ECG Flashcards
SA node inherent discharge rate
60-100 times per minute
- results in 60-100 BPM
AV node inherent discharge rate
40-60 times per minute
- generates HR 40-60 BPM
His-Purkinje fibers node inherent discharge rate
30-40 times per minute
- HR of 30-40 BPM
automaticity
able to discharge/depolarize without stimulation from a nerve, as is typical in other striated muscle cells
conductivity
The ability to spread impulses to adjoining cells very quickly without nerve involvement
P wave
atrial depolarization
PR interval
time between signal from SA node to AV node
Why do the purkinje fibers wrap back up the heart?
ventricles need to contract from the bottom up to push blood towards aorta
QRS complex
R and L ventricular depolarization
T wave
repolarization of the ventricles
Leads V1 and V2 are placed over the _________ of the heart
right side
Leads V3 and V4 are located over the ________________
interventricular septum
Leads V5 and V6 demonstrate changes on the ___________ of the heart.
left side
saying for telemetry leads
White right
snow over grass
brown ground
smoke over fire
What is first degree AV block? What will be seen on the ECG?
the impulse is initiated in the SA node but is delayed on the way to the AV node
- The delay may be initiated in the AV node itself, and the AV conduction time is prolonged
- long PR interval (> 0.2 sec)
first degree AV block saying
If R is far from P, then you have first degree
second degree AV block (Wenckeback)
Transient disturbance that occurs high in the AV junction and prevents conduction of some of the impulses through the AV node
- P wave starts normal then each subsequent one gets longer until it drops
- Drop means p wave with no signal (QRS)
- This progressive lengthening of the P-R interval followed by a dropped QRS complex occurs in a repetitive cycle
second degree AV block (Wenckeback) saying
Longer, longer, drop, then you have Wenckeback
second degree AV block (Mobitz II) saying
If some p’s don’t get through, then you have Mobitz II
- p wave followed by no QRS wave
third degree AV block
No impulses that are initiated above the ventricles are conducted to the ventricle
- P waves and QRS complex have no relationship
Very bad
- Ventricles are firing on their own because they are not getting p wave signal
What HR would you expect with third degree AV block?
very slow HR because ventricles cannot beat that fast on their own
third degree AV block saying
If Ps and Qs don’t agree, then you have 3rd degree
Paroxysmal atrial tachycardia (PAT)/paroxysmal supraventricular tachycardia (PSVT)
- sudden recurrence of atrial tachycardia
- normal rhythm then a random run of tachycardia
symtpoms of Paroxysmal atrial tachycardia (PAT)/paroxysmal supraventricular tachycardia (PSVT)
- tachycardia
- dizziness
- weakness
- SOB
atrial flutter ECG
sawtooth pattern - uniform due to only one ectopic focus
A-fib
erratic quivering or twitching of the atrial muscle caused by multiple ectopic foci in the atria that emit electrical impulses constantly
What does a fib have the potential for developing?
mural thrombi - clots inside the heart endothelium
When are PVCs considered serious?
- paired together
- multifocal in origin
- more frequent than 6 per minute
- land directly on the T wave
- present in triplets or more
Vtach
- 3 or more PVCs in a row
- absent P waves
- prolonged Q-T interval
- squiggly lines
treatment for vtach
cardioversion or defibrillation
CO during vtach
severely diminished
- this is a medical emergency
Vfib
erratic quivering of the ventricular muscle resulting in no cardiac output
- multiple ectopic foci fire creating asynchrony
- Start CPR
What lead typically sees cardiac hypertrophy?
Typically seen in V5 because it is the left side of the heart
What is an indication of ischemia on an ECG?
- inverted T wave
- S-T segment depression
How many squares on an ECG = 1 sec? 6 sec?
5 big squares = 1 sec.
30 big squares = 6 sec.
How to calculate HR w/ normal sinus rhythm?
300 divided by the number of big boxes in between each QRS
