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Flashcards in EKG Basics Deck (17):
1

12 Leads

* Bipolar Limb Leads
* I - R arm (-) to L arm (+)
* II - R arm (-) to L leg (+)
* III- L arm (-) to L leg (+)

* Augmented limb leads
* aVR - all other leads (-) to R arm (+)
* aVL - all other leads (-) to L arm (+)
* aVF - all other leads (-) to L foot (+)

* Precordial (unipolar) Leads
* V1/V2 in 4th intercostal space; R and L sternal border respectively
* V3
* V4- 5th intercostal space mid sternal
* V5
* V6- mid axillary

2

7 Steps of Interpretation

* 1- Calibration/connections

* 2- Measurable Values - rate, axis, intervals

* 3- Rhythm

* 4- Conduction

* 5- Hypertrophy

* 6- Ischemia, Injury or Infarct

* 7- Other ST and T Wave Abnormalities

3

Calibration/Connections

* Calibration rectangle is 10 mm high/5 mm wide

* Check if Lead II = Lead I + Lead III

* Check if R amp inc as you go from V1 —> V6 (makes sense b/c getting closer to apex)

* Check if Lead I similar in size to V6

4

How to measure rate (2 methods)

* Count # large boxes b/n QRS complexes
* 1 box - 300 bp
* 2 boxes - 150 bpm
* 3 boxes - 100 bpm
* 4 boxes - 75 bpm

* # complexes in 6 second strip (b/n 2 bold vertical lines) x 10 (beats/60 sec or beats/min)

5

How to determine frontal axis/ what are normal values?

* Orthogonal Approach - height of QRS above baseline in Lead I is horizontal in direction of +; then height of QRS in aVF drawn down from tip of lead I vector; then complete vector and this 3rd vector is frontal plane axis (-30 to +110 is normal)

* -30 to -90 is L deviation
* +110 to +180 is R deviation

6

3 Intervals to Measure (+normal values)

* PR interval - represents AV delay (normal = 120-200 ms)

* QRS duration - timed required to depolarize ventricles (normal = or < 100 ms)

* QT interval - time required for ventricles to repolarize; differs by HR so must correct
* QTc = QT / square root of RR interval

7

3 Major Types of Rhythm

* If driven by atrium… normal sinus rhythm OR atrial fibrillation (irregularly irregular QRS- no clear P)

* If driven by junction (AV node not SA node) … narrow QRS; p wave not seen or abnormal

* If driven by ventricle… slow (accelerated idioventricular rhythm) OR fast (ventricular tachycardia); both show wide/odd QRS

8

Types of AV Block

* 1st degree - all signals make it to ventricle but SLOWER; PR >200 ms

* 2nd degree - most signals get to ventricles
* Type 1 Mobitz - prolonged PRs then dropped QRS
* Type 2 Mobitz - no prolongation; just dropped QRS

* 3rd degree- many or all signals do not make it to ventricle; no connection b/n p wave rate and QRS rate

9

Types of Distal Block

**once thru bundle of His - worse b/c no intrinsic pacemaker activity at this point**

* Right Bundle Block - V1/V2 - bunny ears R wave; QRS > 120 ms

* Left Bundle Block - I/V5/V6 - wide R w/ poss notch; QRS > 120 ms

* Anterior Fasicle L Bundle - I/aVL - R axis deviation and qR

* Posterior Fasicle L Bundle - I/aVL - L axis deviation and rS

10

R atrial hypertrophy

* tall p wave in inferior leads (II) or V1; P pulmonale

11

L atrial hypertrophy

* longer duration p wave in inferior leads (II) or V1; P mitral

12

R ventricle hypertrophy

consider if large R wave in V1 or V2

13

L ventricle hypertrophy

consider if large R waves in I II III, aVL, aVF or V5/V6

14

Ischemic

Injury

Infarction

+How to tell location

* Ischemia - T wave inversion
* Injury (acute infarction) - ST elevated
* Infarction - denoted by Q waves

* Lateral - I aVL
* Septal - V1/V2
* Anterior - V2 to V4 (L anterior descending artery)
* Inferior - II/III/aVF (R coronary)

15

Evidence of Digoxin Use on EKG

ST depression; “scooped out T wave"

16

Hyperkalemia v Hypercalcemia on EKG

* Hyperkalemia = Tall narrow peaked t waves

* Hypercalcemia = Dec QTc

17

Pericarditis v. Early Repolarization on EKG

* Early repolarization = ST elevation is diffuse (in many leads) and not ischemic injury b/c same leads show higher T amp - normal in young healthy adults

* Pericarditis = ST elevation is diffuse but not ischemic injury b/c also PR depression