Case Study: 9-Week-Old with Tachypnea and Retractions

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Pediatric cardiology presents some fascinating and challenging cases — and one of the most important skills in primary care is knowing when to act. In the middle of a full schedule of well-child visits, sick calls, and chronic disease management, recognizing the patient who needs an urgent cardiology referral is no small feat. I remember that challenge well from my own time in general pediatrics. Here we will highlight a case to help sharpen that clinical instinct — what we call the “index of suspicion.”

Presentation

A 9-week-old girl was seen as a same-day work-in for persistent tachypnea, present since approximately one week of age and worsening in recent days. Her parents reported that she had been feeding adequately, though weight gain had been slow. Notably, her brother had a history of a vascular ring requiring surgical repair.

Examination Findings

Respiratory	Tachypneic with mild subcostal retractions
Cardiac auscultation	No murmur appreciated
Femoral pulses	Absent bilaterally
Oxygen saturation	Normal
Blood pressure	Could not be obtained

ECG

Echocardiogram — Pre-Operative Images

These are echocardiogram images of the aortic arch. The images below demonstrate severe narrowing in the juxtaductal region — the area where the ductus arteriosus typically inserts — and into the proximal descending aorta, consistent with a severe coarctation of the aorta. Left ventricular function was also diminished, a finding that is not uncommon in the setting of significant outflow obstruction.

Figure 1. 2D image of the aortic arch demonstrating severe narrowing in the juxtaductal region and proximal descending aorta.

Figure 2. Color Doppler image demonstrating very limited flow past the coarctation.

Echocardiogram — Post-Operative Image

Figure 3. Post-repair Color Doppler image demonstrating marked improvement in flow through the previously narrowed segment.

Discussion

Coarctation of the aorta exists on a spectrum from mild to critical. While many severe cases are identified in the immediate newborn period, some infants — even those with significant aortic narrowing — can go undetected in the nursery or NICU. This happens because a patent ductus arteriosus (PDA) can maintain adequate lower body perfusion, effectively masking the classic clinical findings. Once the PDA closes, symptoms may emerge rapidly. In some cases, the development of collateral vessels provides a degree of compensatory blood flow to the lower body, further obscuring the diagnosis.

The classic clinical features of coarctation include reduced lower body perfusion, absent or diminished femoral pulses, a systolic murmur best heard over the back, tachypnea, and poor feeding. When blood pressure can be obtained, a significant gradient between upper and lower extremities — with higher pressures in the upper extremities — is a key finding. Oxygen saturations are typically normal, though lower extremity saturations may be reduced in the setting of a severe coarctation with a concurrent PDA.

When a significant coarctation goes unrecognized, the left ventricle is forced to pump against persistent outflow obstruction. Over time, this leads to left ventricular dysfunction — and if left untreated, cardiogenic shock can follow.