Exam 4 Lecture 4 Flashcards
What is the thin, elastic, stretchy connective tissue that is clear and surrounds the heart called?
Visceral Pericardial Layer
What type of triangle does Einthoven’s Law apply to?
An equilateral triangle
Where are the bundle branches located?
Interventricular Septum
In which type of refractory period will bidirectional electrical firing cause conduction and pumping issues?
Relative Refractory Period b/c able to fire an AP
In an AP, what is the safety mechanism the heart uses?
The refractory Period
Why are Gap Junctions effective in cardiac tissue?
They are very fast due to Na+ influx and some Ca++ influx
If you only had Ca++ come in during an AP, would it be faster or slower than a normal Na+ AP?
Slower
Where are all the 3 Lead EKG Electrodes Placed
2 (+) on L Leg
2(-) on R arm
1 (+), 1(-) on L Arm
If your electrical axis is pointed towards the R foot, how would Lead 1 look?
*Name 2 causes
- deflection [deep breath or BBB]
What is the View from a 3 Lead EKG
Frontal/Coronal Plane
Which Deviation of Electrical Axis will a Bundle Branch Block cause?
L or R
How does the (+) electrode work?
*How does Schmidt describe it?
Eyeball/sensor to see depolarization towards/away
* Current Towards + electrode: - to + = + deflection
*Current Away + electrode: + to - = - deflection
What direction do you turn the heart to achieve a Left Axis Deviation?
Rotated to the left [counterclockwise]
How is the Atrial P wave compared to the QRS net depolarization wave?
Very similar and still at 59 degrees
What angle is the normal mean electrical axis of the heart of depolarization?
59 degrees towards L foot
If a Pt has COPD, how would their Lead 2 look?
Fairly + deflection
How do you get a negative degree in the mean electrical axis?
Counting counterclockwise from horizontal
3 Lead EKG: Lead 3 Setup
*What type of View
*Electrical Axis in Degrees
(+) Lead in L foot
(-) Lead in L arm
*Up and Towards L arm view
*120 degrees
What is Einthoven’s Law?
Lead 1 + Lead 3 = Lead 2
What deviation will decreased lung volume cause? [pushing air out of the lungs]
Heart rested on L side for a L sided Deviation
If you had a 90 degree electrical axis, what 2 leads would be the same amplitude?
Lead 2 and 3
Lead 1 [0] + Lead 3 = Lead 2
What leads are in “Augmented Leads”
1, 2, 3, aVR, aVL, aVF
Which lead has the largest deflections in a 59 degree angled electrical axis?
*Why
Lead 2 b/c it is fully “seeing” the depolarization wave
Which directions can electrical impulses fire with Gap Junctions?
*Is this good or bad?
Bidirectional
*Bad, can lead to stray AP and electrical firing
Do all leads show Q and S waves?
No
3 Lead EKG: Lead 1 Setup
*What type of View
*Electrical Axis in Degrees
(+) Lead: L arm
(-) Lead: R Arm
*Horizontal View
*0 Degrees
If a Pt has COPD, how will their Lead 1 look?
*Why
No Lead 1, as no current R to L
*COPD makes the heart Electrical Mean Axis Perpendicular at 90 degrees, so no horizontal current
3 Lead EKG: Lead 2 Setup
*What type of View
*Electrical Axis in Degrees
(+) Lead in L foot
(-) Lead in R arm/shoulder
*Best View/Largest Deflections in Normal 59 degrees
*60 Degrees
Per lecture, only 2 phases of ventricle depolarization do not result in all leads having a positive deflection. Which are they?
*Compare all leads for both
1.) All vent depolarized except Superior Lateral Portion
*Lead 1 = +
*Lead 2,3 = -
2.) Full ventricle depolarization = 0 deflections in all leads
If you could see Atrial Repolarization, what kind of deflection would it be?
Why?
Negative deflection b/c repolarization happens in the same direction as depolarization
Where is the Parietal Pericardium attached to?
the Serous Pericardial Layer
*Think parietal tissue pain
What is a Right Deviation in Einthoven’s Triangle?
> 90 degrees or for our class, >59 degrees
What deviation will taking a really deep breath cause?
R Axis Deviation
What is a Left Deviation in Einthoven’s Triangle?
<0 degrees or for our class, <59 degrees
Which is thicker: R ventricle wall or L ventricle wall?
*Why
L b/c has to pump against body
*R has to only pump against pulmonary
What direction do you turn the heart to achieve a Right Axis Deviation?
Rotated to the right [clockwise]
