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Cardiac Cycle and Sounds

Cardiac Cycle and Sounds. Prof. K. Sivapalan. Cardiac cycle. Venous blood flows into the atria [collectors]. It fills the ventricles when relaxed - diastole. Ventricular contraction –systole- ejects blood into circulation [pump]. Cardiac cycle usually means ventricular cycle.

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Cardiac Cycle and Sounds

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  1. Cardiac Cycle and Sounds Prof. K. Sivapalan

  2. Cardiac cycle. • Venous blood flows into the atria [collectors]. • It fills the ventricles when relaxed - diastole. • Ventricular contraction –systole- ejects blood into circulation [pump]. • Cardiac cycle usually means ventricular cycle. Cardiac Cycle and Sound

  3. Phases of Cardiac Cycle. • When left ventricle begins contraction, aortic valve remains closed. • Mitral valve closes when ventricular pressure exceeds atrial pressure. • Isovolumetric contraction phase follows.[0.05 sec] • Aortic valve opens when ventricular pressure exceeds aortic pressure. • Ejection phase [0.25 sec]- Blood flows forwards due to the momentum created by the contraction even when ventricular pressure falls below aortic pressure. • Aortic valve closes due to back flow caused by elastic recoil of aorta. • Isovolumetric relaxation phase follows.[0.05 sec] • Mitral valve opens when ventricular pressure falls below atrial pressure- filling phase. [0.45 sec.] Cardiac Cycle and Sound

  4. Pressure changes in atria. • a wave - atrial contraction. • c wave - ventricular contraction, AV valves bulging and/or back pressure. • v wave [raising] -venous blood flow in. • v wave [fall] - blood flow into ventricles. Cardiac Cycle and Sound

  5. Volume changes. • End systolic volume – 50 ml. • Early diastole – filling due to venous pressure. • Atrial systole adds last 30% filling. • End diastolic volume is 120 ml. • ECG, Heart sounds corrilated. Cardiac Cycle and Sound

  6. Muscles and Valves in Heart. • All four valves are in the fibrous skeleton. • Muscles above the skeleton [right] are atria and on the other side ventricles. Cardiac Cycle and Sound

  7. Apex Beat • During ventricular contraction, apex remain in place and thrusts on the chest due to rotation. • The fibrous ring moves left and right. Cardiac Cycle and Sound

  8. Surface anatomy of the heart. • Atria are right to the sternum. • Right ventricle is anterior. • Left ventricle is posterior with one cm above R. ventricle. • Apex: fifth intercostal space, 1 cm medial to MCL • All valves are placed in oblique plane. Cardiac Cycle and Sound

  9. Heart sounds. • Normal heart sounds are produced by vibrations caused by closure of the valves. • Mitral and tricuspid valves- 1st sound. • Aortic and pulmonary valves- 2nd sound. • Rapid filling – 3rd and 4th sounds. • Sounds from each valve is best heard at different places on the chest. Cardiac Cycle and Sound

  10. Abnormal heart sounds. Cardiac Cycle and Sound

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