# Clinical Cases: Pediatric Cardiac Disorders

## Case 1: Tetralogy of Fallot with Hypercyanotic Spell

### Patient Demographics
- **Age:** 6-month-old male
- **Sex:** Male

### Chief Complaint
"My baby turned blue and went limp while crying."

### History of Present Illness
A 6-month-old male with known tetralogy of Fallot (TOF) awaiting surgical repair is brought to the emergency department after experiencing an episode of sudden cyanosis and limpness while crying this morning. The mother reports that the infant was crying vigorously when he suddenly became deeply blue, appeared to be struggling to breathe, and then became limp and unresponsive for approximately 30 seconds. She instinctively brought his knees to his chest, and he slowly improved over the next few minutes. This is his third similar episode in the past two weeks, though the previous two were milder. He was diagnosed with TOF at 2 weeks of age after a murmur was detected at his newborn visit. He has been followed by cardiology and is scheduled for complete surgical repair next month.

### Physical Examination
- **General:** Alert infant, mildly tachypneic, visible cyanosis of lips and nail beds
- **Vital signs:** HR 160 bpm, RR 44/min, SpO2 78% on room air, BP 75/50 mmHg
- **HEENT:** Central cyanosis, no respiratory distress at rest
- **Cardiovascular:** Hyperdynamic precordium, systolic ejection murmur at left upper sternal border (softer than previously documented), single S2
- **Respiratory:** Clear breath sounds bilaterally
- **Abdomen:** Soft, no hepatomegaly
- **Extremities:** Clubbing of fingers, peripheral cyanosis

### Workup
- **CBC:** Hemoglobin 17.2 g/dL (polycythemia), Hct 52%
- **ABG:** pH 7.28, pCO2 32 mmHg, pO2 45 mmHg, HCO3 15 mEq/L
- **Chest X-ray:** Boot-shaped heart with decreased pulmonary vascular markings
- **ECG:** Right axis deviation, right ventricular hypertrophy
- **Echocardiogram:** Large VSD with overriding aorta, severe infundibular stenosis, RV hypertrophy; RV outflow tract gradient increased from baseline

### Diagnosis
**Tetralogy of Fallot with hypercyanotic (tet) spell**

### Clinical Reasoning
The classic presentation of a tet spell in an infant with known TOF is characteristic. The episode was triggered by crying, which increases oxygen demand and can precipitate infundibular spasm, worsening the right-to-left shunt. The softer murmur during the episode reflects decreased blood flow across the pulmonary outflow tract (less turbulence when more blood is shunted right-to-left). The polycythemia represents a compensatory response to chronic hypoxemia. The metabolic acidosis reflects tissue hypoxia during the spell.

### Management
1. **Immediate treatment:** Knee-to-chest position, supplemental oxygen, IV access
2. **Pharmacotherapy:** Morphine 0.1 mg/kg IV for sedation and decreased catecholamine response; consider phenylephrine if persistent (increases SVR, decreases R-to-L shunt)
3. **If refractory:** Propranolol IV to relax infundibular spasm
4. **Long-term:** Oral propranolol 1 mg/kg/day divided Q6h until surgical repair
5. **Urgent surgical consultation:** Expedite complete repair given recurrent tet spells
6. **Parent education:** Knee-to-chest positioning, avoid excessive crying when possible

### Clinical Image
![Tetralogy of Fallot anatomical diagram](case_01_image.jpg)

**Image Description:** Anatomical diagram of tetralogy of Fallot showing the four characteristic features: ventricular septal defect, overriding aorta, right ventricular outflow tract obstruction, and right ventricular hypertrophy.

**Source:** Wikimedia Commons
**URL:** https://commons.wikimedia.org/wiki/File:Tetralogy_of_Fallot.svg
**License:** CC BY-SA 3.0

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## Case 2: Kawasaki Disease

### Patient Demographics
- **Age:** 3-year-old male
- **Sex:** Male

### Chief Complaint
"He's had a high fever for 5 days and now has a rash."

### History of Present Illness
A 3-year-old previously healthy male presents with 5 days of persistent high fever (39-40°C) that has not responded to acetaminophen or ibuprofen. Over the past 2 days, his parents have noticed red eyes without discharge, cracked red lips, a red rash on his trunk, and swelling of his hands and feet. He has been irritable and refusing to eat. He has had no cough, runny nose, or diarrhea. There is no known sick contacts. He received all vaccinations on schedule and has no significant past medical history.

### Physical Examination
- **General:** Irritable, ill-appearing child
- **Vital signs:** Temp 39.8°C, HR 140 bpm, RR 28/min, BP 90/60 mmHg
- **HEENT:** Bilateral conjunctival injection without exudate, cracked erythematous lips, strawberry tongue, right anterior cervical lymph node 2 cm and tender
- **Cardiovascular:** Tachycardic, regular rhythm, no murmur, normal S1/S2
- **Respiratory:** Clear to auscultation
- **Abdomen:** Soft, mildly tender diffusely, no hepatosplenomegaly
- **Skin:** Diffuse polymorphous macular rash on trunk and extremities
- **Extremities:** Erythema and edema of hands and feet

### Workup
- **CBC:** WBC 18,000/μL with left shift, Hgb 10.8 g/dL, Platelets 450,000/μL
- **CMP:** Normal
- **ESR:** 68 mm/hr (elevated)
- **CRP:** 12.5 mg/dL (elevated)
- **Urinalysis:** Sterile pyuria (15 WBC/hpf)
- **Echocardiogram:** Normal coronary arteries, mild pericardial effusion, normal LV function

### Diagnosis
**Kawasaki disease (acute phase)**

### Clinical Reasoning
This patient meets diagnostic criteria for Kawasaki disease: fever for at least 5 days plus 4 of 5 clinical criteria (bilateral non-exudative conjunctivitis, oral mucosal changes, polymorphous rash, extremity changes, and cervical lymphadenopathy >1.5 cm). The elevated inflammatory markers and sterile pyuria are supportive findings. Early echocardiogram shows no coronary involvement yet, but he remains at risk without treatment.

### Management
1. **IVIG:** 2 g/kg as single infusion over 10-12 hours
2. **High-dose aspirin:** 80-100 mg/kg/day divided Q6h until afebrile for 48-72 hours
3. **Transition to low-dose aspirin:** 3-5 mg/kg/day once afebrile
4. **Repeat echocardiogram:** At 2 weeks and 6-8 weeks
5. **Monitor for IVIG resistance:** If fever persists >36 hours after IVIG completion, consider second IVIG dose, corticosteroids, or infliximab
6. **Continue low-dose aspirin:** For 6-8 weeks if no coronary abnormalities; indefinitely if coronary involvement develops

### Clinical Image
![Kawasaki disease clinical features](case_01_image.jpg)

**Image Description:** Clinical photograph demonstrating the classic features of Kawasaki disease including conjunctival injection, cracked erythematous lips, and strawberry tongue.

**Source:** Wikimedia Commons
**URL:** https://commons.wikimedia.org/wiki/File:Kawasaki_symptoms.png
**License:** CC BY-SA 4.0