Table of contents · 7 sections
Heart auscultation is a key physical examination method that allows for the assessment of valve function, detection of valvular defects, and evaluation of hemodynamic disturbances. Despite the development of echocardiography, auscultation remains the primary and mandatory step in a cardiac examination. This article provides a comprehensive overview of auscultation points, sound characteristics, murmurs, and their clinical significance.
Heart auscultation points
The classic 5 auscultation points correspond to the direction of blood flow rather than the anatomical location of the valves:
| Point | Localization | What is auscultated |
|---|---|---|
| 1st (mitral valve) | Apex of the heart — 5th intercostal space at the left midclavicular line | Mitral valve defects, first heart sound (S1) |
| 2nd (aortic valve) | 2nd intercostal space to the right of the sternum | Aortic valve defects, second heart sound (S2, aortic component) |
| 3rd (pulmonary valve) | 2nd intercostal space to the left of the sternum | Pulmonary valve defects, second heart sound (S2, pulmonic component) |
| 4th (tricuspid valve) | Base of the xiphoid process | Tricuspid valve defects |
| 5th (Erb's point) | 3rd intercostal space to the left of the sternum | Aortic regurgitation, additional heart sounds |
Heart sounds: normal auscultatory findings
Normally, two main heart sounds are auscultated:
- First heart sound (S1) — closure of the atrioventricular valves (mitral + tricuspid). Synchronous with the apical impulse and carotid pulse. Best heard at the apex
- Second heart sound (S2) — closure of the semilunar valves (aortic + pulmonary). Best heard at the base of the heart (2nd intercostal space)
Localization mnemonic: S1 is louder at the apex (1st point), S2 is louder at the base (2nd and 3rd points). If S1 is louder at the base, suspect pathology.
Additional sounds
| Sound | Timing | Significance |
|---|---|---|
| Third heart sound (S3) | Early diastole (rapid filling phase) | Normal up to age 30. After 40 — chronic heart failure (CHF), volume overload. "Gallop rhythm" |
| Fourth heart sound (S4) | Presystole (atrial systole) | Always pathological: left ventricular hypertrophy, hypertension, aortic stenosis, hypertrophic cardiomyopathy (HCM) |
| Opening snap (OS) | After S2 | Mitral stenosis (the shorter the S2-OS interval, the more severe the stenosis) |
| Systolic click | Mid-systole | Mitral valve prolapse (MVP) |
Heart murmurs: systolic and diastolic
Murmurs are classified by cycle phase, shape, localization, and radiation:
| Murmur | Phase | Character | Radiation |
|---|---|---|---|
| Aortic stenosis | Systolic | Crescendo-decrescendo, harsh | To the carotid arteries |
| Mitral regurgitation | Systolic (pansystolic) | Blowing, constant intensity | To the axilla |
| VSD | Systolic (pansystolic) | Rough, loud | Over the entire precordial region |
| Mitral stenosis | Diastolic | Low-frequency rumble with presystolic accentuation | Non-radiating (listen with the bell!) |
| Aortic regurgitation | Diastolic | High-frequency blowing, decrescendo | Along the left sternal border (Botkin's point) |
Functional vs. organic murmurs
- Functional (innocent): systolic, soft, inconstant, non-radiating, unaccompanied by other auscultatory findings. Common in children and young adults
- Organic: rough, constant, radiating, accompanied by altered heart sounds or additional sounds
- Diastolic murmurs are always pathological — this is a rule without exceptions
Auscultation maneuvers
- Valsalva maneuver (straining) — ↓ preload → most murmurs soften, EXCEPT HCM and MVP (become louder)
- Squatting — ↑ preload → HCM and MVP murmurs soften, others become louder
- Inspiration — ↑ venous return to the right heart chambers → right-sided murmurs become louder (Rivero-Carvallo sign)
- Left lateral decubitus position — brings the apex closer to the chest wall → mitral stenosis is heard better
Frequently asked questions
How to differentiate aortic stenosis from mitral regurgitation?
Both are systolic murmurs, but: aortic stenosis is crescendo-decrescendo (diamond-shaped), best heard at the 2nd intercostal space, radiates to the carotids; mitral regurgitation is pansystolic (plateau), best heard at the apex, radiates to the axilla. Valsalva maneuver: AS softens, MR also softens (both decrease with ↓ preload). The key distinction is the character and radiation.
Why is the stethoscope bell required for the auscultation of mitral stenosis?
The mitral stenosis murmur is a low-frequency rumble. The stethoscope bell conducts low frequencies better, while the diaphragm filters them out. Auscultation in the left lateral decubitus position at end-expiration further improves audibility.
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