Heart Auscultation

The first heart sound. The first heart sound is caused by the closure of the mitral and tricuspid valves at the beginning of ventricular systole. It is best heard at the apex.

The second heart sound. This is caused by the closure of the pulmonary and aortic valves at the end of ventricular systole and is best heard at the left sternal edge. It is louder and higher pitched than the first sound and normally the aortic component is louder than the pulmonary one. Physiological splitting of the second heart sound occurs because left ventricular contraction slightly precedes right ventricular systole. As a consequence, the pulmonary valve shuts after the aortic valve. This increases at the end of a quiet inspiration because the increased venous filling of the right ventricle further delays pulmonary valve closure. Conversely, the separation disappears on expiration (Fig. 3.26). The resultant splitting of the second sound is best heard at the left sternal edge using the diaphragm of the stethoscope. On auscultation, the clinician hears 'lub d/dub' (inspiration) 'lub-dub' (expiration).

Third heart sound. The third heart sound is a low-pitched sound best heard with the bell of" the stethoscope at the apex. It coincides with the phase of rapid ventricular filling

Auscultation Aortic Regurgitation

Fig. 3.27 Auscultating the heart. B Listen with the lightly applied bell with the patient in the left lateral position for the murmur of mitral stenosis. [E Listen with the diaphragm with the patient leaning forward for the murmur of aortic incompetence.

Expiration

Physiological S-| splitting

Inspiration

Expiration Fixed splitting of second sound

Inspiration

Expiration

Reversed splitting of -second sound

Inspiration

Note: a single . second sound in inspiration is normal in adults

True fixed splitting is a characteristic of atrial septal defect. Increased splitting occurs in right bundle branch block and pulmonary hypertension. It is not fixed.

Reversed splitting occurs in left . ventricular outflow obstruction and left bundle branch block

Fig. 3.26 Normal and pathological splitting of the second heart sound.

immediately after opening of the AV valves and therefore occurs at the beginning of mid-diastole. A third heart sound is therefore heard after the sccond as 'lub-dub-dum'. A third heart sound is a normal finding in children, young adults and during pregnancy.

Examination sequence

□ With the patient sitting semirecumbenl auscultate all over the precordium, listening in turn at the base of the heart, apex, right and upper left sternal edges with both bell and diaphragm. Also auscultate over Ihe carotids and, where appropriate, into the axilla.

□ At cach site identify the first and second heart sounds and assess the character with regard to intensity and splitting.

□ Then listen specifically during systole and diastole, first lor added sounds and then for murmurs.

□ Roll the patient on to the left side and listen at the apex using the bell pressed lightly on to the skin to detect the murmur of mitral sienosis (Fig. 3.27 A).

□ Sit the patient up, leaning forward, and listen over the right second interspace and then down at the left sternal

Fig. 3.27 Auscultating the heart. B Listen with the lightly applied bell with the patient in the left lateral position for the murmur of mitral stenosis. [E Listen with the diaphragm with the patient leaning forward for the murmur of aortic incompetence.

edge with the diaphragm for the murmur of aortic incompetence (Fig. 3.27B). □ Note the features of any murmur heard.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Responses

  • willis
    Where to listen for mitral stenosis location?
    7 years ago
  • Fosca
    Where to listen for aortic regurgitation?
    7 years ago

Post a comment