TOW #32: Heart Murmurs

February is Heart Month. In honor of Valentine's Day, we will do a heart-related topic and review one of the biggies in evaluating pediatric hearts: assessing heart murmurs!

Materials for this week:

Take-home points for heart murmurs:

  1. Innocent murmurs are typically vibratory (or musical), of low intensity, and best audible at the left-sternal border (LSB). They are usually midsystolic—never purely diastolic—and nonradiating. Their intensity varies with position-typically loudest lying down and decreased while sitting up. Innocent murmurs (like pathologic ones) are louder with fever, anemia, or any increased cardiac output. The two most common innocent murmurs are Still's murmur (typically early systole vibratory "twangy" murmur at LLSB most common in ages 2-6) and pulmonary outflow murmurs (mid-systolic crescendo-decrescendo murmur at LUSB).
  2. Murmurs loudest at LLSB: here we are usually dealing with Still's murmur but the most common pathologic murmur to consider is VSD – typically holosystolic and may radiate more than Still's. Murmurs loudest at the LUSB: usually pulmonary outflow murmurs, but also consider supraclavicular murmur (also innocent) or ASD or pulmonary stenosis.
  3. Two continuous murmurs: common in childhood are venous hum and PDA. Venous hum is an innocent murmur heard on the low anterior part of the neck lateral to the sternocleidomastoid muscle, but can extend below the clavicle (usually on the right). It is usually louder during diastole and while the patient is upright. PDA is the classic "machinery" like murmur heard most often during S2 over the second left intercostal space, or in the left infra- or supraclavicular region.
  4. Clinical features suggestive of pathologic murmurs: Murmurs with long duration (pansystolic/holosystolic), greater intensity (grade≥3), and harsh quality are more suggestive of cardiac lesion/defect. Be concerned about murmurs in the setting of decreased exercise/activity tolerance, palpitations, chest pain, syncope, or a family history of congenital heart disease, arrhythmias, or sudden cardiac death. A systolic murmur that gets louder with Valsalva is consistent with hypertrophic cardiomyopathy (due to reduction of venous return to the heart and resultant narrowing of the left ventricular outflow).
  5. Further evaluation of murmurs: To avoid unnecessary costs, most often it is helpful to directly refer a suspected pathologic murmur to a pediatric cardiologist for further workup. If you are going to a study first, an EKG has the lowest cost and may help identify some patients at risk.

Wishing you all a happy heart day and month!