CCMA EKG Review: Electrode Placement, Artifacts and the Rhythms to Recognize

Six questions is a small slice of the CCMA, 4% of the score, but EKG items are precise: an electrode is in the right intercostal space or it isn't, and a rate calculation is right or wrong. NHA's CCMA test plan puts EKG and Cardiovascular Testing (subdomain 3F) inside Clinical Patient Care, and its knowledge statements are specific enough to study from directly.

What NHA's test plan lists for CCMA EKG and cardiovascular testing

The plan's seven tasks for subdomain 3F:

1. 3F1 Prepare the patient for an EKG or ambulatory cardiac monitoring
2. 3F2 Identify types of leads and proper anatomical electrode placement
3. 3F3 Perform EKG tests
4. 3F4 Recognize abnormal or emergent EKG results (for example, dysrhythmia, arrhythmia, versus artifact)
5. 3F5 Assist the provider with ambulatory cardiac monitoring (for example, stress tests, Holter and event monitoring)
6. 3F6 Transmit results or report them to the medical record and the provider
7. 3F7 Ensure proper functioning and storage of EKG equipment

Behind them are knowledge statements k147 to k157: techniques and methods, how to minimize artifact, artifact and electrical interference (the plan's examples are "fuzz, wandering baseline"), preparing, positioning and draping the patient, patient characteristics such as adult versus pediatric, supplies such as paper, leads, razor and tape, limb and chest electrode placement, signs of adverse reaction during testing, abnormal rhythms, waveforms, intervals and segments, and calibration.

Preparing the patient for a 12-lead EKG

MedlinePlus's EKG article, NHLBI's heart tests page and the American Heart Association's EKG standardization statement cover the basics:

• Ask first. MedlinePlus says the provider should know every medicine the patient takes, because some can interfere with results. Ask about allergy to tape or electrode adhesive too, which MedlinePlus and NHLBI mention for monitor electrodes
• Keep the patient warm and relaxed. MedlinePlus says any movement, including shivering, can alter the results, and advises no exercise or cold water immediately before the test
• Prepare the skin. Clean the electrode sites and shave or clip hair where needed so the patches stick (MedlinePlus); the AHA statement adds that cleaning and gentle abrasion of the skin can reduce noise
• Position the patient. Lying down and still, per MedlinePlus and NHLBI

Where the 10 EKG electrodes go

A standard 12-lead EKG uses 10 electrodes: four on the limbs and six on the chest. From them the machine produces 12 leads, the limb leads I, II, III, aVR, aVL and aVF, and the chest leads V1 to V6. The AHA statement gives the chest positions:

Three placement points that make good exam questions:

• V1 and V2 placed too high. The AHA calls superior misplacement in the second or third intercostal space "a common error." It can reduce R-wave amplitude and produce false signs of an anterior heart attack
• V4 before V3. Because the AHA defines V3 as midway between V2 and V4, find V4 first, then place V3 between them, and keep V5 and V6 in the horizontal plane of V4. For patients with large breasts, the statement notes that chest electrodes are most commonly placed beneath the breast
• Wires can be swapped. The AHA notes that lead wires are color-coded under manufacturing standards but can still be misconnected, and that transposing chest lead wires can imitate an infarction pattern. Match each wire to its labeled position (RA, LA, RL, LL, V1 to V6) rather than relying on color alone

EKG artifact: what distorts the tracing

The test plan asks you to tell a true dysrhythmia from artifact. The sources describe the main kinds of interference this way:

Why it matters: the AHA statement says skin preparation and electrode placement "have important effects on the ECG," and misplaced or swapped electrodes can imitate disease on the tracing. That's why the test plan pairs recognizing abnormal results with recognizing artifact, and asks you to report results to the provider (task 3F6) rather than decide what they mean.

Reading EKG paper: speed, boxes and calibration

The standard grid, from the Essential Electrocardiography module of the University of Miami's Gordon Center and Loyola University Chicago's EKG lesson:

• Paper speed. Normally 25 mm per second
• Small square. 1 mm, or 0.04 seconds
• Large square. 5 mm, or 0.2 seconds, so five large squares equal one second
• Calibration. The standard calibration mark is 1 millivolt = 10 mm of height

And three ways to calculate heart rate:

• Regular rhythm, large squares. 300 divided by the number of large squares between two R waves (Gordon Center)
• Regular rhythm, small squares. 1,500 divided by the number of small squares, since 60 seconds ÷ 0.04 seconds = 1,500 (Passy's arithmetic)
• Irregular rhythm. Count the beats in a 6-second strip and multiply by 10 (Loyola), or, on a full 10-second record, multiply by 6

For example (Passy's arithmetic), 4 large squares between R waves gives 300 ÷ 4 = 75 beats per minute, and 20 small squares gives 1,500 ÷ 20 = 75 as well. The Gordon Center module puts a normal PR interval at 0.12 to 0.20 seconds (3 to 5 small squares) and a normal QRS duration at 0.10 seconds or less. The CCMA vital signs guide covers the pulse side of the same numbers, and EKG-rate math is explained step by step in planned CCMA practice.

Rhythms a CCMA candidate should recognize

The test plan's tasks are to recognize abnormal or emergent results and report them; it doesn't ask you to diagnose. California's Medical Board, for example, says medical assistants may not interpret test results. The rhythms below are the ones worth knowing on sight, with the features the sources describe:

NHLBI's arrhythmia types page is a plain-language reference for the whole list. For the emergent end of it, MedlinePlus's guidance on a person who has stopped breathing is to call for emergency help and perform CPR if you know how, and in a public place to look for an AED and follow its directions; in a clinic, follow your office's emergency protocol.

Holter monitoring and stress testing

Task 3F5 covers ambulatory monitoring, naming stress tests, Holter monitoring and event monitoring. MedlinePlus's Holter monitor article gives the patient instructions a medical assistant often explains:

• The monitor is worn for 24 to 48 hours during normal activity
• The patient keeps a diary of activities and symptoms, which the provider matches to the recording
• Electrodes must stay firmly attached; the patient learns how to replace one that comes loose
• Avoid electric blankets, high-voltage areas, magnets and metal detectors
• Shower or bathe before the test, since the monitor can't get wet

A stress test, per MedlinePlus, is an EKG recorded while the patient exercises or is under light stress; NHLBI's heart tests page adds that blood pressure is monitored too and the test is stopped if the patient shows any sign of a heart problem. During testing, the test plan expects you to know the signs of an adverse reaction; its examples are signs of distress, elevated blood pressure and respiration.

Two CCMA-style EKG questions written by Passy

These are original practice questions, not NHA items.

1. A medical assistant is placing chest electrodes for a 12-lead EKG. Where should V4 be placed?

• A. Fifth intercostal space, midclavicular line
• B. Fourth intercostal space, right sternal border
• C. Fourth intercostal space, left sternal border
• D. Fifth intercostal space, midaxillary line

Keyed answer: A. The AHA statement places V4 in the fifth intercostal space in the midclavicular line. B is V1, C is V2, and D is close to V6, which sits at the midaxillary line in the horizontal plane of V4.

2. On a regular rhythm strip recorded at 25 mm per second, there are 4 large squares between consecutive R waves. What is the heart rate?

• A. 60 beats per minute
• B. 75 beats per minute
• C. 100 beats per minute
• D. 120 beats per minute

Keyed answer: B. With a regular rhythm, the Gordon Center module divides 300 by the number of large squares: 300 ÷ 4 = 75. A would need 5 large squares, C 3, and D 2.5.

Missed one? Every EKG question you miss waits in the planned Fix It list for another try.

Your next step with CCMA EKG review

Give EKG its share and no more: about 2 of 60 study hours in the CCMA study plan, mostly spent drilling positions and rate math. Then check yourself with the 20 free CCMA practice questions, and when the rest of Clinical Patient Care is next, practice EKG questions alongside the other clinical subdomains in planned CCMA prep.