13.12: Assessment of the Cardiovascular System IV: Auscultation

Cardiac auscultation is a clinical skill used to assess heart function and detect abnormalities. It involves listening to heart sounds at specific anatomical locations through a stethoscope.

Normal Heart Sounds

S1 (First Heart Sound)-

S1 is made by the closure of the mitral and tricuspid valves (atrioventricular valves), marking the beginning of systole.

S2 (Second Heart Sound)-

S2 is made by the closure of the aortic and pulmonic valves (semilunar valves), marking the end of the systole.

Abnormal Heart Sounds

S3 (Third Heart Sound)-

S3 occurs early in diastole during rapid ventricular filling. It is normal in children and athletes; however, it indicates heart failure in older adults.

S4 (Fourth Heart Sound)-

S4 occurs late in diastole during atrial contraction. It often suggests conditions like left ventricular hypertrophy, aortic stenosis, ischemic heart disease, or hypertensive heart disease.

Steps of the Procedure

Position the Patient-

Place the patient comfortably in a position such as supine or left lateral decubitus.

Using the Stethoscope-

1. Use the diaphragm for high-pitched sounds like S1 and S2.
2. Use the bell for low-pitched abnormal sounds like S3 and S4.

Auscultation

S1 Sound Assessment-

1. Assess the S1 sound at the tricuspid area at the fourth or fifth left intercostal space near the lower left sternal border, reflecting tricuspid valve closure.
2. Assess S1 at the mitral area (apical area) at the fifth left intercostal space at the midclavicular line, indicating mitral valve closure. This is where the loudest S1 sound can be heard.

S2 Sound Assessment-

1. Start assessing the S2 sound at the aortic area at the second right intercostal space, indicating aortic valve closure.
2. Then, assess the S2 sound at the pulmonic area at the second left intercostal space adjacent to the sternum.

S1 and S2 Sound Assessment-

1. For equal S1 and S2 intensity, Erb's point is auscultated at the third left intercostal space.

Additional Heart Sounds Assessment-

1. Assess S3 and S4 with the bell at the mitral area.