Normal EKG

Question 1

What is normal heart rate?

Answer 1

Normal for SA node= 60-100 bpm

Question 2

What are all of the leads on a 12 lead EKG?

Answer 2

Lead I: right arm (-), left arm (+)
Lead II: right arm (-), left leg (+)
Lead III: left arm (-), left leg (+)
avR: right arm (+)
avL: left arm (+)
avF: feet (+)
Precordial leads V1-V6: all of these should be (+), takes snapshot of the heart

Question 3

What leads correspond to which sections of the heart?

Answer 3

Lateral: I, aVL, V5, V6
Anterior: V3, V4
Septal: V1, V2
Inferior: II, III, aVF

Question 4

What are basics of EKG paper?

Answer 4

Vertical axis= amplitude
1mm per square so one box= 5 mm
Horizontal axis= time
1mm=0.04 sec so 1 box= 0.2 sec

Easiest way to think of it is that each box is a 5x5

Question 5

What is axis deviation and where can we see it at?

Answer 5

Average direction of depolarization as impulse travels through ventricles.
Axis refers to the direction of depolarization of QRS complex.
Examine leads: I, II, III AND aVR, aVF, aVL
DONT USE PRECORDIAL LEADS TO LOOK AT AXIS DEVIATION
Sandy tells us to look at limb lead I and aVF to calculate it

Question 6

What are values for axis deviation?

Answer 6

Normal: between -30 and +90
Left axis: more negative than -30
Right axis: more positive than 90

Question 7

What are some causes for extreme axis?

Answer 7

Emphysema
Hyperkalemia
Lead transposition
Artificial cardiac pacing
V tach

Question 8

What are causes of right axis deviation?

Answer 8

Normal finding in kids and tall thin adults
RVH
Chronic lung disease
Anterolateral MI
Left posterior hemiblock
Pulmonary embolus
Atrial septal defect
Ventricular septal defect

Question 9

What are causes of left axis deviation?

Answer 9

Left anterior hemiblock
Q waves of inferior MI
Artificial cardiac pacing
Emphysema
Hyperkalemia

Question 10

What is difference between an interval and a segment?

Answer 10

Interval always has a wave form associated with it.

Segment is usually isoelectric

Question 11

T/F: if there is a p wave for every QRS and they are in same direction it is considered sinus rhythm?

Answer 11

True

Question 12

What are characteristics of P wave and what is normal amplitude?

Answer 12

Represents depolarization of atrial myocardium.

Normal= not wider than 3 little boxes (0.11 sec) and not talker than 3 mm, not notched or peaked

Question 13

What does the P wave look like on the different leads?

Answer 13

Positive and rounded in I, II, aVF
Upright in V4-V6
Negative in aVR
Positive, negative, or biphasic in leads III, aVL, V1-V3

Question 14

What are characteristics of PR interval?

Answer 14

Represents atrial depolarization plus normal delay at AV node (to optimize filling)

Normal: 0.12-0.20 sec/no longer than one large box

Question 15

What are characteristics of PR segment?

Answer 15

Should be isoelectric

Can be elevated with atrial infarction or pericarditis

Question 16

What are characteristics of QRS complex? Normal characteristics?

Answer 16

Represents depolarization of ventricular myocardium

Normal width= 0.07-0.11 sec (best to look at I and V1)
Normal amplitude= no smaller than 6mm in I, II, III and no taller than 25-30 mm in precordial leads

Question 17

What are normal characteristics of Q wave?

Answer 17

Represent septal depolarization and must be distinguished between pathological Q waves which indicate a MI.

Normal: present only in leads I, aVL, V5, V6; small in leads aVF and V5 (normal variant)

Normal width= 0.04 sec (one tiny box)

Normal amplitude= not deeper than 1/3 of QRS complex

Question 18

What are characteristics of ST segment?

Answer 18

Represents time when ventricle cells are in plateau phase, and when ventricles are in absolute refractory period and will not response to stimulation.

Should be isoelectric.

Question 19

What causes ST elevation?

Answer 19

Vessel occlusion

Question 20

T/F: ST deviation and T wave abnormalities are seen with MI.

Answer 20

True

Question 21

What are characteristics of T waves?

Answer 21

Represent repolarization of ventricles.

Should have same polarity as QRS complex.

T waves are very fickle and not as reliable as ST depression or elevation in dx of ischemia.