Recognizing Cyanotic Congenital Heart Disease Masked by Infant Pneumonia in a Resource-Limited Setting: A Somali Case Report of Tetralogy of Fallot.

Background: In resource-limited settings lacking routine newborn screening, common lower respiratory tract infections like community-acquired pneumonia (CAP) can obscure or delay the diagnosis of underlying cyanotic congenital heart disease (CHD). Tetralogy of Fallot (TOF) is the most common cyanotic CHD, yet its co-occurrence with CAP creates significant diagnostic masking, as acute pulmonary signs often conceal cardiac abnormalities. Case Presentation: A 5-month-old male presented in Borama, Somalia, with severe respiratory distress, fever, cough, and bilateral crackles, leading to an initial clinical diagnosis of severe CAP. Detailed history revealed unrecognized pre-existing signs of structural heart disease, including failure to thrive (Moderate Acute Malnutrition, weight 4.6 kg, z-score < 2) and feeding diaphoresis. Although cardiovascular examination on admission demonstrated a precordial thrill and a harsh systolic murmur, clinical management was initially anchored on severe pneumonia. Following antibiotic escalation and resolution of acute fever and lung crackles, persistent resting oxygen desaturation (SpO2 88% on room air, dropping to 78-82% during crying) and unmasked feeding diaphoresis prompted echocardiography. Transthoracic echocardiography demonstrated features consistent with TOF (large 8.5 mm perimembranous ventricular septal defect, 45-50% overriding aorta, severe infundibular/valvular right ventricular outflow tract obstruction with a peak gradient of 67.2 mmHg, and severe right ventricular hypertrophy) with a concomitant 4.2 mm atrial septal defect. Double-outlet right ventricle and pulmonary atresia were ruled out. Given the total lack of open-heart surgical infrastructure in Somalia, the patient was stabilized on oral propranolol (1 mg/kg/day) and low-flow nasal cannula oxygen (1.5-2 L/min) and registered with international humanitarian cardiac surgical networks. Discussion: Acute respiratory infections can precipitate physiological stress and obscure classic cardiac physical signs in infants with underlying structural heart defects. Subtle red flags-such as feeding-induced sweating, fatigue during feeds, poor weight gain, and persistent post-pneumonia cyanosis-are critical diagnostic clues pointing to an underlying cardiac lesion in resource-limited environments. Conclusion: Persistent cyanosis, feeding diaphoresis, poor weight gain, or unexplained arterial desaturation following the resolution of acute pneumonia must serve as red flags for frontline clinicians. These findings should immediately prompt structured cardiovascular re-evaluation, pulse oximetry reassessment, and urgent echocardiography or pediatric surgical referral.