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Cardiac Cycle Phases, Valvular Events, and Heart Sounds S1-S4

Phases of systole and diastole, isovolumetric periods, ejection/filling, and physiologic basis of S1-S4 heart sounds for clinical exams.

12 cards· by GuruOwl

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  1. 01
    The cardiac cycle lasts approximately 0.8 seconds at a heart rate of 75 beats per minute.
    This duration accounts for both systole and diastole.
    Flashify::Medical::Cardiovascular::Physiology
  2. 02
    Atrial systole contributes approximately 20-30 percent of total ventricular filling.
    The majority of filling occurs passively during early diastole.
    Flashify::Medical::Cardiovascular::Physiology
  3. 03
    The first heart sound (S1) is produced by the closure of the mitral and tricuspid (AV) valves.
    S1 marks the beginning of isovolumetric contraction.
    Flashify::Medical::Cardiovascular::Physiology
  4. 04
    During isovolumetric contraction, ventricular pressure rises rapidly while all four heart valves remain closed and volume remains constant.
    This phase occurs immediately after the QRS complex.
    Flashify::Medical::Cardiovascular::Physiology
  5. 05
    The second heart sound (S2) is produced by the closure of the aortic and pulmonic (semilunar) valves.
    S2 marks the end of ventricular systole and the start of diastole.
    Flashify::Medical::Cardiovascular::Physiology
  6. 06
    Physiologic splitting of S2 occurs during inspiration due to delayed closure of the pulmonic valve.
    Inspiration increases venous return to the right heart, prolonging RV ejection time.
    Flashify::Medical::Cardiovascular::Physiology
  7. 07
    The S3 heart sound occurs during early diastole due to rapid ventricular filling and is associated with volume-overload states.
    It is normal in children and young adults but often pathologic (e.g., HF) in older adults.
    Flashify::Medical::Cardiovascular::Physiology
  8. 08
    The S4 heart sound occurs in late diastole and is caused by atrial contraction into a stiff, non-compliant ventricle.
    S4 is always pathologic in adults over age 40.
    Flashify::Medical::Cardiovascular::Physiology
  9. 09
    Right-sided heart murmurs generally increase in intensity during inspiration.
    Inspiration decreases intrathoracic pressure, increasing venous return to the right side of the heart.
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  10. 10
    The dicrotic notch on an arterial pressure tracing corresponds to the closure of the aortic valve (S2).
    It represents a brief rise in pressure as the aortic valve snaps shut.
    Flashify::Medical::Cardiovascular::Physiology
  11. 11
    A normal left ventricular ejection fraction (LVEF) is approximately 55-70 percent.
    EF = (Stroke Volume / End-Diastolic Volume) x 100.
    Flashify::Medical::Cardiovascular::Physiology
  12. 12
    On an ECG, the P wave precedes atrial systole, while the QRS complex initiates ventricular systole.
    Electrical depolarization must precede mechanical contraction.
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