Weekend 2 lecture 5

Question 1

Placement postions for the bipolar limb leads

Answer 1

I: Left arm to right arm

II: Left leg and right arm

III: Left leg and left arm triangle postions

Question 2

Augmented Limb Leads

Answer 2

AVR: right arm

AVL: left arm

AVF: left leg

Question 3

Precordial leads ragne from V1- V? all take place in what plane??

Answer 3

V6 the transverse plane

Question 4

Phases of the EKG diagram whats phase 0 phase 1 phase phase 2 & 3 phase 4

Answer 4

Phase 0: depolarization occurs
Phase 1: impulse propagation
Phase 2 & 3: represent the refractory, repolarization and restoration of resting membrane potential occurs during these phases
Phase 4: resting membrane potential
Remember there are leaky ion channels
slide 10 of the powerpoints give us a visual depiction of this process

Phase 0 – influx of the sodium ions (depolarization) raising the resting membrane potential from generally -70mV to -50mV

Phase 1- propergation

Phase 2 – repolarization - outward distribution of K or Cl to make the membrane more negative again

Phase 3 – Ditto

Phase 4- you have reached the resting membrane potential again

Phase 3- K out

Question 5

What is the P wave what is the P-R interval what comprises of the QRS complex what is the S wave and what is the T-wave

Answer 5

SA node is silent
P-wave is the atrial depolarization
P-R is the AV node firing there is a pause before the QRS cause of the vnetricular delay to allow it fill up and the bundle of his and the prejunkie fibers
QRS complex- is the ventricular depolarization
s wave- isoeletric period
T wave- is the ventricular repolarization

Question 6

what is the calibration speed and what is the calibration voltage?

Answer 6

Initial assessment
Calibration for paper speed 25mm/sec
Calibration for voltage 1mV = 10mm

Question 7

how to count the rate on a EKG strip

Answer 7

Box to box or peak to peak method or in O-bags case the R-R interval which essentially saying the same thing.

Question 8

what is the formula for calculating the R-R or BPM

Answer 8

BPM = (60,000msec/minute)

msec/beat

Question 9

Questions to ask to see if the rhythm is off or not.

Answer 9

Is there a p wave?
Is every p wave followed by a QRS?
Is the P wave upright in leads I, II, & III?
Is the PR interval in normal range?

Question 10

What is the axis average? What does it mean?

Answer 10

Represents the average of the instantaneous forces generated during the sequence of ventricular depolarization.
Normal value is –30 to +90 (or +100, depending on which text you refer to)

Question 11

How to calculate the axis? refer to leads 1 and 2 on the body diagram then what

Answer 11

Look at leads I & II, if the QRS is primarily positive in both of these leads then the axis is in normal range
Look at leads I and AVF to determine quadrant
Next look for the most isoelectric lead to estimate the axis
Refer to slide 22

Question 12

What is the time for the PR wave to occur

What is the time for the “QRS” complex to occur?

What is the Q-T range if the heart rate is normal?

Answer 12

Normal PR = .12-.2ms
Normal QRS = < 0.10msec
Normal QT = < one-half of the R-R, if heart rate is normal

Question 13

Wave form analysis of the P-wave

How should the wave appear in lead 1 avl and v3-v6

how does it in other leads and what is the typical height

Answer 13

P wave
Must be upright in lead II, if it originates in the sinus node
Should be upright also in leads I, aVL, and V3-6
Biphasic in V1
Other leads exhibit variable pwave morphology
Normally is less than 3mm in Lead

Question 14

Exam of the QRS complex. how does the height of the “r wave” progress from lead V1 to V6 and where does it switch over?

Answer 14

Examination of the QRS complex
Widened QRS complexes
Progression of the height of the r wave
Should increase in height from V1 to V6 with the transitional lead usually being V4

Question 15

how will a left bundle branch block appear?

Answer 15

Left BBB
Initial force travels across the septum from right to left, there is an initial negative deflection in lead V1 and an initial upright deflection in V6
The EKG may not be used to ascertain ischemic changes during exercise

Question 16

How will a Right bundle branch block appear.

does the septum hit the left first and then it intiates the right true or false

Answer 16

Right BBB
Initial force due to left to right activation of the septum is normal, after the septum is depolarized the impulse travels through the mass of the left ventricle…after the left ventricle has been partially depolarized, the right ventricle depolarizes
Triphasic impulse (rabbit ears=R’R wave)

True and Rabbit ears two peaks will appear in the top of the R-wave

Question 17

How long is a non-specific intraventricular conduction without a RBBB or LBBB pathology

Answer 17

Non specific intraventricular conduction delay is a QRS >120msec, without the morphology of the RBBB or LBBB

Question 18

How does the S-T segement appear if there is an “acute” injury. How does after recent injury

Answer 18

The injury current”
Acute
Elevation of the ST segment and peaking of the T wave
Within hours or days the T wave inverts
Recent
ST segment returned to baseline, but t wave remains and there is a significant Q wave

Question 19

What does the EKG look like if there is a remote injury?

Answer 19

Remote injury

The only manifestation is the resence of the Q waves

Question 20

What happens in non Q wave Myocardial Infraction

Answer 20

What about non Q wave MIs?

MIs where there is no development of a widened QRS complex, but the ST segment changes and T wave changes occur.

Question 21

What leads control the following areas of the heart

Anterior septal

anterior

extensive anterior

anterior lateral

high lateral

inferior

posterior

Answer 21

anterior septal- V1 and V2

Anterior V1-V4

extensive Anterior - V1-V6, I, AVL

Anterior Lateral - V3 -V6, I, AVL

high lateral - I AVL

inferior - II, III, AVF think legs

posterior V1, V2 (ST depression tall R waves noted)

Question 22

explain Failure to capture:

Failure to Sense:

Answer 22

Failure to Capture: pacemaker fires, but does not cause the appropriate electromechanical action of the heart

Failure to Sense: pacemaker is firing at inappropriate time

Question 23

What is an EKG

Answer 23

eletrical recording of the heart

Question 24

Whats the J point and where can you usally pick out a MI

Answer 24

ST- segement great for picking out an MI

J point is the end of the S-wave and sometimes this can be a predictor of the MI

Question 25

How much time is one little single box and how much time is a big box the one between the two black heavy lines

Answer 25

EKG Paper:
Each box is 0.04 seconds in length
Meaning there are 0.2 seconds between the darkest lines
X-axis
Time
Y-axis
1 mV

Question 26

How to count the Artial contractions (think P-wave)

Answer 26

Atrial Rhythm
Measure the distance between the start of one P wave and the beginning of the next P wave
Using a ruler or index card, mark this distance
Using this measurement, compare the 2nd and 3rd P waves
Continue for each P wave of the strip
If all P waves are equidistant, the rhythm is regular
If P waves are at different distances, the rhythm is irregular

Question 27

How do you count the rate using boxes explain please

Answer 27

Find portion of P wave or QRS complex that falls on a dark line
Count off each next heavy, dark line as follows: 300, 150, 100, 75, 60, 50
Find the next portion of the P wave or QRS complex
Provide an approximate rate based on where between the lines the portion of the wave falls

Question 28

second way to count rate using the small boxes

Answer 28

Use the black spacer bars at the top of the EKG strip to calculate a 6 second strip
Each bar indicates 3 seconds
Either count the number of P waves or QRS complexes in this 6 second strip
Multiply by 10 to get your rate

Question 29

types of depressed ST segments

Answer 29

upsloping- .08 seconds after QRS 30 - 40 % error rate

downsloping - very rare type of ST depression .08

horizontal slopping - ..08 after QRS complex completes rate is less than one 1mV 5-10 percent of the time it happens

Question 30

How does a T-wave present itself over a course of time if there is an injury.

Answer 30

Response to Injury
Initial peaking of T wave
Within hours to days T wave inverts
Within 2 weeks to 1 year T wave resumes normal morphology

Question 31

how to detect a PVC

Answer 31

Widen QRS complex or Q wave arises earlier than expected