Heart Rhythmicity and Normal ECG Starting with Objective 06 Flashcards
Axis for Lead I
Two electrodes on two arms:
R= negative
L= positive
Direction of the lead = O degrees
Axis for lead II
Electrodes on right arm and left Leg:
A= negative
L= positive
Direction of the lead = 60 degrees
Axis for lead III
Electrodes on left arm and left leg:
A= negative
L= positive
Direction of the lead = 120 degrees
What is the mean electrical axis of the heart?
+59 degrees
What is the J point?
Referring to currents of injury
reference point for analyzing current of injury
When does the J point occur and what does it signal?
occurs at the very end of the QRS wave and is the point at which all parts of the ventricle, including the injured, have become depolarized
What is a Vector?
an arrow that points in the direction of the electrical potential generated by the current flow. Length of the arrow is drawn proportional to the voltage
what is a vector
an arrow that points in the direction of the electrical potential generated by the current flow, with the arrowhead in the positive direction
What is the length of a vector arrow proportional to?
the voltage of the potential
What is the instantaneous mean vector?
the summated vector of the generated potential at a particular instant
In what direction does the reference vector extend?
it runs horizontal towards a person’s left side; this reference direction = 0 degrees
What is the average direction of the vector during spread of the depolarization wave through the ventricles results in the apex of the heart remaining positive with respect to the base of the heart known as?
the mean electrical axis of the heart
During the T-wave where is the greatest portion of ventricular mass to repolarize first found?
the entire outer surface of the ventricles, especially near the apex
What is the first area to be repolarized during the atrial T-wave
the sinus node area
