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76 Cards in this Set
- Front
- Back
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What is the Absolute Refractory Period?
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The period of time when the cardiac cells have not completed repolarization and cannot contract again
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What is artifact?
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Interference or static seen on the monitor
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What is biphasic (diphasic)?
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Going in two opposite directions; describes a complex component that is both above and below the baseline
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What are complex components?
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Set of waves seen on a monitor, which represent an electrical impulse traveling through the electrical conduction pathway of the heart; it includes P, Q, R, S, and T waves
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What is an electrode?
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Adhesive pads that are attached to the patient's skin
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What are leads?
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Wires that connect the electrodes to the monitor or telemetry unit, also called lead wires
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What are Leads?
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Specific placement of electrodes on the patient's skin
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What is a monitor?
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A TV-like screen that shows the conduction of electrical impulses as they travel through the electrical conduction pathway of the heart
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What is the P to P Interval?
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Length of time between one P wave and the next P wave
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What is a rate?
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Number of electrical impulses conducted in 1 minute
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What is the refractory period?
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Time between depolarization and repolarization
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What is the relative refractory rperiod?
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The period of time when cardiac cells have repolarized enough that some cells can be stimulated to depolarize
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What is rhythm?
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Regularity of the appearance of the complex components
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What is the R to R Interval?
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Length of time between one R wave and the next R wave
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What is telemetry?
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Telemetry refers to the process of monitoring cardiac electrical activity by transmitting the information to a monitor or telemetry unit. This process includes a machine, graph paper, the identification of complex components, and the interpretation of rhythm strips.
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What is an electrocardiograph?
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A machine that records the movement of electrical impulses through the heart
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Does the electrocardiograph show actual contractions of the heart?
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NO. Remember that the monitor does not show the actual contraction of the cardiac muscle, only the conduction of the electrical impulses through the heart. Cardiac contractions can only be confirmed by the presence of a pulse.
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What is necessary to confirm cardiac contractions?
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Presence of a pulse
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What is the graph paper?
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A printed record of cardiac electrical activity
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What is represented on the graph paper?
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Time is measured on the horizontal line
and Amplitude is measured on the vertical line |
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How is time determined on the graph paper?
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Each small square in the horizontal direction is equal to 0.04 second, and each large square (five small squares) is equal to 0.20 second.
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How long is a rhythm strip usually?
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6 seconds long
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How is the amplitude determined on the graph paper?
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Each small square in the vertical direction on the graph paper is equal to 0.1 millivolt (mV), and each large square (five small squares) is equal to 0.5 mV.
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What is a positive deflection?
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A wave above the baseline that indicates electrical flow toward a positive electrode
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What is a negative deflection?
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A wave below the baseline that indicates an electrical flow away from a positive electrode
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What are the five major waves on a single heart beat?
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P, Q, R, S, and T.
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What is a cardiac cycle?
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The combination of the five waves, plus the baseline
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How is a cardiac cycle measured?
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From the beginning of one P wave to the beginning of the next P wave
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What is a P wave?
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The first positive (upward) deflection before the QRS complex
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What does the P wave represent?
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The depolarization of both the right and the left atria
(**the repolarization of the atria is not usually seen on the rhythm strip because the wave that shows the recovery of the atrial cells is buried in the QRS complex) |
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What is a normal P wave?
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A normal P wave is well rounded and two small boxes or less in height (<0.2 mV high)
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What is a peaked P wave?
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More than two small boxes in height (> 0.2 mV high)
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What is a notch P wave?
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“M” shaped
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What is an inverted P wave?
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Negative deflection below the baseline
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What is an absent P wave?
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No P wave
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What is a biphasic or diphasic P wave?
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Deflection above and below the baseline
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What are peaked P waves indicative of?
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May indicate enlargement of the right atria
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What are notched P waves indicative of?
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May signify enlargement of the left atria
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What are negative/inverted and absent P waves indicative of?
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Usually a sign of electrical conduction that is initiated from the AV junction
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What are biphasic or diphasic P waves indicative of?
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May indicate enlargement of both atria, seen only with a 12 lead ECG
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What does the PR interval (PRI) represent?
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The time it takes an electrical impulse to be conducted through the atria and the atrioventricular node until the impulse begins to cause ventricular depolarization
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What is the normal range for the PRI?
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0.12 to 0.20 second
(three to five small squares horizontally on the graph paper) |
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What is an abnormal PRI indicative of?
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A disturbance in the electrical conduction pathway
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What does the QRS complex represent?
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Ventricular depolarization, or the conduction of an electrical impulse from the bundle of His through the ventricular muscle
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What is the normal value for the QRS complex?
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Less than 0.12 second
(less than three small squares on the graph paper) |
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What does a value for the QRS complex greater than 0.12 second indicative of?
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A disturbance in the electrical conduction pathway
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What do changes in the ST segment indicate?
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Changes, as little as one small box (0.1 mV) above or below the baseline, may indicate cardiac problems, such as ischemia (decreased supply of oxygen) or cardiac disease
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What does the T wave represent?
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The repolarization of the ventricular myocardial cells
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What does an inverted (depressed) T wave indicative of?
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A previous cardiac ischemia
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What does a biphasic/diphasic or a flat T wave indicative of?
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These variations could also be evidence of heart muscle ischemia or of changes in the blood level of potassium
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What does the rhythm strip represent?
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ONLY the conduction of electrical impulses through the myocardial cells
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What is the refractory period?
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1. The time between depolarization and the return of the cardiac cells to the ready or polarized state
2. While the cells are recovering, the atria and ventricles are refilling with blood, preparing to contract again |
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What is the absolute refractory period?
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The cardiac cells have not completed repolarization and cannot be stimulated to conduct an electrical impulse and contract again (depolarize)
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How is the absolute refractory period measured?
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This period is measured from the beginning of the QRS complex through approximately the first half of the T wave
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What is the relative refractory period?
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1. The cardiac cells have repolarized to the point that some cells can again be stimulated to depolarize, if the stimulus is strong enough
2. However, if these cells are stimulated during this period, they will probably conduct the electrical impulse in a slow, abnormal pattern 3. The relative refractory period is also known as the vulnerable period of repolarization |
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How is the relative refractory period measured?
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From the end of the absolute refractory period (approximately the first half of the T wave) to the end of the T wave
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What is the atrial rate?
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The number of P waves on the rhythm strip (adjusted for 1 minute)
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What is the ventricular rate?
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The number of R waves on the rhythm strip (adjusted for 1 minute)
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Which rate represents the approximate heart rate?
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Ventricular rate (the number of R waves)
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What is an artifact?
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An interference or static seen on the monitor screen or rhythm strip
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What causes an artifact?
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1. The electrode losing contact with the patient's skin
2. Patient movement or shivering 3. Broken cable or lead wire 4. Improper grounding 5. Lead cable touching a metal object |
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What can cause the electrode from losing contact with the patient's skin?
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1. Excessive chest hair
2. Sweaty skin 3. Loss or drying of conductive gel |
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What is a wandering baseline?
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An artifact in which the baseline moves up and down randomly
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What causes a wandering baseline?
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Patient movement or deep, rapid breathing
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True or False:
The monitor shows the conduction of the electrical impulses through the heart, not the actual contraction of the heart muscle. |
True
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True or False:
Leads are color-coded wires that connect the telemetry unit to the patient's cardiac muscle. |
False
(electrodes are adhered to patient's skin, and do not connect to the cardiac muscle) |
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True or False:
Lead II and MCL1 are the two Leads most often used to monitor patients. |
True
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True or False:
It is important to check complex formation, rhythm, and rate when interpreting a rhythm strip. |
True
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The P wave represents the depolarization of both the right and left
a. ventricles b. atria and ventricles c. valves d. atria |
d. Atria
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The normal PR interval measures
a. 0.04 to 0.12 second b. 0.4 to 0.12 second c. 0.12 to 0.20 second d. 0.04 to 0.20 second |
c. 0.12 to 0.20 second
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The measurement of a normal QRS complex is
a. 0.4 to 0.12 second b. 0.12 to 0.20 second c. 0.4 to 0.20 second d. 0.04 to 0.12 second |
d. 0.04 to 0.12 second
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What components and intervals are included in one complete cardiac cycle?
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a. P wave
b. PR interval c. QRS complex d. ST segment e. T wave f. QT interval g. Baseline |
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The T wave represents
a. depolarization of the ventricles b. repolarization of the atria c. polarization of all cardiac cells d. repolarization of the ventricles |
d. Repolarization of the ventricles
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What does a normal QT interval measure?
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Less than one half the R to R interval of that complex to the R wave of the following complex
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Three common causes of artifact are
a. patient movement; low amplitude; 60-cycle interference b. patient movement; slow respirations; loose leads c. patient movement; chest Leads; 60-cycle interference d. patient movement; loose leads; 60-cycle interference |
d. Patient movement; loose leads; 60-cycle interference
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What is the difference between the relative refractory period and the absolute refractory period?
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Absolute refractory period occurs when the cardiac cells have depolarized and cannot transmit any electrical stimulus. Relative refractory period occurs when some of the cardiac cells have repolarized to the point where they can be depolarized again, if the electrical stimulus is strong enough.
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