1. Cardiac cycle
Dr. shafali singh

2. Learning Objectives
Interpret in correct temporal relationship, the pressure, volume, heart sound, and ECG changes in the cardiac cycle.
Identify the intervals of isovolumic contraction, rapid ejection, reduced ejection, isovolumic relaxation, rapid ventricle filling, reduced ventricular filling and atrial contraction.
Contrast the relationship between pressure and flow into and out of the left and right ventricles during each phase of the cardiac cycle.
Interpret ventricular pressure-volume loop and on it label the phases and events of the cardiac cycle (ECG, valve movement).

3. CARDIAC CYCLE ELECTRICAL CHANGE MECHANICAL CHANGE HEMODYNAMIC CHANGE
HEART SOUNDS

4. Cardiac cycle Atria Ventricle
The cardiac events that occur from beginning of one heart beat to the next are called the cardiac cycle
Atria
Atrial systole
Atrial diastole
Ventricle
Ventricular systole
Ventricular diastole

5. Heart beat duration (rate is 75 beat/min)

6. Duration of cardiac cycle
HEART RATE : 75/MIN
HENCE DURATION FOR ONE CYCLE IS: 60/75 = 0.8 Sec
ATRIAL CYCLE
ATRIAL SYSTOLE SEC
ATRIAL DIASTOLE- 0.7 SEC
VENTRICULAR CYCLE
VENTRICULAR SYSTOLE – 0.3 SEC
VENTRICULAR DIASTOLE – 0.5 SEC

7. What happens to time spent and systole and diastole with tachycardia?
Under Normal condition:n1/3rd time in systole and 2/3rd in diastole
Tachycardia : time spent in diastole decreases dramatically whereas time spent in systole falls to lesser extent.

8. CARDIAC CYCLE IF HR ↑ - 150 / MIN CARDIAC CYCLE – 0.4 Sec
SYSTOLE Sec
DIASTOLE Sec
HENCE LITTLE TIME FOR VENTRICULAR FILLING

9. Mechanical Events of Cardiac cycle
Atrial systole
Isovolumic contraction phase
Rapid ejection phase
Reduced ejection phase
Isovolumic relaxation phase
Rapid filling phase
Reduced filling phase (Diastasis)
Last rapid filling phase

10. ATRIAL SYSTOLE Last phase of ventricular diastole
Drives some more blood into the ventricles
Increases the ventricular filling by 35%
0.1 Sec
Coincides with ‘a‘ wave of JVP
Contraction of atria-Fourth Heart sound

11. VENTRICULAR SYSTOLE

12. 1.ISOVOLUMETRIC CONTRACTION
Coincides with ‘c ‘wave in JVP
Semilunar valve : remain closed
AV valves close – First Heart sound
Closed chamber – Contracts
No change in the volume
BLOOD INCOMPRESSIBLE
Intraventricular pressure ↑

13. 2.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

14. EJECTION PHASE MAXIMAL EJECTION –
Due to High Pressure gradient - Blood is ejected into Aorta/Pul. Art.
REDUCED EJECTION –
Due to decreased Pressure gradient
STROKE VOLUME – 70 ml
END SYSTOLIC VOLUME = ml
EDV – SV = ESV [120 – 70 = 50]

15. Ventricular diastole 1.Protodiastolic period –
2.Isovolumetric relaxation –
3.Rapid filling phase –
4.Reduced filling phase (Diastasis)
5.Last rapid filling phase/ Atrial systole follows

16. 1.PROTODIASTOLIC PHASE Ventricle relaxes Intraventricular pressure
< pressure in the aorta/Pul.Arteries
Blood flows back from aorta/pul art into ventricle
SLV closes -Second heart sound

17. 2.ISOVOLUMETRIC RELAXATION
SLV and AV valves closed
Ventricle relaxes as closed chamber
No volume change
Intraventricular pressure ↓

18. 3.RAPID INFLOW PHASE
↓Intraventricular pressure< intra atrial pressure
Hence AV valves open
Blood flows from atria to ventricle
Third heart sound

19. 4.DIASTASIS
↑ in intraventricular pressure due to ↑blood flow from atria
Blood flow from atria to ventricle at low rate or static
Duration of diastasis variable

20. During diastole there is passive filling of the relaxed left ventricle
During diastole there is passive filling of the relaxed left ventricle. The ventricle does not suck blood into the lumen. Filling is by the venous pressure.

21. The first sign of activity in the heart is the atrial contraction
The first sign of activity in the heart is the atrial contraction. This weak structure pushes a small amount of blood into the ventricle (atrial kick)
Blood is also propelled back into the veins giving rise to the A-wave.
Not vital.

22. Isovolumetric contraction occurs as the ventricle starts to contract
Isovolumetric contraction occurs as the ventricle starts to contract. The mitral valve closes The ventricular pressure rises toward aortic pressure .
The mitral valve bulges into the atrium causing the C wave in venous pressure

23. Ejection phase starts as the aortic valve opens
Ejection phase starts as the aortic valve opens. The ventricular contents are ejected during this time.

24. Isovolumetric relaxation begins as the aortic valve closes
Isovolumetric relaxation begins as the aortic valve closes. Ventricular pressure falls from aortic to left atrial during this period.

25. Diastolic filling begins again as the mitral valve opens Accumulated blood in the atrium rushes into the ventricle
Movement of blood into the ventricle causes venous pressure to drop suddenly causing the V wave

26. EKG EVENT VALVULAR EVENT SOUND
P wave
Atrial depolarisation
Mitral valve open
(ventricle is filling) S4
(S3 prior to P wave)
PR interval
AV Node conduction -
QRS
Ventricular depolarization
Mitral valve close S1
QT interval
Ejection phase
Aortic valve is open
No sound
T wave
Ventricular repolarization
Aortic valve closure S2

27. HEMODYNAMIC CHANGES
Pressure and volume changes in the atria & ventricle during cardiac cycle
Intra atrial pressure curve
Intraventricular pressure curve
Aortic pressure curve
Ventricular volume curve

28. INTRA-ATRIAL PRESSURE CURVE
Pressure changes in the atria is reflected in the veins near the heart, eg.jugular vein
acv curve – Jugular Phlebogram - JVP

29. PHLEBOGRAM 3 Positive waves – a,c &v 2 Negative waves x &y 3 4 2 a 1 vAS VS VD

30. The jugular pulse waves are superimposed on the respiratory fluctuations in venous pressure. Venous pressure falls during inspiration as a result of the increased negative intrathoracic pressure and rises again during expiration

32. Venous Pulse
a wave Highest deflection of the venous pulse and produced by the contraction of the right atrium Correlates with the PR interval Is prominent in a stiff ventricle, pulmonic stenosis and insufficiency Is absent in atrial fibrillation and other atrial arrhythmias
The jugular pulse waves are superimposed on the respiratory fluctuations in venous pressure. Venous pressure falls during inspiration as a result of the increased negative intrathoracic pressure and rises again during expiration

33. Venous Pulse
c wave Mainly due to the bulging of the tricuspid valve into the atrium (rise in right atrial pressure) Occurs near the beginning of ventricular contraction (is coincident with right ventricular isovolumic contraction)
The jugular pulse waves are superimposed on the respiratory fluctuations in venous pressure. Venous pressure falls during inspiration as a result of the increased negative intrathoracic pressure and rises again during expiration

34. Venous Pulse
x descent Produced by a decreasing atrial pressure during atrial relaxation Separated into two segments when the c wave is recorded v wave Produced by the filling of the atrium during ventricular systole when the tricuspid valve is closed Corresponds to T wave of the EKG A prominent v wave would occur in tricuspid insufficiency and right heart failure

35. Venous Pulse
y descent Produced by the rapid emptying of the right atrium immediately after the opening of the tricuspid valve A more prominent wave in tricuspid insufficiency and a blunted wave in tricuspid stenosis

36. A more prominent v wave in tricuspid insufficiency and a blunted wave in tricuspid stenosis

38. A common diagnostic technique is to place catheters at various points in the cardiovascular system and record their pressures.

39. Similar recordings to the systemic venous pulse are obtained when recording pulmonary
capillary wedge pressure. Left atrium mechanical events are transmitted
in a retrograde manner, although they are somewhat damped and delayed. The
figure below shows the pressure recording from the tip of a Swan-Ganz catheter
inserted through a systemic vein through the right side of the heart into the pulmonary
circulation and finally with the tip wedged in a small pulmonary artery.
The pressure recorded at the tip of the catheter is referred to as pulmonary capillary
wedge pressure and is close to left atrial pressure and is an index of preload
on the left ventricle

40. INTRAVENTRICULAR PRESSURE CURVE
Ejection phase
Closure of SLV 4
SLV opens
Protodiastole 3 5
Isovolumetric Relax
Isovolumetric contr
Right Ventricular pressure changes
Similar to LV pressure changes
Peak pressure during systole is 25 mm Hg
Diastole pressure 2 mm Hg 6
AV valves open
Atrial systole VD 2 7 1
Closure of AV Valve AS VS VD

41. AORTIC PRESSURE CURVE 1 – SLV open 2 – Max. Ej. Phase
2-3 – Reduced Ej. Phase
– End of Vent. Diastole
SLV closes
– Small positive wave 2
120 5 3
100 4
Incisura 1 80 VS VD

42. VENTRICULAR VOLUME CHANGES
120 I V R I V C A S
60ml VS VD

44. Blood pressure rises during systole and falls during diastole.
The difference between the peak and the trough is called the pulse pressure

45. A is atrial systole.
Causes the A wave in atrial pressure.
Helps fill the ventricle.

46. B is Isovolumic contraction.
It starts with mitral valve closure
Both the aortic and mitral valves are closed so the ventricle’s volume is constant.

47. C is rapid ejection period.
It starts with aortic valve opening.
Ventricular pressure leads aortic.
Flow out of the ventricle is accelerating.

48. D is the reduced ejection period.
Aortic pressure leads ventricular.
Flow out of the ventricle is decelerating.

49. E is the isovolumetric relaxation period.
Begins with aortic valve closure.
Ventricular volume is constant
Gives rise to the V wave as blood accumulate in the atrium

50. F is the rapid filling period.
Begins with opening of the mitral valve.
Gives rise to the y wave as blood accumulated in the atrium rushes into the ventricle. y

51. G is the reduced filling period(diastasis).
Ventricular filling is now in equilibrium with venous return.

52. Events on the right side are the same except the pressure is lower.

53. Left ventricular end-diastolic volume (LVEDV)
Left ventricular end-systolic volume (LVESV)
stroke volume= LVEDV-LVESV
 cardiac output = stroke volume x heart rate

54. Since there are no valves between the atrium and veins atrial pressure is essentially equal to venous pressure.
Notice the venous pressure trace with A, C and V waves

55. Ventri Q1. Ventricular filling begins at point?
D and B
Q1. Ventricular filling begins at point?
Q2. Closure of mitral valve begins at point?

56. The volume and pressure tracings for the left ventricle of a 34 year old male are shown below. Which of the following points correspond to aortic valve opening? A B C D E

57. PRESSURE-VOLUME LOOPS

58. 1 → 2 (isovolumetric contraction)
1 → 2 (isovolumetric contraction). The cycle begins during diastole at point 1. The left ventricle is filled with blood from the left atrium and its volume is about 140 mL (end-diastolic volume). Ventricular pressure is low because the ventricular muscle is relaxed. On excitation, the ventricle contracts and ventricular pressure increases. The mitral valve closes when left ventricular pressure is greater than left atrial pressure. Because all valves are closed, no blood can be ejected from the ventricle (isovolumetric).
b. 2 → 3 (ventricular ejection). The aortic valve opens at point 2 when pressure in the left ventricle exceeds pressure in the aorta. Blood is ejected into the aorta, and ventricular volume decreases. The volume that is ejected in this phase is the stroke volume. Thus, stroke volume can be measured graphically by the width of the pressure-volume loop. The volume remaining in the left ventricle at point 3 is end-systolic volume
c. 3 → 4 (isovolumetric relaxation). At point 3, the ventricle relaxes. When ventricular pressure decreases to less than aortic pressure, the aortic valve closes. Because all of the valves are closed again, ventricular volume is constant (isovolumetric) during this phase.
d. 4 → 1 (ventricular filling). Once left ventricular pressure decreases to less than left atrial pressure, the mitral (AV) valve opens and filling of the ventricle begins. During this phase, ventricular volume increases to about 140 mL (the end-diastolic volume

60. Q.On the graph showing left ventricular volume and pressure, isovolumetric contraction occurs from point
(A) 4 → 1
(B) 1 → 2
(C) 2 → 3
(D) 3 → 4
Q The aortic valve closes
at point
(A) 1
(B) 2
(C) 3
(D) 4

61. Q The first heart sound corresponds to point
(B) 2
(C) 3
(D) 4

62. If the heart rate is 70 beats/min, then the cardiac output of this ventricle is closest to
(A) 3.45 L/min
(B) 4.55 L/min
(C) 5.25 L/min
(D) 8.00 L/min
(E) 9.85 L/min
140 70

63. The ejection fraction equals
b. 0.55
c. 0.60
d. 0.65
e. 0.70

67. Mechanically Altered States
Preload
Afterload
Increased contractility
Exercise
Heart failure
Aortic stenosis
Aortic insufficiency
Mitral stenosis
Mitral insufficiency