Nersi EKG Guide Flashcards
1
Q
What leads are involved in an inferior MI?
A
II, III, aVF
2
Q
What leads are involved in an anterior MI?
A
V1, V2 and V3
3
Q
What leads are involved in a posterior MI?
A
inversions of V1 and V2
4
Q
What leads show the left side of the heart?
A
I, aVL, V4 V5 and V6
5
Q
What leads show the right side of the heart?
A
aVR and V1
6
Q
In what leads can a biphasic p wave be normal? How about a negative p wave?
A
III and V1 - biphasic
aVR - negative
7
Q
A normal p wave is shorter than what? If it’s taller, what’s the likely diagnosis?
A
less than 0.25 mV - two and a half small boxes
right atrial hypertrophy if taller
8
Q
How wide is a normal p wave?
A
.12 s or three small boxes
9
Q
How long is a normal PR interval?
A
0.12 s to 0.20 s (3-5 small boxes)
not usually bigger than 1 big box
10
Q
What should happen to the R wave as you progress through the precordial leads?
A
should get taller - R wave progression (while the S wave gets smaller)
11
Q
Where is the normal transition point in the precordial leads?
A
V3 or V4 (this is where the R and S waves are roughly equal)
12
Q
How long is a normal QRS interval?
A
0.12 s or less
13
Q
The QT interval is generally less than ___ of the R-R interval.
A
half
14
Q
The axis is normal if the QRS complex is positive in what two leads?
A
I and aVF
15
Q
If the QRS is positive in 1 but negative in aVF, what’s the axis?
A
left deviation
16
Q
If the axis is right deviated, what will the QRS be in 1 and aVF?
A
negative in 1
positive in aVF
17
Q
What’s another way to tell axis?
A
look for the isoelectric QRS and then go 90 degrees from there
18
Q
When can you say an axis is indeterminate?
A
when the QRS is isoelectric in multiple leads
19
Q
What leads do we look at for atrial enlargmetn?
A
II and V1
20
Q
What will the P look like in II for RAE?
A
the first part becomes asymmetrically taller and sooner, so there will be a small hump at the end
but it stays about the same width
21
Q
What will the P look like in V1 for RAE?
A
biphasic, with a taller upward peak first
22
Q
What will the p look like in II for LAE?
A
wider with a taller hump at the end (instead of at the beginning like in RAE)
23
Q
What will the P lok like in V1 for LAE?
A
biphasic with a deeper trough at the end
24
Q
What will happen in the precordial leads with right ventricular hypertrophy?
A
you’ll lose the normal R wave progression, such that the QRS complex is more positive on the right (V1) and less positive on the left (V6), which is the opposite of what these leads normally show
25
What are the sokolow-lyon criteria for LVH?
Height of S in V1 or V2 plus height of R in V5 or V6 total >35 mmHg
OR
If the R wave in aVL is at least 11 mmHg, that's LVH
26
What are the cornell criteria for LVH?
add the height of S in V3 and R in aVL. if this is greater than 28 mmHg in men or 20 mmHG in women, LVH
27
With severe ventricular hypertrophy, particularly as it becomes severe, there can be repolarization abnormalities such that you get asymmetric ST segment depression with a slope, as well as T wave inversion. What leads does this commonly occur in for RVH?LVH? What's this called?
V1 and V2 for RVH
V5 and V6 for LVH
called a ventricular strain pattern
28
How are grade II AV nodal blocks described (both type I and II)?
in terms of how many beats there are until the QRS is dropped. If there are three beats and then the fourth QRS is dropped, it's a 4:3 second degree block
29
Which grade II block has the PR interval that gradually widens?
type I - Wenchebach
30
What will the QRS look like with a bundle branch block?
the ventricles won't fire quite in synch, so you get an R-S-R' pattern
31
Where will you see the RSR' with a right BBB?
V1 and V2
| and you'll see a large S in V5 and V6
32
Where will you see the RSR' pattern with a left BBB?
V5 and V6, but also I and aVL
however - note that the RSR' in LBBB isn't quite as distinct as in the RBBB and may appear as a notched. widened R wave
(and a large S in V1 and V2)
33
What other scary looking thing can happen in the same leads as the RSR' with BBB?
ST segment depression and T wave inversion
34
What will the QRS look like in an incomplete bundle branch block?
the RSR' is evident, but the QRS isn't prolonged
35
If the QRS is prolonged, but there is no RSR', what's that called?
nonspecific intraventricular conduction delay
36
True or false: do left fascicular blocks prolong the QRS?
False - even thought the depolarization would have to travel longer through the anatomotic loop, it happens so quickly that you don't get widening.
37
FOr a left anterior fascicular block, the axis becomes deviated____
leftward
38
For a left posterior fascicular block, the axis becomes deviated___
rightward
39
If the R-R intervals are not consistent, but all the P waves are upright, where is the arrhythmia coming from?
has to be from the atria because anything originating below the atria will spread backwards and cause a negative p wave
40
Why do atrial arrhythmias have narrow complexes?
because conduction through the AV node and the ventricular bundles is normal
41
Describe what a PAC looks like.
the P wave looks different from other P waves
the P and QRS will come earlier than would be expected based on the other R-R
the QRS and T are followed by a relative pause
42
If several repeated beats from an ectopic atrial focus occur after a PAC, what is this called?
paroxysmal atrial tachycardia (PAT)
43
Parosyxmal atrial tachycardia in a normal heart usually has a 1;1 conduction, but PAT in what context have have multiple p waves per QRS and why?
when on digoxin because it blocks AV node conduction
44
What do you call it when there are 3 or more p wave morphologies?
wandering atrial pacemaker
45
What do you call it if there is a wandering atrial pacemaker and the rate is over 100 bpm?
multifocal atrial tachycardia
46
What differentiates wandering atrial pacemaker from atrial fibrillation?
the p waves may look different from each other, but there are always distinguishable p waves
47
What are the two varieties of atrial re-entrant arrhythmia?
atrial fibrilation
| atrial flutter
48
How do you describe an atrial flutter?
by how many flutter waves there are per QRS complex, liked 3:1
49
Besides not having clearly discernible P waves, how does atrial fibrillation differ from flutter?
Flutter still sends depolarization down to the ventricles in a regular fashion
fibrillation doesn't, so you get an irregularly irregualr rhythm
50
Where do junctional arrhythmias arise form?
the AV junction
51
Do junctional arrhythmias have narrow or wide complexes?
narrow
52
So junctional arrhythmias and atrial arrhythmias are both examples of what?
supraventricular arrhythmias, or wide complex arrhythmias
53
How are junctional arrhythmias distinguished from atrial arrhythmias?
junctional rhythms don't have normal p waves - can have retrograde - or upside down- p waves
54
The AV junction can create an early depolarization wave, called what?
premature junctional beats (basically the AV version of PACs)
55
If there are multiple rapid junctional beats in a row that begin suddenly, this is called...
paroxysmal junctional tachycardia
56
What's the tip-off that you're looking at an escape rhythm?
you'll have a beat that fires later than expected based on th eprevious R-R intervals, which is in contrast to premature beats
57
What would be the rate of an atrial escape?
60-80 bpm
58
What would be the rate of a junctional escap?
40-60
59
Ventricular escape rhythms are more commonly called what?
idioventricular rhythms
60
What is the typical rate for an idioventricular rhythm?
20-50 bpm
61
if an idioventricular rhythm is occurring faster than 50 bpm, what is this called?
accelerated idioventricular rhythm (often occurs with MI or after the myocardium is reperfusd in a cath lab)
62
Usually PVCs will occur in isolation, but if they alternate between 1 normal beat and 1 PVC, what's this called? How about 2 normals to 1 pvc?
bigeminy
| trigeminy
63
If there are two PVCs in a row, followed by a normal beat, what is this called?
a couplet
64
How about three PVCs in a row followed by a normal beat?
a triplet
65
If you have more than three PVCs in a row....
ventricular tachycardia
66
If the ventricular tachycardia lasts more than 30 seconds...
sustained ventricular tachycardia (if it runs for less, it's non-sustained vtach)
67
What do you call it if the ventricular tachycardia is PVCs occurring at regular intervals with very similar heights and widths?
monomorphic ventricular tachycardia
68
If the QRS complexes of the vtach do not resemble each other, what is this called? What's a good example?
polymorphic ventricular tachycardia
| torsades de pointes
69
If an EKG has a series of irregular, chaotic, dissimilar waves with none of the identifiable morphologies of a normal beat, what is this....
ventricular fibrillation
70
What is the typical EKG sequence of events in an MI?
T wave changes (hyperacute T waves first, then later inversions) = ischemia
J point elevation (where the ST segment begins at baseline and then slopes upward such that the ST segment is indiscernible from the T wave)
ST elevation (where the J point is 1 mm above the baseline in two or more contiguous leads) = injury
pathologic Q waves = completed infarct
71
Define pathologic Q waves
a Q wave with width greater than 1 little box and height greater than 2 little boxes
or
greater than 1/3 the entire QRS
present in 2 or more contiguous leads
72
In what lead do we not care about q waves?
aVR - per usual
73
How do th ST depressions of ventricular strain differ from that of an NSTEMI?
with strain, the t wave inversions are assymetric - gradually downslping ST segments ending in a T wave that rapidly rises
while the NSTEMI ST depressions show more symmetric T waves and flattened ST segments, not downsloping
74
What are reciprocal changes?
they are essentially opposite findings in the leads opposite from the infarct - so tall R waves instead of Q waves, ST depression instead of ST elevation
75
Why do pre-excitation syndromes typically have shortened PR intervals?
because they are usually due to an accessory pathway that conducts more quickly than the relatively slow AV node
76
What is the main example of a pre-excitation syndrome?
Wolf-Parkinson-White (with the bundle of Kent)
77
Describe the EKG findings of WPW.
1. short PR interval
2. delta wave (up-swoop of the early QRS complex)
3. widened QRS (because of the Delta wave, but the rest of the QRS will appear normal)
78
Describe the accessory pathway in Lown-Ganong-Levine syndrome.
James fibers that connect the atria directly to the bundle of His, bypassing the AV node
79
Describe the EKG changes in LGL.
the only finding is a short PR interval because the QRS won't be widened at all
80
What will digoxin do to the heart at normal therapeutic levels?
1. gradual downsloping of the R wave at the end of the QRS complex
2. can be accompanied by ST depressions and T wave inversions
81
What will digoxin toxicity look like on EKG?
1. the downsloping of the R wave and possible ST dep/T inv as above
2. sinus bradycardia
3. loss of sinuns rhythm altogether
4. AV nodal blocks
5. can also be tachyarrhythmic with PACs, PVCs, PAT, etc.
82
What electrolyte issue will potentiate digoxin toxicity?
hypokalemia, because low K will cause further inhibition fo the Na-K ATPase that is already inhibited by dig
83
What EKG change can be seen with hypercalcemia?
shortened QT segment (less than 0.35 s)
84
What EKG change can be seen with hypocalcemia?
QT interval prolongation (greater than 0.45s)
85
What other electrolyte abnormality can lead to prolonged QT?
hypomagnesemia
86
What is the earliest finding in hyperkalemia?
peaked T waves - tall, narrow and symmetric (unlike hyperacute T waves) occurring in all leads
87
What will happen with worsening hyperkalemia?
The P waves will flatten, PR interval lengthens and the QRS widens
may widen so much that you get a sinusoidal pattern, which is a precursor to ventricular fibrillation
88
What EKG change happens with hypokalemia?
T waves flatten
as it worsens, you can get a second positive wave after the T wave, called a U wave
89
What other electrolyte abnormalities/pathologies can also have a U wave?
hypercalcemia
hyperthyroidism
dig toxicity
LVH
90
What can happen on the EKG with hypothermia?
bradycardia (as metabolism slows)
tremors - background noise from shivering
irregular rate
OSBORN WAVE, which is a sudden, narrow, positive wave immediately after the QRS complex, starting at the J point - these can also be called J waves. Look like a camel hump (sometimes hard to distinguish from a bundle branch block)
91
What can you see on EKG with a pulmonary embolism?
1. evidence of RVH and a strain pattern
2. right bundle branch block
3. sinus tachycardia!!!
S1Q3T3: large S in I, large Q in III and occasionally an inverted T in lead III
(T waves may also invert in the more right-sided precordial leads - V1 through V4)
92
What will happen on EKG in pericarditis?
DIFFUSE ST elevations
93
What will happen on EKG if a pericardial effusion develops?
1. voltage may be decreased (due to dampened signal)
2. Electrical alternans (alternating large and small amplitude QRS complexes) as the depolarization axis points in different directions as the heart bounces around in the fluid
94
What is the tip-off that you're looking at a paced rhythm?
there will be a very narrow spike (called a pacer spike) that looks like a vertical line just prior to the P wave (if the PM is in the atrium) or before the QRS (if the PM is in the ventricle)
95
What will the QRS look like if there is a pacemaker in the ventricle?
It will be wide (because the right ventricle will not fire before the left) - thus resembling a left BBB
can also cause ST elevations in the anterior leads (much like a LBBB)
