cardiac cycle- II for first year mbbs student

ppt on cardiac cycle

1. CARDIAC CYCLE-I
DR. KANIMOZHI SADASIVAM, MD
PROFESSOR
DEPT OF PHYSIOLOGY

2. OBJECTIVES

Definition & phases of cardiac
cycle

Heart sounds

The mechanical, electrical &
other events occurring during
the cardiac cycle

4. CARDIAC CYCLE
The sequence of cyclical events
that take place during one heart
beat (one systole and one
diastole) to the beginning of the
next

5. EVENTS DURING THE
CARDIAC CYCLE
Mechanical – volume & pressure
changes
Electrical - ECG
Chemical
Thermal
Changes in position of heart & apex
beat
Movement of the valves
Heart sounds

6. CARDIAC CYCLE
Heart rate : 72/min
Hence duration for one cycle is: 60/72 = 0.8 seconds
Atrial cycle

Atrial systole -0.1 sec
Atrial diastole-0.7 sec

7. VENTRICULAR CYCLE

VENTRICULAR SYSTOLE – 0.3 sec

Isovolumic / isometric contraction phase – 0.05 sec

Ventricular ejection

Rapid ejection phase -0.1sec

Slow ejection phase – 0.15 sec

VENTRICULAR DIASTOLE – 0.5 sec

Protodiastole – 0.04sec

Isovolumic / isometric relaxation phase – 0.06sec

Rapid passive filling phase – 0.11 sec

Reduced filling phase – 0.19 sec

Last rapid filling phase – 0.1sec

8. CARDIAC CYCLE

IF HR ↑ - 150 / MIN

CARDIAC CYCLE – 0.4 Sec

SYSTOLE 0.25 Sec

DIASTOLE – 0.15 Sec

Hence little time for ventricular
filling.

9. CARDIAC CYCLE

RA contracts before LA

LV contracts before RV
S D-0.7
D S-0.3 D-0.4
ATRIAL EVENTS
VENTRICULAR EVENTS
Whole heart is Quiescent

10. ATRIAL SYSTOLE
0.10 Sec
Coincides with last rapid phase of
ventricular diastole
Coincides with ‘a ’ wave of JVP
Contraction of atria-Fourth Heart
sound
AV valves opened
Increases the ventricular filling by
30%

11. ATRIAL DIASTOLE

Duration: 0.7sec

Coincides with VS & most of the VD

Beginning of AD- 0.3sec – AV valves closed

Pressure decreases in atria and increase in
ventricle.

Late of AD- 0.4sec – AV valves opened

Pressure falls in the ventricles

Contribute to 80% ventricular filling

12. VENTRICULAR SYSTOLE

0.3 SECONDS

ISOVOLUMETRIC CONTRACTION -
0.05 SEC

EJECTION PHASE- 0.25 SEC

RAPID EJECTION – 0.10 SEC

SLOW EJECTION – 0.15 SEC

AV open, SLV closed

13. ISOVOLUMETRIC
CONTRACTION

0.05 Sec

Coincides with c wave in JVP

Semilunar valve : Closed

AV valves closed – First Heart sound

Closed chamber – Contracts

No change in the volume

Intraventricular pressure ↑

14. EJECTION PHASE
↑ Intraventricular pressure
> 80mm Hg - Diastolic pressure
of Aorta (Or) > 10mmHg-
Diastolic pressure of Pulmonary
arteries
Semilunar valves forced to open
Blood flows into arteries from
ventricle

15. EJECTION PHASE
0.25 Seconds
RAPID EJECTION PHASE – 0.10 SEC
Due to High Pressure gradient - Blood is ejected into
Aorta / Pulmonary artery.
SLOW EJECTION PHASE – 0.15 SEC
Due to decreased Pressure gradient
STROKE VOLUME = 80 ml (Blood ejected out by each
ventricle during each systole)
END DIASTOLIC VOLUME= 130ml
END SYSTOLIC VOLUME = 50ml
EDV – SV = ESV [130 – 80 = 50]

16. CARDIAC CYCLE

17. Ventricular diastole -
PHASES :

0.50 seconds

Protodiastolic period – 0.04 Sec

Isovolumetric relaxation – 0.06 Sec

Rapid passive filling – 0.10 sec

Reduced filling / Diastasis – 0.20 sec

Last rapid filling– 0.10 sec

18. PROTODIASTOLIC
PHASE
0.04 Sec
Ventricle relaxes
Intraventricular pressure falls
Blood flows back from aorta /
pulmonary artery into ventricle
Semilunar valve closes - Second
heart sound
Dicrotic notch seen in the aortic
pressure

19. ISOVOLUMETRIC
RELAXATION

0.06 Sec

SLV and AV valves closed

Ventricle relaxes as closed
chamber

No volume change

Intraventricular pressure ↓

At the end AV valve open- v wave

20. RAPID PASSIVE FILLING PHASE

0.10 sec

↓Intraventricular pressure
< intra atrial pressure

Hence AV valves open

Blood flows from atria to
ventricle (70%)

Third heart sound

21. REDUCED FILLING/DIASTASIS

0.20 Sec

in intraventricular pressure

Blood flows from atria to
ventricle at slow rate (10%)

22. LAST RAPID FILLING PHASE

0.10 Sec

Coincides with atrial systole

20% of ventricular filling

25. HEART SOUNDS

Due to dynamics of blood flow

Valvular,
Vascular
Muscular vibrations

2 audible heart sounds

lubb, dupp

4 recordable heart sounds

26. AUSCULTATION AREAS
2
nd
ICS
Right sternal border
5
th
ICS
Left sternal border
2
nd
ICS
Left sternal border
5
th
ICS
Apex beat

27. AUSCULTATION AREAS

AORTIC

PULMONARY

TRICUSPID

MITRAL

28. FIRST HEART SOUND-S1

Character – Low pitch,
Booming, longer

Duration : 0.1 - 0.17 sec.
Frequency : 24 – 45 / sec
Best heard in :
Mitral & Tricuspid area

Closure of AV valves – LUBB

Vibrations of Chordae
tendinae

Vascular – Turbulence of
blood flow

Muscular – vibrations in
ventricular muscle as it
starts to contract
Coincides with :

Isometric contraction
phase

Peak of R wave of ECG

Phlebogram – Onset of
C wave
Has 2 components

Mitral – M
1 & Tricuspid –
T
1
Mitral precedes tricuspid
due to earlier closure of
Mitral valves

29. SECOND HEART SOUND-S
2

Character : High pitched

Duration : Shorter , 0.10 -
0.14 sec

Frequency : 50 Hz / sec
Best heard in : Aortic and
Pulmonary area

Closure of Semi Lunar Valves
– DUPP
Coincides with :

Onset of ventricular
diastole(Protodiastole)

Preceded/coincides or
follows T wave

Phlebogram – Ascending
limb of v wave
2 components
•Aortic (A2) & Pulmonary (P2)
•Normally P2 softer than A2

30. S
1 and S
2
S
1 - beginning of Ventricular
systole
S
2 – end of ventricular systole
Interval between S
1
& S
2
–
Duration of ventricular systole
Interval between S
2 & S
1 –
Duration of ventricular diastole

31. THIRD HEART SOUND-S3

Low intensity

Duration : 0.07 - 0.1 sec

Low frequency : 20Hz

Low pitched. Can be recorded
by Stethograph

Due to Rapid ventricular
filling

Vibrations of ventricular
wall

Frequently heard in
children

Thin walled chest

Patient with
Ventricular failure

If heard in adult –
cardiac abnormality
(eg. Mitral
regurgitation)

32. FOURTH HEART SOUND-S4

Not heard in normal
subjects

Only recorded

Just before first
heart sound

Freq < 20 Hz

Atrial systole causes
vibrations of atrial
wall, AV valves and
ventricular walls

Heard in abnormal
conditions –
hypertrophy of
atrium

Absent in atrial
fibrillation
Recorded by stethograph

33. PHONOCARDIOGRAM

Graphic recording of heart
sounds

Duration, amplitude and
frequency of vibrations

34. Clinical Significance
Useful for detecting
abnormalities in heart sound
Variations in heart sounds
Loudness, length, interval
between sounds
Splitting of sounds
Additional sounds
Murmurs

35. NORMAL & MURMUR

36. Thank You