deck_16882703 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.