Pack Flashcards
What are the cases of deflection in the ECG?
Like towards like = positive deflection So, postive charge (depolarization) toward the positive electrode = positive deflection
When is the main thing that we focus on in a lead?
The position of the positive electrode (its the one that measures)
What makes up einthoven’s triangle?
The first three leads (I, II, III)
What is the position of lead I?
The postive electrode is at the left arm, and the negative is at the right (remember the first photo)
What is the position of lead II?
Postive electrode on the left leg, Negative electrode on the right arm (remeber the second photo that he showed us)
What is the position of lead III ?
Postive electrode at the left leg, Negative electrode at the left shoulder.
What lead is the usually the best view of the heart?
Lead II, bc it shows us the depolariztion of the apex of the heart.
What is the p wave?
Results from the movement of a wave of depolarization as the AP spreads away from the SA node throughout the atria (at 1 m/s).
What is the PQ interval?
Is the time of atrial depolarization plus the time of the passage of the action potential through the av node.
What is QRS?
QRS reflects the steps of ventricular depolarization.
(bc it is 3 steps)
What is the ST segment?
The ST segment reflects the period of time that the ventricles are fully depolarized during the plateau phase of the ventricular action potential.
What is the T wave?
The T wave represents ventricular repolarization.
What is the QT interval?
The QT interval represents the period of time from the beginning of ventricular depolarization to the end of ventricular repolarization
What is a mnemonic to memorize P wave, PQ, QRS, ST, T wave, QT in that order?
Pretty People Quickly Run Straight Towards QTs”
P wave: Pretty
PQ interval: People Quickly
QRS complex: Run
ST segment: Straight
T wave: Towards
QT interval: Qt’s
What is the Q deflection of the QRS complex?
It is a small negtive deflection on the ECG bc of the spreading of the AP from the left ventricle (where the postive electrode is located) to the right ventricle (away from the postive electrode).
What is the R wave of the QRS complex? Why is there a sharp spike in the ECG?
Is the segment where the early ventricular depolarization occurs
The strong spike in the ECG is due to the fact that LV is more muscular than the RV, so it “steals” more electricity and takes it towards the postive electrode.
What is the S wave of the QRS complex? Why is there a sharp spike downwards in the ECG?
The depolarization reaches the purknjie fibers and therefore goes up the walls of the heart (away from the postive electrode) causing a sharp spike downwards on the ecg.
What is the t wave? Why does it have a postive deflection?
The repolarization of the ventricles.
It has a postive deflection bc the negative charges are moving away from the electrode.
What is the duration of the pq/pr interval?
0.12-0.2 seconds
What is the duration of the qt interval?
< 400ms
What is the QT interval?
From Q deflection, till T wave.
From the start of venticular depolarization, till the end of venticular repolarization,
What takes place during th QT segment? Diatole or systole?
Venticular systole
What is the PQ/PR segement?
The period of time between the end of p wave, and begining of Q deflection.
The time that the AP takes to pass through the AV node.
What is the duration of the ST segment?
Lasts about 120 ms
What is a cause of prolongation of the PQ interval
may suggest damage to the atrial
conducting pathways or slowing of conduction via the AV node.
What is a cause of prolongation of the QT interval
myocardial damage, coronary
ischemia, conduction abnormalities as well as by genetic syndromes
What is a common cause of ST segment elevation?
Myocardial
Infarction
What is a common cause of ST segment depression?
common during angina for example
due to ischemia/coronary insufficiency.
What is the R-R interval?
time between successive heart beats
How do you measure the heart rate based on the R-R interval?
Heart rate (beats per min) = 60 / R-R interval (in sec).
What is the TP segment?
The period between the T wave and the start of the new P wave.
The period of diastole
Where are the limb leads placed?
Left and right wrists and left and right ankles
What is the signifcance of the 4th lead
it is placed on the right ankle and acts as a neutral lead to bridge the conncection
What are the electrode positions for the avR?
avR
right arm+ve
left arm -ve
left foot -ve
What are the electrode positions for the avL?
Left arm is +ve,
right arm is -ve,
left foot is -ve.
What are the electrode positions for the avF?
Left foot is +ve
Right and left arm -ve
what are the frontal leads?
In what plane do they record?
Lead I
Lead II
Lead III
avR
avL
avF
Record in: Frontal plane
What are the precordial leads?
How do they record?
What is unique about them?
Special: All Precordial leads are positive.
Share a common negative
(Wilson’s central terminal)
record electrical activity in a
transverse plane through the
heart.
What are the angles of the augmented leads?
avR: -150
avL= -30
avF=+90
How many seconds does the ECG trace cover?
10 seconds of time?
What do the top 3 sets trace?
2.5 seconds from each of the 12 leads
What do the bottom 3 sets trace?
some chosen leads that are traced for the whole 10 second period
(V1, Lead II and V5 over a 10 second period in this example)
What are the leads that look at the heart inferiorly?
aVF bc inferior has F
II, III (bc they are small numbers)
Pia bc pia matter is on the bottom
RCA bc right is deoxygenated, so inferior to oxygenated
What are the leads that look at the heart lateraly?
bc it is lats, so, strong, so V5 V6, aVL and Lats, I Looks like an L
and the Lc 500 has a strong engine so lats LCx
What are the leads that look at the heart anteriorly?
V3 and V4 bc it is higher than septal
Lad bc the v3 and v4 will be your daily driver
What is the septal view?
