heart valves and sounds; valvular and congenital heart defects Flashcards
ch 23 pg 283 guyton
Cause of s1 sound
vibration of AV valves as they close at the beginning of systole
duration of s1 sound
0.14s
frequency s1 sound
25-45Hz
cause of s2 sound
vibrations associated with closure of semi lunar valves at the end of systole
where does s2 occur on ECG?
after the T wave
duration of s2
0.11s
frequency of s2
50Hz
why does s1 have a longer duration than s2?
SL valves are tauter than A-V valves, so they vibrate for a shorter period of time
why does s2 have higher frequency than s1?
- tautness of semilunar valves compared to less taut A-V
- greater elastic coefficient of the taut arterial walls, which provides the principal vibrating chambers for the second sound, in comparison with the much looser, less elastic ventricular chambers, which provide the vibrating system for the first heart sound
aortic valve produces a loud sound in…?
systemic hypertension
pulmonary valve produces a loud sound in…?
pulmonary hypertension
cause of s3 heart sound
oscillation of blood back and forth in the ventricles initiated by in-rushing blood from the atria
when does s3 occur?
middle third of diastole
duration of s3
0.1s
frequency of s3
20-30Hz
where does s3 become loud and audible?`
- aortic regurgitation
- cardiac failure
- cardiomyopathy
where does s3 occur in ECG?
between T and P wave
causes of 4th heart sound
inrush of blood into the ventricles
in what condition is 4th sound audible?
- left ventricular hypertrophy
- long standing hypertension
- aortic stenosis
when does s4 occur
last third of diastole (just before s1)
what is rheumatic fever?
how does rheumatic fever affect heart valves?
which valve is most affected in rheumatic fever?
what is stenosis and regurgitation?
what causes aortic stenosis murmurs?
what causes aortic regurgitation murmurs?
what causes mitral stenosis murmurs?
what causes mitral regurgitation murmurs?
classify the murmurs as systolic or diastolic
