ekg club repolarization
DESCRIPTION
Made available to EKG Club for educational purposes. Slides developed by Hopenfeld.TRANSCRIPT
Activation and Repolarization
OverviewOctober 2008
Heart is an “Electrically” Controlled Pump
All normal ECG waveforms result from coordinating the pump• coordinating contraction of the pump
(QRS complex)• coordinating relaxation of the pump (ST
segment/T wave/U wave)
0 50 100 150 200 250900
950
1000
1050
1100
1150
contract
hold relax
Contraction Sequence
Inside of the heart contracts inwards • known as circumferential shortening
Diastole End Systole
Contraction Sequence
And longitudinally
Diastole End Systole
Contraction Sequence
Then, outside of the heart twists/wrings
Contraction Sequence
In addition to the inside outside sequence, there is • an anterior posterior sequence • apical (bottom) basal (top) sequence
Relaxation Sequence
(Mostly) opposite to contraction Outside of the heart untwists
• associated with rapid suction of blood back into heart
Then inside of the heart relaxes Basal (top) to apical (bottom)
relaxation However, the anterior posterior
contraction sequence is the same (not opposite) as the relaxation sequence
Electrical Sequences
Follow (cause!) mechanical sequences
Electrical activation (depolarization) of the heart is from the inside out
Repolarization of the heart is from the outside in (T wave)
Activation
TOP
MID
BOT
In vivo canine heart
Wigger’s Diagram
Heart Cells and Dominoes
Dominoes all standing = no current
V=0+ -
Heart Cells and Dominoes
They start falling – current flows
V=5+ -
Heart Cells and Dominoes
All down – no current flows
V=0+ -
Heart Cells and Dominoes
Some start standing – current flows
V=5+ -
Heart Cells and Dominoes
Notice that voltage depends on wherewe measure
V=-5 +-
What about activation potentials?
Before wave reaches epi.
After wave reaches epi. - simulations
What about activation potentials?
Activation & Repolarization
Comments?