Weekend 2 lecture 5 Flashcards
Placement postions for the bipolar limb leads
I: Left arm to right arm
II: Left leg and right arm
III: Left leg and left arm triangle postions
Augmented Limb Leads
AVR: right arm
AVL: left arm
AVF: left leg
Precordial leads ragne from V1- V? all take place in what plane??
V6 the transverse plane
Phases of the EKG diagram whats phase 0 phase 1 phase phase 2 & 3 phase 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
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
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
what is the calibration speed and what is the calibration voltage?
Initial assessment
Calibration for paper speed 25mm/sec
Calibration for voltage 1mV = 10mm
how to count the rate on a EKG strip
Box to box or peak to peak method or in O-bags case the R-R interval which essentially saying the same thing.
what is the formula for calculating the R-R or BPM
BPM = (60,000msec/minute)
msec/beat
Questions to ask to see if the rhythm is off or not.
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?
What is the axis average? What does it mean?
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)
How to calculate the axis? refer to leads 1 and 2 on the body diagram then what
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
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?
Normal PR = .12-.2ms
Normal QRS = < 0.10msec
Normal QT = < one-half of the R-R, if heart rate is normal
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
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
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?
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
how will a left bundle branch block appear?
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
How will a Right bundle branch block appear.
does the septum hit the left first and then it intiates the right true or false
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
How long is a non-specific intraventricular conduction without a RBBB or LBBB pathology
Non specific intraventricular conduction delay is a QRS >120msec, without the morphology of the RBBB or LBBB
How does the S-T segement appear if there is an “acute” injury. How does after recent injury
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
What does the EKG look like if there is a remote injury?
Remote injury
The only manifestation is the resence of the Q waves
What happens in non Q wave Myocardial Infraction
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.
What leads control the following areas of the heart
Anterior septal
anterior
extensive anterior
anterior lateral
high lateral
inferior
posterior
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)
explain Failure to capture:
Failure to Sense:
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
What is an EKG
eletrical recording of the heart
Whats the J point and where can you usally pick out a MI
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
How much time is one little single box and how much time is a big box the one between the two black heavy lines
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
How to count the Artial contractions (think P-wave)
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
How do you count the rate using boxes explain please
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
second way to count rate using the small boxes
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
types of depressed ST segments
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
How does a T-wave present itself over a course of time if there is an injury.
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
how to detect a PVC
Widen QRS complex or Q wave arises earlier than expected
