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Dr. Enas (2009)1 By. 2 Objectives Cardiac Cycle Definition Phases Events, their names & duration Pressure changes  Atria  Ventricles  Aorta Volume.

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Presentation on theme: "Dr. Enas (2009)1 By. 2 Objectives Cardiac Cycle Definition Phases Events, their names & duration Pressure changes  Atria  Ventricles  Aorta Volume."— Presentation transcript:

1 Dr. Enas (2009)1 By

2 2 Objectives Cardiac Cycle Definition Phases Events, their names & duration Pressure changes  Atria  Ventricles  Aorta Volume changes  Ventricles ECG & Cardiac Cycle Heart Sounds & Cardiac Cycle

3 Dr. Enas (2009)3 It is the cardiac events that occur from the beginning of one heart beat to the beginning of the next one.

4 Dr. Enas (2009)4 The cardiac cycle consists of one systole- diastole sequence of the heart,& it lasts about 0.8 sec. It starts by atrial systole (contraction). Followed by ventricular systole then diastole (relaxation) of the whole heart.

5 Dr. Enas (2009)5 ‘Heart’ Dual Pump

6 Dr. Enas (2009)6 What is the meaning of Systole Diastole and

7 Dr. Enas (2009)7 There are seven (7) phases of cardiac cycle: 1- Atrial systole.(0.1 second). Ventricular Systole: divided into 3 phases:- 2- Isovolumetric ventricular contraction.(0.05 sec.). 3- Rapid ventricular ejection.(0.15 sec.). 4- Reduced ventricular ejection.(0.1 sec.). Ventricular Diastole: divided into 3 phases:- 5- Isovolumetric ventricular relaxation.(0.06 sec.). 6- Rapid ventricular filling. (0.1 sec.). 7- Reduced ventricular filling (diastasis) (0.2 sec.).

8 Dr. Enas (2009)8

9 9 1- Atrial Systole In this phase, both atria contract leading to blood evacuation into the ventricles. 1- Atrial pressure:- This initially increases (due to reduction of arterial volume,then decrease again due to evacuation of blood into corresponding ventricle. 2- Ventricular pressure:- This initially increase slightly (due to entry of blood) then drop due to ventricular dilation. 3- Ventricular volume:- Increase slightly due to ventricular dilation. 4- Valves: A-V valves are open while seilunar valves are closed. 5- Aortic Pressure:-Decrease gradually due to continuous blood flow from the aorta to the periphery. 6- Heart sounds: 4 th heart sound is recorded in this phase. 7- ECG :- P wave start about 0.02 before this phase. While main P wave,P-R segment & Q wave occure during it.

10 Dr. Enas (2009)10 2- Isometric (Isovolumetric) ventricular contraction phase This is the early phase of vent. systole in which the ventricle contract but not ejection occurs. Its events include the following :- 1. Ventricular pressure & volume: The ventricles contract isometrically i.e. without shortening of the cardiac muscle.So vent. pressure rises sharply while vent. Volume remain constant 2. Valves: Vent. Press. Become greater than atrial press. Causes closure of A-V valves producing 1 st heart sound while semi lunar valves are still closed. 3. Sound: 1 st heart sound due to sudden closure of A-V valves 4. Atrial pressure: slightly increased due to bulging of A-V cusps into the atria. 5. Aortic pressure: this decrease to a minimum of about 80 mmHg at the end of this phase (diastolic blood pressure). 6. ECG: The Q wave starts about 0.02 second before this phase, while the R &S waves occur during it.

11 Dr. Enas (2009)11 3- Rapid ventricular ejection phase: In this phase, the semilunar valves open &blood is ejected into the great arteries. Its events include : 1. Ventricular volume & pressure : vent. Contract isotonically (i.e cardiac musc. Fibers are shortened).So vent. Volume is rapidly decreased while its pressure is markedly increased to maximum 120 mmHg. 2. Valves: A-V valve are still closed while semilunar valve. Will open b/c vent. Press. Will exceed aortic press. 3. Sound: continuation of 1 st heart sound. 4. Atrial pressure: decreased b/c its widening of its cavity then increase due to its filling by venous return. 5. Aortic pressure: is markedly increased due to ejection of blood to it & reach maxim.120mmHg.(systolic blood pressure) 6. ECG: The S-T segment is present in this phase and T wave start in its late part.

12 Dr. Enas (2009)12 4- Reduced ventricular ejection phase: The event in this phase are a continuation of those occurring in the preceding phase: 1. Ventricular volume:- this is further decreased. 2. Ventricular pressure:- This is slightly decreased due to ejection of most blood in preceding phase 3. Aortic pressure:- is slightly decreased. 4. Valves: still the semilunar valve are open &the AV valves closed. 5. Sound: there are no sound in this phase. 6. Atrial pressure: this is still increasing due to venous return. 7. ECG: this show most of the ascending limb and the top of the T wave.

13 Dr. Enas (2009)13 5- Isovolumetric ventricular relaxation phase: This is the early phase of ventricular distole in W’ventricles relax but no filling occurs. Its events include : 1. Ventricular volume:- remains unchanged 2. Ventricular pressure:- falls sharply (to 0- 5mmHg.) 3. Aortic pressure:- is initially increase (due to elastic recoil of aorta ) then gradually decrease due to continuous flow of blood to peripheral arteries. 4. Valves:- Semilunar valves are suddenly closed & A-V valve is still closed. 5. Sound: the 2 nd heart sound 6. Atrial pressure: this is still increasing due to continuous venous return. 7. ECG: most of the descending limb of the T wave is present in this phase.

14 Dr. Enas (2009)14 6- Rapid ventricular filling phase:- In this is phase, the atrial pressure exceeds the ventricular pressure, so the AV valve open and rapid filling of the ventricles. Its events include : 1. Ventricular volume & pressure: there is initial decrease in pressure due to vent. Relaxation then increase markedly while volume is increased gradually 2. Atrial pressure: initial increase due to rush of blood into ventricles then increase due to venous return. 3. Aortic pressure: still decrease due to continuous flow of blood to the periphery. 4. Valves: the 5. Sound: the 3 rd heart sound. 6. ECG: the early of the T-P segment and the U wave are present in this phase.

15 Dr. Enas (2009)15 7- slow ventricular filling phase: In this is phase, Its events include : 1. Ventricular volume & pressure: these still gradually increase but at a slower rate. 2. Atrial pressure: this is still increasing due to venous return. 3. Aortic pressure: this is still decreasing due to continuouse blood flow from the aortic to the peripheral arteries. 4. Valves: the AV valves are open while the semilunar valve are closed. 5. Sound: there are no sound in this phase. 6. ECG: the late part of the T-P segment and the start of the P wave are present in this phase.

16 Dr. Enas (2009)16 Changes in ventricular pressure& volume in systole& diastole

17 Dr. Enas (2009)17


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