Dpt

1. CARDIAC CYCLE
Presented by: Dr. Ayesha Anwer Ali

2. contents
Cardiac Cycle
01
Events of Cardiac Cycle
02
Phases of Cardiac Cycle
03

3. Cardiac Cycle
Cardiac cycle is defined as the
succession of coordinated events
taking place in the heart during
each beat.
Each heart beat consists of
two major periods called
systole and diastole.

4. Cardiac Cycle
During diastole heart relaxes and blood is filled
in the heart.
During Systole heart contracts and pumps
the blood through arteries.
All these events are repeated in
a cyclic manner.

5. Events of Cardiac
Cycle;
Events of Cardiac cycle are divided into
artrial events and ventricular events
although both are occurring at the
same time.

6. ATRIAL EVENTS
These include ;
Period of rapid ventricular filling
Diastasis
Atrial contraction

7. Atria have low pressure and receive blood from the great veins .
When atria are filled with blood, atrial pressure become more than
the pressure in the ventricles
.
Due to this AV valves open and about 75% of blood enters from the
atria into the ventricles. This is called period of rapid ventricular
filling.
Period of Rapid
Ventricular filling

8. Diastasis
When AV valves are still open , blood
from large veins go directly to ventricles
through atria without staying in atria.
.This period is called Diastasis.
This is the longest period of Cardiac

9. Atrial contraction
Finally atria themselves contract and push
remaining 25% blood into ventricles.This is
called period of atrial contraction.
.As atrial contraction simply increases
ventricular filling by 25%, they act as primer

10. The waves
include;
Wave "a":
Wave "c":
Wave "v":
X- descent:
Y- descent:
.Normal pressure in right atrium is zero
and that in left atrium is 0-2 mm Hg.
Atrial pressure changes during cardiac
cycle produce three positive and two
negative pressure Waves.
These are called jugular venous pressure
Waves or JVP.
Atrial Pressure (JVP)

12. VENTRICULAR EVENTS:
These are divided into
ventricular diastole and
ventricular systole.

13. Diastole

14. Ventricular diastole corresponds to atrial events. It's three
phases are similar to that of atrial events i.e.
Period of rapid ventricular filling
Diastasis
Period of atrial contraction
Diastole

15. Systole

16. Closure of AV valves -First heart
sound
Period of isometric contraction
Opening of semi lunar valves
Period of rapid ejection
Period of slow ejection
Protodiastole
Closure of semi lunar valves -second
heart sound
Period of isometric relaxation
Ventricular Events
during Systole
include;

17. THANK YOU！