Heart Sounds & Murmurs

11/03/2020

Heart Sounds & Murmurs

Auscultation for heart sounds is mainly done in 4 areas, namely Mitral, Tricuspid, Aortic & Pulmonic. Remember these areas do not correspond to the location of heart valves, but the areas where the cardiac sounds are best heard. Some cardiac sounds can be heard with the unaided ear (e.g. Prosthetic valve clicks).

Use your stethoscope for cardiac auscultation. Apart from the 3rd and 4th heart sounds and the mid-diastolic murmur of Mitral Stenosis, all the other heart sounds are best heard with the diaphragm of your stethoscope. You should firmly press your “diaphragm” to chest wall whereas apply only light pressure when you are auscultating with the “bell” of your stethoscope.

There is no standard order for auscultation. But starting from Apex and proceeding with Tricuspid (LLSB), Aortic & Pulmonic areas is easy to practice.

You should first concentrate only on “heart sounds” (carefully assess their intensity & splitting). Then auscultate for “added sounds” (Murmurs, Clicks, Opening Snaps & Pericardial rubs). If you hear a murmur, completely assess it with regards to its timing, duration, location, intensity, pitch, character, radiation, change with position and respiration.

HEART SOUNDS

FIRST HEART SOUND (S1)

  • Produced by the closing of AV valves (Mitral & Tricuspid). Best heard in Mitral & Tricuspid areas on precordium. M1 is preceded T1 only slightly.
  • It marks the beginning of systole (or ventricular contraction).
  • High pitched – Hence auscultated using the Diaphragm of Stethoscope.

ABNORMAL FIRST HEART SOUND

  1. Loud S1 – Mitral Stenosis
  2. Soft S1 – Mitral Regurgitation
  3. Widened-Split S1 – Right Bundle Branch Block (Delayed T1)

SECOND HEART SOUND (S2)

  • Produced by the closing of Semilunar valves (Aortic &Pulmonary).
  • Best heard in Aortic & Pulmonary areas on precordium.
  • A2 is preceded P2 only slightly. It marks the end of systole (& beginning of diastole).
  • High pitched – Hence auscultated using the Diaphragm of Stethoscope.

ABNORMAL SECOND HEART SOUND

  1. Loud S2 – Pulmonary Hypertension
  2. Soft S2 – Pulmonary Stenosis
  3. Physiological Splitting of S2 – Normal in Inspiration (Young Patients)
  4. Fixed Splitting of S2 – Atrial Septal Defect (ASD)

THIRD HEART SOUND (S3 – Ventricular Gallop)

  • Produced by rapid filling (& expansion) of ventricles. It occurs just after S2 in diastole when the AV valves open.
  • It may be a normal finding in young patients & pregnancy, but almost always pathological after 40 years.
  • The most common cause of pathological S3 is a congestive cardiac failure.

FOURTH HEART SOUND (S4 – Atrial Gallop)

  • Produced by forceful atrial contractions forcing blood into stiff ventricles. It occurs immediately before S1 in late diastole.
  • Unlike S3, S4 is always pathological.
  • Low pitched – Hence auscultated using the Bell of Stethoscope.
  • It usually indicates atrial hypertrophy (seen in AS) or stiff ventricles (seen in myocardial infarction causing fibrous tissue formation)

HEART MURMURS

Murmurs are caused by the blood flow across the valve (either from increased blood flow or defective valve).

1. TIMING

It refers to the timing of the murmur in relation to the cardiac cycle.

  • Systolic Murmurs – Heard between S1 & S2
  • Diastolic Murmurs – Heard between S2 & S1

2. DURATION

It refers to the length of the murmur in relation to the phase of the cardiac cycle.

  • Early Systolic Murmurs – Heard in the early phase of systole
  • Pan Systolic – Heard throughout the systole
  • Mid diastolic – Heard in the middle part of diastole

3. LOCATION

It refers to the location of the precordium where the murmur is best heard.

  • Aortic – 2nd Right ICS
  • Pulmonic – 2nd Left ICS
  • Mitral – 5th Left ICS, midclavicular line (Apex)
  • Tricuspid – 4th left ICS

4. INTENSITY (GRADE)

It refers to the loudness of the murmur and graded according to the Levine scale 1-6.

  • Grade 1 – Only audible when listening carefully
  • Grade 2 – Faint murmur, but immediately audible
  • Grade 3 – Loud murmur readily audible
  • Grade 4 – Loud murmur with a thrill
  • Grade 5 – Murmur loud enough to be heard with stethoscope just touching the chest
  • Grade 6 – Murmur loud enough to be heard even with stethoscope just lifted off the chest

5. SHAPE

The shape refers to the change of intensity of the murmur over time as seen in phonocardiograms.

  • Crescendo – Progressively increasing in intensity
  • Decrescendo – Progressively decreasing in intensity
  • Crescendo-Decrescendo – Progressively increasing in intensity followed by progressively decreasing in intensity (Diamond shaped)

6. RADIATION

It refers to where the sound of the murmur radiates from the main location of it. As a rule of thumb, the murmur radiates in the direction of the blood flow.

  • Axillary Radiation – Seen in Mitral Regurgitation
  • Carotid Radiation – Seen in Aortic Stenosis

7. PITCH

It can be low, medium or high pitches. Depending on the pitch you select the chestpeice of the stethoscope you place to hear the murmur best.

  • Low pitched Murmurs (eg: MS) – Auscultated using the Bell
  • High Pitched Murmurs (eg: MR) – Auscultated using the Diaphragm

8. CHARACTER (QUALITY)

It refers to unusual characteristics of the murmur which makes it unique in quality.

  • Rumbling Murmur – Seen in Mitral Stenosis
  • Blowing Murmurs – Seen in Mitral Regurgitation

9. CHANGE WITH PHASE OF RESPIRATION

Right-sided murmurs are louder in inspiration (due to increased venous return) and left side murmurs are louder in expiration.

  • Aortic Regurgitation – louder in expiration
  • Pulmonary Regurgitation – louder in inspiration

10. CHANGE WITH POSITION

Some murmurs are best heard using some maneuvers which should be performed when you auscultate.

  • Lateral Decubitus Position – In Mitral Stenosis
  • Sitting & Leaning Forward – In Aortic Regurgitation

ADDITIONAL HEART SOUNDS – OPENING SNAPS

Usually, the opening of cardiac valves does not make any sound. Opening snap occurs due to forceful “Opening” of a stenosed valve and it is described in Mitral stenosis (Refer MS). Hence it is always pathological. It is a high-pitched sound that occurs after S2.

ADDITIONAL HEART SOUNDS – PERICARDIAL RUBS

The pericardial rub is a pathognomic physical sign of Pericarditis. It is characterized by a “scratchy or grating” sound best appreciated along the sternal border with respiration suspended and the patient leading forward.

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