EKG Flashcards
How long should the P wave be? QRS? A-T interval?
P: 0.12-0.20 sec
QRS: under 0.10 sec
Q-T: under 0.38
What does the P wave correspond with? QRS? T?
P: atrial depolarization (contraction)
QRS: ventricular depolarization (and atrial repolarization)
T: ventricular repolarization
A 12-lead EKG has how many views of the heart? How many electrodes?
10 electrodes
12 views of the heart (“lead”=views)
Where are V1, V2, and V3 placed?
V1 4th intercostal space R sternal border
V2 4th intercostal space L sternal border
V3 between V2 and V4
Where are V4, V5, and V6 placed?
V4: 5th intercostal, midclavicular line
V5: 5th intercostal, anterior axillary line
V6: 5th intercostal, midaxillary line
What view of the heart do leads I, II, and III show?
I: lateral
II: inferior
III: inferior
What view of the heart does aVR, aVL, and aVF show?
aVR: L main
aVL: lateral
aVF: inferior
What view of the heart does V1-V6 show?
V1, V2: septal
V3, V4: anterior
V5, V6: lateral
When given a 12-lead EKG, how do you determine what points to plot on the chart to see the axis the heart is laying?
Take a few of the views and subtract the top number of boxes of the QRS from the bottom number of boxes QRS. Draw a perpendicular line from the point that is plotted. The lines overlap in an area, that’s the axis the heart is laying in. Normal is the bottom R quadrant.
What EKG changes show ischemia? Injury? Infarction/necrosis?
Ischemia: T wave inversion
Injury: ST elevation
Infarction/necrosis: Q wave
Which area MI happens with occlusion of RCA?
Posterior/inferior MI
Which area MI happens with occlusion of LCA?
Anterolateral MI
Which area MI happens with occlusion of LAD?
Anteroseptal MI
Which area MI happens with occlusion of LCX?
Lateral MI
Where are you more likely to have a heart attack? LV/RV?
LV (only 10% of heart attacks are RV)
The area of myocardium most vulnerable to ischemia is the left ventricular subendocardium
What gets shorter in sinus tachycardia, systole or diastole?
Diastole
Q-T is systole
T-Q is diastole
What do junctional rhythms look like on the EKG?
Junctional escape rhythm has slow HR (40-60) bc AV is pacemaker, no P wave
Accelerated junctional looks like NSR but no p wave
What do ventricular rhythms look like?
Idioventricular rhythm: slow HR (15-40) because ventricle is pacemaker, wide QRS, low EF
Vtach: fast HR with wide QRS, no time to fill so very low CO
Vfib: no blood is being moved, ventricle is fibrillating
Ventricular standstill: constant P waves with no QRS
What is the difference between PAC, PJC, and PVC? (premature atrial contraction, premature junctional contraction, and premature ventricular contraction)
PAC has a P before the premature QRS
PJC has NO P wave before the premature QRS
PVC has a premature wide QRS (more likely to get this with caffeine)
What is first degree heart block?
Normal HR, every P has a QRS, but P-R interval is lengthened but uniform
What is third degree heart block?
Slow HR (low CO), P and QRS are not communicating, going at their own speeds without listening to each other, wide QRS
What is second degree heart block type 1?
Longer, longer, drop, must be Wenckebach
P-R interval increases until QRS is missing
What is second degree heart block type 2?
P-R interval is normal and constant, but QRS only fires for 1/2 or 1/3 of them, slow HR
AKA Mobitz
