What is the diagnosis and treatment approach for newly detected heart murmurs?

Diagnosis and Management of Newly Detected Heart Murmurs

Echocardiography should be performed for all patients with diastolic or continuous heart murmurs, holosystolic or late systolic murmurs, grade 3 or higher systolic murmurs, or any murmur with concerning features or symptoms. 1

Diagnostic Approach

Initial Assessment of Heart Murmurs

• Classify the murmur based on timing (systolic, diastolic, continuous), intensity (grade 1-6), location, radiation, and response to physiological maneuvers 1
• Diastolic and continuous murmurs (except for cervical venous hum or mammary souffle during pregnancy) always require echocardiography as they typically indicate pathology 1
• Systolic murmurs require further characterization to determine if they are innocent or pathologic 1

Characteristics of Innocent Murmurs

• Grade 1-2 intensity at the left sternal border 1
• Systolic ejection pattern 1
• Normal intensity and splitting of the second heart sound 1
• No other abnormal sounds or murmurs 1
• No evidence of ventricular hypertrophy or dilatation 1
• No increase in intensity with Valsalva maneuver or standing from squatting position 1
• Common in high-output states such as anemia and pregnancy 1

Red Flags Suggesting Pathologic Murmurs

• Holosystolic or diastolic murmur 1
• Grade 3 or higher intensity 1, 2
• Harsh quality 2
• Abnormal second heart sound 2
• Maximal intensity at upper left sternal border 2
• Systolic click 2
• Increased intensity with standing or Valsalva maneuver (suggests hypertrophic cardiomyopathy or mitral valve prolapse) 1
• Increased intensity during transient arterial occlusion or sustained handgrip (suggests mitral regurgitation or ventricular septal defect) 1

Dynamic Auscultation

• Valsalva maneuver: Increased intensity suggests hypertrophic obstructive cardiomyopathy or mitral valve prolapse 1
• Standing: Increased intensity suggests hypertrophic obstructive cardiomyopathy or mitral valve prolapse 1
• Squatting: Decreased intensity in hypertrophic obstructive cardiomyopathy or mitral valve prolapse 1
• Handgrip exercise: Increased intensity suggests mitral regurgitation or ventricular septal defect 1

Diagnostic Testing

Echocardiography Indications

• All diastolic or continuous murmurs 1, 3
• Holosystolic or late systolic murmurs at apex or left sternal edge 1
• Midsystolic murmurs of grade 3 or greater intensity 1
• Softer murmurs with dynamic auscultation suggesting specific diagnosis (e.g., hypertrophic cardiomyopathy) 1
• Grade 1-2 murmurs with symptoms or signs of infective endocarditis, thromboembolism, heart failure, myocardial ischemia/infarction, or syncope 1
• Murmurs with abnormal physical findings (widely split second heart sounds, systolic ejection sounds) 1
• All neonatal heart murmurs (higher likelihood of structural heart disease) 2

Role of Echocardiography

• Defines primary lesion in terms of cause and severity 1
• Defines hemodynamics 1
• Identifies coexisting abnormalities 1
• Detects secondary lesions 1
• Evaluates cardiac chamber size and function 1
• Establishes reference point for future comparisons 1
• Allows re-evaluation after intervention 1

Other Diagnostic Tests

• Electrocardiography and chest radiography rarely assist in diagnosis of murmurs but may provide additional information in selected cases 2
• Exercise testing can provide valuable information, especially in patients with difficult-to-assess symptoms 1
• Cardiac catheterization is not necessary in most patients with normal or diagnostic echocardiograms but may be useful when there is discrepancy between echocardiographic and clinical findings 1

Management Approach

• Treatment depends on the specific underlying cardiac condition identified by echocardiography 1
• Innocent murmurs require no treatment or follow-up 1
• Pathologic murmurs require management based on the specific valve lesion or structural abnormality 1
• Referral to a pediatric cardiologist is recommended for children with potentially pathologic murmurs or when a specific innocent murmur cannot be identified 2

Important Considerations

• Trivial, minimal, or physiological valvular regurgitation may be detected by echocardiography in many normal patients without murmurs 1
• The correlation between murmur intensity by auscultation and severity of valve disease by echocardiography can be poor, particularly for diastolic murmurs 4
• Optimal auscultation by well-trained examiners can reduce unnecessary echocardiography for insignificant murmurs 1
• Multiple valvular abnormalities may coexist, making clinical diagnosis challenging and echocardiography essential 5