Ecg

Front 1

factors that alter the amplitude of the vector (3)

Back 1

mass of muscle, conduction velocity, degree of cancellation due to propagation in diff directions simulataneously

Front 2

standard limb leads

Back 2

lead I goes from R arm to L arm (0 degrees); lead II goes from R arm to L foot (+60 dg); lead III goes from L arm to L foot (+120 dg)

Front 3

augmented leads

Back 3

aVR goes from (L arm + L foot) to R arm (-150 dg); aVL goes from (R arm + L foot) to L arm (-30 dg); aVF goes from (R arm + L arm) to L foot (+90 dg)

Front 4

central terminal of Wilson

Back 4

connect each of the limb electrodes through high resistance resistors -> behaves as if it is located in the center of the chest; used as negative pole for precordial leads

Front 5

inferior leads

Back 5

II, III, aVF

Front 6

lateral leads

Back 6

I, aVL, V5, V6 (all look at left lateral heart wall)

Front 7

septal leads

Back 7

V1 and V2 (influenced by RV and septal changes)

Front 8

anterior leads

Back 8

V3 and V4

Front 9

placing precordial leads

Back 9

V1 is in 4th intercostal space just right of the sternum; V2 is in 4th intercostal space just left of the sternum; V3 is half way between V2 and V4; V4 is in 5th intercostal space in mid axillary line; V5 is lateral to V4 in anterior axillary line; V6 is lateral to V4 in mid axillary line

Front 10

what do the ECG boxes represent

Back 10

10 mm (2 big boxes) vertical deflection = 1 mV; 1 mm horizontally (one small box) = 40 msec and 5 mm horizontally = 200 msec (one big box)

Front 11

RR interval det roughly by big boxes

Back 11

1 big box = 300 bpm; 2 = 150 bpm; 3 = 100 bpm; 4 = 75 bpm; 5 = 60 bpm; 6 = 50 bpm

Front 12

normal PR, how to measure

Back 12

120 to 200 msec (3-5 small boxes); from beginning of P to beginning of QRS

Front 13

normal QRS

Back 13

less than 100 msec (2.5 small boxes); greater than 120 (3 small boxes) is clearly abnormal

Front 14

PR prolonged causes

Back 14

1st degree AV block, 2nd degree AV block (Mobitz 1) if skipped beats

Front 15

QRS prolonged causes (4)

Back 15

LBBB or RBBB; ventricular/junctional rhythm (in that case, no p before QRS); Mobitz II 2nd degree AV block; WPW bypass conduction

Front 16

QTc calculation

Back 16

QTc = QT/rt(RR)

Front 17

what should QT be for a HR of 60? how does it change with HR?

Back 17

about 400 msec (two big boxes); QT interval gets shorter w/ incr HR b/c APD decr to accomodate diastole

Front 18

normal/abnormal QRS axis

Back 18

normal = -30 to +90; left = -30 to -90; right +90 to +180

Front 19

leads I and II - use to det QRS axis

Back 19

if both +, then likely normal (if unsure, check aVF); if I negative, then right axis deviation; if II or aVF negative, then left axis deviation

Front 20

first part of the ventricle activated during QRS and how does it show on ECG

Back 20

septum from L to R over left bundle branches -> appears as small R in V1 and small Q in V6

Front 21

net vector in middle of QRS, how does it show on ECG

Back 21

net vector through the apex; shows as large S in V1 and large R in V6, I, and II ---- this produces a characteristic R wave precordial progression (downward large S in V1/V2 becomes upwards R in V5/V6)

Front 22

frontal plane leads

Back 22

I, II, III, aVR, aVL, aVF

Front 23

T wave morphology in frontal plane leads

Back 23

us. faces the same direction as QRS because depolarization occurs endo to epi, but epi APs are shorter, so repolarization occurs epi to endo

Front 24

ECG leads to dx bundle branch block

Back 24

I, V1, V6

Front 25

RBBB

Back 25

initial portion of QRS looks normal (i.e. narrow R in I and V6), but late R ventricular activation causes broad S at end of QRS in leads I, aVL, and V6 and broad R' in V1

Front 26

when do we see RSR'

Back 26

RBBB - see it in V1 due to late RV activation

Front 27

LBBB

Back 27

wide R waves in leads I, aVL, and V6 and wide S wave in V1 due to delayed LV activation, poor R wave progression from V1 to V6

Front 28

standard paper speed and voltage amplification; what should the calibration box look like

Back 28

25 mm/s and 10 mm/mV -> should yield calibration box that is 1 large box wide and 2 large boxes high

Front 29

HR calculation

Back 29

1500/small boxes or 300/big boxes

Front 30

how to tell if p waves comes from SA node

Back 30

should be upright in II (and prob I and III too)

Front 31

short PR causes

Back 31

WPW, AV junctional beat with retrograde atrial activation

Front 32

2nd degree AV blocks

Back 32

Mobitz I (Wenckebach) - Increasing PR until nonconducted P wave occurs (after which PR is short again); Mobitz II - fixed PR intervals plus nonconducted p waves, us has wide QRS; if every other beat is skipped (2:1) we cannot look at PR interval and instead must look at QRS interval; if multiple beats in a row are skipped then it must be Mobitz II

Front 33

how to measure QT

Back 33

from beginning of QRS to end of T

Front 34

WPW normal conduction

Back 34

Kent bundle causes early activation of the ventricles (delta wave - slurred upstroke), wide QRS, and short PR interval

Front 35

left axis deviation seen in (3)

Back 35

left anterior fascicular block, LVH, LBBB

Front 36

left anterior fasicular block

Back 36

axis -45 to -90 (left); rS in leads II, III, aVF; small q in leads I and/or aVL; R peak time in aVL >.04 w/ slurred R downstroke; poor R progression in V1-V3; deeper S in V5 and V6; QRS interval normal

Front 37

Left posterior fascicular block

Back 37

axis us. >100 (right); rS complex in lead I; qR in leads II, III, aVF (R in lead III > II); r/o RVH (aVR and V1 should be neg, p wave should be normal w/o RA enlargement) QRS interval normal

Front 38

right axis deviation seen in (2)

Back 38

Left posterior fascicular block, RVH (more common)

Front 39

1st degree AV block

Back 39

PR > 200 ms, but every P has a QRS

Front 40

sinus tachycardia on EKG

Back 40

>100 bpm; upright p waves in leads I,II, III

Front 41

atrial fibrillation on EKG

Back 41

p waves replaced by "bag of worms" (random undulations) or by flat line (too quick to make out); ventricular response is rapid but irregularly irregular

Front 42

atrial flutter on EKG

Back 42

uniform saw tooth atrial activity (us 300/min -> one large box) seen best on inferior leads (II, III, aVF); regular ventricular response that is always even integer of atrial rate

Front 43

paroxysmal supraventricular tachycardia on EKG

Back 43

regular, narrow QRS; episodes us. provoked by exercise or stress (catecholamines)

Front 44

supraventricular vs ventricular tachycardias on EKG

Back 44

supraventricular us. have narrow QRS (no bundle block), while ventricular have wide QRS

Front 45

ventricular tachycardia: EKG

Back 45

wide, regular QRS

Front 46

ventricular fibrillation: EKG

Back 46

absence of QRS (disorganized, chaotic activity)

Front 47

WPW syndrome AV reentry EKG

Back 47

EKG shows absence of delta wave and prolongation of PR interval to normal, with upside-down p wave after QRS (when signal travels over bypass tract back into ventricles)

Front 48

AV nodal reentry EKG

Back 48

two tracts in AV node: fast beta pathway w/ long refractory period, slow alpha pathway w/ short refractory period; premature impulse travels over alpha pathway (blocked by long refractory period in beta pathway) from A -> V, then travels back from V -> A over beta pathway; causes EKG w/ long PR (alpha pathway is slow), then normal QRS, then upside down (short, pointy) P very soon after (fast beta pathway causes atria depolarization in reverse)

Front 49

det sinus p wave

Back 49

sinus p wave will be positive in lead II; non-sinus may be negative in lead II

Front 50

det SVT vs VT

Back 50

SVT has narrow QRS and a p before every QRS; VT has wide QRS