Heart sounds Flashcards
How are heart sounds produced?
Vibrations caused by sudden valve closure
Myocardial contraction
Vibration caused by rushing of blood into the heart chambers
How many heart sounds are there?
Four
Four heart sounds can be recorded by phonocardiography
Only the first and second heart sounds can be heart through a stethoscope
How is the first heart sound produced?
Sudden closure of AV valves at the beginning of ventricular systole/isovolumetric contraction phase
What are the characteristics of the first heart sound?
Low pitched (25 – 45 Hz)
Longer duration (0.14 Sec)
Give the sound of Lub
At what sites can the first heart sound be auscultated?
Mitral area: At the apex of heart in the 5th intercostal space mid-clavicular line
Tricuspid area: Between the 4th and 5th space close to lower left quadrant of sternum
How is the second heart sound produced?
Closure of the semilunar valves (aortic and pulmonary valves) at the end of ventricular systole/isovolumetric relaxation phase
What are the characteristics of the second heart sound?
High pitched (50 Hz)
Shorter duration (0.11 sec)
Give the sound of Dub
At what sites can the second heart sound be auscultated?
Auscultated in the aortic and pulmonary areas (right and left 2nd intercostal space)
How is the third heart sound produced?
Rushing of blood from the atria to the ventricles during the rapid filling phase
What are the characteristics of the third heart sound?
Gallop sound
Give the sound Ken…tuc-ky
In what conditions can the third heart sound be heard?
Physiological causes: Normally heard in children, athletes and pregnant females
Pathological causes: Congestive heart failure, aortic regurge and dilated cardiomyopathy
How is the fourth heart sound produced?
Atrial systole causes vibration of ventricular wall
In what conditions can the fourth heart sound be heard?
Concentric ventricular hypertrophy (stiff ventricular walls)
