Cardiac Cyle 🫀

Question 1

Atrial Systole (Late Diastole)

Answer 1

• Duration: 0.1 s
• Ventricular Volume: ↑ to 130 ml (EDV)
• Ventricular Pressure:
• To 9 in LT ventricle
• To 4 in RT ventricle
• Valves:
• AV valves: Opened
• Semilunar valves: Closed
• Heart Sounds: Not heard
• Aortic Pulmonary Pressure:
• ↓ to minimum
• = 80 mmHg (aorta)
• = 10 mmHg
• Atrial Pressure: +ve a wave due to limited blood flow back into veins due to contraction of cardiac muscle around orifices
• ECG: P wave precedes this phase

Question 2

Isovolumetric Contraction Phase

Answer 2

• Duration: 0.05 s
• Ventricular Volume: Constant
• Ventricular Pressure:
• ↑ rapidly
• To 80 in LT ventricle
• To 10 in RT ventricle
• Valves:
• AV valves: Sudden closure
• Semilunar valves: Closed
• Heart Sounds: 1st (continue)
• Aortic Pulmonary Pressure: ↑ to 120 mmHg; to 25 mmHg
• Atrial Pressure: +ve C wave due to bulging of cusps
• ECG: QRS complex

Question 3

Rapid Ejection Phase

Answer 3

• Duration: 0.1 s
• Ventricular Volume: ↓ rapidly
• Ventricular Pressure:
• ↑ to 120 in LT ventricle
• ↑ to 25 in RT ventricle
• Valves:
• AV valves: Closed
• Semilunar valves: Opened
• Heart Sounds: Not heard
• Aortic Pulmonary Pressure: Momentum keeps blood moving forwards
• Atrial Pressure: -ve X-wave due to downward pull of cusps
• ECG: Beginning of T wave

Question 4

Reduced Ejection Phase

Answer 4

• Duration: 0.15 s
• Ventricular Volume: ↓ to 60 ml (ESV)
• Ventricular Pressure: ↓
• Valves:
• AV valves: Closed
• Semilunar valves: Opened
• Heart Sounds: Not heard
• Aortic Pulmonary Pressure: Near end of this phase: dicrotic notch
• Atrial Pressure: +ve V wave due to ↑ VR

Question 5

Isovolumetric Relaxation Phase

Answer 5

• Duration: 0.1 s
• Ventricular Volume: Constant
• Ventricular Pressure: ↓
• Valves:
• AV valves: Closed
• Semilunar valves: Sudden closure
• Heart Sounds: 2nd
• Aortic Pulmonary Pressure: Dicrotic wave due to bouncing of blood upward due to elasticity of the valve
• Atrial Pressure: +ve V wave due to ↑ VR
• ECG: T wave

Question 6

: Rapid Filling Phase

Answer 6

• Duration: 0.1 s
• Ventricular Volume: ↑ rapidly (80% of blood pass from atria to ventricle passively)
• Ventricular Pressure: ↓ as ventricles relax to accommodate more blood
• Valves:
• AV valves: Opening
• Semilunar valves: Closed
• Heart Sounds: 3rd (not heard except in children)
• Aortic Pulmonary Pressure: ↓ as blood flow to periphery
• Atrial Pressure: -ve y wave due to rapid flow of blood from atria to ventricle

Question 7

Reduced Filling Phase

Answer 7

• Duration: 0.2 s
• Ventricular Volume: ↑ slowly
• Ventricular Pressure: Little rise
• Valves:
• AV valves: Opened
• Semilunar valves: Closed
• Heart Sounds: Not heard
• Aortic Pulmonary Pressure: Little rise
• Atrial Pressure: Little rise