Nursing care
Heart sounds nursing assessment: where to listen and what S1, S2, S3 and S4 mean
Written and reviewed by Kevin Patel, MSN, RN, CCRN · 5 min read · Updated November 2026
Short answer
A heart sounds nursing assessment covers five points: aortic (second right intercostal space), pulmonic (second left), Erb's point (third left), tricuspid (fourth left sternal border) and mitral (fifth intercostal space, midclavicular line). S1 and S2 make the normal lub-dub. An S3 or S4 is an extra sound the nurse documents and reports when it is new.
The five auscultation points and what each one is for
Nursing programs teach the sequence with the memory aid APE To Man: aortic, pulmonic, Erb's point, tricuspid, mitral. The Open RN Nursing Skills text starts at the aortic area with the diaphragm, identifies S1 and S2, then moves down to the apex. These points sit over where valve sounds carry best, not directly over each valve.
| Area | Where to place the stethoscope | What to focus on there |
|---|---|---|
| Aortic | Second intercostal space, right of the sternum | S2 sounds louder than S1; aortic stenosis and regurgitation murmurs |
| Pulmonic | Second intercostal space, left of the sternum | S2 louder than S1; splitting of S2 with inspiration |
| Erb's point | Third intercostal space, left sternal border | Middle checkpoint between the base and the apex |
| Tricuspid | Fourth intercostal space, left sternal border | Tricuspid murmurs and ventricular septal defect murmurs |
| Mitral (apex) | Fifth intercostal space, midclavicular line | S1, mitral murmurs, and S3 or S4 using the bell |
Use the diaphragm for high-pitched sounds and the bell for low-pitched ones. MSD Manuals adds a detail students miss: press the bell lightly, because firm pressure stretches the skin into a diaphragm and filters out the low sounds you were trying to catch.
What S1, S2, S3 and S4 mean and the nursing action for each
S1 and S2 are expected. S3 and S4 are extra sounds whose meaning depends on age, rhythm and the rest of the assessment, which is why they cannot be judged in isolation.
| Sound | Timing and cause | Expected or not | Nursing action |
|---|---|---|---|
| S1 | Start of systole; mostly mitral valve closure | Expected | Confirm a regular rhythm; compare apical and radial rates if irregular |
| S2 | Start of diastole; aortic then pulmonic closure, normally splitting on inspiration | Expected; a split that does not change with breathing is not | Document; report a new fixed or unusually wide split |
| S3 | Early diastole, right after S2 (lub-dub-dah) | Can be normal up to about age 40 and in pregnancy; in older adults it usually signals ventricular dysfunction | Check lung sounds, weight, edema and oxygen saturation; report if new |
| S4 | Late diastole, just before S1 (ta-lub-dub) | Abnormal; points to a stiff ventricle or ischemia | Ask about chest pain, check vital signs; report if new |
MSD Manuals describes S4 as heard far more often than S3 and as a sign of a lesser degree of dysfunction, usually diastolic. Open RN links an S3 with fluid overload, such as an acute heart failure exacerbation.
Worked example: one hypothetical client, step by step
Hypothetical practice case, not a real exam item: a 74-year-old client with known heart failure reports three days of worsening breathlessness and swollen ankles. The nurse performs a focused cardiac assessment before the morning medication pass.
Worked example
- Diaphragm at the aortic and pulmonic areas: S1 and S2 heard, S2 louder, rhythm regular.
- Diaphragm at Erb's point, tricuspid area and apex: no murmur heard.
- Turn the client to the left side and place the bell lightly at the apex while the client breathes out.
- A third sound follows S2 in a lub-dub-dah pattern: an S3.
- Cluster the cues: S3 plus bibasilar crackles, 2+ ankle edema and weight above baseline.
The weak choice here is charting the S3 as a normal variant. That reading only fits younger adults or pregnancy. In this client it joins crackles and edema to suggest a worsening exacerbation, so the right move is an SBAR report and continued respiratory monitoring.
Where heart sound findings mislead
Age and context change the meaning. An S3 in a healthy 25-year-old or a pregnant client can be expected, while the same sound at 74 is a warning. An S4 cannot occur in atrial fibrillation because there is no organized atrial contraction, so a missing S4 in that client tells you nothing about ventricular stiffness.
Technique creates false negatives. Listening only with the diaphragm, with the client flat on their back, misses many gallops; MSD Manuals notes a left ventricular S3 is heard best with the client lying on the left side during expiration. A pericardial friction rub is a different sound again, scratchy and best heard with the client sitting up and leaning forward.
How nurses document heart sounds
A normal note usually states that S1 and S2 are present in a regular rhythm with no murmurs or extra sounds, along with the location of the point of maximal impulse at the fifth intercostal space, midclavicular line. Open RN's sample documentation also records the absence of heaves, thrills and jugular vein distension.
An abnormal note names the sound, where and how it was heard, and the cues it fits with. For example: S3 heard at the apex with the bell in left lateral position, bibasilar crackles, bilateral 2+ pitting edema, provider notified. Writing only 'abnormal heart sounds' gives the next nurse nothing to compare against.
Sources and further reading
MSD Manual Professional Version: Cardiac Auscultation. Bell vs diaphragm and light bell pressure, S1 and S2 causes and splitting, S3 meaning and age exception, S4 always abnormal and absent in atrial fibrillation, left lateral position in expiration, friction rub technique.
Open RN Nursing Skills 2e: 9.3 Cardiovascular Assessment. APE To Man auscultation points and intercostal locations, starting at the aortic area, S2 louder at the base, S3 with fluid overload and in pregnancy, S4 description, murmurs by area.
Open RN Nursing Skills 2e: Sample Documentation (cardiovascular). Examples of expected and unexpected cardiac documentation, including PMI location and an S3 charted with crackles and edema.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our cardiovascular practice questions are the closest set to what this page covers.
Common questions
Where do you listen to heart sounds?
Over five areas: aortic (second right intercostal space), pulmonic (second left), Erb's point (third left), tricuspid (fourth left sternal border) and mitral (fifth intercostal space at the midclavicular line). Use the diaphragm first, then the bell at the apex for low-pitched sounds.
What does an S3 heart sound mean?
An S3 is an early diastolic sound right after S2. In adults over about 40 it usually signals ventricular dysfunction, often with fluid overload in heart failure. It can be a normal finding in younger adults and in pregnancy.
How do nurses document heart sounds?
State whether S1 and S2 are present and the rhythm is regular, then any murmur or extra sound with its location, stethoscope part and client position. Add related cues such as crackles or edema, and note who was notified if the finding is new.
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