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

Abstract

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.

Introduction

Tetralogy of Fallot (TOF) is the classic prototype of cyanotic congenital heart disease (CHD), characterized by four cardinal anatomical features: a ventricular septal defect (VSD), right ventricular outflow tract obstruction (RVOTO), an overriding aorta, and secondary right ventricular hypertrophy.¹ Globally, TOF accounts for 3% to 5% of all congenital cardiac malformations,² representing a complex conotruncal defect driven by specific genetic and developmental factors.³ In high-resource healthcare systems, TOF is routinely detected in utero via fetal anomaly scans or during the early neonatal period through universal pulse oximetry screening and prompt pediatric echocardiography.⁴

In contrast, in low-resource settings such as Somalia, frontline pediatric care faces a dual burden: an exceptionally high background incidence of severe lower respiratory tract infections—such as community-acquired pneumonia (CAP)^5,6—and a complete absence of routine newborn pulse oximetry or routine antenatal ultrasound screening. This absence of routine perinatal diagnostic pathways reflects a fractured perinatal care cascade that frequently leaves severe congenital anomalies unnoticed until acute decompensation occurs.⁷ In this environment, infants born with underlying cyanotic CHD or other structural cardiac defects frequently remain undiagnosed until an acute intercurrent illness or cardiovascular stress brings them to medical attention.^8,9 When an infant with unrepaired TOF develops CAP, clinicians face severe diagnostic anchoring bias. The dramatic presentation of severe pulmonary infection—characterized by high fever, tachypnea, accessory muscle use, and prominent lung adventitia—routinely captures clinical focus. Consequently, underlying cardiac signs, such as a systolic murmur or mild baseline cyanosis, are frequently attributed entirely to the acute pulmonary process or masked by respiratory noise.¹⁰

Diagnostic delay in these settings carries profound risks. The physiological strain of severe infection, fever, dehydration, and crying can precipitate acute hypoxemic “tet” spells or life-threatening desaturation.⁸ Therefore, recognizing specific clinical red flags that fall outside the typical picture of simple pneumonia—such as diaphoresis during breastfeeding, rapid feeding fatigue, poor weight gain (failure to thrive), and persistent hypoxemia after pulmonary symptoms clear—is essential for unmasking underlying CHD.

In Somalia, diagnostic and therapeutic pathways for pediatric cardiology are severely constrained. Public facilities lack dedicated pediatric cardiology units, point-of-care pediatric echocardiography is available in only a handful of urban diagnostic centers at substantial out-of-pocket expense for families, and open-heart cardiothoracic surgery is nonexistent within the national health system.^10,11 To our knowledge, this report presents one of the few documented pediatric cases from Somalia of Tetralogy of Fallot unmasked during the clinical management of severe community-acquired pneumonia in a 5-month-old male infant,¹² detailing the diagnostic reasoning, bedside oxygenation parameters, therapeutic bridge management, and systemic referral barriers inherent to this resource-limited environment.

Case Presentation

A 5-month-old male infant presented to our facility in Borama, Somalia, with severe respiratory distress, high fever, productive cough, poor feeding, excessive sweating during feeds, and cyanosis triggered by crying. Antenatal history revealed that the mother had received limited prenatal care with no anomaly ultrasound scans. The infant was delivered at home via spontaneous vaginal delivery at term, with an estimated birth weight of 3.1 kg. The neonatal course was reported as unremarkable, and no pulse oximetry screening or cardiac auscultation had been performed prior to this encounter. Immunizations were up to date for age according to local expanded programs on immunization. There was no family history of congenital heart disease or early infant death.

Detailed developmental and nutritional review revealed chronic failure to thrive. On admission, the infant’s weight was 4.6 kg and length was 58 cm, corresponding to a Weight-for-Age z-score < −3 and Weight-for-Height z-score < −2, confirming Moderate Acute Malnutrition (MAM). On maternal questioning, the mother recalled that since approximately 2 months of age, the infant experienced forehead diaphoresis and marked fatigue after taking small volumes of breast milk, often forcing him to rest frequently during feeds. These subtle red flags had been previously interpreted by the family as minor infant fatigue.

On examination, his pulse rate was 130 beats per minute, temperature was 37.7°C, respiratory rate was 34 breaths per minute, and initial spot pre-ductal oxygen saturation (SpO₂) was 88% on room air at rest, which dropped precipitously to 78–82% during episodes of crying or agitation. Simultaneous pre-ductal (right hand) and post-ductal (right foot) pulse oximetry demonstrated equal saturation values (88% on room air), excluding differential cyanosis.

Respiratory examination revealed marked subcostal and intercostal retractions, nasal flaring, diffuse wheezing, and bilateral coarse crackles. Cardiovascular examination was notable for a hyperdynamic precordium, a palpable systolic thrill at the left mid-to-lower sternal border, and a grade 4/6 harsh pansystolic murmur loudest at the left third and fourth intercostal spaces. Head, neck, abdominal, and neurological examinations were otherwise unremarkable. Given the acute presentation of fever, distress, and lung crackles, clinical management was initially anchored on severe CAP, while the cardiac findings were documented for secondary evaluation once the acute pulmonary infection was stabilized. A comprehensive timeline of the clinical presentation, management trajectory, and follow-up chronology is detailed in Table 1.

Table 1.

Timeline and Management Chronology

Chronology (Time)	Clinical Events & Findings	Interventions & Management Decisions
Day 1 (Admission)	Severe dyspnea, fever (37.7°C), cough, coarse crackles, room air SpO2 88% (dropping to 78% on crying). Precordial thrill and grade 4/6 pansystolic murmur noted.	Diagnosed clinically with severe CAP (per WHO IMCI criteria); started on IV ceftriaxone (100 mg/kg/day), IV paracetamol, and low-flow nasal cannula oxygen (1.5 L/min).
Day 3	Persistent spikes of high fever (38.5°C), persistent cough, and marked respiratory distress without clinical improvement.	Empirical antibiotic escalation to IV vancomycin (15 mg/kg Q8H) and oral co-trimoxazole syrup per local severe sepsis protocol.
Day 5	Resolution of fever and lung crackles. However, resting SpO2 remains low at 88% on room air, with pronounced feeding diaphoresis and crying cyanosis.	Unmasked cyanosis and desaturation prompt urgent pediatric transthoracic echocardiography to investigate structural heart disease.
Day 6	TTE reveals non-restrictive perimembranous VSD (8.5 mm), 45–50% aortic override, severe RVOTO (peak gradient 67.2 mmHg), RV hypertrophy, and 4.2 mm ASD.	Initiated oral propranolol (0.5 mg/kg/day BID, titrated to 1.0 mg/kg/day) as medical bridge therapy; continued low-flow oxygen.
Day 14 (Discharge)	CAP completely resolved. Hemodynamically stable, room air resting SpO2 88–89% (94% on 1.5 L/min oxygen). Propranolol well tolerated.	Discharged on oral propranolol (1 mg/kg/day BID) and home oxygen; referred to national referral center and international cardiac mission networks.
1-Month Follow-Up	No cyanotic spells or readmissions. Weight increased to 5.0 kg on hypercaloric feed support. Resting SpO2 stable at 88–90% on room air.	Continued propranolol bridge therapy; pending international surgical humanitarian flight.

Diagnostic Assessments

In accordance with local resource-limited diagnostic pathways, chest radiography and blood culture services were unavailable at admission. Routine laboratory investigations revealed a white blood cell count of 8100/µL with a lymphocyte predominance of 61.2% (4900/µL), hemoglobin of 13.1 g/dL, hematocrit of 44.1%, and a platelet count of 355,000/µL. Rapid diagnostic tests for malaria and the dengue virus were negative. The clinical diagnosis of severe CAP was based on WHO Integrated Management of Childhood Illness (IMCI) criteria (acute cough, severe tachypnea, accessory muscle use, and bilateral crackles).

Transthoracic echocardiography (TTE) was performed on Day 5 after antibiotic therapy successfully cleared the pulmonary crackles. TTE demonstrated classic anatomical features consistent with Tetralogy of Fallot (TOF) alongside a secondary atrial septal defect (ASD). Color Doppler echocardiography in the parasternal long-axis view demonstrated a large 8.5 mm perimembranous ventricular septal defect with bidirectional/right-to-left shunting and overriding of the aorta (Figure 1). 2D imaging confirmed aortic override of 45–50% over the interventricular septum alongside severe concentric right ventricular hypertrophy with an end-diastolic wall thickness of 6.2 mm (Figure 2). Continuous-wave Doppler interrogation revealed severe right ventricular outflow tract obstruction with a peak systolic velocity of 4.1 m/s and a peak pressure gradient of 67.2 mmHg across the narrowed infundibulum and pulmonary valve (Figure 3). A detailed quantitative summary of structural echocardiographic measurements is presented in Table 2.

Figure 1.

Color Doppler transthoracic echocardiogram (parasternal long-axis view) displaying a large 8.5 mm perimembranous ventricular septal defect (VSD, labeled) with a prominent right-to-left shunt jet (red/blue mosaic flow) and overriding of the dilated aorta (Ao) over the interventricular septum.

Abbreviations: LV, Left Ventricle; RV, Right Ventricle.

Figure 2.

2D transthoracic echocardiogram in the parasternal long-axis view showing classic overriding of the aorta (Ao) over the interventricular septum (IVS) and severe concentric right ventricular hypertrophy (RV wall thickness = 6.2 mm).

Figure 3.

Color and continuous-wave Doppler transthoracic echocardiogram demonstrating turbulent, high-velocity systolic flow across the narrowed right ventricular outflow tract (RVOT) and pulmonary valve, with a peak systolic velocity of 4.1 m/s and peak pressure gradient of 67.2 mmHg, indicative of severe infundibular and valvular pulmonary stenosis.

Table 2.

Key Quantitative and Structural Echocardiographic Findings

Anatomical Parameter	Measured Value/Finding	Clinical Significance
Ventricular Septal Defect (VSD)	8.5 mm perimembranous VSD	Large, non-restrictive defect permitting equalization of RV and LV systolic pressures with right-to-left shunting.
Aortic Override	45–50% override over the interventricular septum	The aorta directly straddles the VSD, receiving desaturated blood directly from the right ventricle.
RVOT Obstruction (RVOTO)	Severe infundibular and valvular stenosis; Peak velocity: 4.1 m/s; Peak gradient: 67.2 mmHg	Severe restriction to pulmonary blood flow, driving right-to-left intra-cardiac shunting and systemic cyanosis.
Right Ventricular Wall Thickness	6.2 mm (end-diastole)	Concentric RV hypertrophy secondary to chronic high-pressure RV outflow resistance.
Atrial Septal Defect (ASD)	4.2 mm secundum ASD	Concomitant inter-atrial communication (Pentalogy of Fallot variant).
Mitral-Aortic Continuity	Present (Fibrous continuity preserved)	Excludes Double-Outlet Right Ventricle (DORV).
Pulmonary Valve Patent Flow	Present (Anterograde systolic flow documented)	Excludes Pulmonary Atresia with VSD.

Crucially, differential conotruncal anomalies were systematically evaluated and excluded: 1. Double-Outlet Right Ventricle (DORV): Excluded by confirming direct fibrous continuity between the posterior aortic cusp and the anterior leaflet of the mitral valve in parasternal long-axis views. 2. Pulmonary Atresia with VSD: Excluded by confirming patent pulmonary valve leaflets and persistent anterograde systolic flow across the pulmonary valve on color and spectral Doppler.

Therapeutic Intervention

The infant was initially treated for severe CAP with intravenous ceftriaxone (100 mg/kg/day). Due to persistent fever spikes (38.5°C) and clinical distress on Day 3, antimicrobial coverage was empirically escalated to IV vancomycin (15 mg/kg Q8H) and oral co-trimoxazole syrup to cover resistant staphylococcal or atypical pathogens per regional severe sepsis protocols. Supplemental humidified oxygen was delivered via low-flow nasal cannula at 1.5 to 2.0 L/min (targeting SpO2 92–94%), which successfully raised SpO2 from 88% to 94–95%.

Following echocardiographic confirmation of TOF features, medical bridge therapy with oral propranolol was initiated at 0.5 mg/kg/day in two divided doses and titrated over 48 hours to 1.0 mg/kg/day (0.5 mg/kg BID). Propranolol was administered under close inpatient monitoring for heart rate, blood pressure, and blood glucose to prevent infundibular muscle spasm and reduce the risk of acute hypercyanotic “tet” spells. The infant tolerated propranolol without bradycardia or hypoglycemia. Parents were extensively counseled on knee-chest positioning during crying episodes, maintaining adequate oral hydration, and recognizing signs of severe desaturation.

Follow-Up and Outcomes

By Day 14, the active pulmonary infection had completely resolved, with total disappearance of fever, cough, and crackles. The infant was discharged on oral propranolol (1 mg/kg/day BID) and low-flow home oxygen therapy. Because definitive pediatric cardiothoracic surgical services are absent in Somaliland and Somalia, the patient was formally referred to the national tertiary referral center in Mogadishu and registered with international humanitarian medical programs (including the Qatar Red Crescent “Little Hearts” initiative) for potential overseas surgical transfer.

At the 1-month outpatient follow-up, the infant remained clinically stable without any reported hypercyanotic spells, hospital readmissions, or drug adverse effects. Resting SpO2 on room air was stable at 88–90%. With hypercaloric nutritional support, the infant’s weight increased from 4.6 kg to 5.0 kg. The infant remains on close clinical follow-up while awaiting international humanitarian surgical repair.

Discussion

This case illustrates the profound diagnostic and therapeutic complexities encountered when managing acute lower respiratory tract infections in infants with unrecognized cyanotic congenital heart disease within resource-constrained healthcare environments. In sub-Saharan Africa, where lower respiratory tract infections represent a primary cause of infant morbidity and mortality, frontline clinicians routinely experience diagnostic anchoring bias.⁸ When an infant presents with severe fever, tachypnea, accessory muscle use, and bilateral adventitial lung sounds, clinical reasoning naturally becomes trapped within an acute infectious paradigm, attributing all systemic signs to severe community-acquired pneumonia.^13,14 Such diagnostic masking of structural defects by dominant acute infectious presentations represents a recognized clinical pitfall in Somali pediatric care, where acute infectious signs can obscure complex underlying structural anomalies during initial triage.¹⁵ In the present case, although a palpable precordial thrill and a grade 4/6 pansystolic murmur were detected upon initial presentation, the immediate physiological threat of severe respiratory failure dominated clinical decision-making. The prominent acoustic noise of diffuse crackles and wheezing masked the full diagnostic weight of the cardiovascular physical examination. It was only after aggressive antimicrobial therapy cleared the acute pulmonary adventitia that persistent resting hypoxemia (oxygen saturation of 88% on room air) and unmasked feeding-induced diaphoresis forced clinicians to re-evaluate the primary pathophysiology and pursue urgent pediatric echocardiography.

Disentangling underlying cyanotic congenital heart disease from uncomplicated lower respiratory infection requires frontline clinicians to recognize subtle, highly specific clinical red flags that fall outside the expected recovery trajectory of pneumonia.¹¹ In this infant, a triad of historical and physical findings pointed directly toward underlying structural heart disease rather than isolated parenchymal pulmonary illness. First, the maternal report of forehead diaphoresis and rapid fatigue during breastfeeding reflects hyperadrenergic sympathetic compensation during physical exertion in an infant operating with a fixed cardiac stroke volume and severely diminished cardiopulmonary reserve. Second, the presence of chronic growth failure, evidenced by Moderate Acute Malnutrition (weight-for-age z-score < −3), indicates sustained cellular hypoxia, systemic malabsorption, and the heightened metabolic demands of chronic, unrepaired congenital heart disease.¹⁶ Third, the persistence of resting arterial desaturation (88% on room air, falling precipitously to 78% during crying) following the total resolution of fever and lung crackles is physiologically incompatible with uncomplicated, resolving pneumonia. This fixed, exertional hypoxemia is pathognomonic for right-to-left intra-cardiac shunting driven by severe right ventricular outflow tract obstruction.¹

In health systems where pediatric cardiologists and echocardiography are geographically scarce or financially inaccessible to the majority of the population, establishing low-cost, bedside diagnostic surveillance strategies is essential.¹⁷ Frontline healthcare providers must implement a systematic cardiac reassessment protocol for every infant recovering from severe pneumonia once acute adventitial sounds clear. Evaluating room air pulse oximetry before and immediately after breastfeeding provides a highly sensitive, low-cost surrogate marker for exertional cyanosis, where a post-feed drop in arterial saturation accompanied by forehead sweating strongly indicates underlying structural heart disease.¹⁷ Furthermore, expanding point-of-care pediatric ultrasound protocols can aid early triage in data-scarce regions.¹⁸ Assessing oxygen responsiveness provides critical diagnostic differentiation: whereas acute pulmonary parenchymal disease typically demonstrates substantial saturation gains in response to low-flow oxygen, fixed anatomical right-to-left intra-cardiac shunts yield a blunted, incomplete saturation response. Recognizing these bedside red flags provides frontline clinicians with a clear, objective rationale to prioritize patients for urgent echocardiography or specialized tertiary referral, even in settings with severe diagnostic bottlenecks.¹¹

The pharmacological management of unrepaired Tetralogy of Fallot in resource-limited environments highlights profound global health equities and surgical access gaps.¹⁰ Initiating oral beta-blocker therapy with propranolol (1 mg/kg/day) serves as a vital medical bridge by relaxing dynamic infundibular muscle spasms, stabilizing right ventricular outflow tract resistance, and decreasing the frequency of life-threatening hypercyanotic spells.¹⁹ However, non-selective beta-blockade, supplemental oxygen, and meticulous fluid maintenance must be strictly understood as temporary stabilization measures rather than definitive therapeutic solutions.¹⁹ Prolonged reliance on medical bridge therapy leaves the infant exposed to severe, progressive systemic sequelae, including chronic systemic tissue hypoxia, secondary polycythemia, hyperviscosity, cerebrovascular accidents, brain abscess formation, infective endocarditis, irreversible right ventricular myocardial fibrosis, and sudden cardiac death.^1,2 In this patient, ongoing dependence on supplemental oxygen after pneumonia clearance indicates persistent, high-risk anatomical disease rather than therapeutic success. Establishing sustainable local pediatric cardiothoracic surgical capacity, alongside strengthening international humanitarian transfer pathways such as visiting surgical missions, remains an urgent, unmet imperative for Somalia and the broader sub-Saharan African region.²⁰

Strength and Limitation

This case highlights the clinical vigilance required to detect underlying cyanotic heart disease in resource-constrained settings. The main limitation is the lack of immediate, local pediatric cardiothoracic surgical capacity to provide definitive corrective repair for the patient, as well as the limited resolution of diagnostic imaging modalities locally available.

Conclusion

Community-acquired pneumonia can mask underlying cyanotic congenital heart defects in infants, particularly in healthcare settings lacking routine neonatal pulse oximetry screening. In infants managed for severe pneumonia, persistent arterial desaturation, feeding diaphoresis, severe failure to thrive, or a cardiac thrill after pulmonary symptoms clear must serve as immediate red flags for underlying structural heart disease. While oral propranolol and oxygen therapy provide essential short-term bridge stabilization against hypercyanotic spells, definitive open-heart surgical evaluation remains an urgent necessity to prevent catastrophic long-term hypoxemic complications.

Funding Statement

No funding was granted for this research.

Data Sharing Statement

Data supporting the conclusions of this report are contained within the report.

Ethical Considerations

The case details were reviewed and approved for publication by the SOMALILAND MEDICAL ASSOCIATION INSTITUTIONAL REVIEW BOARD (SMA-IRB). Written informed consent was obtained from the patient’s parents for the publication of this case report.

Informed Consent

Written informed consent was obtained from the patient’s parents for the publication of this case report and the associated de-identified echocardiography images.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.