Exam 1 nuggets Flashcards
Why does lead I have a more pronounced q wave then lead II?
Lead I is closer to the left side of the heart, and the vector is moving AWAY.
What does the T wave look like in lead V1 vs V6? Why?
T wave is often inverted in lead V1 d/t small R wave
T wave is positive in lead V6 because the R wave is large.
Explain the evolution of an MI.
1a Hyperacute T waves
1b T wave inversions (often skipped)
2. QT elevation
3. Pathologic Q wave formation (irreversible damage)
Which hypertrophy/enlargement corresponds to Mc-donald’s “M’s” on P wave?
Left atrial enlargement (hump after Left atrial depolarization).
If this lead has an R wave > 11 mm, the patient has LVH
aVL
unless the patient is >35 yo and does not have repolarization abnormalities
What changes are common ventricular hypertrophy (both RVH and LVH) and what leads do you see them in?
Repolarization anormalities
Amplitude changes in ventricular depolarization.
Secondary repolarization abnormalities
Downsloping ST segment depression
T-wave inversions
Seen in left lateral leads. (I, aVL, V5, V6) for LVH
Seen in right sided leads (V1 and V2 sometimes) for RVH
In what leads are T-wave inversions normal? Why?
V1, V2, and V3 in children and black athletes with persistent juvenile T-wave abnormality
Remember - V1-V3 have smaller R waves, making the leads more likely to have inverted T waves!
What are the stages of hyperkalemia and how do you differentiate it from an MI?
- Starts with tall, peaked T waves (that are not broad like hyperacute T waves of an MI). Very diffuse with no reciprocal T wave inversions!
- QRS widen (more than 2 boxes) and T waves get taller and broader
- Sine wave pattern - shark teeth - difficult to evaluate what is what (profound hyperkalemia)
Evolution of hypokalemia
- Presence of U wave > T wave
- Flattened T wave, Presence of U waves, prolonged QT segment (everything is flat) - lose T-wave shape
When is a U wave pathologic? What does it mean?
If the U wave is larger than the T wave
Indicates hypokalemia
What do you see in pericarditis?
- J point elevation (perry, jeremy)
- Diffuse ST elevation with no reciprocal ST depression
- PR segment depression
What is the pattern in PE?
S1Q3T3
Lead 1 has an S wave
Q wave and T wave inversion in lead 3
When is a large T wave abnormal?
If the QRS complex is not extremely large as well (aka the T wave is a similar size as the QRS complex).
What differs T waves in hyperkalemia and stemi?
Hyperkalemia = peaked and narrow
Stemi = wider
What differs T wave inversions in MI from repolarization abnormalities?
T wave inversions are symmetric in stemi, while there is a more down slope linear into the inverted T wave for repolarization abnormalities
What is an NSTEMI on EKG?
Just ST reciprocal changes withOUT ST elevation
How many leads do you need to diagnose a STEMI?
Just the majority (3/4 or 2/3)
If you have a posterior STEMI, what do you see on EKG?
Inferior ST elevation with out-of-proportion reciprocal changes in the anterior leads (out-of- proportion ST depression in anterior leads)
In order to have RAE, what does V1’s P wave need to be? Lead 2’s P wave?
Should be predominantly positive
Lead 2 should be >2.5 mm
If you have an isoelectric lead, where is the main axis?
+/- 90 degrees
What are the repolarization abnormalities?
T wave inversion and ST segment depression in the hypertrophied leads
LVH = problems with V5, V6, lead 1, and aVL (sometimes lead 2)
RVH: V1, V2
What is common to see in aVL if you have RVH?
It is negative (because we are saying the right side of the heart hogs most of the electricity)
RVH is not black and white
If you are unsure what a wave is in a lead, what can you do?
Look at the lead above or below and match the wave - it all happens at the same time!
Why is case 70 not RAE, LAE, and LVH?
Idk, check!
