EKG test Flashcards
How much time is one small box? One big box?
40 msec (.04 sec) 200 msec (0.2 sec)
What is the height of one small box?
0.1 mm
What is the trick for determining rate? What’s the math for determining rate?
Count the big boxes between each peak (300, 150, 100, 75, 60, 50); count the number of big boxes, and then do 300/that number
If something originates in the SA node, what rhythm is it?
Sinus rhythm!
What are the best leads to look at the p-wave?
leads II and V1 (if you see p-waves before each QRS, it’s sinus rhythm
What are the pacemaker rates in the SA, AV, and ventricules?
SA = 60-100; AV = 40-60; Ventricle = 20-40
What is a normal QRS?
0.08 - 0.10 seconds (should be less than 1 big box!)
What is a wide QRS?
120 msec (120 is three small boxes)
If the rhythm is ventricular, what will it do to the QRS?
cause a wide QRS
What are the 2 causes of a wide QRS?
rhythm started in the ventricle OR there is RBBB (started in the atrium in this case, just takes longer to complete depolarization due to the BBB)
What are the best leads for looking at axis?
leads I and aVF
What is the most common cause of AV dysfunction?
Age (AV node takes more time to think about what’s happening - you will see a prolonged PR interval)
What’s a normal PR interval?
120msec - 200msec (3-5 small boxes)
What’s a normal QT interval?
400 - 430 msec (greater than 2 big boxes)
What is the QTc? What’s high for a woman, man?
QT/(square root RR interval); 460, 440
Atrial flutter causes ectopic reentrant activity, that usually causes a rate in the atrium of __, but the __ cuts in half.
300; AV node (ventricular rate ends up being about 150)
Name 3 causes of R axis deviation
1) RVH; 2) PE (puts pressure or increased volume on right side); 3) RBBB
Name 3 causes of L axis deviation
1) LVH (HTN or AS); 2) LBBB; 3) MI (puts pressure or increased volume on L side)
How do you diagnose RBBB?
QRS gt 120; RsR’ in V1; Slurred S in V6
What leads point to an inferior wall STEMI? Septal? Lateral? Anterior?
II, III, AVF
Septal: V1, V2
Anterior: V3, V4
Lateral: I, AVL V5, V6
What are reciprocals to look for in STEMIs
inferior vs lateral
anterior vs posterior
septal vs none
What defines a STEMI?
Need to see ST segment elevations in at least 2 contiguous leads of 2mm in precordial leads or 1mm in limb leads
How do you determine LVH?
Add S in V1 and R in V5 or V6 and if sum is gt 35 = about 7 big boxes, you have LVH
If V1 is positive what’s the next question and what could it mean?
Is QRS narrow or wide?
If narrow think RVH (also RVH with strain shows an inverted T-wave)
If wide think RBBB
Wolff Parkinson White has an accessory pathway that bypasses the AV node reaching the ventricles faster but causing ventricular depolarization (instead of through AV) - what does this mean for PR and QRS?
Short PR (since AV node is not being used and that slows conduction down) and widened QRS (since ventricular contraction is slow)
How do you tx pt with WPW?
Procainamide
Wide complex tachycardia should make you think what?
Vtach (torsades too)
Diffuse ST elevations and __ are diagnostic of __. __ lead will be the opposite of the others.
PR depression; pericarditis; aVR
