Cardiac Cycle and the heart soundss.pptx

Cardiac Cycle and the heart sounds

1. The Cardiac Cycle and myocardial contractility 13- Jun- 23 Physiology of the heart 2

2. The cardiac cycle 13- Jun- 23 Physiology of the heart 3 Events occurring from the beginning of one heart beat to the beginning of the next

3. 13- Jun- 23 Physiology of the heart 4 The cardiac cycle divided into four separate periods two occurring during Diastole Ventricular Filling Period Isovolumetric Relaxation Period two occurring during Systole Isovolumetric Contraction Period Ventricular Ejection Period

4. 13- Jun- 23 Physiology of the heart 5 The cardiac cycle Ventricular Filling Period (VFP) The first phase Occurs during diastole Division Rapid filling Reduced filling

5. Events of the cardiac cycle Rapid ventricular filling At the start of VFP the heart is in a polarized state Ventricular pressures are below atrial pressure AtrioVentricular Valves Open Triscupid valve Mitral valve Semilunar valves closed Aortic valve Pulmonary valve 13- Jun- 23 Physiology of the heart 6

6. Events of the cardiac cycle AtrioVentricular Valves Open Triscupid valve Mitral valve Semilunar valves closed Aortic valve Pulmonary valve 13- Jun- 23 Physiology of the heart 7 Rapid ventricular filling blood moves passively thru the atria past the A- V valves and into the ventricles. Last for about the 1 st 3 rd of the diastole

7. Events of the cardiac cycle Reduced filling As the ventricles continue to fill with blood and expand become less compliant • AtrioVentricular Valves Open Triscupid valve Mitral valve Semilunar valves closed Aortic valve Pulmonary valve 13- Jun- 23 Physiology of the heart 8

8. Events of the cardiac cycle AtrioVentricular Valves Open Triscupid valve Mitral valve Semilunar valves closed Aortic valve Pulmonary valve 13- Jun- 23 Physiology of the heart 9 Reduced filling intraventricular pressures rise reduces the pressure gradient across the AV valves the rate of filling falls.

9. Events of the cardiac cycle AtrioVentricular Valves Open Triscupid valve Mitral valve Semilunar valves closed Aortic valve Pulmonary valve 13- Jun- 23 Physiology of the heart 10 Reduced filling Aortic pressure & pulmonary arterial pressures continues to fall during this period. Last during the mid third of diastole

10. Events of the cardiac cycle During the last 3 rd of diastole Atrial depolarization occurs causes the atria to contract recorded on the ECG as the p wave . Atrioventricular valves open Semilunar valves closed 13- Jun- 23 Physiology of the heart 11

11. Events of the cardiac cycle Atrioventricular valves open Semilunar valves closed 13- Jun- 23 Physiology of the heart 12 Atrial depolarization occurs forces additional blood past the tricuspid and bicuspid valves, filling the ventricles. Account for 20% of ventricular filling Atria acts as “primer pumps”

12. Events of the cardiac cycle All Valves close 13- Jun- 23 Physiology of the heart 13 Isovolumetric Contraction Period (ICP) The second phase begins during systole initiated by the ventricular depolarization Recorded as QRS complex of the ECG

13. Events of the cardiac cycle All Valves close 13- Jun- 23 Physiology of the heart 14 Isovolumetric Contraction Period (ICP) ventricular contraction causes intraventricular pressure to exceeds atrial pressure closing A- V valves But the pressure - Not enough to push open semilunar valves Additional 0.02- 0.03s needed to build sufficient pressure

14. Events of the cardiac cycle All Valves close 13- Jun- 23 Physiology of the heart 15 Isovolumetric Contraction Period (ICP) During this time period ventricular pressure rises rapidly With no change in ventricular volume no ejection occurs Contraction, therefore, is said to be "isovolumic" or "isovolumetric."

15. Events of the cardiac cycle Semilunar Valves open Aortic & pulmonary valves Atrioventricular valves closed Triscupid & mitral valves 13- Jun- 23 Physiology of the heart 16 Ventricular Ejection Period (VEP) The third period is a continuation of the systolic phase Has 2 phases Rapid ejection & Slow ejection Rapid ejection When the interventricular pressures exceed the pressures within the aorta and pulmonary artery > 80mmHg LV & >8mmHg RV

16. Events of the cardiac cycle The pressure differential forces the semilunar valves open and blood is ejected from the ventricles into the arteries rapidly Semilunar Valves open Aortic & pulmonary valves Atrioventricular valves closed Triscupid & mitral valves 13- Jun- 23 Physiology of the heart 17

17. The cardiac cycle Semilunar Valves open 13- Jun- 23 Physiology of the heart 18 Aortic & pulmonary valves Atrioventricular valves closed Triscupid & mitral valve Reduced ejection Approx 0.15- 0.20s after the QRS, ventricular repolarization occurs ( T- wave ) Ventricular active tension decrease & the rate of ejection (ventricular emptying) falls.

18. Events of the cardiac cycle All valves closed 13- Jun- 23 Physiology of the heart 19 Isovolumetric Relaxation Period (IRP ) The final period occurs during diastole As the ventricles relaxes at the end of systole Due to ventricular repolarization (T wave) intraventricular pressures fall & pressures in the outflow tracts increases This causes pressure reversal which closes the semilunar valves

19. Events of the cardiac cycle All valves closed 13- Jun- 23 Physiology of the heart 20 Isovolumetric Relaxation Period (IRP ) For another 0.03- 0.06s Ventricular pressures continue to decrease however, volumes remain constant because all valves are closed Giving rise to the period of isovolumic/isometric relaxation

20. Events of the cardiac cycle Isovolumetric Relaxation Period (IRP ) During this period The intraventicular pressures decrease rapidly back to their low diastolic level And the A- V valves open to begin a new cycle All valves closed 13- Jun- 23 Physiology of the heart 21

21. 13- Jun- 23 Physiology of the heart 22

22. Diagram :Events of the cardiac cycle Phase 1: Rapid filling (6) Phase 2: reduced filling(7) Phase 3: Atrial Contraction (1) Phase 4 Isovolumetric Contraction (2) Phase 5 Rapid Ejection(3) Phase 6: Reduced Ejection(4) Phase 7 Isovolumetric Relaxation (5) occurs during diastole Note that: distole period phase 5,6,7& 1 Systole period:phases 2,3 & 4 13- Jun- 23 Physiology of the heart 23

23. Pressure Changes in the Cardiac Cycle 13- Jun- 23 Physiology of the heart 24

24. 13- Jun- 23 Physiology of the heart 25

25. 13- Jun- 23 Physiology of the heart 26 A graphic analysis of the pumping activity of the work can be given by plotting the volume- pressure which gives diastolic and systolic pressure curves of the left ventricle during the cardiac cycle. The curve follows the changes in volume as the ventricles relaxes and contracts during diastole and systole respectively. Curve can be divided into four stages, a, b, c and d.

26. 13- Jun- 23 Physiology of the heart 27

27. 13- Jun- 23 Physiology of the heart 28 At beginning of phase a- point 4, the mitral valve has just opened at the end of isovolumetric relaxation when the pressure in ventricles become lower than pressure in the atria. The ventricles are at this time the End Systolic Volume (ESV) of about 50ml. The blood flows continuously into the ventricles till the end of phase where the ventricular systole starts and contraction starts. The volume at this time about 130ml and this is the End Diastolic Volume (EDV)

28. 13- Jun- 23 Physiology of the heart 29 At the beginning of b- point 1, the ventricles start contracting with the aortic valve closing almost immediately( 1st heart sound). The ventricles will be contracting against two closed valves hence against a fixed volume (isovolumetric contraction. This continues till the pressure in ventricles exceed that in the aorta which causes the aortic valve to open at point 2.

29. 13- Jun- 23 Physiology of the heart 30 This leads to the period of ejection represented by curve 3. This continues with pressure still building (as the ventricles are still contracting) up till the point when the ventricles start relaxing and the pressure start reducing (with ejection still continuing)

30. 13- Jun- 23 Physiology of the heart 31 At point 3, the pressure in the ventricles become less than in aorta leading to the closing of the aortic valve (2nd heart sound). However, the mitral valve is still closed hence the ventricles will be relaxing against a fixed volume (isovolumetric relaxation) represented by curve d. The volume at point 3 is the ESV. At point 4, the cycle is repeated again

31. 13- Jun- 23 Physiology of the heart 32 Normal heart sounds and their causes Listening with a stethoscope to a normal heart (Auscultation) One hears a sound usually described as Lub, Dub, Lub, Dub The Lub is associated with closure of A-V valves at the beginning of systole First heart sound The Dub is associated with closure of semilunar valves at the end of systole Second heart sound

32. 13- Jun- 23 Physiology of the heart 33 Valves and heart sounds 1 st heart sound: Contraction of ventricles cause sudden back flow of blood against the A- V valves, causing them to bulge towards the atria till the chordae tendinae abruptly stop the back bulging. The tautness of the chordae tendinae and the valves then causes the back surging blood to bounce forward again into respective ventricle Causes blood, ventricular walls and the taut valves to vibrate, vibrations which are heard as sound on chest wall

33. 13- Jun- 23 Physiology of the heart 34 Along with the vibration of the adjacent blood, walls of the heart and major vessels around the heart Duration of the pitch O.14 seconds

34. 13- Jun- 23 Physiology of the heart 35 2 nd Heart sound Due to sudden closure of semilunar valves at end of systole When they close, they bulge backward towards the ventricles, elastic stretch recoils the blood back into arteries causing a short period of reverberation of blood back and forth between artery walls and the valves, and valves and ventricular walls Vibrations transmitted mainly along arteries and this sound is what is heard

35. 13- Jun- 23 Physiology of the heart 36 1 st sound duration about 0.14 seconds 2 nd sound about 0.1 seconds Difference mainly because semi lunar valves more taut 2 nd sound has higher frequency

36. 13- Jun- 23 Physiology of the heart 37 3 rd Heart sound Is a weak rumbling sound at the beginning of middle third of diastole Thought due to oscillation of blood back and forth between the walls of ventricles initiated by inrushing blood Very low frequency and may not be heard by the ear

37. Pressure Changes in the Cardiac Cycle 13- Jun- 23 Physiology of the heart 38

38. 13- Jun- 23 Physiology of the heart 39 4 th heart sound Is an atrial heart sound Cannot be heard via stethoscope mostly Occurs when atria contract Inrushing of blood into ventricles

39. Relationship between the ecg, cardiac cycle and heart sounds Ist heart sound Closure of A-V valves When ventricles contracts 2 nd heart sound Closure of semilunar valves When pressure inside vessels exceeds intraventricular pressures 3 rd heart sound Inrushing blood from atria 4 th heart sound Atrial contraction 13- Jun- 23 Physiology of the heart 40

40. 13- Jun- 23 Physiology of the heart 41 Valvular lessions Rheumatic valvular lessions Most valvular lessions due to rheumatic fever Autoimmune disease destroying heart valves Begins with streptoccoci infection caused by group A hemolytic streptoccoci Initially bacteria causes sore throat, scarlet fever and/or ear infection Bacteria produces several proteins where the body produces antibodies against

41. 13- Jun- 23 Physiology of the heart 42 The antibodies react not only with the streptococcal protein but also with other protein tissues of the body often causing severe immunological damage This reactions continue to take place as long as the antibodies persist in body – upto one year or more Degree of vulvular damage dependent on concentration and persistance of the antibodies

42. 13- Jun- 23 Physiology of the heart 43 Large hemorrhagic, fibrinous , bulbous lesions grow along the inflamed edges of heart valves Mitral valve most seriously affected followed by the aortic valve Right heart valves less affected The valves may scar and if this is extensive and blood may be unable to flow through them Said to be stenosed

43. 13- Jun- 23 Physiology of the heart 44 At times may be unable to close as the ventricles contract hence regurgitation of blood Stenosis may also be congenital

44. 13- Jun- 23 Physiology of the heart 45 Heart murmur Abnormal heart sounds Systolic Murmur In aortic stenosis, blood ejected through a very small fibrous opening of aortic valve Due to high resistance to ejection, the blood pressure in left ventricle may rise up to 300mmHg while pressure in aorta is still normal

45. 13- Jun- 23 Physiology of the heart 46 Thus , a nozzle effect is created during systole with blood jetting at tremendous velocity through small opening in the valve Causes severe turbulence of blood in root of the aorta causing intense vibration The sound is harsh and in severe stenosis may be so loud it can be heard several feet away Vibrations may also be felt with hand on upper and lower neck, a phenomenon known as “thrill”

46. 13- Jun- 23 Physiology of the heart 47 Diastolic Murmur of Aortic Regurgitation No abnormal sound heard in systole During diastole, blood flows back into ventricles from the aorta causing a “blowing” murmur of relatively high pitch with swishing quality heard maximally over the left ventricle

47. 13- Jun- 23 Physiology of the heart 48 Systolic murmur or mitral regurgitaion Blood flows into left atrium during systole Causes high frequency blowing sound as in aortic regurgitation but occuring in systole Heard to hear the sound since left atrium deep in chest cavity