2. DR. ZAHOOR ALI SHAIKH CARDIOVASCULAR SYSTEM LECTURE - VII

3. CARDIAC CYCLE

4. Cardiac events occurring during one beat (systole & diastole) are repeated during the next beat Cardiac cycle time : 0.8 second when heart rate is 75 beats per minute.

5. We will discuss mechanical & electrical changes during Cardiac Cycle Mechanical changes: 1.Phases of cardiac cycle 2.Heart sounds 3.Pressure changes during cardiac cycle 4.Volume changes during cardiac cycle Electrical Changes 5.Electrocardiogram (ECG)

6. PHASES OF CARDIAC CYCLE

7. Atrial systole: 0.1 second Atrial diastole : 0.7 seconds  Ventricular systole : 0.3 seconds  Ventricular diastole : 0.5 seconds

8. Ventricular events Ventricular systole 1.Isovolumetric contraction 2.Ejection phase Rapid ejection Slow ejection Protodiastolic phase Ventricular Diastole 1.Isovolumetric relaxation phase 2.Filling phase Rapid filling Slow filling Last rapid filling

11. Q: Which Valves are open/closed during Isovolumetric contraction phase of cardiac cycle? A:All Valves are closed (AV valves & Semilunar Valves)

12. Q:Time for ventricular systole? A:0.3 Sec Q: Time for Ventricular Diastole? A: 0.5 Sec Q:Time for Cardiac Cycle? A: 0.8 Sec