Intraventricular Conduction: Difference between revisions
→Mechanisms of aberrant conduction
| Line 62: | Line 62: | ||
Mechanisms of aberration: | Mechanisms of aberration: | ||
#Phase 3 aberration | #Phase 3 aberration | ||
#Phase 4 abberation or deceleration dependant | |||
#Acceleration dependant | #Acceleration dependant | ||
#Retrograde invasion | #Retrograde invasion | ||
| Line 69: | Line 69: | ||
===Phase 3 Aberration=== | ===Phase 3 Aberration=== | ||
Phase 3 aberration occurs when conduction fibers receive a new impulse, before they have fully repolarized. A premature impulse is encroaching on the refractory period of the bundle branch. This is a physiological phenomenon. This can sometimes be observed at the start of paroxysmal supraventricular tachycardias or in a long-short sequence in which the refractory period of the long sequence is prolonged. | Phase 3 aberration occurs when conduction fibers receive a new impulse, before they have fully repolarized. A premature impulse is encroaching on the refractory period of the bundle branch. This is a physiological phenomenon. This can sometimes be observed at the start of paroxysmal supraventricular tachycardias or in a long-short sequence in which the refractory period of the long sequence is prolonged. This is also called Ashman phenomenon. | ||
===Phase 4 Aberration or deceleration dependant=== | |||
Phase 4 aberration only occurs after prolonged pause. During such a pause (e.g. in second degree AV block) the Purkinje fibers can depolarize spontaneously. As their membrane potential becomes more positive, the conduction velocity decreases and can even be blocked altogether. This is usually a pathological response, but can be normal at very low heart rates (e.g. 40 bpm) | |||
===Acceleration dependant=== | ===Acceleration dependant=== | ||
A small increase in rhythm resulting in aberrancy due to an abnormal response of tissue that has diminished excitability. | A small increase in rhythm resulting in aberrancy due to an abnormal response of tissue that has diminished excitability. | ||
===Retrograde Concealed Conduction=== | ===Retrograde Concealed Conduction=== | ||
| Line 83: | Line 83: | ||
<biblio> | <biblio> | ||
#Garcia isbn=0763722464 | #Garcia isbn=0763722464 | ||
# | #Wellens isbn=9781416002598 | ||
</biblio> | </biblio> | ||
}} | }} | ||
[[Category:ECG Textbook]] | [[Category:ECG Textbook]] | ||