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In EMS, routine auscultation of heart tones is largely ignored. Often times this is due to a lack of education on what to listen for. The goal of this study guide is to equip the EMS provider with the tools necessary to add routine heart tone auscultation to their patient assessment.

Heart tones are often difficult to hear as they require a very quiet environment to detect through our stethoscopes. We rarely have an environment conducive to detecting heart tones due to the loud background noises present during patient care. The time to auscultate heart tones is usually on scene where road noise and/or lights & sirens are not likely to be heard.

When a heart valve opens and closes, it gives off vibrations. These vibrations occur as the blood flow inside the heart's chambers rapidly accelerates or slows through an opening or closing valve. The ability to auscultate these sounds can vary from patient to patient. If you have a morbidly obese patient with excess tissue on their chest wall, auscultation will obviously be more challenging. If you are auscultating heart tones on a frail elderly patient, the sounds will be heard much more clearly.

What is a normal heart tone?

  • S1 and S2 are the names given to normal heart tones.
  • S1: This heart tone is described as a “lubb” sound. The sound itself is low-pitched and dull. This sound is auscultated during the contraction of the ventricles, which is also when the tricuspid and mitral valves are closing.
  • S2: This heart tone is described as a “dubb” sound. The sound itself is high-pitched, louder, and shorter in length than S1. S2 can be auscultated when the ventricles have relaxed, which is also when the pulmonic and aortic valves are closing.

What is an abnormal heart tone?

  • S3 is the name given to abnormal heart tones. Often called a “Gallop,” the S3 sound can be heard in healthy children and adolescents. In adults, however, it is a negative sign that is often associated with heart failure. The S3 sound is called a gallop because it comes at the end of the S1-S2 sequence and sounds like a horse galloping. S3 occurs because of the vibrations created from rapid ventricular filling on the walls of the ventricles.

How to Auscultate the 4 Heart Valves

  • Mitral Valve

Mitral Valve Heart Tone

  • Pulmonary Valve

Pulmonary Valve Heart Tone

  • Aortic Valve

Aortic Valve Heart Tone

  • Tricuspid Valve

Tricuspid Valve Heart Tone

Feel free to check out our video on Heart Tones on our YouTube page

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