EKG Interpretation

Question 1

The Conduction System of the Heart: Supraventricular

Answer 1

SA Node (60-100 bpm)
AV Node (45-60 bpm)
Bundle of His (40-45 bpm)

Question 2

The Conduction System of the Heart: Ventricular

Answer 2

Right and Left Bundle Branches (40-45 bpm)
Purkinje Fibers (20-40 bpm)

Question 3

Standard Limb Leads:

Answer 3

I: positive lead is above the left breast or on the left arm and the negative lead is on the right arm
II: positive lead is on the left abdomen or left thigh and negative lead is on right arm.
III: positive lead is also on the left abdomen or left lower lateral leg negative lead is on the left arm.

Question 4

Augmented Limb Leads:

Answer 4

AVR, AVL, AVF

Question 5

Precordial Leads

Answer 5

V1 - fourth intercostal, right sternal border.
V2 - fourth intercostal, left sternal border.
V3 - equal distance between V2 and V4.
V4 - fifth intercostal, left mid clavicular line.
V5 - anterior axillary line, same level with V4.
V6 - mid axillary line, same level with V4 and V5

Question 6

EKG Distributions

Answer 6

Anteroseptal: V1, V2, V3, V4
Anterior: V2–V4
Anterolateral: V4–V6, I, aVL
Lateral: I and aVL, V5, V6
Inferior: II, III, and aVF
Inferolateral: II, III, aVF, and V5 and V6

Question 7

J point

Answer 7

point of transition from S wave to T wave

Question 8

Determine regularity

Answer 8

Look at the R-R distances (using a caliper or markings on a paper)

Question 9

Lack of normal P waves caused by

Answer 9

Atrial fibrillation
Atrial flutter
Junctional or ventricular rhythm

Question 10

R atrial enlargement (P pulmonale)

Answer 10

Lead II- biphasic hump

Right atrial enlargement = increased height (> 1.5mm) in V1 of the initial positive deflection of the P wave.

Question 11

PR interval

Answer 11

conduction from the SA node to the AV node

Question 12

Prolonged PR interval is called?

Answer 12

1st degree block

Question 13

Short PR interval is caused by

Answer 13

WPW

Question 14

The QRS Axis

Answer 14

Represents the overall direction of the heart’s activity

Axis of –30 to +90 degrees is normal

Question 15

Left Bundle Branch Block criteria

Answer 15

QRS > 120 ms
Dominant S wave in V1
Broad R wave in leads I, AVL, V5-V6
Absent Q waves in leads I, V5, V6 but may have a narrow one in AVL
ST and T waves normally opposite direction to QRS

Question 16

Left Ventricular Hypertrophy

Answer 16

The R wave in V5 plus the S wave in V1 exceeds 35 mm

Baseline ST depression in V5, V6

Question 17

ECG Changes with ischemia

Answer 17

Appearance of pathologic Q-waves
ST elevation & depression
T-waves are peaked, flattened or inverted

Question 18

Lengthened QT Interval

Answer 18

a biomarker for ventricular tachyarrhythmias like torsades de pointes and a risk factor for sudden death