Cardiovascular system cardiac cycle heart sounds
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CARDIOVASCULAR SYSTEM CARDIAC CYCLE HEART SOUNDS. LECTURE – 4 DR. ZAHOOR ALI SHAIKH. HEART SOUNDS. There are four heart sounds SI, S2, S3 & S4. Two heart sound are audible with stethoscope S1 & S2 (Lub - Dub).

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CARDIOVASCULAR SYSTEM CARDIAC CYCLE HEART SOUNDS

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CARDIOVASCULAR SYSTEM CARDIAC CYCLEHEART SOUNDS

LECTURE – 4

DR. ZAHOOR ALI SHAIKH


HEART SOUNDS


  • 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.


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


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


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.


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


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


EVENTS

1 st Heart Sound

2 nd Heart Sound

3 rd Heart Sound

4 th Heart Sound

HEART SOUNDS


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.


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.


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.


We will discuss

PRESSURE VOLUME LOOP

2. EVENTS OF CARDIAC CYCLE


Relationship between Lt. ventricular volume & pressure changes


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


THANK YOU


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