Lesson 22 — Electrocardiography
All procedural steps, PURPOSE rationales, and topic content below are verbatim from MedCerts HLT420B Storyline modules. Quiz items have been normalized to multiple-choice format with verbatim source rationales. Reference textbook: Niedzwiecki & Pepper, Kinn's The Clinical Medical Assistant, 15th ed., Chapter 11. No outside material added.
- Define electrocardiography, the cardiac cycle, and the PQRST complex
- Discuss the electrocardiograph and supplies used to perform an ECG/EKG
- Demonstrate performance of an electrocardiogram
- Differentiate artifacts and rhythm abnormalities
- Summarize the role of the medical assistant in electrocardiography
ECG Graph Documentation
If asked to perform an E-C-G, the clinical medical assistant will load special paper into the E-C-G machine. This is required if not using an automated system that documents the E-C-G directly into the patient's E-H-R. The paper may be Z-fold or eight-point-two-five by eleven-inch paper. The stylus burns the E-C-G tracing, or heart activity, into specially coated, heat- and pressure-sensitive paper.
To ensure the integrity of E-C-G paper, it should be stored in a dry, cool, and dark location. It should not be exposed to heat, bright light, or ultraviolet light. Storage with vinyl, shrink wrap, or plastics should be avoided. Do not to expose paper to alcohol, adhesives, solvents, or cleaners.
Graph paper displays standard markings that represent standard dimensions. There are small blocks, and there are large blocks. Each large block consists of five horizontal and five vertical small blocks, or a five-by-five square. Twenty-five small blocks squared make up one large block.
Vertical measurements on an E-C-G graph represent voltage. Voltage indicates the strength of the heartbeat. It is based on the height of the Q-R-S complex. Each vertical square equals one millimeter. Five small squares equal five millimeters. Ten squares equal ten millimeters or one millivolt.
Horizontal measurements on an E-C-G graph represent time. Time determines the rate of the heartbeat. Each small square, or block, equals point-zero-four seconds: Two small blocks equal point-zero-eight seconds. Three small blocks equal point-twelve seconds. Four small blocks equal point-sixteen seconds. Five small blocks equal point-twenty seconds and five large blocks equal one full second.
Only physicians can analyze an E-C-G tracing and determine a diagnosis. The M-A should be able to recognize potential irregularities on the tracing and alert the physician. This may include an extremely fast heart rate or a slow heart rate. The physician may diagnosis this as tachycardia or bradycardia. A patient's heart rate can be quickly determined by counting squares. In this example, a Q-R-S complex is seen every five large blocks. Five blocks are equal to one second. Since there are sixty seconds in a minute, the heart rate is sixty beats per minute.
Holter Monitor
Goal: To establish a possible correlation between ECG abnormalities and the patient's 24-hour daily activities.
- Patient's health record
- Holter monitor with new batteries
- Disposable electrodes
- Razor
- Sharps container
- Gauze pads or abrasive tool as needed
- Activity diary
- Carrying case with belt or shoulder strap
- Alcohol swabs
- Cloth tape (nonallergenic)
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Sanitize your hands.Purpose
To ensure infection control.
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Greet the patient and confirm his or her identity by name and date of birth.
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Assemble the needed equipment, and install batteries in the monitor.Purpose
New or fully charged batteries ensure accurate monitor function for 24 hours.
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Explain the procedure.Purpose
An informed patient helps ensure testing accuracy.
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Ask the patient to disrobe to the waist and to sit at the end of the examination table or to lie down.Purpose
Placing the patient at the best working level for the medical assistant.
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Clean each electrode application site with an alcohol swab and allow the sites to air dry.Purpose
To remove all surface skin oil to ensure maximum electrode adherence. If shaving will be necessary, clean before shaving to prevent irritation and patient discomfort.
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If the patient has a hairy chest, dry shave the area at each of the electrode sites.Purpose
The skin must be hairless to provide maximum electrode adherence.
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Fold a gauze pad over your index finger and briskly rub the sites or use an abrasive tool as indicated.Purpose
To help electrodes stick more tightly to the skin.
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Apply the electrodes to the sites recommended by the manufacturer; use enough pressure to make sure they adhere completely to the skin. Rub the edges of each electrode a second time to make sure the electrode will stay in place.Purpose
Secure attachment of the electrodes is absolutely necessary to produce an accurate tracing.
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Attach the lead wires to the electrodes and connect the end terminal to the patient cable.
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Place a strip of cloth tape over each electrode.Purpose
To help secure the electrodes in place in case the wires are pulled during the testing period.
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Attach the test cable to the monitor and plug it into the electrocardiograph. Run a baseline test tracing as directed by the manufacturer's guidelines.Purpose
To ensure proper connections of the electrodes and running of the monitor.
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Help the patient get dressed without disturbing the connected electrodes.
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Make sure the cable extends through the buttoned front or out the bottom of the shirt or blouse.
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Place the monitor in the carrying case and attach it to the patient's belt or pocket or place it over the shoulder. Be sure the wires are not being pulled or bent.Purpose
Taut or badly bent wires may loosen or malfunction.
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Plug the electrode cable into the monitor.
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Record the patient's name and date of birth and the starting date and time in the patient's activity diary.Purpose
To establish the starting time of the test and cardiac activity.
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Give the patient the activity diary and advise him or her to begin by writing in his or her present activity. Include patient education information on the importance of continually recording activities in the diary; using the event marker on the monitor if he or she experiences any symptoms; and correlating the event with a recording in the diary, including the time and details of the related activity before or during the event.Purpose
The diary should correlate the patient's activity with any cardiac symptoms.
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Schedule the patient for a return appointment in 24 hours.
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Sanitize your hands.Purpose
To ensure infection control.
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Record the procedure in the patient's health record.Purpose
A procedure is not considered done until it is documented in the patient's health record.
Knowledge-check items
Click an answer to lock it in — you'll see the rationale below. Reset any time to re-attempt. Items originally formatted as true/false, fill-in-blank, or drag-and-drop have been normalized to multiple choice; the source format is noted in the eyebrow.
L22-01 · ECG Graph Documentation
"To ensure the integrity of E-C-G paper, it should be stored in a dry, cool, and dark location. It should not be exposed to heat, bright light, or ultraviolet light. Storage with vinyl, shrink wrap, or plastics should be avoided."
ECG paper is heat and pressure sensitive and requires careful storage away from environmental factors that could compromise its integrity.
"Each large block consists of five horizontal and five vertical small blocks, or a five-by-five square. Twenty-five small blocks squared make up one large block."
One large block contains exactly 25 small blocks because the large block is a 5×5 grid of small blocks.
"Vertical measurements on an E-C-G graph represent voltage. Voltage indicates the strength of the heartbeat. It is based on the height of the Q-R-S complex. Each vertical square equals one millimeter."
Vertical measurements represent voltage, which indicates heartbeat strength, not time which is measured horizontally.
"Each small square, or block, equals point-zero-four seconds: Two small blocks equal point-zero-eight seconds. Three small blocks equal point-twelve seconds. Four small blocks equal point-sixteen seconds. Five small blocks equal point-twenty seconds and five large blocks equal one full second."
Each small horizontal block equals 0.04 seconds, and these measurements determine the rate of the heartbeat.
"Only physicians can analyze an E-C-G tracing and determine a diagnosis. The M-A should be able to recognize potential irregularities on the tracing and alert the physician."
The physician has sole authority to interpret ECG tracings and make diagnoses. The MA's role is to recognize abnormalities and notify the physician.
L22-03 · Holter Monitor
"Attach the test cable to the monitor and plug it into the electrocardiograph. Run a baseline test tracing as directed by the manufacturer's guidelines. PURPOSE: To ensure proper connections of the electrodes and running of the monitor."
The baseline test verifies proper connection of the electrodes to the monitor before the patient wears the device.
"Give the patient the activity diary and advise him or her to begin by writing in his or her present activity."
The activity diary is specifically designed to track the patient's daily activities in correlation with any cardiac events or symptoms recorded during the 24-hour monitoring period.
"The diary should correlate the patient's activity with any cardiac symptoms."
The purpose of the activity diary is to document what the patient is doing when cardiac symptoms occur, establishing the correlation between activities and ECG abnormalities.
"Assemble the needed equipment, and install batteries in the monitor. PURPOSE: New or fully charged batteries ensure accurate monitor function for 24 hours."
New or fully charged batteries are essential because the monitor must function continuously for the entire 24-hour monitoring period.
"Explain the procedure. PURPOSE: An informed patient helps ensure testing accuracy."
Patient understanding of the procedure and its importance directly affects the accuracy and quality of the monitoring results obtained.