Diagnosis: Wolff-Parkinson-White (WPW) Syndrome

ECG Findings in This 2-Week-Old

Why WPW and Not Normal Neonatal ECG?

• The short PR interval (normally ~80-100 ms in a neonate, even shorter here)
• The delta wave (slurred upstroke at the start of QRS) - this is NOT a normal neonatal finding
• QRS widening beyond what is normal for age

Mechanism

Clinical Significance in a 2-Week-Old

• WPW is the most common cause of SVT in neonates - it accounts for ~80% of neonatal SVT
• Heart rate in SVT can reach 240-300 bpm, causing rapid hemodynamic compromise and heart failure (35% incidence of CHF if untreated under age 4 months)
• Neonates may present with poor feeding, irritability, pallor, or tachypnea
• Rare but serious risk: pre-excited atrial fibrillation → ventricular fibrillation → sudden cardiac death

Management

1. Acute SVT: Adenosine IV (first-line) - also diagnostic (reveals preexcitation by blocking AV node)
2. Prophylaxis: Propranolol or digoxin (note: digoxin is controversial/contraindicated in WPW by many guidelines due to risk of facilitating rapid AP conduction)
3. Curative: Radiofrequency catheter ablation - typically deferred until >15-20 kg unless refractory
4. Spontaneous resolution occurs in up to 30-40% of neonates by 1 year of age as the accessory pathway involutes

Key References

• WPW in neonates - population study: PR 80 ms vs 98 ms in controls, QRS 74 ms vs 56 ms, significantly taller R-V1 (1562 vs 1010 µV)
• Case report - neonate with WPW/SVT: Diagnostic criteria - short PR (<120 ms), prolonged QRS (>80 ms), delta wave
• Fuster and Hurst's The Heart, 15th Ed. - Preexcitation section

Bottom line: This ECG in a 2-week-old shows WPW pattern (short PR + delta waves + wide QRS). This child is at high risk for SVT and needs cardiology referral, continuous monitoring, and arrhythmia management.

Diagnosis: Right Ventricular Hypertrophy (RVH)

Most Likely Underlying Cause: Congenital Heart Disease with Right Heart Pressure Overload (e.g., Pulmonary Stenosis, Tetralogy of Fallot, or similar RVOTO)

ECG Findings in This 5-Month-Old Female

The Key Diagnostic Finding

Differential Diagnosis for RVH at 5 Months

Next Steps

1. Echocardiogram - mandatory to identify structural defect and measure RV pressures/gradients
2. Chest X-ray - boot-shaped heart (ToF) vs. cardiomegaly, pulmonary vascularity
3. Cardiology referral urgently
4. Pulse oximetry - detect any desaturation suggesting right-to-left shunting (ToF)

Bottom line: This ECG in a 5-month-old female shows significant RVH based on right axis deviation, tall R wave in V1, and most importantly an upright T wave in V1 (which alone is diagnostic of RVH in a child aged 1 week to 10 years). This is a pathological finding requiring urgent echocardiography to identify the underlying congenital heart defect.

ECG Interval Measurements

Note: Both ECGs are printed at standard paper speed 25 mm/s (1 small square = 40 ms, 1 large square = 200 ms). The first ECG (2-week-old) is printed in a rotated/vertical format, which makes precise counting harder - measurements should be confirmed on the original tracing.

ECG 1 - 2-week-old infant (WPW)

ECG 2 - 5-month-old female (RVH)

Normal Pediatric Reference Ranges for Comparison

Important caveat: These are approximate measurements from a photograph of a printed ECG. For clinical decisions, always measure directly on the original digital tracing or caliper-measured paper trace. The short PR (~60-80 ms) with widened QRS in ECG 1 is the most clinically significant interval finding, confirming WPW preexcitation.