Patent ductus arteriosus: A misleading clue to hidden severe pathology

Dear Sir, A 3-day-old term newborn presented with cyanosis and respiratory distress, initially diagnosed with a large patent ductus arteriosus (PDA). Despite cardiac improvement, worsening respiratory distress postextubation prompted evaluation for airway pathology. Bronchoscopy revealed grade 3 laryngeal stenosis. This case highlights that noncardiac lesions can mimic congenital heart disease (CHD), underscoring the need for careful clinical assessment and early recognition of alternative etiologies. CASE DESCRIPTION A 3-day-old term newborn girl, appropriate for gestational age, was brought to the pediatric emergency department with cyanosis and respiratory distress immediately after birth, requiring intubation and mechanical ventilation. A screening echocardiogram performed at a peripheral center suggested a large PDA, and she was referred to our pediatric cardiology unit. On clinical evaluation, the patient was hemodynamically stable with euthermia. The capillary refill time was <3 s. Heart rate was 127/min, respiratory rate 36/min (on mechanical ventilation, FiO2 – 50%), SpO2 was 95% preductal and 96% postductal, and blood pressure was 96/38 mmHg. Peripheral pulses were high volume. Cardiovascular examination revealed normal heart sounds with a continuous murmur, without thrill, heard at the parasternal area. Respiratory examination did not reveal any crepitations/wheeze. Central nervous system and abdominal examinations were normal. Initial blood gas analysis revealed compensated respiratory acidosis, which subsequently improved [Table 1]. Chest X-ray demonstrated cardiomegaly with a cardiothoracic ratio of 0.7 and pulmonary plethora. The electrocardiogram showed a normal sinus rhythm at 137/min, right axis deviation, and a normal QTc interval of 440 ms.Table 1: Daily analysis of venous blood gases of the neonateEchocardiography revealed a large PDA (5 mm) with left-to-right shunt and low-velocity flow (peak gradient 21 mm Hg and end diastolic gradient 2 mm Hg), a small muscular ventricular septal defect, and two small atrial septal defects with left-to-right shunt. Severe pulmonary hypertension was present, along with left atrial and left ventricular dilation and secondary moderate mitral regurgitation. Blood investigations were unremarkable, with no evidence of sepsis or anemia. Congestive heart failure was managed with diuretics (furosemide) and dobutamine infusion, leading to gradual improvement. The patient was successfully weaned off mechanical ventilation to nasal continuous positive airway pressure (CPAP) by day 7 of life. At extubation, the ductus arteriosus remained patent. Two days after extubation, serial venous blood gases showed worsening respiratory acidosis, necessitating increased CPAP support. There was no stridor or wheeze; however, worsening respiratory distress with a weak cry prompted re-initiation of mechanical ventilation. On mechanical ventilation, the child remained hemodynamically stable on minimal pressure support, with improvement in pH and pCO2. By this time, the PDA had closed spontaneously, and pulmonary hypertension had resolved. During intubation, difficulty was noted while advancing the endotracheal tube, raising suspicion of significant upper airway narrowing. Bronchoscopic evaluation revealed grade 3 laryngeal stenosis with pinhole narrowing [Figure 1]. The bronchoscope could not be negotiated beyond the obstruction, and saline flush failed to relieve it. Computed tomography was performed to evaluate the longitudinal extent of the stenosis, showing mild luminal narrowing at the subglottic location. The patient was subsequently planned for tracheostomy.[1,2]Figure 1: Bronchoscopic image showing grade 3 laryngeal stenosis with pinhole narrowing. The bronchoscope could not be negotiated beyond the stenotic segment, confirming severe obstructionThis case underscores that not all neonatal cyanosis and respiratory distress are cardiac in origin. Noncardiac lesions – such as congenital airway malformations, vascular rings, metabolic disorders, arterial thrombosis, or sepsis – can mimic CHD and may complicate diagnosis when symptoms are atypical or nonclassical.[3,4] A thorough history, meticulous clinical examination, and careful interpretation of all clinical data remain indispensable, even in the era of advanced imaging. Early recognition of alternative etiologies can prevent delays in diagnosis and management. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.