Innocent pediatric murmurs

Background

• 72% of all school-age children have innocent murmurs
• Congenital heart disease- 0.8% of live births

Clinical Features

• Goal to distinguish innocent (benign) murmurs from clinically significant pathology
• Red flag features that may point to pathology, not innocent murmurs:
  • Poor weight gain: check height and weight- left-to-right can cause decrease in weight, but are usually symptomatic
  • Color - cyanosis of hands, feet, perioral on exertion
  • Feeding - fatigue or short feeding times for infants- perspiring, grunting, coughing, tachycardia while feeding. Severe CHF may show at rest deep breathing with dyspnea with distress
  • Enlarged heart (ie ASD) can cause bulging of chest
  • Older kids - activity causing dyspnea/cyanosis- keeping up with peers, grunting, coughing, tired from stairs. syncope/presyncope, fatigue, palpitations/angina can occur with hypertrophic cardiomyopathy
  • Yet older - Aortic valve with rheumatic fever, myocarditis (history of URI), endocarditis (IV drug use)
  • Pregnancy history - Maternal diabetes (ASD, coarctation of the aorta, cardiomyopathies), CMV, Coxsackie B5, warfarin, AEDs use, EtOH (ASD,VSD), prematurity (PDA)
  • Worry when - family history of [[HCM]]/sudden death and prominent apical thrust (indicates LVH)

Differential Diagnosis

Valvular Emergencies

• Mitral stenosis
• Mitral regurgitation
  • Mitral valve prolapse
• Aortic stenosis
• Aortic regurgitation

Evaluation

• Most innocent murmurs are
  • Not holo or diastolic
  • Not >grade III
  • Hockey stick dist
  • Normal S1 & S2

Types

Still's

• Mid-Systolic, best at left lower sternal border, likely from harmonic vibrations of LV outflow tract (chordae tindinae)
• All ages, particularly young school age
• Low pitch, musical
• Decreased with inspiration, sitting, standing. Not a VSD- not regurgitant or with thrill

Innocent Pulmonary Flow Murmur

• Systolic best at left upper sternal border, minor turbulence in RV outflow tract and main pulmonary artery
• Often infants and preschool age. Higher pitched than still's, less musical
• Not PS- no ejection click, no increased RV impulse. no wide s2 split
• Not Pulm M of ASD, no fixed splitting, no diastolic tricuspid flow rumble, no increased RV impulse
• Decreased on inspiration/sitting/standing

Innocent Pulmonary Branch Murmur of Infancy

• Systolic ejection murmur from turbulence in pulmonary artery branches (one or both)
• Medium pitch
• Physiologic in neonates, becoming audible at L,R,B USB between 0-2wks
• Transmits well to back and axilla. common in premature; disappears early in infancy
• Not PS- no ejection click, no increase in RV impulse

Supraclavicular Bruit

• Systolic ejection murmur of medium pitch from physiologic turbulence of carotid/subclavian and heard at base of neck
• Can be palpable. Disappears on hyperextension of shoulders
• Not AS which is loudest at URSB with systolic thrill, sometimes with click

Venous Hum

• Continuous murmur from turbulent flow in SVC heard at L,R,or B infraclavicular position while sitting/standing
• Not PDA (bounding pulse, systolic>diastolic sound) or AV malformation
• Disappears in recumbent position, rotation of head, by pressure at jugular

Mammary Souffle

• Blood flow in A and V to engorged breast
• Systolic or continuous, disappears with stethoscope pressure

Cardiorespiratory murmur

• High pitched cooing, anywhere, but especially apex
• Breath sound so not timed to heart, disappear when holding breath

Management

• By definition, "innocent" murmurs typically require no management

Disposition

• Discharge with reassurance if:
  • Murmur has classic innocent characteristics (soft, systolic, grade I-II, no radiation)
  • Normal vital signs and growth parameters
  • No concerning associated symptoms (syncope, cyanosis, exercise intolerance)
  • Normal ECG and/or echocardiogram if obtained
• Refer to pediatric cardiology for:
  • Diastolic murmurs
  • Loud murmurs (grade III or higher)
  • Murmurs with associated symptoms
  • Abnormal ECG findings
  • Murmurs in neonates (consider echocardiography)

See Also

• Heart Murmurs
• Valvular Emergencies (Valve)