Clinical EKG made simple
.
*The height = voltage = how strong is the muscle contracts.
*Duration : how long or short the conduction is , look for electrolyte imbalance (especially
potassium K+j and blocks.
for example p wave is prolonged in left atrial enlargement (LAE), PR interval is shortened
in WPWS and prolonged in av-block 1st degree
——————————————————————————
Some basics about conduction system and heart axis:
Pacemaker cells are found at various sites throughout the conducting system,
with each site capable of independently sustaining the heart rhythm. The rate of
spontaneous depolarisation of pacemaker cells decreases down the conducting
system because the richness in sodium funny channels responsable for
automaticity decreases from SAN to purkinji:
1-SA node (60-100 bpm)thats’s why it’s the pacemaker because it has the
highest automaticity and has the richest amount of funny Na+ channels
responsible for automaticity.
2-AV node (40-60 bpm)
3-Ventricles (20-40 bpm, less than 40)
Under normal conditions, subsidiary pacemakers (alternative electric boxes)
are suppressed by the more rapid impulses from the main electricity
generator (SAN rhythm) . Junctional and ventricular escape rhythms arise
when the rate of supraventricular impulses arriving at the AV node or ventricle
is less than the intrinsic rate of the ectopic pacemaker.
SAN structure has two types of cells one inside and responsible for
generating the impulse and one outside responsible for propagation of the
impulse (just like a car you enter key to turn it on and ignite engine then press
on accelerator to go off ) if the car can’t be turned on it’s sinus arrest (Sinus
pause or absence is due either to failure to generate a sinus node
depolarization or failure of a generated sinus node depolarization to exit the
sinus node and enter the atria.)
-When engine is ignited but it stops suddenly then work suddenly , slower
then faster , bradycardia then tachycardia this is called sick sinus syndrome.
propagation slowed down then the sympathetic system started to say wake
up SAN and started to speed up u get TC then SAN goes back to sleep again because it’s getting sick or tired and cycle repeats itself.
(most commonly seen in postoperative congenital heart disease).
, In sinus arrest the back up system is taking over (escapes rythmes)
-Sinus pause mostly in the young people with high vagal tone in severe anxiety pain fear Or in hypoxia .
-Sinus arrest :It’s because of ischemia ,CHF,Inflammatory process,Rheumatic diseases ,Infiltrative disease to the
To note that sinus arrest is more than 2-3 seconds pause is less
aess asec.naitisss.ec
bigsoas
s
sinusarrest 3sec
EKG interpretation system organization:
1-rythm (sinus or not).
2-rate (tachy or bradycardia).
3-axis (right or left axis deviation).
4-waves and intervals (axis,duration,amplitude,morphology) :
(P wave, PR interval, QRS complex, ST segment, QT interval ,T wave) .
1-Is it sinus rythm or not?:
Look at p wave in DII if positive then it is sinus (or if it is positive in DI and AVF). Because sinus node vector is directed downward and
leftward like in the figures below:
2-Heart rate: normal is between 50 or 60 to 100 bpm
1-If regular rate:divide 300 by number of big boxes between 2 R waves
(Ex.We have tachycardia if there are less than 3 boxes between 2 R waves,and bradycardia if 5 or 6 boxes between 2 R waves)
2-If irregular rate: each big box is 5 small boxes,each small box is 0,04sec ,(note that in the ekg strip every 5 boxes are grouped
together) , 5X0,04=0,2 seconds for the big box and 1 sec for the group of 5 boxes, so either we calculate number of R waves in 30 big
boxes then multiply by 10 ( 30 X 0,2 = 6 seconds multpiled by 10 we have 60 sec) or we count the QRS complexes in 10 seconds and
multiply by 6 .
.
*The height = voltage = how strong is the muscle contracts.
*Duration : how long or short the conduction is , look for electrolyte imbalance (especially
potassium K+j and blocks.
for example p wave is prolonged in left atrial enlargement (LAE), PR interval is shortened
in WPWS and prolonged in av-block 1st degree
——————————————————————————
Some basics about conduction system and heart axis:
Pacemaker cells are found at various sites throughout the conducting system,
with each site capable of independently sustaining the heart rhythm. The rate of
spontaneous depolarisation of pacemaker cells decreases down the conducting
system because the richness in sodium funny channels responsable for
automaticity decreases from SAN to purkinji:
1-SA node (60-100 bpm)thats’s why it’s the pacemaker because it has the
highest automaticity and has the richest amount of funny Na+ channels
responsible for automaticity.
2-AV node (40-60 bpm)
3-Ventricles (20-40 bpm, less than 40)
Under normal conditions, subsidiary pacemakers (alternative electric boxes)
are suppressed by the more rapid impulses from the main electricity
generator (SAN rhythm) . Junctional and ventricular escape rhythms arise
when the rate of supraventricular impulses arriving at the AV node or ventricle
is less than the intrinsic rate of the ectopic pacemaker.
SAN structure has two types of cells one inside and responsible for
generating the impulse and one outside responsible for propagation of the
impulse (just like a car you enter key to turn it on and ignite engine then press
on accelerator to go off ) if the car can’t be turned on it’s sinus arrest (Sinus
pause or absence is due either to failure to generate a sinus node
depolarization or failure of a generated sinus node depolarization to exit the
sinus node and enter the atria.)
-When engine is ignited but it stops suddenly then work suddenly , slower
then faster , bradycardia then tachycardia this is called sick sinus syndrome.
propagation slowed down then the sympathetic system started to say wake
up SAN and started to speed up u get TC then SAN goes back to sleep again because it’s getting sick or tired and cycle repeats itself.
(most commonly seen in postoperative congenital heart disease).
, In sinus arrest the back up system is taking over (escapes rythmes)
-Sinus pause mostly in the young people with high vagal tone in severe anxiety pain fear Or in hypoxia .
-Sinus arrest :It’s because of ischemia ,CHF,Inflammatory process,Rheumatic diseases ,Infiltrative disease to the
To note that sinus arrest is more than 2-3 seconds pause is less
aess asec.naitisss.ec
bigsoas
s
sinusarrest 3sec
EKG interpretation system organization:
1-rythm (sinus or not).
2-rate (tachy or bradycardia).
3-axis (right or left axis deviation).
4-waves and intervals (axis,duration,amplitude,morphology) :
(P wave, PR interval, QRS complex, ST segment, QT interval ,T wave) .
1-Is it sinus rythm or not?:
Look at p wave in DII if positive then it is sinus (or if it is positive in DI and AVF). Because sinus node vector is directed downward and
leftward like in the figures below:
2-Heart rate: normal is between 50 or 60 to 100 bpm
1-If regular rate:divide 300 by number of big boxes between 2 R waves
(Ex.We have tachycardia if there are less than 3 boxes between 2 R waves,and bradycardia if 5 or 6 boxes between 2 R waves)
2-If irregular rate: each big box is 5 small boxes,each small box is 0,04sec ,(note that in the ekg strip every 5 boxes are grouped
together) , 5X0,04=0,2 seconds for the big box and 1 sec for the group of 5 boxes, so either we calculate number of R waves in 30 big
boxes then multiply by 10 ( 30 X 0,2 = 6 seconds multpiled by 10 we have 60 sec) or we count the QRS complexes in 10 seconds and
multiply by 6 .
