How to read a 12-lead
What is the primary pacemaker in the cardiac electrical conduction system?
SA Node
"Ectopic beat"
A wave or complex that originates outside the normal conduction system and is frequently early
No P-waves
A-Fib and anything ventricular (V-Fib, V-Tach, Polymorphic V-Tach (Torsades de Points), Idioventricular, SVT)
Rate: 60-99, regular/ regularly irregular
Sinus Rhythm, Accelerated Junctional, 1st Degree AV Block, 2nd Degree AV Block Type 1 (reg. irreg.), 2nd Degree AV Block Type 2 (reg. irreg.)
Conduction System defects:
Types
Things to identify in each
Subgroups in each
1) BBB, AVB, Accessory Pathway
2) BBB: QRS is minimum 120ms wide, a pattern of QRS in V1 and V6
AVB: prolonged PRI
Accessory Pathway: wide QRS, slurred upstroke (delta wave), short PRI
3) BBB: IVCD (not a complete BBB; missing V1 and V6 pattern), hemiblocks (branch of bundle branch blocked)
AVB: 1st Degree (long PRI), 2nd Degree Type 1 (PRI gets progressively longer, then resets with dropped beat), 2nd Degree Type 2 (consistantly prolonged PRI with dropped beats), 3rd Degree with Junctional Escape (no PRI, QRS: 40-59, P-waves: 60-99), 3rd Degree with Ventricular Escape (no PRI, QRS: 40 or less, P-waves: 60-99)
Accessory Pathway: WPW, ST, SVT, A-Fib, A-Flutter, MAT, JT)
Which wave represents:
atrial depolarization
ventricular depolarization
ventricular repolarization
atrial repolarization
1) P
2) QRS
3) T
4) No visible wave; happens during QRS
PJC
P-waves are inverted and before, during, or after QRS
Inverted; before, during, or after QRS
Junctional rhythm/escape/accelerated/etc.
Rate: Below 60, regular
Sinus Bradycardia (59-), Junctional Rhythm (40-59), Junctional Bradycardia (less than 40), Idioventricular (40 or less), 3rd Degree AV Block with Junctional Escape (40-59), 3rd Degree AV Block with Ventricular Escape (40 or less)
PAC
P-wave is early, has different P-wave morphology
When you are wanting to really "zoom in" on the P-wave, what is the best lead to analyze?
V1
PVC
no associated P-waves; early and wide QRS
Upright, P for QRS, NOT QRS for P
2nd Degree AV Blocks
Rate: Fast; 100+
Sinus Tachycardia (100+), Junctional Tachycardia (100+), Atrial Tachycardia (100+), V-Tach (fast), V-Fib (fast), Polymorphic V-Tach (fast), SVT (fast)
Define:
ventricular bigeminy
ventricular trigeminy
ventricular quadrigemini
1) repeating pattern of a regular QRS, then PVC; every other beat
2) repeating pattern of two regular QRS, then PVC; every 3rd beat
3) repeating pattern of three regular QRS, then PVC; every 4th beat
On a 12-lead ECG, how do you know if the P-waves are "sinus?"
Upright I, upright II, upright III, upright AVL, upright AVF, inverted AVR
What happens during:
PRI
QT
1) Atrial kick
2) Ventricular depolarization and repolarization
Upright, QRS: 40-59, P-waves: 60-99
3rd Degree AV Block with Junctional Escape
What does a:
long QTc indicate?
short QTc indicate?
1) TDP (Torsades de Pointes)
2) risk for A-Fib or V-Fib
Define:
couplet
triplet
"run of v-tach"
fibrillation
1) two PVCs in a row
2) three PVCs in a row
3) four or more PVCs in a row
4) chaotic quivering without contraction
What two methods are there to determine the rate of rhythm on an EKG strip?
6-second strip and multiply by 10
Count large boxes from R to R (300, 150, 100...)
What structures are innervated by the:
sympathetic nerves
parasympathetic nerves
1) SA AV nodes and Purkinje fibers
2) SA and AV nodes
Upright, QRS: 40 or less, P-waves: 60-99
3rd Degree AV Block with Ventricular Escape
QTc:
Define
Makes it long
Makes it short
1) ventricular depolarization and repolarization
2) more than 450ms
3) less than 300ms
Wandering Atrial Pacemaker
3 or more P-wave morphologies with a rate of 99 or less