Chapter 7: Axis Flashcards
Axis refers to the _________ of the ________ of ______________.
direction, movement, depolarization
p. 203
We can demonstrate the general direction of the movement of depolarization by…
…using a vector.
p. 204
______________ of the ventricles and their ___________ is represented by the QRS complex.
Depolarization, contraction
p. 205
If we add up all the small _______ of ventricular depolarization (considering both _________ and _________), we have one large “____ ___ ______” that represents the general direction of ventricular depolarization.
vectors, direction, magnitude
“Mean QRS Vector”
(p. 207)
By convention, we consider the origin of the Mean QRS Vector to be the __ ____, so the ____ of the vector is always the __ ____.
AV Node, tail, AV Node
p. 207
Since the depolarization vectors of the thicker left ventricle are larger, the Mean QRS Vector points more toward the ____.
left
p. 207
The limb leads are used to determine the position (“____”) of the mean QRS Vector in the _______ plane.
Axis, frontal
p. 209
The Vector normally points ________ and to the patient’s ____, that is, between _ and __ degrees.
downward, left
0, 90
(p. 209)
The axis of the heart is simply the Mean QRS Vector when located by degrees in the frontal plane. Note that 0 degrees is on the patient’s ____, that the lower half of the circle is “________” degrees, and that axis is often denoted in the medical literature as “_”, as in “A = 30 degrees”, and it may be called __________ ____.
left, positive, A, electrical axis
p. 209
In obese individuals the increased __________ _______ often pushes the diaphragm upward so the position of the displaced heart may be called “__________ _____”.
abdominal pressure, horizontal heart
p. 210
With hypertrophy of one ventricle, the greater depolarization activity of the hypertrophied side displaces the Mean Vector…
…toward the hypertrophied side.
p. 211
In a myocardial infarction, there is a necrotic area of the heart that has lost its _____ ______ and does not __________. The unopposed vectors from the other side draw the Mean Vector…
…blood supply, depolarize.
…away from the infarct.
p. 212
“Axis” is the Mean QRS Vector when given in _______, and the normal axis range is _ to __ degrees in the _______ plane.
degrees, 0 to 90, frontal
p. 213
Lead I uses the left arm as the _______ electrode and the right arm as the ________ electrode.
positive, negative
p. 215
The inferior leads are ___, ___, and ___, and use the ____ ____ as the positive electrode.
II, III, AVF, left foot
p. 218
The lateral leads are ___ and ___, and use the ____ ____ as the positive electrode.
I and AVL, left arm
p. 218
The only horizontal lead is lead __ and the only vertical lead is __.
lead I, AVF
p. 218
Considering Lead I, if the QRS is mainly negative (downward), the Vector points to the patient’s ____ side.
right
p. 220
If the QRS is negative in lead I (Vector points toward patient’s right side), this is known as _____ ____ _________.
right axis deviation
p. 221
Which lead is the best for detecting right axis deviation (RAD)?
Lead I
p. 222
If the QRS complex is positive in lead I (which it _______ __), this indicates that there is no ____, because the Vector is pointing to the left side of the patient.
usually is
R.A.D.
(p. 222)
When we switch the EKG machine to monitor lead AVF, the machine makes the electrode on the ____ ____ positive. The lower half of the imaginary sphere is ________. The center of the sphere is the __ ____.
Considering lead AVF of the EKG, if the QRS is mainly positive on the tracing, then the Mean QRS Vector points ________ into the positive half of the sphere, toward the positive (lead AVF) electrode.
left foot positive AV Node downward (p. 223)
If the QRS is positive in lead I and also positive in AVF, the Vector points _________ and to the patient’s ____. This is the ______ axis range.
downward, left
normal
(p. 227)
If the Vector points upward (from the AV Node) and to the patient’s left, this is ____ ____ _________.
left axis deviation
p. 228
