Regardless of pattern observed, what is a health professionals primary concern?
The patients condition
What is an EKG?
A graphic representation of the heart
What is the machine used to record the electrocardiogram?
Electrocardiograph
The EKG is a graphic tracing of:
The electrical activity of the heart
How can the electrical activity be sensed?
Electrodes placed on the skin surface
What depicts the heart's electrical impulses as patterns of waves on the monitor screen?
Cardiac monitor
Why must the impulses be amplified by the EKG machine?
The electrical impulses on the skin surface are very low voltage.
What is the printed record of the electrical activity of the heart?
Rhythm or EKG strip
What is an electrode?
An adhesive pad that contains conductive gel & is designed for attachment to the patients skin
What are leads?
Color-coded electrodes connected to a cardiac monitor or EKG machine by wires also known as a pair of electrodes: Lead I, II, MCK, etc., - Generally capitalized.
What is necessary for the EKG machine to receive a clear picture of the electrical impulses generated by the heart's electrical conduction system?
There must be a positive (+), negative (-), and a ground lead.
What is the purpose of the ground lead?
To minimize outside electrical interference
What does the exact portion of the heart being visualized depend upon?
The placement of the electodes.
An EKG strip analysis can obtain information on the ____________.
Heart rate
An EKG strip analysis can obtain information on __________ or regularity.
Rhythm
An EKG strip analysis can obtain information on Impulse _______ _______ .
conduction pathways
An EKG strip analysis can obtain information on _______ ______ pathways.
Abnormal conduction
An EKG strip analysis __________ obtain information on pumping action.
can not
An EKG strip analysis can NOT obtain information on _________ output.
Cardiac
An EKG strip analysis can NOT obtain information on blood ___________.
pressure
An EKG strip analysis can not obtain information on cardiac ______ _______.
muscle hypertrophy
What is cardiac muscle hypertrophy?
Thickening of the heart muscle walls, typically due to abnormal cardiac symptoms such as high blood pressure.
What is a dysrhythmia?
Abnormal rhythm of the heart
What is a bipolar lead?
Often referred to as limb leads, they have one positive and one negative electrode.
What is the most common EKG used in hospitals and clinics?
12-lead
What type of EKG is most common in the field?
3-lead EKG. However, a 4th lead - representing the right leg.
Which lead is sufficient for detecting life-threatening dysrthymias?
3-Lead EKG
Which lead(s) are most common for cardiac monitoring because of their ability to visualize P waves?
Lead II and MCL (Modified Chest Lead)
Which leads are bipolar leads?
Chest Leads I, II, and III.
Placement of the bipolar leads: Lead I
+ Left arm - Right arm
Placement of the bipolar leads: Lead II
+ Left leg - Right arm
Placement of the bipolar leads: Lead III
+ Left leg - Left arm
What is the inverted triangle formed around the heart for proper placement of the bipolar leads?
Einthoven's triangle
What are EKG waveforms?
A wave recorded on an EKG strip that refers to movement away from the baseline.
What is another name for baseline?
Isoelectric line
What is deflection?
A positive or negative movement above or below the baseline or isoelectric line.
What is a baseline?
The straight line seen on an EKG strip that represents the beginning and end point of all waves
What is measured on the vertical line?
Amplitude or voltage
What is measure on the horizontal line?
Time
How many large squares = 1 mV (millivolts)?
2
How is EKG graph paper divided?
Small squares, each is 1 millimeter (mm) in height and width, representing a time interval of .04 seconds.
What do the dark lined squares represent?
5 squares (vertically and horizontally), each representing .20 seconds (5 x .04 = .20)
What does each of the squares represent?
The measurement of the length of time required for the electrical impulse to traverse a specific part of the heart.
Proper interpretation of EKG rhythms is dependent upon what?
The understanding of the time increments as represented on the EKG paper.
What causes the waveforms produced on the graph paper?
The electrical impulse after leaving the SA node
How is one complete cardiac cycle represented on the EKG graph paper?
5 major waves - P wave: Q, R, S waves (referred to as the QRS complex) and the T Wave
How doe the P wave occur?
When the SA node fires during a normal cardiac cycle, the "firing" event sends the electrical impulse outward to stimulate both atria.
What does the P wave look like on the EKG graph paper?
A smooth, rounded upward deflection.
What does the P wave represent?
Depolarization of the left and right atria
What is the length of the P wave?
About .10 seconds in length
What does the PR interval represent? (Hint: Physiology)
Represents the time interval necessary for the impulse to travel from the SA node through the internodal pathways in the atria and downward to the ventricles.
What is an abreviation for PR?
PRI (PR interval)
What does the PRI represent?
The distance from the beginning of the P wave to the beginning of the QRS complex.
How is the PR measured?
3 - 5 small squares of the EKG graph paper
What is the time interval of the PR interval?
.12 - .20 seconds in length
What is the QRS complex?
Q, R, S waves
What does the QRS complex represent?
Represents the conduction of the electrical impulse from the bundle of His throughout the ventricular muscle, or ventricular depolarization.
Where is the Q wave?
The first downward deflection following the PRI
Where is the R wave?
The first upward deflection of the QRS complex and is normally the largest deflection seen in chest Leads I and II
Where is the S wave?
Immediately follows the R wave in a downward deflection.
How is the QRS complex measured?
From the beginning of the Q wave to the point where the S wave meets the baseline.
What is the time frame for the QRS complex?
Less than .12 second or less than 3 small squares on the EKG graph paper
Are all QRS complexes the same in every individual?
No, the QRS complex will vary from individual to individual and not all three waves are necessarily present.
Describe the ST segment.
The time interval during which the ventricals are depolarized and ventricular repolarization begins.
What is typical of the ST segment?
Normally the ST segment is isoelectric or consistent with the baseline.
What may cause the ST segment to be elevated or depressed?
Cardiac diseases such as ischemia, infarction, or both.
When does the T wave occur and what does it represent?
Follows the ST segment, which represents ventricular repolarization.
What does the T wave look like?
Normally seen as a slightly asymmetrical, slightly rounded, positive deflection.
The __________ is NOT an electrical event associated with ventricular musculature.
ventricular repolarization
What is the T wave referred to?
The resting phase of the cardiac cycle.
What is a refractory period?
The amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation.
The T wave is either ________________ in the presence of current or previous cardiac ischemia
elevated or depressed
What is represented by the P-QRS-T pattern?
One complete cardiac cycle
Which lead should be placed on the left arm?
Lead I (+)
Ventricular diastole refers to ventricular:
relaxation
The electrocardiogram is used to:
Evaluate electrical activity of the heart
The PR interval shuld normally be __________second or smaller.
0.20
The QRS interval should normally be _______ second or smaller.
0.12
The T wave on the EKG strip represents:
Rest period
The coronary circulation has now many main arteries.
Two
When interpreting dysrhythmias, the heath care provoder should remember thta the most important key is the:
Patient's clinical appearance
A graphic record of the electrical activity of the heart is an:
Electrocardiogram
While EKG analysis serves as a useful diagnostic tool, the health care professional must be cognizant of the fact that EKG is a graphic tracing of the electrical actiity of the heart, but not the __________________ activity.
mechanical
Which lead serves to minimize outside electrical interference?
Ground
The exact portion of the heart being visualized depends, in large part, on the placement of the:
Electrodes
Lead II is most commonly used for cardiac monitoring because of it ability to visualize
P
_______________ leads are those that have one positive and one negative electrode.
Bipolar
Which bipolar lead is ALWAYS +?
Left leg
Which bipolar lead is ALWAYS -?
Right arm