CARDIOVASCULAR SYSTEM CARDIAC CYCLE-IIHEART SOUNDS

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DR. Mohammed Sharique Ahmed Quadri

Ventricular Systole0.3 sec.

Ventricular Diastole0.5 sec.

Ventricular Systole0.3 sec.

Isometric contraction phase Ejection phase

Isometric Relaxation phase

Rapid inflow phaseDiastasis

Atrial Systole

Cardiac cycle time = 0.8 Sec. (if the heart rate is 75 beats/min.)

Systole Diastole Systole

Phonocadiogram

Electrocardiogram

Ventricular volume

Ventricular pressure

120

80

0

Cardiac cycle

P

Q

R

S

T P

Q

R

S

T

1st 2nd 3rd

Aortic pressure

Systole Diastole Systole

Atrial pressurea c va c v

Events of cardiac cycle

Mitral valve closes

Aortic valve opens

Aortic valve closes

Mitral valve opens

Relationship between Lt. ventricular volume & pressure changes

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Pressure changes during cardiac cycle9

Rt- Atrium = 0-7mm Hg.

Lt- Atrium = 2-10 mm Hg.

Rt – Ventricle = 25 / 6(2-8) mm Hg.

Lt – ventricle = 120 / 8(2-10) mm Hg.

Aorta = 120 / 80 mm Hg.

Pul. Artery = 25 / 10 mm Hg.

• Ejection fraction (EF) is the percentage of ventricular end diastolic volume (EDV) which is ejected with each stroke.

EF =

10

SV (EDV – ESV)

EDVX 100

75

120X 100 = 62.5%

Normal ejection fraction is about 60 – 65 %.

Ejection fraction is good index of ventricular function.

HEART SOUNDS

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• 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.

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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

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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

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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.

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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

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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 age17

AD AS

VS VD

EVENTS

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HEART SOUNDS

0.7 Sec. 0.1 sec.

0.3Sec. 0.5 sec.

1 st Heart Sound 2 nd Heart Sound 3 rd Heart Sound 4 th Heart Sound

AS – Atrial Systole; AD – Atrial Diastole ; VS – Ventricular systole; VD – Ventricular diastole

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Heart Murmurs

• Murmurs are abnormal sounds produced due to 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.

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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.

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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.

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THANK YOU

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