- Syncope
- Palpitations
- RCM: Symptoms are usually due to systemic and pulmonary congestion from high atrial pressures. They are usually more evident late in the disease.
- Dyspnea with exertion
- Abdominal pain
- Chest pain
- Palpitations
Cardiomyopathy - physical exam
- Cardiac:
- DCM: Tachycardia, cardiomegaly, hepatomegaly, SHCM: Can be normal or have systolic murmur owing to mitral regurgitation and/or LV outflow tract obstruction. The presence of outflow tract obstruction produces a systolic ejection murmur of variable intensity related to the degree of obstruction; the murmur increases in intensity with Valsalva and decreases in magnitude with squatting. A parasternal or carotid thrill may be present.
- RCM: Jugular venous pulse either fails to fall or rises during inspiration (Kussmaul sign): The presence of S
- Respiratory (DCM and RCM): Tachypnea, rales, wheezing
- Abdominal (DMC and RCM): Hepatomegaly, ascites, tenderness to palpation
- Extremities (DCM): Edema in extreme cases
Cardiomyopathy - tests
Nonspecific tests:
- Chest radiograph: Cardiomegaly, pulmonary venous congestion, pulmonary edema, and pleural effusions; segmental atelectasis from compression of the bronchioles
- EKG: Supraventricular or ventricular arrhythmia may be seen. DCM: Sinus tachycardia, nonspecific ST segment and T-wave changes; HCM: Hypertrophy, deep Q waves; RCM: Atrial enlargement, nonspecific ST and T wave changes
Cardiomyopathy - lab
DCM: In addition to routine inflammatory markers, specific tests should be obtained to establish the cause:
- Metabolic: Carnitine level, serum organic acids, and urine organic and amino acids, pyruvate, lactate
- Genetic: Chromosomal analysis, genetic mutations of the dystrophin gene
- Infectious: Enterovirus, coxsackievirus A/B, hepatitis, cytomegalovirus, Epstein-Barr virus, herpes simplex virus, and human immunodeficiency virus
- Brain natiuretic peptide (BNP) is often used to follow heart failure in patients with DCM.
Cardiomyopathy - imaging
Electrocardiogram:
- Allows for assessment of systolic function, ventricular dimensions, outflow tract obstruction, and diastolic filling properties
- DCM: Significant dilation of left (and right) ventricle with decreased systolic function
- HCM: Gold standard for diagnosis: LV hypertrophy, intraventricular pressure gradient, and systolic anterior motion of the mitral valve
- RCM: Disproportionately dilated atria with impaired diastolic filling by Doppler. LV function is normal until late stages.
Cardiomyopathy - diag proced-surgery
Cardiac catheterization:
- DCM: Rarely used as the primary diagnostic tool in this disease; the procedure is used to delineate coronary anatomy and to perform endomyocardial biopsies.
- HCM: Determination of the presence or absence of LV outflow tract obstruction, evaluation of diastolic dysfunction, classic spike and dome arterial pulse tracing, Brockenbrough phenomenon (a beat following a premature ventricular contraction exhibits an arterial pulse pressure less than that of a control beat).
- RCM: Atrial pressures are elevated and equal. Ventricular pressures exhibit a rapid and deep early decline at the onset of diastole followed by a rapid rise to a plateau in early diastole (dip and plateau or square-root sign).
Cardiomyopathy - differencial diagnosis
- DCM: Children and young adults often present with symptoms that mimic other disease states:
- For example, abdominal distention, right upper quadrant pain, nausea, and anorexia indicate right heart failure, but could be mistaken for hepatic or gallbladder disease.
- Wheezing, tachypnea, and dyspnea on exertion may be diagnosed as bronchitis or asthma.
- Cardiomegaly on chest radiograph may be mistaken for a large pericardial effusion.
- HCM: This disease must be differentiated from the LV hypertrophy that is seen in a well-trained athlete.
- RCM: Should be distinguished from constrictive pericarditis because the latter is usually a remediable process. A history of tuberculosis, trauma, or cardiac surgery may suggest constrictive pericarditis.
Cardiomyopathy - TREATMENT
Cardiomyopathy - initial stabilization
Patients with DCM may present critically ill requiring intubation and inotropic support.
Cardiomyopathy - general measures
- DCM:
- At the time of diagnosis, a trial of IV gamma globulin and/or other immunomodulators (prednisone, azathioprine) to treat possible myocarditis
- Diuretics
- After load reduction (enalapril, captopril)
- Inotropic agents (milrinone, dobutamine, digoxin)
- Aldactone (improves New York Heart Association [NYHA] functional class)
- Anticoagulation to avoid embolic complications
- Antiarrhythmics as needed, β-adrenergic blockers (metoprolol, carvedilol)
- Ventricular assist devices have been used in those with end-stage heart failure either as a bridge to recovery or to transplantation.
- HCM: β-adrenergic blockers remain 1st-line medical therapy. Calcium channel blockers or disopyramide may also be used. Antiarrhythmics may also be part of the medical regimen. There is no evidence that prophylactic medical treatment will reduce the risk of sudden death.
- If medical therapy is not effective, other options may include myotomy or myectomy (for severe outflow obstruction) and atrioventricular sequential pacing.
- The placement of an implantable cardioverter defibrillator (ICD) may be indicated.
- RCM: The mainstay of medical therapy is symptomatic treatment:
- Diuretics can be used with caution to treat venous congestion without reducing the ventricular filling pressure.
- Antiarrhythmics are used to treat the high incidence of atrial arrhythmias.
- ICDs have also been used to treat life-threatening ventricular arrhythmias.
- Anticoagulation is used owing to the high risk of thrombus formation and embolic complications from hemostasis in the dilated atrium.
- Because of the natural history of this disease, most patients eventually require a cardiac transplant.
Cardiomyopathy - surgery
- DCM or RCM: Heart or heart–lung transplantation (if the pulmonary vascular resistance is elevated); transplantation may be necessary if all therapeutic endeavors prove to be futile.
- HCM: Myotomy or myectomy if indicated
Cardiomyopathy - FOLLOW UP
Cardiomyopathy - prognosis
- DCM: The survival rate at 1-year follow-up is 63–90% with a 5-year survival rate of 25–34%. A general rule for idiopathic DCM is that 1/3 of patients exhibit improved cardiac function, 1/3 of patients have stable cardiac dysfunction, and 1/3 of patients progress to significant cardiac dysfunction.
- HCM: Overall incidence of sudden death is 4–6% in children and adolescents and as low as 1% in adults. Between the ages of 12 and 35 years and in young athletes, HCM is the most common cause of sudden death. Obstruction may slowly develop or progress. Heart failure symptoms usually do not occur until adulthood.
- RCM: The reported median survival in RCM is 1.4 years in children.
Cardiomyopathy - complications
- CHF can occur in all 3 forms of cardiomyopathy.
- Arrhythmias may be seen and are frequently ventricular in origin.
- Thrombus formation can be seen owing to the stasis of blood in dilated cardiac chambers and the hypocontractile ventricle. Therefore, systemic or pulmonary emboli are possible.
Cardiomyopathy - patient monitoring
Patients require careful follow-up and should be referred for a transplant evaluation, as deemed clinically necessary.
Cardiomyopathy - bibliography
- Akagi T, Benson LN, Lightfoot NE, et al. Natural history of dilated cardiomyopathy in children. Am Heart J. 1991;121:1502–1506.
- Ammash NM, Seward JB, Bailey KR, et al. Clinical profile and outcome of idiopathic restrictive cardiomyopathy. Circulation. 2000;101:2490–2496.
- Arola A, Tuominen J, Ruuskanen O, et al. Idiopathic dilated cardiomyopathy in children: Prognostic indicators and outcome. Pediatrics. 1998;101:369–376.
- Burch M, Blair E. The inheritance of hypertrophic cardiomyopathy. Pediatr Cardiol. 1999;20:313–316.
Chan DP, Allen HD. Dilated congestive cardiomyopathy. In: Emmanouilides GC, ed. Moss and Adams Heart Disease in Infants, Children, and Adolescents Including the Fetus and Young Adult, 5th ed. Baltimore: Williams & Wilkins; 1995: 1365–1381.- Charron P, Dubourg O, Desnos M. Diagnostic value of electrocardiography and echocardiography for familial hypertrophic cardiomyopathy in genotyped children. Eur Heart J. 1998;19:1377–1382.
- Denfield SW, Rosenthal G, Gajarski RJ, et al. Restrictive cardiomyopathies in childhood: Etiologies and natural history. Tex Heart Inst J. 1997;24:38–44.
- Kelly DP, Strauss AW. Mechanisms of disease: Inherited cardiomyopathies. N Engl J Med. 1994;330:913–919.
- Lewis AB, Chabot M. Outcome of infants and children with dilated cardiomyopathy. Am J Cardiol. 1991;68:365–369.
- Lipshultz SE, Sleeper LA, Towbin JA, et al. The incidence of pediatric cardiomyopathy in two regions of the United States. N Engl J Med. 2003;348:1647–1655.
- Maron BJ. Hypertrophic cardiomyopathy in childhood. Pediatr Clin N Am. 2004;51:1305–1346.
- Maron BJ. Sudden death in young athletes. N Engl J Med. 2003;349:1064–1075.
- Pelliccia A, Maron BJ, Spataro A, et al. The upper limit of physiologic cardiac hypertrophy in highly trained elite athletes. N Engl J Med. 1991;324:295–301.
- Towbin JA. Pediatric myocardial disease. Pediatr Clin North Am. 1999;46:289–312.
- Towbin JA, Lowe AM, Colan SD, et al. Incidence, causes, and outcomes of dilated cardiomyopathy in children. JAMA. 2006;296:1867–1876.
Cardiomyopathy - CODES
Cardiomyopathy - icd9
425.4 Cardiomyopathy
Cardiomyopathy - FAQ
- Q: Should family members be evaluated once a cardiomyopathy is diagnosed in a 1st-degree relative?
- A: Yes. In some forms of cardiomyopathy, there is a strong genetic component and family members should be evaluated. If the cardiomyopathy is known to be acquired, evaluation of relatives is not required.
- Q: Does the cardiomyopathy of infants of diabetic mothers carry the same clinical course and outcome as that of patients with HCM?
- A: No. The pathophysiology is initially similar in that asymmetric hypertrophy of the ventricular septum is often seen with or without LV outflow obstruction. However, the clinical course of the cardiomyopathy in these infants is usually benign and resolves within the 1st 6 months of life.
- Q: What are the differentiating features of HCM and the benign physiologic hypertrophy of an athlete’s heart?
- A: Several criteria are used to make this distinction. For example, a familial history of HCM raises the suspicion of this entity. Studies have suggested specific echocardiographic LV dimensions to differentiate benign hypertrophy and HCM (i.e., a wall thickness of ≥15 mm or LV cavity dimension <45 mm are more consistent with HCM). Also, ECG evidence of abnormal mitral valve inflow is suggestive of HCM.
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Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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