1.05 S4 Heart Sound.

Cardiovacular system reveiw for the USMLE Step 1 exam.

• The S4 heart sound, also called an S4 gallop or atrial gallop, is an extra sound that is heard in late diastole, just before S1
• It is caused by a stiff ventricle
• S4 is mostly pathogenic and almost never normal, unlike S3
• It is associated with diseases that cause the ventricles to stiffen like hypertrophic cardiomyopathy and diastolic heart failure
• In the case of an athlete with physiological hypertrophy of the ventricles, growth of the ventricles can be a normal response to cardiovascular conditioning and lead to them developing an S4 heart sound
• S4 can be heard best when at the apex of the heart when the patient is placed in the left lateral decubitus position