Cardiac Auscultation

Cardiac auscultation is one of the keys to an effective physical exam and can often assist in the assessment of a patient’s hemodynamic function. Similar to each component of an exam, auscultation is only a piece of the puzzle and should be used in combination with other findings.

Figure 1. Heart Auscultation Areas

Key (Items in bold indicate primary auscultation areas)

1. Aortic Region: Right 2nd intercostal space, parasternal
2. Pulmonic Region: Left 2nd intercostal space, parasternal
3. Erb’s point: Left 3rd intercostal space aka Left Lower Sternal Border
4. Triscupid Region: Left 4th intercostal space, parasternal
5. Mitral Region: Left 5th intercostal space, midclavicular 

Directions:

• Auscultation should include the 4 primary auscultation areas (Figure 2) of the heart using the diaphragm, staring with the patient in the supine or seated position.
• Start by finding the angle of Louis (sternal angle aka manubriosternal junction) located at the 2^nd rip, which is easily felt as a small protuberance along the sternum.
• Auscultate each point starting with the Aortic region using the following Mnemonic

All – Physicians – Take – Money

OR

All – Physical – Therapists – Move

Normal Heart Sounds

S1 “Lub” The first heart sound is the sound occurs with ventricular contraction an marks the approximate beginning of systole. The sound is created by the closurevof the Atrioventricular valves  (Tricuspid and Mitral)

S2 “Dub” The second heart sound marks the beginning of ventricular relaxation and end of systole. Thus it also marks the approximate beginning of diastole. The sound is created by closure of the Semilunar valves (Aortic and Pulmonic). The second heart sound is of shorter duration and higher frequency than the first heart sound.

Example

• Normal S1-S2

Figure 2. Wigger’s Diagram

The Wigger’s Diagram depicts the events that occur during a normal cardiac cycle.

Extra Heart Sounds 

Splitting 

Split S1

• You may notice that the mitral and triscupid valve sounds (M1 and T1) are slightly asychronous. This is a is normal findings as the mitral closure may preceding tricuspid closure by 20 to 30 msec (0.02 to 0.03 sec.). This produces two audible components (M₁-T₁) referred to as normal or physiologic splitting of the first heart sound (S1). Such narrow splitting is usually best heard at the lower left sternal border with the stethoscope diaphragm. The tricuspid component, which may increase with inspiration, is best heard in this location but is poorly transmitted to the apical region. The mitral component, in contrast, is best heard at the apex but is intense enough to be heard throughout the anterior chest wall.

• Wide splitting of the first sound is almost always abnormal. The split may be increased to 50-60 msec in patients with right bundle branch block (RBB), Ebstein’s anomaly, or other conditions in which there is electrical delay in activitation of one of the two ventricles (e.g., ventricular ectopic beats, ventricular tachycardia, AV block with idioventricular rhythm, and left ventricular pacing).

Example

• Split S1, Asynchronous closure of mitral and tricuspid valves, durations greater than 50-60msec consider RBB

Split S2

• The second heart sound (S2) is of shorter duration and higher frequency than the first heart sound. It has two audible components, the aortic closure sound (A₂) and the pulmonic closure sound (P₂), which must be separated by more than 20 msec (0.20 sec) in order to be differentiated and heard as two distinct sounds. It is very important to determine the presence and degree of respiratory splitting and the relative intensities of A₂ and P₂. Normal or Physiologic splitting is demonstrated during inspiration in normal healthy individuals, since the splitting interval widens primarily due to the delayed P₂. During expiration, the A₂–P₂ interval is so narrow that only a single sound is usually heard.  Splitting of S2 is best identified in the second or third left ICS, since the softer P₂ normally is confined to that area, whereas the louder A₂ is heard over the entire precordium, including the apex. 

• Persistent (audible) expiratory splitting suggests an audible expiratory interval of at least 30 to 40 msec between the two sounds. Persistent splitting that is audible during both respiratory phases with appropriate inspirational and expirational directional changes (i.e., further increase of the A₂–P₂ interval with inspiration). Persistent splitting S2 may occur in the recumbent position in normal children, teenagers, and young adults however, the second split should resolve on expiration following sitting, standing, or a Valsalva maneuver. If splitting of S2 does not change with these measures or if found in adults it is indicative of a pathological change to the heart.

Example 

• Transient Split S2, Pulmonic valve closing slightly after aortic changes with inspiration

• Fixed Split S2, Pulmonic valve closing slightly after aortic NO change with inspiration

Gallops 

S3 occurs at the beginning of diastole after S2 and is lower in pitch than S1 or S2 as it is not of valvular origin.

• Indicative of ventricular failure.

SLOSH’-ing-in          SLOSH’-ing-in

S1     S2 – S3             S1      S2 – S3

Example S3

S4 Occurs prior to S1, produced by the sound of blood being forced into a stiff or hypertrophic ventricle.

• Indicative of LVH or possibly HCOM

a-STIFF’-wall                  a-STIFF’-wall

S4 – S1         S2               S4 – S1           S2

Example S4

Murmurs 

Heart murmurs are extra sounds during the cardiac cycle, such as whooshing or swishing made by turbulent blood flow often due to a faulty valve or structural changes in the myocardium.

Murmurs should be assessed on the following characteristics:

• Shape
  • Crescendo (grows louder), decrescendo, crescendo-decrescendo, plateau
• Location
  • Determined by the site where the murmur originates
    • A, P, T, M listening areas
• Timing
  • Murmurs are longer than heart sounds
  • Systolic, diastolic, continuous
• Intensity
  • Graded on a 6 point scale
    • Grade 1 = very faint
    • Grade 2 = quiet but heard immediately
    • Grade 3 = moderately loud
    • Grade 4 = loud*
    • Grade 5 = heard with stethoscope partly off the chest*
    • Grade 6 = no stethoscope needed*
• Pitch
  • High, medium, low

*Note:  Thrills are assoc. with murmurs of grades 4 – 6

Common Murmurs 

Examples

• Mid-Systolic Murmur (ie Aortic Stenosis or HCOM)

• Severe Aortic Stenosis (Absent S2)

• Mid Systolic Click (ie Mitral Valve Prolapse)

• Crescendo-decrescendo Mid Systolic Murmur (Pulmonary Stenosis)

• Early Diastolic Murmur (Aortic Regurgitation)

• Mid Diastolic Murmur (Mitral Stenosis)

References

GIESE E et al, The Athletic Preparticipation Evaluation: Cardiovascular Assessment Am Fam Physician. 2007 Apr 1;75(7):1008-1014. http://www.aafp.org/afp/2007/0401/p1008.html

Felner JM. The Second Heart Sound. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 23. Available from: https://www.ncbi.nlm.nih.gov/books/NBK341/

http://www.med.umich.edu/lrc/psb_open/repo/primer_heartsound/primer_heartsound.html