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Careful history-taking and examination are highly sensitive for pathologic causes of cardiac murmurs. Murmurs that are harsh, diastolic, or holosystolic, loud (grade III/VI or higher), or associated with symptoms should be evaluated. Conversely, soft systolic murmurs in asymptomatic children that increase when supine are usually innocent.

The majority of murmurs heard in children and adolescents are benign. Distinguishing between innocent and pathologic murmurs is essential to avoid unnecessary anxiety and medical testing.

Characteristics of Innocent Murmurs

Innocent murmurs, such as the pulmonary flow murmur, are typically characterized by the following:

• •Timing: Almost exclusively systolic.
• •Quality: Soft, low-pitched, and non-harsh.
• •Positional Changes: Typically increase in intensity when the patient is supine (lying down) due to increased venous return.
• •Associated Symptoms: None; the patient is asymptomatic.

Red Flags for Pathologic Murmurs

Murmurs that require further investigation (ECG, echocardiogram, or cardiology referral) include:

• •Timing: Any diastolic or holosystolic murmur.
• •Intensity: Loud (Grade III/VI or higher) or harsh quality.
• •Positional Changes: Systolic murmurs that increase with standing or Valsalva maneuvers.
• •Family History: Early cardiac death or unexplained sudden death in relatives.

Management

For children with soft, systolic murmurs and no associated symptoms, the clinical diagnosis is an innocent murmur. The appropriate management is reassurance for the family, as the likelihood of underlying heart disease is extremely low.