Intro to ECG Part 1 Flashcards
movement of the charge:
if a postive charge moves away from the positive electrode, a ____ deflection is created.
a downward deflection.
movement of the charge:
if charge is moving, but not directly toward the positive lead, the deflection will be ___
will be smaller.
movement of the charge:
if the charge moves toward and then away, a ___ waveform will be created
if the charge moves toward and then away, a BIPHASIC waveform will be created.
movement of the charge:
if the charge moves perpendicular to the leads, then a ____ deflection results
then a very very small deflection results.
movement of the charge:
when will there be no deflection on the lead?
- if the charge is not moving
- if the tissue is very small
All 6 limb leads are ___ degreees apart.
30 degrees apart
einthoven’s triangle
the sum of all 3 leads is 0
positioning of 6 precordial leads
which leads are limb leads? Which ones are precordial?
how to calculate the rate in an ECG lead?
To calculate: 300 divided by number of big squares between beats
300/4 = 756 bpm
calculate the rate
300/2 = 150
there are 3 types of rhythm
regular
irregular with a pattern
irregular with no pattern
analyze the rhythm
regular but fast
analyze the rhythm
skipped a beat
analyze the rhythm
irregular with a pattern
analyze the rhythm
irregular with no pattern
note:
interpret this ECG
Nonexistant P wave– very diminished
interpret this ECG
P waves are present, and they are all on the same size and shape. BUT there are not as many QRS segments compared to P segments. There are more.
what does it mean if there are P waves without QRS’s?
AV node is not working properly or there is an SA block in the conduction between atria and ventricle.
the P wave indicates atrial depolarization. if there is no QRS, something is wrong with the ventricle. either something isn’t reaching the ventricle or it isn’t contracting
what is going on to the P waves? Why is there still a QRS?
These are not P waves– this is baseline garbage. there is no atria conduction. It’s even hard to determine the T wave.
This is atrial fibrillation. Can get QRS wihtout the P wave because there might be a pacemaker somewhere else in the heart that allows the ventricle to receive electricle stimulation even if the SA node is not functioning properly.
A p wave inversion can happen if the ___ node is the pacemaker rather than the ___ node.
A p wave inversion can happen if the AV node is the pacemaker rather than the SA node.
What are these P waves doing?
P wave is behind the QRS and then going before.
how do you tell if the PR interval is short, normal or long?
Short is less than 3 little squares (<0.12 sec)
Normal is 3-5 little squares (0.12 to 0.20 sec)
Long is more than 5 little squares (>0.20 sec)
the PR interval measures conduction through the AV node
the PR interval measures conduction through the ____ node
the PR interval measures conduction through the AV node
note: if there are more P waves than QRS complexes, then some P waves won’t have a PR interval, because
there will be no “R” from the absent QRS
how long is the PR interval?
4.
note: each square is about .04 seconds
how long is the PR interval
7 square x 0.04 = 0.28s. it’s a bit long.
why is there no PR interval?
Some P waves don’t have PR intervals because there is no QRS
how long is the PR interval?
2.5 = short PR interval. PR interval in this one is constant.
There is only one question for the QRS complex
for single lead ECG:
Is the width of the QRS complex narrow
(normal) or wide?
Normal QRS is less than 3 little squares (0.12s)
causes of a wide QRS:
- delay through the normal conducting system
- the beat that is conducted through the cardiac muscle.
A slow conduction/slow moving event will cause a wide QRS. Could be due to diseased conducting system .
analyze QRS complex
normal
analyze QRS complex
4 units. a bit wide.
4 options for a pacemaker
if the ventricle is the pacemaker, the QRS will be ___.
will be wide. therefore, a narrow QRS rules out the ventricle .
what part of the ECG will be affected if there is a junctional pacemaker.
will not have a normal PR interval.
therefore, a normal PR interval rules out the AV node as a pacemaker. Also rules out the ventricles as the pacemaker because you would see a QRSD elongation
What is the pattern for atrial fibrillation
atrial fibrillation is irregular with no pattern. A regular rhythm rules out fibrillation.
what is the pattern for ventricular fibrillation?
has no QRS’s. thus, the presence of QRS’s rules out VF
Note;
inverted P waves usually rule out the ___ node
usually rule out the SA node.
