Pediatric Heart & Lung Sounds: Auscultation in Children

A guide to pediatric cardiac and respiratory auscultation · Updated 2026

Children are not small adults — their heart rates are faster, their chest walls are thinner, and sounds that would be pathological in a 50-year-old are completely normal in a 5-year-old. Knowing what's expected at each age is the key to not over-referring innocent findings or missing real pathology.

What's normal in pediatric cardiac auscultation

• Faster heart rates: neonates 120–160 bpm, infants 100–140, toddlers 80–120. S1 and S2 are closer together than in adults — don't mistake a fast rate for a gallop rhythm.
• Physiologic split S2: splitting of S2 on inspiration is normal in children and is more easily heard through the thin chest wall. A fixed split (no change with respiration) suggests an ASD.
• S3 in children: a soft S3 is a normal finding in children and young adults — it reflects rapid ventricular filling in a compliant ventricle, not heart failure.
• Sinus arrhythmia: the heart rate speeds up on inspiration and slows on expiration. Completely normal — it can sound alarming if you're listening for the first time.

Innocent vs pathological murmurs

Up to 80% of children will have an innocent murmur heard at some point. The features of an innocent murmur:

The classic innocent murmurs

• Still's murmur — low-pitched, musical/vibratory, best at LLSB. Most common innocent murmur in children aged 3–6.
• Pulmonary flow murmur — soft systolic ejection murmur at the upper left sternal border. Common in thin children and adolescents.
• Venous hum — continuous humming, best heard at the right supraclavicular area. Disappears when the child lies down or turns their head.
• Peripheral pulmonary stenosis (PPS) — a soft systolic murmur radiating to the axillae, normal in neonates and typically resolves by 6 months.

Pediatric lung sounds

The thinner chest wall in children means you hear more — transmitted sounds are louder, and upper airway noise easily reaches the stethoscope:

• Transmitted upper airway sounds: nasal congestion and secretions can sound like crackles or wheezes. Ask the child to cough or clear their nose and re-listen.
• Stridor: a high-pitched inspiratory sound suggesting upper airway obstruction — croup, laryngomalacia or foreign body. Not heard in adults except in critical airway narrowing.
• Bronchiolitis wheezes: fine expiratory wheezes and crackles in infants with RSV — the most common reason you'll hear adventitious lung sounds in pediatrics.
• Grunting: a short expiratory sound made by neonates in respiratory distress — they close the glottis to maintain end-expiratory pressure. Always pathological.

Congenital heart disease sounds to know

• VSD: harsh pansystolic murmur at the LLSB, often with a thrill. Small VSDs are paradoxically louder than large ones.
• ASD: fixed split S2 with a soft systolic flow murmur at the pulmonic area. The murmur is from increased flow across the pulmonary valve, not the defect itself.
• PDA: continuous "machinery" murmur best heard at the left infraclavicular area. Loudest in systole but continues into diastole.
• Coarctation of the aorta: systolic murmur best heard between the scapulae posteriorly, with diminished femoral pulses.
• Tetralogy of Fallot: harsh systolic ejection murmur at the LUSB (from RVOT obstruction). Intensity decreases during a tet spell as less blood crosses the obstruction.