LECTURE 25 11/02/22 (LECTURE 12/13 SLIDES: EKG SUPPLEMENTAL SLIDES) Flashcards
For this course what angles on Einthoven’s Triangle will be considered a left axis deviation?
What will be considered a right axis deviation?
Any angle less than 59 degrees to -90 degrees will be considered a left axis deviation.
Any angle greater than 59 degrees to 180 degrees will be considered a right axis deviation.
(10:50)
Per Dr. Schmidt, a vector pointed between what angles will be considered an extreme axis deviation?
Extreme Axis Deviation: Vector would be pointed between 180 degrees and -90 degrees (11:00)
What specific area in the heart is being depolarized?
How is the current moving in this picture?
Where is the mean axis deviation pointing?
Septum depolarization (14:12)
Current is moving from negative charge on the outside of the cell (area of depolarization) to area of positive charge on the outside of the cell (resting). (14:30)
Left Foot or Lead II’s eyeball.
If you need to look at the heart from a different angle using Einthoven’s triangle. What additional leads can you use?
What is another name for these leads?
Name the leads (full name).
Augmented Leads (16:00)
Unipolar Leads
aVR (Augmented Vector Right)
aVL (Augmented Vector Left)
aVF (Augmented Vector Foot)
For aVR, where is the positive electrode located on the body?
What about the negative electrode?
Positive electrode for aVR is stuck on the right arm (17:50)
Negative lead will be a combination of connections placed on the left leg and left arm. (18:00)
Normally, the ________ lead will be observing current going away from it resulting in a negative QRS deflection.
The ________ lead will be observing negative current coming towards it from the origin in the middle of right arm and left arm.
The ________ lead will be observing negative current coming towards it from the origin in the middle of right arm and left leg.
aVR (18:45)
aVF (20:03)
aVL
Typically, aVR is going to be witnessing current moving _______.
You would expect to see aVR’s P-wave, R-wave, and T-wave to have a ________ deflection.
Away from the positive lead (eyeball) (19:04)
Negative deflection (19:10)
A perfectly normal heart is depolarization from RIGHT to LEFT. Depolarization is moving away from the aVR lead.
For aVF, where is the positive electrode located on the body?
What about the negative electrode?
Positive electrode on left leg
Negative electrode is a combination of leads placed on the right arm and left arm. (19:45)
If a current is directly traveling towards aVF what degree of deflection is that vector?
If a current is directly traveling towards aVL what degree of deflection is that vector?
If a current is directly traveling towards aVR what degree of deflection is that vector?
+90 degree deflection
-30 degree deflection
-150 degree deflection
For aVL, where is the positive electrode located on the body?
What about the negative electrode?
Positive electrode is on the left arm.
Negative lead is a combination of the right arm and left leg. (20:20)
Which of the three augmented leads is least useful?
aVR (22:00)
How would you categorize the mean electrical axis if the current is traveling directly towards aVR?
Extreme Axis Deviation
V1 and V2 of the precordial leads are located on opposite sides of the sternum. Between which ribs are these leads placed between?
Because of V1 and V2’s proximity to the heart, they are thought of as ________________ leads.
Rib #4 and Rib #5 (4th Intercostal Space). (24:40)
Septal (25:30).
Where should V4 be placed?
Where should V3 be placed?
Because of V3 and V4’s positions on the chest, they are thought of as _________ leads.
V4 should be placed at the left mid-clavicular line between the 5th intercostal space (26:00)
V3 should be between V2 and V4
Anterior (26:25)
Where should V6 be placed?
Where should V5 be placed?
Because of V5 and V6’s positions on the body, they are thought of as _________ leads.
V6 should be placed at the lateral end of the left clavicle, 5th intercostal space on the mid-axillary line. (27:00)
V5 should be placed between V4 and V6 on anterior axillary line.
Lateral
Why do we see a negative QRS deflection in V1 and V2?
V1 and V2 are situated on top of the AV node, depolarization current will go away from these two leads. (28:09)
Which precordial lead has a biphasic QRS complex?
Which precordial lead has the tallest QRS complex?
What precordial lead will be used as an indicator for a current of injury?
V3 (biphasic)
V4 (tallest QRS complex)
V2 (current of injury)
(29:30)
What makes V2’s position unique for indicating current of injury?
V2 can see current coming towards it from the posterior side of the heart or away from V2, if the current originates in the anterior side of the heart. (30:00)
What is a current of injury?
Damaged cardiac tissue that remains partially, or totally depolarized because the myocytes are unable to reset/repolarize themselves after depolarization. (32:03)
How does the heart reset after an action potential:
-Name what will transport Ca2+ out into the ECF
-What about the ICF calcium used for depolarization?
-What about the sodium?
NCX (15%) and PMCA (plasma membrane calcium ATPase(5%)
**75% of the TOTAL ECF calcium is removed through the NCX
**25 % of the TOTAL ECF calcium is removed through the PMCA
SERCA Pump (80%)
Sodium Potassium ATPase
(30:55)
(Exam 3 Recall)
What are causes of current of injury (3)?
- Local ischemia or infarction
- Mechanical Trauma
- Infection
Where would ischemia most likely occur in the heart?
Endocardium (34:30)
Endocardium sees the highest pumping pressures and higher energy consumption than the epicardial tissue.