Approach to a murmur (pediatrics): Clinical sciences

A heart murmur is a sound produced by blood flowing through the heart and large vessels. While innocent murmurs are common in healthy infants and children, clues from the history and physical exam can identify pathological murmurs that require additional investigation. Now, there are three main types of murmurs: systolic, diastolic, and continuous.

If a child presents with a murmur, you should first perform an ABCDE assessment. If the patient is unstable, stabilize the airway, breathing, and circulation. Next, obtain IV access, consider IV fluids, and begin continuous vital sign monitoring, including blood pressure, heart rate, and oxygen saturation. Finally, if needed, provide supplemental oxygen.

Okay, now let’s go back to the ABCDE assessment and look at stable patients. Your first step is to perform a focused history and physical exam. Physical examination will reveal a heart murmur, which you can characterize based on its location, timing and duration, quality, and intensity.

You can assign a grade to the murmur, according to its intensity, which can vary from I, which is barely audible, to grade VI, which can be heard with the stethoscope barely touching the chest wall. In addition, be sure to note any positional changes in the murmur, and determine whether the murmur radiates to other locations. Once you identify a heart murmur, assess for characteristics of an innocent murmur. These include a musical or vibratory quality, murmurs that are systolic, grade I to II out of VI, low-intensity and soft, and the absence of abnormal cardiac signs and symptoms.

If these characteristics are present, consider innocent murmurs. These include adolescent Ejection murmur, Carotid bruit, Still’s murmur, Peripheral pulmonic stenosis, and Venous hum. To easily remember these innocent murmurs, think of the mnemonic Every Child Should Play Vigorously!

A short crescendo-decrescendo murmur best heard at the right or left upper sternal border that typically does not radiate and becomes softer when the patient is upright is suggestive of an adolescent ejection murmur.

Now, let’s move on to carotid bruits, which are detected over the carotid area. The murmur classically produces a whooshing sound, with transmission to the skull or ear. These findings indicate the presence of a carotid bruit.

Next up is a vibratory murmur, which is typically heard in children between 3 and 6 years old. During Physical exam auscultation at the lower left sternal border, reveals a musical, vibratory, or humming systolic ejection murmur. When your patient is lying supine, the murmur becomes louder, and if they sit upright or perform a Valsalva maneuver, its intensity decreases. With these findings, you can diagnose a vibratory murmur.

On the other hand, a peripheral pulmonic stenosis murmur is commonly detected in infants. Physical exam at the left upper sternal border reveals a soft, low-pitched, blowing systolic ejection murmur. You may also notice the murmur radiating to the back or axillae. With these findings, you can diagnose peripheral pulmonic stenosis.

Finally, a venous hum can be detected at any age. It is best heard below the clavicle, and is characterized by a soft or low-pitched continuous murmur. The murmur will disappear when your patient is in a supine position, or once they rotate their head to the side while seated upright. With these findings, there’s a high chance that you’re hearing venous hum.

Alright, let’s turn our attention to patients in whom characteristics of an innocent murmur are absent. Your next step should be to assess the timing of the murmur within the cardiac cycle. This means determining whether the murmur is systolic, diastolic, or continuous. Let's first look at systolic murmurs.

For a systolic murmur, proceed by assessing its timing within systole. If the murmur begins shortly after S1 and it has a crescendo-decrescendo pattern, your patient has a systolic ejection murmur. This should make you consider semilunar valve stenosis, which includes aortic and pulmonic valve, atrial septal defect, or hypertrophic cardiomyopathy. Your next step should be to order an echocardiogram.

Let’s first discuss aortic stenosis. Patients can present with exertional chest pain, dyspnea, or fatigue. Physical exam will reveal a murmur at the right upper sternal border that may become softer during a Valsalva maneuver. Additionally, you may detect a thrill at the left sternal border, as well as an early ejection click. Echocardiogram will reveal a stenotic aortic valve, and in some cases, a bicuspid aortic valve or left ventricular hypertrophy, which confirms the diagnosis of aortic stenosis.

Next, let’s discuss pulmonic stenosis. These patients may experience fatigue, exertional dyspnea, and syncope. Affected neonates might develop cyanosis if stenosis is severe. Physical exam reveals a murmur at the left upper sternal border, and you may detect a loud S1 and a systolic ejection click, as well as a left parasternal lift. Echocardiogram will demonstrate a stenotic pulmonic valve, and occasionally right ventricular hypertrophy, which confirms the diagnosis of pulmonic stenosis.

Now let’s discuss atrial septal defect, or ASD. This is often asymptomatic, although children with large defects may develop fatigue and exercise intolerance. Physical exam reveals a murmur at the left upper sternal border, with fixed splitting of S2. Sometimes, you’ll detect a diastolic rumble at the lower left sternal border. If echocardiogram shows left-to-right flow across an atrial septal defect, possibly with right atrial enlargement, diagnose ASD.

Finally, there’s hypertrophic cardiomyopathy, or HCM. This is frequently asymptomatic, but may present with atypical chest pain. History may reveal unexplained syncope or episodes of nonsustained ventricular tachycardia, and family history could be significant for sudden cardiac death. Physical exam will reveal a murmur at the left lower sternal border. The murmur increases in intensity with the Valsalva maneuver and while standing.

Echocardiogram will reveal a left ventricular wall thickness that’s 2 or more standard deviations above the mean for age and sex, which is highly suggestive of HCM. You can confirm the diagnosis with genetic testing.