- The fourth charactersitic of the
heart muscle;
- Specialised conducting systme to
ensure that excitation travels to all the heart
muscle fibres and in a certain pre-defined
pattern.
Conducting Pathways include:
- Anterior, Middle and
Posterior Internodal Atrial bundles
- A-V node - only
pathway from atria to AV bundle; slow conduction
and a long absolute refractory period
- A-V bundle
- Right and Left Bundle
Branch
- Purkinje Fibres
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Heart Block
- Failure of impulses arising at
Atria to reach Ventricles
- Blockage at AV node or Bundle
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Two Main types of
Heart Block
- Partial -
When some impulses fail to pass, This can be
divide into : Regular - ratio
between atrial and ventricular rhythm is
constant; Irregular - no fixed
ratio.
- Complete -
when all atrial impulses fail to
reach the ventricles; atria and ventricles beat
at their own rhythm and ther is no co-ordination.
Another classification for heart block
divides into three:
- 1st degree: delay
in conduction
- 2nd degree: partial
block
- 3rd degree: complete
block
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