3.2 Heart Failure & Cardiomyopathies

Pediatric Heart Failure: A Syndrome, Not a Single Disease

Heart failure in children is the clinical syndrome in which cardiac output is insufficient for metabolic needs or is maintained only at the cost of elevated filling pressures. Causes include cardiomyopathy, unrepaired or palliated congenital heart disease, myocarditis, arrhythmia, hypertension, and ischemia related to anomalous coronaries or Kawasaki sequelae. The CCRN-Pediatric exam expects you to classify cardiomyopathy phenotype, recognize congestion versus low-output physiology, select phenotype-appropriate medications, and teach families how to prevent decompensation.

Cardiomyopathy Phenotypes

Dilated Cardiomyopathy (DCM)

The ventricle enlarges and thins; systolic function falls (reduced ejection fraction). Children present with fatigue, tachypnea, feeding intolerance, gallop, and mitral regurgitation from annular dilation. Etiologies include genetic sarcomere/cytoskeletal defects, prior myocarditis, anthracycline toxicity, and neuromuscular disease. ICU threats are low-output shock, atrial or ventricular arrhythmias, and thrombus from blood stasis — anticoagulation may be indicated when the ventricle is severely dilated and hypokinetic.

Hypertrophic Cardiomyopathy (HCM)

Inappropriate myocardial hypertrophy, often septal, creates a stiff ventricle and sometimes left-ventricular outflow tract obstruction (LVOTO) and systolic anterior motion of the mitral valve. Diastolic dysfunction dominates; systolic ejection fraction may look "hyperdynamic." Triggers for syncope or sudden deterioration include hypovolemia, tachycardia, and increased contractility. Avoid dehydration, pure inotropes, and aggressive afterload reduction that worsen dynamic obstruction. In obstructive crisis with hypotension, specialists may use vasoconstriction (for example phenylephrine) and volume to stabilize the outflow gradient while arranging definitive care.

Restrictive Cardiomyopathy (RCM)

Ventricular walls are rigid with severe diastolic filling impairment and often biatrial enlargement. Systolic function may be preserved early. Children develop marked venous congestion, pulmonary hypertension, and syncope. They tolerate hypovolemia poorly yet also congest easily — a narrow preload window. Transplant evaluation is often needed earlier than in other phenotypes because medical therapy is limited.

Idiopathic and Other Phenotypes

Idiopathic cardiomyopathy means a thorough workup has not identified a cause — still treat the physiology. Also recognize left-ventricular noncompaction, arrhythmogenic cardiomyopathy (more often adolescent), and metabolic/storage diseases in infants with multisystem clues (hypoglycemia, hypotonia, dysmorphic features). Parallel evaluation for treatable metabolic disease can be lifesaving in the infant with unexplained cardiomyopathy.

Congestion Versus Low Output

Bedside classification drives therapy:

• Wet (congested): tachypnea, crackles, orthopnea, hepatomegaly, edema, elevated natriuretic peptides, radiographic pulmonary venous hypertension. Priority once perfusion allows: diuretics, salt/fluid stewardship, and afterload reduction.
• Cold (low output): cool extremities, lactate rise, oliguria, narrow pulse pressure, low mixed/central venous saturation, altered mentation. Priority: inotropy, optimize perfusion pressure, consider mechanical support.
• Cold and wet: the sickest PICU phenotype — needs simultaneous support of output and relief of congestion, often ICU-level vasoactives and ventilatory support.

A child can shift profiles over hours. Reassess after every intervention; a diuretic that helps a warm-wet child can crash a cold child who still needed preload.

Medications in Acute and Chronic Management

Acute decompensated care may include oxygen or ventilatory support, IV loop diuretics for congestion, milrinone or epinephrine for low output, cautious nitroprusside/nicardipine or ACE-inhibitor introduction for afterload reduction when blood pressure allows, and arrhythmia-specific therapy (for example amiodarone under specialist guidance). Correct anemia, fever, and uncontrolled pain that inflate oxygen demand.

Chronic cornerstone therapy (tailored by phenotype and age) commonly includes:

• ACE inhibitors or ARBs — afterload reduction and remodeling benefits in DCM/systolic failure
• Beta-blockers (for example carvedilol) — reverse remodeling; introduce when euvolemic and stable
• Mineralocorticoid receptor antagonists (spironolactone/eplerenone)
• Loop ± thiazide diuretics for persistent congestion
• Digoxin in selected residual-symptom cases
• Emerging/specialized agents (ARNI, SGLT2 inhibitors) appear in older children under heart-failure team protocols

HCM-specific outpatient drugs often emphasize beta-blockers or calcium-channel blockers for diastolic filling and gradient control — not the same vasodilator-heavy approach used in DCM. Know the phenotype before reflexively applying an adult "HFrEF cocktail."

Nutrition is therapy: infants with heart failure need calorie-dense feeds, sometimes NG/NJ support, and careful fluid volume. Poor weight gain is both a severity marker and a modifiable driver of decompensation.

Family Teaching Essentials

Families are the early-warning system after discharge. Teach:

1. Red flags: increased work of breathing, feeding refusal or prolonged feeds with sweating, unexplained vomiting/abdominal pain (hepatic congestion), syncope, sudden weight gain from fluid, cool mottled extremities, or lethargy.
2. Medication adherence: use written schedules, teach dosing in mL for liquid meds, and explain not to stop ACE inhibitors/beta-blockers abruptly without the team.
3. Daily weights and intake/output awareness in infants and smaller children when directed by the program.
4. Activity: follow cardiology guidance; many children may attend school with activity limits; competitive sports restrictions are common in HCM and arrhythmia-risk phenotypes.
5. Infection prevention: vaccines are critical; early evaluation of febrile illness because infection precipitates decompensation.
6. Genetic counseling when familial cardiomyopathy is confirmed or suspected — siblings may need screening echocardiography.
7. Device/transplant pathways: prepare families early if VAD or listing is likely, reducing crisis decision shock.

Nursing documentation that captures perfusion exam, intake/output, feeding endurance, and caregiver understanding is as important as the vasoactive drip rate. On the exam, match phenotype → dangerous interventions to avoid, and wet versus cold → diuretic versus inotrope priority.