2. CARDIOVASCULAR SYSTEM CARDIAC CYCLE HEART SOUNDS
LECTURE – 4
DR. ZAHOOR ALI SHAIKH

3. HEART SOUNDS

4. There are four heart sounds SI, S2, S3 & S4.
Two heart sound are audible with stethoscope S1 & S2 (Lub - Dub).
S3 & S4 are not audible with stethoscope Under normal conditions because they are low frequency sounds.
Ventricular Systole is between First and second Heart sound.
Ventricular diastole is between Second and First heart sounds.

5. First heart sound (S1)
It is produced due to the closure of Atrioventricular valves (Mitral & Tricuspid)
It occurs at the beginning of the systole and sounds like LUB
Frequency:50-60 Hz
Time: 0.15 sec

6. Second heart sound (S2)
It is produced due to the closure of Semilunar valves (Aortic & Pulmonary)
It occurs at the end of the systole and sounds like DUB
Frequency:80-90 Hz [ High pitch ]
Time: 0.12 sec
It is short and sharp

7. HEART SOUNDS Important
Sounds are caused by vibrations set within the wall of the ventricles and major arteries during valve closure .
Opening of the valve does not cause sound.

8. Third heart sound (S3)
It occurs at the beginning of middle third of Diastole
Cause of third heart sound – Rush of blood from Atria to Ventricle during rapid filling phase of Cardiac Cycle. It causes vibration in the blood
Frequency:20-30 Htz
Time: 0.1 sec

9. Fourth heart sound (S4) or Atrial Sound
It occurs at the last one third of Diastole
(just before S1)
Cause of Fourth heart sound – Due to Atrial contraction which causes rapid flow of blood from Atria to noncompliant Ventricle and vibration in the blood.
Frequency: < 20 Htz
Note:
Third and Fourth heart sound are low pitched sounds therefore not audible normally with stethoscope
S3 may be heard in children and young adults but usually pathological in old age

10. EVENTS HEART SOUNDS 0.7 Sec. AD AS VS VD 0.3Sec. 0.5 sec. 0.1 sec.
1 st Heart Sound
2 nd Heart Sound
3 rd Heart Sound
4 th Heart Sound
HEART SOUNDS
AS – Atrial Systole; AD – Atrial Diastole ; VS – Ventricular systole; VD – Ventricular diastole

12. Heart Murmurs
Murmurs are abnormal sounds produced due to abnormal flow of blood [turbulent blood flow] through abnormal heart valves e.g.. stenosis or incompetence.
Stenosis means narrow or stiff, valve that does not open completely.
Incompetent means valve which does not close properly and remains open.

14. Heat Murmurs
When blood is forced through stenotic valve, it produces an abnormal whistling sound.
When blood flows backward through incompetent valve, it produces swishing or gurgling murmur sound.
Most common cause of stenosis and incompetent valve is Rheumatic fever, an auto immune disease triggered by Streptococcus bacterial infection.

15. Heat Murmurs
Systolic murmur are produced during the systole of the ventricle, between 1st and 2nd heart sound (Lub – Murmer – Dup).
Diastolic murmur are produced during the diastole of the ventricle, between 2nd and 1st heart sound (Lub – Dup – Murmer – Lub).
During aortic stenosis and mitral incompetence – systolic murmur.
Aortic incompetence and Mitral Stenosis – diastolic murmur.

17. We will discuss
PRESSURE VOLUME LOOP
2. EVENTS OF CARDIAC CYCLE

18. Relationship between Lt. ventricular volume & pressure changes

19. Events of cardiac cycle for Lt
Events of cardiac cycle for Lt. ventricular function showing changes in Lt. atrial pressure, Lt. ventricular pressure, aortic pressure, ventricular volume, ECG & phonocardiogram

20. THANK YOU