Cardiac cycle & sound

Cardiac events and sound

1. THE CARDIAC CYCLETHE CARDIAC CYCLE

3. A period from the beginning of one heart beat to the
beginning of the next one.
It consists of two parts:
1. Contraction called systole.
2. Relaxation called diastole
RELATING:

Mechanical events in the heart

Pressure and volume changes

Electrical activity of the heart (ECG)

Heart sounds
CARDIAC CYCLE

4. PHASES OF CARDIAC CYCLE (0.8 sec)PHASES OF CARDIAC CYCLE (0.8 sec)
* Phase 1 - Atrial Contraction* Phase 1 - Atrial Contraction
* Phase 2 - Isovolumetric Contraction* Phase 2 - Isovolumetric Contraction
* Phase 3 - Rapid Ejection* Phase 3 - Rapid Ejection
* Phase 4 - Reduced Ejection* Phase 4 - Reduced Ejection
* Phase 5 - Isovolumetric Relaxation* Phase 5 - Isovolumetric Relaxation
* Phase 6 - Rapid Filling* Phase 6 - Rapid Filling
* Phase 7 - Reduced Filling* Phase 7 - Reduced Filling

5. EVENTS IN CARDIAC CYCLE EVENTS IN CARDIAC CYCLE
Atrial systoleAtrial systole
Ventricular systole (Atrial Diastole)Ventricular systole (Atrial Diastole)

Isovolumetric contractionIsovolumetric contraction

Rapid ejectionRapid ejection

Reduced ejectionReduced ejection
Isovolumetric relaxationIsovolumetric relaxation

Rapid ventricular fillingRapid ventricular filling

Reduced ventricular fillingReduced ventricular filling
Next cycleNext cycle

6. ATRIAL SYSTOLEATRIAL SYSTOLE

The end of diastole The end of diastole

7. ATRIAL SYSTOLE - HeartATRIAL SYSTOLE - Heart
Prior to atrial systole, blood has been Prior to atrial systole, blood has been
flowing passively from the atrium into flowing passively from the atrium into
the ventricle through the open AV the ventricle through the open AV
valve. valve.
During atrial systole the atrium During atrial systole the atrium
contracts and tops off the volume in contracts and tops off the volume in
the ventricle with only a small amount the ventricle with only a small amount
of blood. Atrial contraction is complete of blood. Atrial contraction is complete
before the ventricle begins to contract. before the ventricle begins to contract.
Duration: 0.1 sec

8. ATRIAL SYSTOLEATRIAL SYSTOLE
ECGECG
An impulse arising from the SA node results in depolarization and An impulse arising from the SA node results in depolarization and
contraction of the atria (the right atrium contracts slightly before the contraction of the atria (the right atrium contracts slightly before the
left atrium). left atrium).
The P wave is due to this atrial depolarization.The P wave is due to this atrial depolarization.
The PR segment is electrically quiet as the depolarization proceeds to The PR segment is electrically quiet as the depolarization proceeds to
the AV node. the AV node.
This brief pause before contraction allows the ventricles to fill This brief pause before contraction allows the ventricles to fill
completely with blood. completely with blood.

9. Ventricular Systole (Ventricular Systole (0.3 sec)0.3 sec)
ISOVOLUMETRIC CONTRACTIONISOVOLUMETRIC CONTRACTION
The Beginning of systole.......The Beginning of systole.......

10. ISOVOLUMETRIC CONTRACTION: HeartISOVOLUMETRIC CONTRACTION: Heart
The atrioventricular (AV) valves The atrioventricular (AV) valves
close at the beginning of this phase.close at the beginning of this phase.
Electrically, ventricular systole is Electrically, ventricular systole is
defined as the interval between the defined as the interval between the
QRS complex and the end of the T QRS complex and the end of the T
wave (the Q-T interval).wave (the Q-T interval).
Mechanically, ventricular systole is Mechanically, ventricular systole is
defined as the interval between the defined as the interval between the
closing of the AV valves and the closing of the AV valves and the
opening of the semilunar valves opening of the semilunar valves
(aortic and pulmonary valves). (aortic and pulmonary valves).
Duration : 0.03 secDuration : 0.03 sec

11. ISOVOLUMETRIC CONTRACTION: ECGISOVOLUMETRIC CONTRACTION: ECG
The electrical impulse propagates from the AV node through The electrical impulse propagates from the AV node through
the His bundle and Purkinje system to allow the ventricles to the His bundle and Purkinje system to allow the ventricles to
contract from the apex of the heart towards the base.contract from the apex of the heart towards the base.
The QRS complex is due to ventricular depolarization, and it The QRS complex is due to ventricular depolarization, and it
marks the beginning of ventricular systole. It is so large that marks the beginning of ventricular systole. It is so large that
it masks the underlying atrial repolarization signal. the it masks the underlying atrial repolarization signal. the
ventricles to fill completely with blood. ventricles to fill completely with blood.

12. RAPID EJECTIONRAPID EJECTION

13. RAPID EJECTION: HeartRAPID EJECTION: Heart
The The SL valvesSL valves open at the beginning open at the beginning
of this phase.of this phase.
But But AV ValvesAV Valves Remain Closed Remain Closed
This phase represents initial, rapid This phase represents initial, rapid
ejection of blood into the ejection of blood into the aorta and aorta and
pulmonary arteriespulmonary arteries from the left and from the left and
right ventricles, respectivelyright ventricles, respectively
when the intra-ventricular pressures when the intra-ventricular pressures
exceed the pressures within the aorta exceed the pressures within the aorta
and pulmonary artery, which causes and pulmonary artery, which causes
the aortic and pulmonic valves to open the aortic and pulmonic valves to open

14. RAPID EJECTIONRAPID EJECTION
ECGECG
No DeflectionsNo Deflections

15. REDUCED EJECTIONREDUCED EJECTION

The end of systole The end of systole

16. REDUCED EJECTION: Heart & ECG REDUCED EJECTION: Heart & ECG
Ventricular pressure falls slightly Ventricular pressure falls slightly
below outflow tract pressurebelow outflow tract pressure
At the end of this phase the semilunar At the end of this phase the semilunar
(aortic and pulmonary) valves close.(aortic and pulmonary) valves close.
But outward flow still occurs due to But outward flow still occurs due to
kinetic (or inertial) energy of the kinetic (or inertial) energy of the
bloodblood
Repolarization leads to a decline in Repolarization leads to a decline in
ventricular active tension and pressure ventricular active tension and pressure
generation; generation;
therefore, the rate of ejection therefore, the rate of ejection
(ventricular emptying) falls(ventricular emptying) falls
The T wave is due to ventricular repolarization. The end of the T wave
marks the end of ventricular systole electrically.

17. ISOVOLUMETRIC ISOVOLUMETRIC
RELAXATIONRELAXATION

The beginning of Diastole The beginning of Diastole

18. ISOVOLUMETRIC RELAXATION: Heart
Phase starts with closure of the AV
valves
When the IV pressures fall sufficiently at
the end of phase 4, the SL valves
abruptly close
The aortic and pulmonary artery
pressures rise slightly
Valve closure is associated with a small
backflow of blood into the ventricles
Although ventricular pressures decrease
during this phase, volumes do not
change
Left atrial pressure rises because of
venous return from the lungs.

19. ISOVOLUMETRIC RELAXATIONISOVOLUMETRIC RELAXATION
ECGECG
No Deflections No Deflections

20. RAPID VENTRICULAR RAPID VENTRICULAR
FILLINGFILLING

21. RAPID VENTRICULAR FILLINGRAPID VENTRICULAR FILLING
HeartHeart
Once the AV valves open, blood that Once the AV valves open, blood that
has accumulated in the atria flows has accumulated in the atria flows
rapidly into the ventricles. rapidly into the ventricles.

22. REDUCED VENTRICULAR REDUCED VENTRICULAR
FILLINGFILLING

(Diastasis) (Diastasis)

23. REDUCED VENTRICULAR FILLING REDUCED VENTRICULAR FILLING
ECGECG
No Deflections No Deflections

25. Pressure Changes in Cardiac CyclePressure Changes in Cardiac Cycle

29. Heart SoundsHeart Sounds
Primary sounds:
S1 & S2
Secondary Sounds
S3 & S4
Heart sounds are associated with heart valves closing,
causing changes in blood flow.

30. S1S1
Closure of AV ValvesClosure of AV Valves
sudden block of reverse blood flow due to closure of the BI and TRI sudden block of reverse blood flow due to closure of the BI and TRI
cuspid valves.cuspid valves.
Begins ventricular contractionBegins ventricular contraction
The papillary muscles are attached to the tricuspid and mitral valves via The papillary muscles are attached to the tricuspid and mitral valves via
chordae tendineae, which bring the cusps or leaflets of the valve closedchordae tendineae, which bring the cusps or leaflets of the valve closed
–Causes of a loud S1Causes of a loud S1
»mitral stenosismitral stenosis
»left to right shuntsleft to right shunts
» short PR interval, atrial premature beatsshort PR interval, atrial premature beats
»hyperdynamic stateshyperdynamic states

31. S2S2
 Sudden block of reversing blood flow due to closure of the semilunar Sudden block of reversing blood flow due to closure of the semilunar
valves (the aortic valve and pulmonary valve)valves (the aortic valve and pulmonary valve)
End of ventricular systole and the beginning of ventricular diastoleEnd of ventricular systole and the beginning of ventricular diastole
 Pressure fall in Ventricles after emptying, blood flow quickly reverses Pressure fall in Ventricles after emptying, blood flow quickly reverses
back toward the ventricle makes the SL valve cups to be closedback toward the ventricle makes the SL valve cups to be closed
–Causes of a widely split S2Causes of a widely split S2
»• • deep inspirationdeep inspiration
»• • RBBBRBBB
»• • pulmonary stenosispulmonary stenosis
»• • severe mitral regurgitationsevere mitral regurgitation

32. Gallop RhythmGallop Rhythm
S3S3
–caused by diastolic filling of the ventriclecaused by diastolic filling of the ventricle
– youth, some trained athletes, and sometimes in pregnancyyouth, some trained athletes, and sometimes in pregnancy
S4

produced by the sound of blood being forced into a stiff or
hypertrophic ventricle.
MURMURS
Heart murmurs are produced as a result of turbulent flow of
blood strong enough to produce audible noise