Here, I discuss all basics of cardiac Cycle related terms and physiology.

1. pankajbubms@gmai.com

2. Cardiac cycle
 The cardiac cycle is the performance of the human heart from the
beginning of one heartbeat to the beginning of the next.
 Principal function of cardiovascular system is to deliver oxygen and
nutrients to and remove carbon dioxide and wastes from metabolizing
tissues.
 It is by two specialized circulations in series
low resistance
pulmonary driven
by right heart high resistance
systemic driven by
left heart

3. Cardiac events beginning of one heart
beat to the beginning of next heart beat.
Duration – 0.8 sec
Initiated by action potential in SA node

4. The cardiac cycle consists of two major periods called
systole and diastole.
During systole
• There is contraction of cardiac muscle
• And pumping of blood
During diastole
• There is relaxation of cardiac muscles
• And filling of blood
DIASTOLE
1)PROTODIASTOLE 0.04
2) ISOMETRIC RELAXATION 0.08
3)RAPID FILLING 0.11
4) SLOW FILLING 0.19
5) LAST RAPID FILLING/ ATRIAL
SYSTOLE 0.11
----------------
0.8 SECONDS
SYSTOLE
SECONDS
1) ISOMETRIC
CONTRACTION 0.05
2) EJECTIO PERIOD 0.22

5. SA Node
Rate – 80-120/min
AV Node
Rate – 40-
60/min
Purkinje fibres
• Rate – 15-
40/min

7.  The first two stages, often considered together as the "ventricular filling"
stage, involve the movement of blood from atria into ventricles.
 The next three stages involve the movement of blood from the ventricles
to the pulmonary artery (in the case of the right ventricle) and the aorta (in
the case of the left ventricle.
 The cardiac cycle describes pressure , volume and flow phenomena in the
ventricles as a function of time.
 Similar for both LV and RV except for the timing, levels of pressure.
 Normal Heart Rate – 60-100
 Average -72 bpm
 So, in 1 hour – 4320
 In one day – 103680
 For a 55 year life span -208 crores

8. Electrical Events Of Cardiac
Cycle

9. The cardiac cycle and Wiggers diagram

10.  A Wiggers diagram, named after its developer, Dr. Carl J. Wiggers, is a
standard diagram that is used in teaching cardiac physiology.[1] In the
Wiggers diagram, the X-axis is used to plot time, while the Y-axis contains all
of the following on a single grid:
 Blood pressure
 Aortic pressure
 Ventricular pressure
 Atrial pressure
 Ventricular volume
 Electrocardiogram
 Arterial flow (optional)
 Heart sounds (optional)
 The Wiggers diagram clearly illustrates the coordinated variation of these
values as the heart beats, assisting one in understanding the entire cardiac
cycle.

12. ANGINA PECTORIS
AP- is the symptom
complex
caused by transient
myocardial ischaemia
Coronary atheroma
Clinical features-
Stable angina is characterised by
central chest pain,(sometimes
radiating to
left arm) , discomfort or
breathlessness.

13. CONGESTIVE CARDIAC
FAILURE Heart failure describes the clinical syndrome that develops when
the heart cannot maintain adequate output, or can do so only at
the expense of elevated ventricular filling pressure
 Symptoms: chest pain, shortness of breath, fast
 breathing, rapid breathing, dizziness, fatigue, fast
 heart rate

14. Acute circulatory failure
(cardiogenic shock)
‘Shock’ is used to describe
the
clinical
syndrome that
develops when there is
critical
impairment of tissue
perfusion
due to some form of acute
circulatory failure

15. Myocardial infarction
 Myocardial infarction (MI) or acute myocardial infarction
(AMI), commonly known as a heart attack, occurs when blood
flow stops to a part of the heart causing damage to the heart
muscle Most MIs occur due to coronary artery disease Often it
is in the centre or left side of the chest lasts for more than a few
minutes.
 Symptoms:
heartburn
shortness of
breath,
nausea,
feeling faint, a
cold sweat,
tired

16. DISEASES OF THE HEART VALVES
A diseased valve may be
narrowed (stenosed) or may
fail to close adequately, and
thus permit regurgitation of
blood.
‘Incompetence’ is a less
precise term for regurgitation
or reflux, and should be
avoided.
Tricuspid
valve disease
Mitral valve
disease
Aortic valve
disease
Pulmonary
valve disease