Innocent Heart Murmurs¶
Learning Objectives¶
Core Knowledge & Clinical Reasoning¶
- [ ] Recognize that murmurs are present in up to 80% of children at some point
- [ ] Identify the 5 classic innocent murmurs by their characteristic features
- [ ] Apply clinical criteria to distinguish innocent from pathologic murmurs
- [ ] Determine when echocardiography is indicated for murmur evaluation
Communication & Counseling¶
- [ ] Reassure families appropriately when an innocent murmur is identified
- [ ] Explain that innocent murmurs require no treatment, restrictions, or follow-up
Key Concept¶
Most childhood murmurs are innocent Up to 80% of children will have an audible murmur at some point; the vast majority are benign
Quick Reference: Murmur Evaluation Algorithm
The 5 Classic Innocent Murmurs¶
1. Still's Murmur (Vibratory Murmur)¶
| Feature | Description |
|---|---|
| Age | 2-7 years (most common innocent murmur) |
| Location | LLSB to apex |
| Quality | Musical, vibratory, "twanging string" |
| Grade | 1-2/6 |
| Timing | Early-mid systolic |
| Variation | Louder supine, softer sitting/standing |
| Cause | Likely LV false tendon vibration |
2. Pulmonary Flow Murmur¶
| Feature | Description |
|---|---|
| Age | 8-14 years, also newborns |
| Location | LUSB (pulmonic area) |
| Quality | Soft, blowing, ejection |
| Grade | 1-2/6 |
| Timing | Systolic ejection |
| Variation | Louder supine, with fever/anemia |
| Cause | Flow across normal pulmonic valve |
3. Venous Hum¶
| Feature | Description |
|---|---|
| Age | 3-6 years |
| Location | Right (or left) supraclavicular/infraclavicular |
| Quality | Continuous, humming |
| Grade | 1-3/6 |
| Timing | Continuous (louder in diastole) |
| Variation | Disappears supine or with neck rotation/compression |
| Cause | Turbulent flow in jugular veins |
4. Carotid Bruit (Supraclavicular Systolic Murmur)¶
| Feature | Description |
|---|---|
| Age | Any age, common in children |
| Location | Supraclavicular, radiates to neck |
| Quality | Harsh, brief |
| Grade | 1-3/6 |
| Timing | Systolic |
| Variation | Diminishes with shoulder hyperextension |
| Cause | Flow in brachiocephalic vessels |
5. Peripheral Pulmonary Stenosis (PPS)¶
| Feature | Description |
|---|---|
| Age | Newborns, resolves by 3-6 months |
| Location | LUSB, radiates to axillae and back |
| Quality | Soft, ejection |
| Grade | 1-2/6 |
| Timing | Systolic |
| Cause | Acute angle at branch PA origins (resolves with growth) |
Characteristics of INNOCENT Murmurs¶
Use the 7 S's mnemonic:
| Feature | Innocent Murmur |
|---|---|
| Soft | Grade 1-2/6 (never >3/6) |
| Systolic | Never diastolic or continuous (except venous hum) |
| Short | Not holosystolic |
| Single S2 | Normal S2 splitting |
| Side (left sternal border)** | LLSB or pulmonic area |
| Sitting diminishes | Decreases with position change |
| Symptomatic: NO | Asymptomatic child |
RED FLAGS: Pathologic Murmur¶
| Finding | Concern |
|---|---|
| Diastolic murmur | Always pathologic |
| Holosystolic murmur | VSD, MR, TR |
| Grade ≥3/6 | Significant turbulence |
| Harsh quality | Structural abnormality |
| Thrill palpable | Grade 4+ murmur |
| Abnormal S2 | Fixed split (ASD), single S2 (aortic atresia, truncus) |
| Clicks | Bicuspid aortic valve, MVP |
| Radiation to back | Coarctation, PPS |
| Radiation to neck | Aortic stenosis |
| Hepatomegaly | Heart failure |
| Cyanosis | Right-to-left shunt |
| Failure to thrive | Significant heart disease |
| Abnormal pulses | Coarctation, PDA, AI |
| Dysmorphic features | Syndrome-associated CHD |
Clinical Approach¶
MURMUR DETECTED
│
▼
HISTORY & PHYSICAL
│
├── Any RED FLAGS?
│ │
│ YES → Echo + Cardiology referral
│
└── NO RED FLAGS
│
├── Fits classic innocent murmur pattern?
│ │
│ YES → Reassurance, no workup needed
│ │ Document murmur character
│ │ No activity restrictions
│ │ No follow-up required
│ │
│ NO/UNCERTAIN → Consider Echo
│ or Cardiology referral
When to Get an Echo¶
Echo INDICATED¶
- Any red flag present
- Diastolic or continuous murmur (except classic venous hum)
- Grade ≥3/6 murmur
- Abnormal S2
- Associated symptoms (syncope, chest pain, dyspnea)
- Failure to thrive
- Abnormal pulses or blood pressure
- Dysmorphic features or syndrome
- Family history of sudden death or cardiomyopathy
- Murmur that doesn't fit classic innocent pattern
Echo NOT ROUTINELY NEEDED¶
- Classic Still's murmur in well child
- Classic venous hum (abolishes with position)
- Peripheral pulmonary stenosis in newborn
- Pulmonary flow murmur with normal exam
When to Refer to Cardiology¶
- Uncertain diagnosis after history/exam
- Any diastolic murmur
- Pathologic murmur suspected
- Parental anxiety despite reassurance
- Need for definitive diagnosis before sports clearance
- Murmur with symptoms
Special Situations¶
Fever/Illness¶
- Innocent murmurs often become louder (increased cardiac output)
- May appear for first time during illness
- Re-evaluate when child is well if uncertain
Athletic Pre-Participation¶
- Innocent murmurs do NOT require clearance
- If uncertain, brief cardiology evaluation is reasonable
- No restrictions for confirmed innocent murmurs
Newborn Nursery¶
- Murmurs in first 24-48 hours are common
- PPS murmur is benign (resolves by 3-6 months)
- Must distinguish from ductal-dependent lesions
- Low threshold for echo in neonates
Board Pearls¶
Pearl: Still's murmur = "Musical/vibratory" at LLSB in 2-7 year old
Most common innocent murmur; sounds like a twanging string
Pearl: Venous hum = Continuous murmur that DISAPPEARS when supine
Only innocent murmur that is continuous
Pearl: Diastolic murmurs are NEVER innocent
Always require evaluation
Pearl: No innocent murmur is >Grade 2/6
Grade 3+ always warrants further evaluation
Pearl: PPS in newborns radiates to back/axillae
Resolves by 3-6 months; distinguish from true PS
Self-Assessment¶
Q1: A 4-year-old presents for well-child visit. You hear a grade 2/6 musical, vibratory murmur at the LLSB that decreases when the child sits up. Vital signs and exam are otherwise normal. What is the most appropriate management?
Answer
**Answer**: Reassurance, no further workup needed **Rationale**: This is a classic Still's murmur - the most common innocent murmur. Features: age 2-7, musical/vibratory quality, LLSB location, grade 2/6, decreases with sitting. No echo or referral needed.Q2: A 2-week-old has a soft systolic murmur heard best at the left upper sternal border, radiating to both axillae and the back. Oxygen saturation is 99%, pulses are normal. What is the most likely diagnosis?
Answer
**Answer**: Peripheral pulmonary stenosis (PPS) **Rationale**: PPS is an innocent murmur of newborns caused by the acute angle at branch PA origins. It radiates to axillae and back (following the branch PAs). Resolves by 3-6 months. Normal sats and pulses are reassuring.Q3: A 5-year-old has a continuous "humming" murmur heard below the right clavicle. It disappears when the child lies down. What is the diagnosis and management?
Answer
**Answer**: Venous hum; reassurance only **Rationale**: Venous hum is the only innocent continuous murmur. Key feature: disappears with supine positioning or neck vein compression. No workup needed.Key Guidelines¶
2022 AHA/ACC Guideline for Clinical Evaluation of Cardiovascular Disease in Children and Adolescents Circulation. 2022 General principles for murmur evaluation in pediatric patients
Related Topics¶
- Heart Sounds & Murmurs - Murmur classification
- Chest Pain - Symptom evaluation
- CCHD Screening - Newborn murmurs
- Sports Cardiology - Pre-participation exam
- Cardiac History & Physical - Exam technique
- Pediatric TTE - When to order echo
References¶
- Frank JE, Jacobe KM. Evaluation and management of heart murmurs in children. Am Fam Physician. 2011;84(7):793-800
- Pelech AN. Evaluation of the pediatric patient with a cardiac murmur. Pediatr Clin North Am. 1999;46(2):167-188
- McConnell ME, et al. Heart murmurs in pediatric patients: when do you refer? Am Fam Physician. 1999;60(2):558-565