Congestive Heart Failure

Basics

Description

  • Heart failure (HF) is the pathophysiologic state in which the heart is unable to pump sufficient blood to meet the metabolic demands of the body.
  • HF can manifest without cardiac dysfunction (e.g., severe anemia, large arteriovenous malformation [AVM]), but this chapter will concentrate on cardiac causes.
  • The most common cardiac causes of HF in pediatric patients include:
    • Congenital heart disease (CHD) with left-to-right shunting, where cardiac performance is normal, but flow is wastefully circular.
    • Congenital causes of LV failure include coarctation of the aorta, aortic stenosis, anomalous coronary origins.
    • Primary cardiomyopathies with inborn issues of structure or function of the myocardium
    • Acute myocarditis
    • Secondary cardiomyopathies due to neuromuscular disease, arrhythmias, history of cardiotoxic chemotherapy, or longstanding renal failure.
  • The management of HF in pediatrics is highly specialty-dependent. Immediate pediatric cardiology consultation is important whenever a cardiac cause of HF is suspected.

Epidemiology

  • Although minor CHD may occur in up to 5% of live births, CHD manifesting as HF is much rarer, <0.1% of the population.
  • Cardiomyopathy (CM) can be divided into:
    • Dilated CM (DCM) (40%)
    • Hypertrophic CM (HCM) (50%) (obstructive or nonobstructive)
    • Restrictive CM (RCM) (<5%)
    • RV cardiomyopathies (<1%) (arrhythmogenic right ventricular dysplasia and Uhl anomaly)
    • Other (5%)

Risk Factors

  • In utero
    • Arrhythmias: chronic supraventricular or ventricular tachycardia, complete heart block (CHB)
    • Volume overload: atrioventricular (AV) valve regurgitation (e.g., Ebstein anomaly)
    • AVM
    • Primary myocardial disease: CM (dilated, hypertrophic), myocarditis
    • Anemia: Rh isoimmune disease, thalassemia, twin-twin transfusion
    • Premature closure of ductus arteriosus with isolated right ventricular failure
  • In neonates
    • Myocardial dysfunction: asphyxia, acidosis, myocarditis, hypoglycemia, CM, ischemia (anomalous left coronary artery from the pulmonary artery), metabolic defects, or pressure overload imposed by aortic stenosis, pulmonary hypertension, or coarctation of the aorta
    • Volume overload: ventricular septal defect (VSD) (large), patent ductus arteriosus (PDA) (large), truncus arteriosus, aortopulmonary window, anomalous pulmonary venous return, AVM in any location
    • Arrhythmias: supraventricular or ventricular tachycardia, CHB
    • Left heart inlet obstruction: mitral stenosis, cor triatriatum, pulmonary venous obstruction
    • Note: Certain cyanotic heart diseases such as hypoplastic left heart syndrome may present with elevated pulmonary blood flow, depressed systemic blood flow, and minimal desaturation. These patients may have HF in the 1st day of life.
  • In infants
    • Myocardial dysfunction: CM (any type), metabolic/mitochondrial diseases, myocarditis, Kawasaki disease, anomalous left coronary artery from pulmonary artery, or chronic pressure overload due to coarctation of the aorta or aortic stenosis
    • Volume overload: large atrial septal defect (ASD), VSD, or PDA; common AV canal defect, partial anomalous pulmonary venous connections.
    • Secondary causes: renal disease (volume overload), severe hypertension, hypothyroidism
    • Arrhythmias: supraventricular or ventricular tachycardia, CHB
    • Pericardial effusion/tamponade due to inflammatory diseases, or following heart surgery
  • In childhood and adolescence:
    • Repaired heart defects with volume and/or pressure overload (e.g., repaired TOF)
    • Acquired: pericarditis, myocarditis, endocarditis, acute rheumatic fever
    • Cor pulmonale (primary pulmonary hypertension, Eisenmenger syndrome, chronic lung disease)
    • CM due to primary or secondary myocardial disease (dilated, hypertrophic, restrictive, ventricular noncompaction), cancer therapies, neuromuscular disease (e.g., Duchenne or Becker muscular dystrophy)

Genetics

  • For about 2/3 of primary cardiomyopathies (not due to metabolic defect or other medical condition), a genetic cause can be identified; higher odds for HCM than DCM
  • Examples:
    • HCM: α-tropomysin, troponin T, β-myosin, etc.; Noonan spectrum (RASopathies)
    • DCM: myosin heavy chain, laminin, RYR2, troponin C, more
    • CM with arrhythmia: lamin A/C, desmin
    • Arrhythmogenic right ventricular dysplasia: desmosomal genes and regulators

General Prevention

  • Limited use of anthracycline drugs in cancer therapy
  • Prompt treatment (within 10 days) of streptococcal pharyngitis to prevent rheumatic fever
  • Angiotensin converting enzyme (ACE) inhibitors slow the progression of CM in muscular dystrophy.
  • Appropriate endocarditis prophylaxis

Etiology

  • Low cardiac output HF (e.g., all CM, severe AV valve regurgitation)
  • High cardiac output HF (left-to-right shunts [e.g., ASD, VSD, PDA], AVM, severe anemia, hyperthyroidism)

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