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Cardiac Cycle - Rapid Filling (Phase
6)
A-V Valves Open
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As the ventricles continue to relax at the end
of phase 5, the intraventricular pressures will at some point fall below
their respective atrial pressures. When this occurs, the AV valves rapidly open and
ventricular filling begins. Despite the inflow of blood from the atria,
intraventricular pressure continues to briefly fall because the ventricles
are still undergoing relaxation. Once the ventricles are completely relaxed,
their pressures will slowly rise as they fill with blood from the atria.
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The opening of the mitral valve causes a rapid fall in
LAP. The peak of the LAP just before the valve opens
is the "v-wave." This is followed by the y-descent
of the LAP. A similar wave and descent are found in the right atrium and in
the jugular vein.
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Ventricular filling is normally silent. When a
third
heart sound (S3) is audible, it may represent tensing of chordae
tendineae and AV ring during ventricular relaxation and filling. This heart sound is
normal in children; but is often pathological in adults and caused by
ventricular
dilation.
Jump to other phases:
Phase 1 - Atrial Contraction
Phase 2 - Isovolumetric Contraction
Phase 3 - Rapid Ejection
Phase 4 - Reduced Ejection
Phase 5 - Isovolumetric Relaxation
Phase 7 - Reduced Filling
RK Revised
04/13/07
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Cardiovascular Physiology Concepts
