Cardiac cycle, pressure-volume loops and heart sounds
The phases of the cardiac cycle with normal chamber pressures, how pressure-volume loops show preload, afterload, contractility and valve lesions, and how the cycle explains heart sounds, the JVP waveform, arterial pulses and bedside manoeuvres.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The cycle has four valve events (mitral closure, aortic opening, aortic closure, mitral opening) dividing it into filling, isovolumetric contraction, ejection and isovolumetric relaxation.
- A pressure-volume (PV) loop plots LV pressure against volume for one beat. Width is stroke volume, area is stroke work, and the end-systolic and end-diastolic boundaries describe contractility and compliance.
- S1 is AV valve closure; S2 is semilunar valve closure; S3 is rapid filling into a full ventricle; S4 is atrial contraction into a stiff one.
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Sources
- Guyton and Hall Textbook of Medical Physiology (14th ed.)Elsevier (Hall and Hall, 2021), 2021
- Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine (12th ed.)Elsevier (Libby et al., 2022), 2022
- 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertensionEuropean Society of Cardiology and European Respiratory Society (Eur Heart J 2022;43:3618-3731), 2022
- 2025 ESC/EACTS Guidelines for the management of valvular heart diseaseEuropean Society of Cardiology and European Association for Cardio-Thoracic Surgery (Eur Heart J 2025, doi:10.1093/eurheartj/ehaf194), 2025
- 2020 ACC/AHA Guideline for the management of patients with valvular heart diseaseAmerican College of Cardiology and American Heart Association (Circulation 2021;143:e72-e227), 2020
- Last updated
- 14 November 2026
What changed
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