CARDIOVASCULAR SYSTEM CARDIAC CYCLE HEART SOUNDS

2. CARDIOVASCULAR SYSTEM CARDIAC CYCLEHEART 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 1 st Heart Sound 2 nd Heart Sound 3 rd Heart Sound 4 th Heart Sound HEART SOUNDS

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. ventricular function showing changes in Lt. atrial pressure, Lt. ventricular pressure, aortic pressure, ventricular volume, ECG & phonocardiogram

20. THANK YOU