3.3 Acquired Heart Disease & Heart Failure
Key Takeaways
- Kawasaki Disease is diagnosed clinically by high fever for ≥5 days plus 4 of 5 classic features (conjunctivitis, strawberry tongue/lip changes, polymorphous rash, extremity changes, cervical lymphadenopathy).
- First-line treatment for Kawasaki Disease requires high-dose IVIG (2 g/kg) and High-Dose Aspirin within 10 days of onset to prevent life-threatening Coronary Artery Aneurysms (CAA).
- Pediatric Myocarditis presents with unexplained persistent tachycardia out of proportion to fever, gallop rhythm, and elevated Troponin I/BNP, requiring cautious fluid management to prevent cardiogenic shock.
- Cardiac Tamponade presents with Beck's Triad (hypotension, distended neck veins, muffled heart sounds) and pulsus paradoxus, requiring emergency pericardiocentesis.
- Pediatric Heart Failure in infants manifests as diaphoresis during feeds, failure to thrive, tachypnea, and hepatomegaly, managed with diuretics, inotropes, and ACE inhibitors.
Acquired Heart Disease & Pediatric Heart Failure
Acquired pediatric cardiac conditions encompass inflammatory, infectious, autoimmune, and structural cardiac disorders that develop after birth. Unlike adult cardiology, where coronary artery disease dominates, pediatric acquired heart disease centers around Kawasaki Disease, Myocarditis, Infective Endocarditis, Pericarditis, and secondary Pediatric Heart Failure. Emergency nurses must recognize early clinical indicators of cardiac involvement to prevent permanent myocardial injury or sudden cardiac death.
Kawasaki Disease (Mucocutaneous Lymph Node Syndrome)
Kawasaki Disease (KD) is an acute, self-limiting systemic vasculitis of small- and medium-sized blood vessels, with a strong predilection for the coronary arteries. It is the leading cause of acquired heart disease in children in developed nations, primarily affecting infants and children under 5 years of age.
Diagnostic Criteria
Diagnosis is clinical, requiring a high fever (typically ≥39°C/102.2°F) lasting at least 5 days plus the presence of at least 4 of the following 5 classic criteria:
- Bilateral Conjunctival Injection: Non-purulent, painless bulbar conjunctivitis sparing the limbus.
- Oral Mucosal Changes: Erythematous, cracked lips; bright red "strawberry tongue"; diffuse pharyngeal mucosal erythema.
- Extremity Changes: Acute phase shows erythema and tense edema of palms and soles; subacute phase features periungual desquamation (peeling) starting around fingernails and toes.
- Polymorphous Exanthem: Diffuse maculopapular, scarlatiniform, or erythema multiforme-like rash, accentuated in the groin area.
- Cervical Lymphadenopathy: Unilateral cervical lymph node enlargement (>1.5 cm in diameter), usually non-tender and non-suppurative.
┌───────────────────────────────────────────────────────────┐
│ Kawasaki Disease Manifestations │
└─────────────────────────────┬─────────────────────────────┘
│
┌───────────────────────────┼───────────────────────────┐
▼ ▼ ▼
┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐
│ Oral & Ocular │ │ Skin & Nodes │ │ Cardiac Risk │
│ • Strawberry │ │ • Polymorphous │ │ • Coronary Art. │
│ tongue │ │ rash │ │ Aneurysms │
│ • Fissured lips │ │ • Cervical node │ │ • Baseline & │
│ • Non-purulent │ │ > 1.5 cm │ │ serial Echo │
│ conjunctivitis│ │ • Palm/sole edema│ │ mandatory │
└─────────────────┘ └─────────────────┘ └─────────────────┘
Cardiac Complications & Pharmacological Management
Without timely treatment, 20–25% of affected children develop Coronary Artery Aneurysms (CAA), risking myocardial infarction or sudden death. Baseline and follow-up echocardiography is essential.
- Intravenous Immunoglobulin (IVIG): Administer a single high-dose infusion of 2 g/kg IV over 10 to 12 hours. IVIG should be initiated within the first 10 days of fever onset to suppress vascular inflammation and reduce coronary aneurysm risk to <5%.
- High-Dose Aspirin (Acetylsalicylic Acid - ASA):
- Acute Phase: 80 to 100 mg/kg/day IV/PO divided every 6 hours for anti-inflammatory effect until the child is afebrile for 48 to 72 hours.
- Subacute Phase: Reduce to low-dose antiplatelet therapy (3 to 5 mg/kg/day PO once daily) for 6 to 8 weeks, or indefinitely if coronary abnormalities are detected on echocardiogram.
- Nursing Alert: Kawasaki disease represents one of the few absolute indications for high-dose aspirin in pediatrics. Parents must be educated to report influenza or varicella exposure due to Reye syndrome risks.
Pediatric Myocarditis
Pediatric myocarditis is an inflammatory disease of the myocardium, most frequently triggered by viral infection (e.g., Coxsackievirus B, Adenovirus, Parvovirus B19, Human Herpesvirus 6, and SARS-CoV-2 / MIS-C).
Emergency Presentation & Diagnostic Triad
Myocarditis in infants often mimics severe sepsis or bronchiolitis. Older children present with non-specific flu-like symptoms followed by sudden cardiac deterioration.
- Clinical Findings: Unexplained tachycardia out of proportion to fever, tachypnea, grunting, exercise intolerance, poor peripheral perfusion, S3/S4 gallop rhythm, new murmur, and hepatomegaly.
- Laboratory Markers: Elevated Cardiac Troponin I or T, elevated Brain Natriuretic Peptide (BNP or NT-proBNP), and elevated inflammatory markers (ESR, CRP).
- 12-Lead ECG: Sinus tachycardia, low-voltage QRS complexes in limb leads, ST-segment elevation or depression, T-wave inversions, and ventricular dysrhythmias.
- Emergency Management: Gentle fluid restriction (avoid aggressive fluid boluses which worsen cardiogenic shock), supplemental oxygen, inotropic support (milrinone, epinephrine, or dopamine), and early ECMO consultation if refractory shock occurs.
Acute Pericarditis & Cardiac Tamponade
Pericarditis is inflammation of the pericardial sac. If pericardial fluid accumulates rapidly under pressure, Cardiac Tamponade ensues, restricting diastolic ventricular filling and reducing cardiac output.
Clinical Assessment & Beck's Triad
- Pericarditis Presentation: Sharp, retrosternal chest pain that worsens when supine and improves when sitting up and leaning forward. A high-pitched, scratchy pericardial friction rub is audible at the left sternal border. ECG reveals diffuse concave ST-segment elevation with PR-segment depression.
- Cardiac Tamponade Assessment (Beck's Triad):
- Hypotension (with narrowing pulse pressure).
- Distended Neck Veins (Jugular Venous Distention - JVD; may be difficult to appreciate in infants).
- Muffled or Distant Heart Sounds.
- Pulsus Paradoxus: An exaggerated drop in systolic blood pressure (>10 mmHg) during normal inspiration.
- Immediate Treatment: Emergency Pericardiocentesis or surgical pericardial window. Administer IV isotonic fluid bolus while preparing for pericardiocentesis to temporarily increase right ventricular filling pressure.
Infective Endocarditis (IE)
Infective Endocarditis is an infection of the endocardium or heart valves, most commonly occurring in children with pre-existing structural CHD, prosthetic valves, or central venous lines.
- Key Clinical Features: Prolonged unexplained fever, new or changing heart murmur, splenomegaly, petechiae, Osler nodes (painful erythematous nodules on pads of fingers/toes), Janeway lesions (painless erythematous macules on palms/soles), and Roth spots (retinal hemorrhages).
- Emergency Management: Obtain three sets of blood cultures from separate venipuncture sites prior to initiating empirical broad-spectrum IV antibiotic therapy (e.g., vancomycin plus gentamicin).
Pediatric Heart Failure Management Summary
Pediatric heart failure results from volume overload (left-to-right shunts), pressure overload (aortic stenosis, coarctation), or myocardial dysfunction (myocarditis, dilated cardiomyopathy).
| Class of Medication | Agent Examples | Mechanism of Action in Pediatric Heart Failure | Nursing & Monitoring Considerations |
|---|---|---|---|
| Loop Diuretics | Furosemide (1 mg/kg IV/PO) | Reduces preload and pulmonary venous congestion | Monitor serum potassium (hypokalemia), daily weights, and urine output |
| Inotropes / Inodilators | Milrinone, Dobutamine, Dopamine | Increases myocardial contractility; milrinone lowers afterload | Continuous ECG and BP monitoring; milrinone requires central line and causes hypotension |
| ACE Inhibitors | Captopril, Enalapril | Reduces systemic vascular resistance (afterload) | Monitor BP for hypotension, renal function, and serum potassium (hyperkalemia) |
| Cardiac Glycosides | Digoxin | Increases inotropy and slows AV conduction | Hold if infant HR <90–110 or child HR <70; assess for toxicity (vomiting, bradycardia) |
A 4-year-old child presents with a 6-day history of high fever (39.5°C), bilateral non-purulent conjunctivitis, cracked erythematous lips, a strawberry tongue, a maculopapular rash, and swollen hands. Which combination of therapies should the emergency nurse anticipate to prevent coronary artery aneurysms?
A 10-year-old child who underwent cardiac surgery 1 week ago presents to the emergency department complaining of severe retrosternal chest pain. Assessment reveals a blood pressure of 76/42 mmHg, distended neck veins, muffled heart sounds, and a 14 mmHg drop in systolic blood pressure during inspiration. Which procedure should the nurse prepare for immediately?
A 3-year-old child with a recent history of a viral upper respiratory infection presents with profound lethargy, tachypnea, grunting, a heart rate of 178 beats/min (temperature 37.0°C), an S3 gallop, and a liver margin palpable 4 cm below the right costal margin. Which diagnostic laboratory test is most specific for evaluating suspected acute myocarditis?