cardiac cycle- II for first year mbbs student

ppt on cardiac cycle

1. CARDIAC CYCLE
DR.P.KALYANI PRABA,MD
ASST.PROFESSOR
DEPT OF PHYSIOLOGY

2. OBJECTIVES

Events occurring during the
cardiac cycle

Pressure changes in the
ventricles, atria, aorta

Volume changes in the ventricles

4. LEFT VENTRICULAR PRESSURE
CHANGES

Atrial systole: Rt ventricle- 6-7mmHg & Lt
ventricle – 7-8mmHg

Isovolumic / isometric contraction: Lt-
80mmHg,Rt -10mmHg

Rapid ejection: Lt – 120mmHg, Rt-
25mmHg

Slow ejection: pressure declines

Protodiastole: pressure declines

Isovolumic / isometric relaxation : Lt- 2-
3mmHg

Rapid filling: slight rise 4-12mmHg
RECORDED BY MANOMETER, CARDIAC
CATHETERIZATION

5. Right Ventricular pressure changes

Similar to LV pressure changes

Peak systolic pressure = 25 mm Hg

Diastolic pressure = 10 mm Hg

6. INTRA-ATRIAL PRESSURE CHANGES

Pressure changes in the atria

Lt atrial pressure – pulmonary wedge pressure in
the pulmonary capillary bed. 2-8mmHg

Rt atrial pressure – 0-5mmHg. Internal jugular
vein

7. PHLEBOGRAM
3 Positive wave – a,c,v 2 Negative wave- x,y
a
c v
x
y
AS VS VD
1
2
3
4
1 - AV valves closes
2 – SLV opens
1 – 2 – Isovolumetric contraction phase
3 – SLV closes
4 - AV valve opens
3 - 4 – Isometric relaxation phase
0
10
20

8. PHLEBOGRAM – a Wave

First positive wave

Due to atrial systole

As atrium contracts – pressure ↑

Rt- 5mmHg, Lt -8mmHg

Precedes QRS complex

Absent in Atrial Fibrillation or Flutter

Prominent in tricupsid stenosis, heart block, pulmonary
hypertension, RVH
a

9. PHLEBOGRAM – c Wave

Second positive wave

Commences at the onset of ventricular systole

AV ring bulges into the atria – (During IVC) – causes
rise in atrial pressure – upstroke

Begins at the end of QRS complex

Prominent in tricuspid incompetance
c

10. PHLEBOGRAM – v Wave

Third positive wave

Filling of atria when AV valves are closed

Occurs after T wave of ECG

Giant V wave – tricuspid regurgitation
v

11. PHLEBOGRAM –X & Y
Negative x wave

Ejection phases – Rapid fall in
pressure- pulls AV ring down
Negative y wave

End of IVR– AV valves open

Blood from atria empties into ventricle
x y

13. ARTERIAL PULSE / AORTIC PRESSURE

Rhythmic distension of arterial wall during
cardiac cycle

Pressure changes in aorta – 80 to 120mmHg

Pulse wave velocity: 5-8 msec

Recorded by sphgmochronograph

14. AORTIC PRESSURE CURVE

Primary wave or percussion wave

Beginning of pulse to beginning of downstroke- stroke volume

Dicrotic notch

notch on downstroke (incisura) due to SLV closure

Dicrotic wave

Rebound of blood column from closed SLV

Tidal wave

Elasticity of aortic wall

Anacrotic limb – ascending limb

Catacrotic limb- descending limb

15. AORTIC PRESSURE
CURVE
80
100
120
Incisura
VS VD
1
2
3
4
5
1 – SLV open
2 – Maximum Ejection Phase
2-3 – Reduced Ejection Phase
3 – End of Ventricular Diastole
4 - SLV closes
5 – Small positive wave

16. PULMONARY ARTERY PRESSURE
CHANGES

SYSTOLE : 15 TO 18mmHg

DIASTOLE: 8 TO 10mmHg

17. VENTRICULAR VOLUME CHANGES
Recorded by Henderson
cardiometry, Cineradiography
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]

19. Thank You