Overview
Definition:
A heart murmur is an extra sound heard during a heartbeat cycle, produced by turbulent blood flow
In children, these can be benign ("innocent" or "functional") or indicative of underlying cardiac pathology.
Epidemiology:
Innocent murmurs are extremely common, found in 30-50% of well children, peaking between 2-6 years of age
Pathologic murmurs are less common and associated with specific congenital or acquired heart conditions.
Clinical Significance:
Accurate differentiation between innocent and pathologic murmurs is crucial for appropriate patient management, timely diagnosis of serious cardiac disease, and avoiding unnecessary anxiety and investigations for families.
Clinical Presentation
Symptoms:
Innocent murmurs: usually asymptomatic
Pathologic murmurs: failure to thrive
Poor feeding
Tachypnea or dyspnea on exertion
Cyanosis (central or peripheral)
Recurrent respiratory infections
Chest pain
Palpitations.
Signs:
Innocent murmurs: generally soft (grade 1-3/6), vibratory or musical quality, short duration, located in the pulmonary or aortic areas, variable with position, no associated abnormal pulses, normal S2, no other signs of cardiac disease
Pathologic murmurs: often loud (grade 4/6 or higher), harsh quality, holosystolic, diastolic, or continuous, associated with a thrill, abnormal S2 (e.g., fixed split, loud P2), presence of other cardiac signs (e.g., hepatomegaly, edema, clubbing, unequal pulses).
Diagnostic Criteria:
No specific diagnostic criteria for innocent murmurs
diagnosis is one of exclusion based on absence of pathologic features
Pathologic murmurs are suspected when significant clinical findings or abnormal auscultatory characteristics are present, prompting further investigation.
Diagnostic Approach
History Taking:
Detailed birth history (gestational age, complications)
Feeding history (poor feeding, failure to thrive)
Activity level
Presence of cyanosis, dyspnea, syncope, palpitations
Recurrent chest infections or pneumonia
Family history of heart disease
Maternal history of infections or teratogens during pregnancy.
Physical Examination:
General appearance (well-nourished, cyanotic, dysmorphic features)
Vital signs (heart rate, respiratory rate, blood pressure in all limbs)
Palpation of peripheral pulses (strength, equality)
Thorough cardiovascular examination: inspection for precordial bulge, palpation for thrills, auscultation from base to apex, including axillae and back, assessing murmur characteristics (timing, intensity, location, radiation, pitch, quality), and S1/S2 sounds
Examination of lungs for rales, abdomen for hepatomegaly, and assessment for edema.
Investigations:
Electrocardiogram (ECG): assesses for chamber hypertrophy, arrhythmias, or ischemia
Chest X-ray (CXR): evaluates heart size and pulmonary vascularity
Echocardiography (2D and Doppler): the gold standard for confirming structural heart disease, assessing ventricular function, valve morphology and function, and blood flow patterns
Cardiac catheterization: may be indicated in complex cases to measure pressures and oxygen saturations, and for intervention.
Differential Diagnosis:
Innocent murmurs: still's murmur, pulmonary flow murmur, venous hum, carotid bruit
Pathologic murmurs: Ventricular Septal Defect (VSD), Atrial Septal Defect (ASD), Patent Ductus Arteriosus (PDA), Coarctation of the Aorta, Tetralogy of Fallot, Rheumatic Heart Disease, Valvular Stenosis/Regurgitation (e.g., Aortic Stenosis, Mitral Regurgitation), Cardiomyopathies.
Innocent Vs Pathologic Murmur Features
Innocent Murmur Characteristics:
Timing: Systolic (mid-systolic, early systolic)
Intensity: Grade 1-3/6
Location: Typically pulmonary area (left upper sternal border) or aortic area
Quality: Soft, vibratory, musical
Duration: Short
S2: Normal
Associated Signs: Absent
Position Variability: Often changes with position.
Pathologic Murmur Characteristics:
Timing: Holosystolic, diastolic, continuous
Intensity: Grade 4/6 or higher
Location: Variable, can radiate widely
Quality: Harsh, blowing
Duration: Long
S2: Abnormal (e.g., loud P2, fixed split, single S2)
Associated Signs: Thrill, cyanosis, failure to thrive, hepatomegaly, unequal pulses
Position Variability: Minimal or absent.
Red Flags For Pathology:
Murmur heard in diastole or holosystole
Murmur intensity grade 4/6 or higher
Presence of a thrill
Abnormal S2 sound
Any murmur in an infant less than 3 months old with other symptoms
Murmur associated with cyanosis, dyspnea, poor feeding, failure to thrive, syncope, or chest pain
Unequal pulses or significant BP difference between upper and lower limbs.
Management
Initial Management:
For suspected innocent murmurs: reassurance of parents and patient
Educate on benign nature
Scheduled follow-up for monitoring
For suspected pathologic murmurs: prompt referral to a pediatric cardiologist for further evaluation and diagnosis.
Medical Management:
Not applicable for innocent murmurs
For pathologic murmurs, medical management is supportive and disease-specific: diuretics for heart failure, antihypertensives, antibiotics for infective endocarditis prophylaxis or treatment
Specific medications are dictated by the underlying cardiac defect.
Surgical Management:
Indicated for significant congenital or acquired heart defects causing hemodynamic compromise or symptoms
Examples include VSD closure, ASD closure, PDA ligation/coiling, valve repair or replacement, and palliative or corrective surgeries for complex congenital anomalies.
Supportive Care:
Monitoring vital signs and clinical status
Nutritional support to optimize growth
Prophylaxis against infective endocarditis for certain defects
Psychosocial support for families.
Prognosis
Factors Affecting Prognosis:
The prognosis for innocent murmurs is excellent, with complete resolution often occurring by adolescence
For pathologic murmurs, prognosis depends heavily on the specific cardiac defect, its severity, timing of diagnosis, and effectiveness of treatment.
Outcomes:
Innocent murmurs resolve spontaneously without sequelae
Pathologic murmurs, if untreated or poorly managed, can lead to heart failure, pulmonary hypertension, arrhythmias, stroke, and premature death
With timely diagnosis and appropriate intervention, many children with cardiac defects can have a normal or near-normal life expectancy.
Follow Up:
Children with innocent murmurs may require routine pediatric follow-up
Children with diagnosed congenital or acquired heart disease require lifelong follow-up with pediatric cardiologists, with the frequency depending on the specific condition and management plan.
Key Points
Exam Focus:
Remember the common innocent murmurs (Still's, pulmonary flow) and their typical characteristics: systolic, soft, vibratory, mid-left sternal border
Distinguish these from diastolic, holosystolic, harsh murmurs or those with abnormal S2, thrills, or systemic symptoms.
Clinical Pearls:
Always auscultate murmurs in multiple positions and with changes in respiration
In a young infant, any murmur not clearly identifiable as innocent warrants thorough investigation
Remember to check blood pressure in all four limbs for coarctation of the aorta.
Common Mistakes:
Over-diagnosing pathology in the presence of common innocent murmurs
Under-investigating murmurs that have concerning features
Failing to differentiate between innocent and pathological murmurs, leading to unnecessary parental anxiety and investigations.