CHAPTER 45

Cardiology Procedures

From the heart's electrical wiring to ECGs, Holter monitors, stress tests, and defibrillators — everything you need to read the rhythm and support the patient.

18
Objectives
37
Key Terms
7
Arrhythmias
10
Quiz Questions

🎯 Objectives

In this chapter, you will learn the following:

KB Knowledge Base

  1. Spell and define, using the glossary, all the Words to Know in this chapter.
  2. Explain the electrical conduction system of the heart.
  3. Explain the reasons for performing an electrocardiogram.
  4. Discuss the equipment and supplies needed to perform an electrocardiogram.
  5. Identify the 12 leads and describe which area of the heart each represents.
  6. Explain the purpose of standardization for an electrocardiogram.
  7. Define artifacts that may be found on an electrocardiogram.
  8. Describe what causes artifacts on an electrocardiogram.
  9. Describe the medical assistant's role in identifying cardiac arrhythmias.
  10. Explain the purpose and procedure for proper hookup of a Holter monitor to a patient.
  11. Describe why cardiac stress testing is performed.
  12. State the purpose of a defibrillator.

S Skills

  1. Instruct and prepare a patient for an electrocardiogram.
  2. Perform electrocardiography.
  3. Document patient care accurately in the medical record.
  4. Demonstrate the procedure for proper hookup of a Holter monitor.

B Behaviors

  1. Incorporate critical thinking skills when performing patient assessment and care.
  2. Explain to a patient the rationale for performance of a procedure.

📖 Key Terms Glossary

Tap any card to expand its definition. Search or filter by category to find a term fast.

Arrhythmia▾
An irregularity in the heart's rhythm — an abnormality in the beat, rate, or rhythm pattern seen on an ECG.Think: "a-RHYTHM-ia" = away from a normal rhythm.
Atrial depolarization▾
The electrical event that triggers the atria to contract, beginning the cardiac cycle. It's recorded on the ECG as the P wave.
Countershock▾
An electrical shock delivered by a defibrillator to convert a dangerous arrhythmia back into a normal sinus rhythm."Clear!" — that jolt in every TV hospital scene is a countershock.
Current▾
The flow of electricity produced by the heart's muscle contractions, which the ECG machine detects and records.
Impulse▾
The tiny electrical signal that starts in the SA node and travels through the heart, triggering each contraction.
Purkinje (fibers)▾
Fibers that spread the electrical impulse through the ventricles, causing them to contract and producing the QRS complex on the ECG.
Repolarization▾
The recovery phase of the ventricles after contraction, before the next beat begins. Shown on the ECG as the T wave.
Voltage▾
The difference in electrical potential measured between two points (like between the right arm and left arm) that the ECG records.
Amplifier▾
The part of the ECG machine that enlarges the heart's tiny electrical impulses so they can be recorded clearly.
Defibrillator▾
A device that delivers a countershock to the heart to convert a life-threatening arrhythmia into a normal sinus rhythm.
Echocardiography▾
A noninvasive diagnostic test that uses sound waves (echoes) to evaluate the structure and function of the heart.
Echoes▾
Sound waves reflected back through the heart during echocardiography, used to create an image of heart structures.
Electrocardiograph▾
The machine used to record the electrical activity of the heart (produces the electrocardiogram).-graph = the machine; -gram = the paper record it produces.
Electrode▾
A small adhesive sensor placed on the patient's skin that picks up the heart's electrical activity and sends it to the ECG machine.
Galvanometer▾
The component that converts the amplified electrical impulses into the mechanical motion that moves the stylus across the paper.
Holter monitor▾
A small, portable ECG recorder worn by a patient — usually for 24 hours (up to 72) — to capture heart activity during normal daily life. Also called an ambulatory ECG.
Multichannel▾
Describes a 12-lead ECG machine that records the heart's electrical activity from all 12 views simultaneously, rather than one at a time.
Stylus▾
The heated, pen-like part of an older electrocardiograph that presses against the tracing paper to draw the ECG waves.
Augmented▾
Means "made larger." The aVR, aVL, and aVF leads are called augmented because the machine enlarges their small impulses to make them readable on paper.
Electrocardiogram▾
The paper (or digital) recording of the heart's electrical activity — abbreviated ECG or EKG.
Interpretive▾
Describes computerized ECG machines that can perform a basic analysis of the tracing — though a provider always reviews the results too.
Interval▾
A measured span of time on the ECG, such as the PR interval — from where the P wave begins to the start of the QRS complex.
Precordial▾
Refers to the six chest leads (V1–V6). Each precordial lead is unipolar, monitoring one electrode against a point within the heart."Precordial" = near the heart (pre- + cordial/heart).
Reliable▾
Describes an accurate, trustworthy ECG reading — which is why standardization is done before every tracing.
Segment▾
A section of the ECG baseline between two waves, such as the PR segment (between the P wave and the QRS complex).
Simultaneous▾
Happening at the same time — a multichannel ECG machine records all 12 leads simultaneously instead of one at a time.
Standardization▾
A calibration mark (normally 2 mm wide × 10 mm high) placed on every ECG so a provider can judge deviations from the standard and trust the reading.
Tracing▾
The wavy line drawn on ECG paper representing the heart's electrical activity over time.
Artifacts▾
Unwanted marks or interference on an ECG tracing that aren't caused by the heart's true electrical activity, and must be identified and corrected.
Cardiology▾
The medical specialty focused on the diagnosis and treatment of heart conditions.
Interference▾
Any outside electrical or physical disturbance (movement, nearby equipment, wiring) that distorts the ECG tracing.
Intermittent▾
Occurring on and off rather than constantly — like chest pain that comes and goes, which is why a Holter monitor may be ordered.
Limbs▾
The arms and legs — where electrodes are placed for the standard bipolar and augmented leads.
Mechanical▾
Physical motion, as opposed to electrical signal — the galvanometer converts electrical impulses into the mechanical motion of the stylus.
Sedentary▾
A lifestyle with little physical activity — a risk factor providers consider, often linked with obesity, when deciding how often to order ECGs.
Somatic (tremor)▾
Related to the body/muscles. Somatic tremor is an ECG artifact caused by shivering, nervousness, or conditions like Parkinson's disease.
Stress test▾
An exercise ECG performed while the patient walks on a treadmill, used to detect heart trouble that isn't obvious on a resting ECG.

⚡ The 12 Leads & ECG Paper

A routine ECG uses 12 leads — 12 different "camera angles" on the heart's electrical activity. Search the table below, or scan the quick facts about the paper itself.

LeadTypeWhat it measures / placement
Standard (Bipolar) Leads — limb electrodes, two points each
Lead IBipolarVoltage difference between the right arm and left arm
Lead IIBipolarVoltage difference between the right arm and left leg
Lead IIIBipolarVoltage difference between the left arm and left leg
Augmented Leads — enlarged, single-point limb readings
aVRAugmentedRight arm electrode vs. a central point between left arm & left leg
aVLAugmentedLeft arm electrode vs. a central point between right arm & left leg
aVFAugmentedLeft leg electrode vs. a central point between right arm & left arm
Precordial (Chest) Leads — unipolar, one electrode + one heart point
V1Precordial4th intercostal space, right margin of sternum
V2Precordial4th intercostal space, left margin of sternum
V3PrecordialMidway between V2 and V4 (placed after V4)
V4Precordial5th intercostal space, left midclavicular line
V5PrecordialHorizontal to V4, at the left anterior axillary line
V6PrecordialHorizontal to V4, at the midaxillary line
25 mm/sec
Standard paper speed (can change to 50 mm/sec if cycles run too close together)
0.04 sec
Each small square (1 mm × 1 mm) represents this much time
0.2 sec
Each large square (5 mm × 5 mm) represents this much time
1.0 sec
Distance across five large squares
2×10 mm
The usual standardization mark, at a sensitivity setting of 1
Turn up to 2
If the tracing is too small — makes the impulse 20 mm high
Turn down to ½
If the tracing is too large — produces a 5 mm high mark

🔁 Path of the Electrical Impulse

One heartbeat, step by step — from the heart's natural pacemaker to full recovery.

1

SA node fires

The impulse begins in the sinoatrial (SA) node, the heart's natural "pacemaker," located in the upper right atrium.

2

Atria contract — P wave

The impulse spreads across the atria, causing atrial depolarization. This is recorded as the P wave, the first wave of the cycle.

3

AV node

The impulse continues to the atrioventricular (AV) node, briefly pausing before passing into the ventricles.

4

Bundle of His & Purkinje fibers

The signal travels through the Bundle of His and spreads through the Purkinje fibers, reaching all of the ventricular muscle.

5

Ventricles contract — QRS complex

The Purkinje fibers trigger the ventricles to contract, producing the QRS complex — the tallest spike on the ECG.

6

Recovery — T wave

The ventricles repolarize (recover) before the next contraction. This shows up as the T wave, completing a normal ECG cycle.

📉 ECG Artifacts

Flip each card to see the cause and the fix. Always check for artifacts before disconnecting the patient.

Somatic Tremor

tap to flip
CauseShivering from cold or nervousness, or a neurological condition like Parkinson's disease, producing muscle voltage artifacts.FixKeep the patient warm and relaxed; place arm electrodes close to the shoulders on the outer arms.

AC Interference

tap to flip
CauseElectrical activity from nearby equipment or wiring within the walls.FixKeep power cords away from the patient, move the table away from the wall, and make sure the patient is properly grounded and connected.

Wandering Baseline

tap to flip
CauseImproperly applied electrodes or improperly cleaned skin — oils, creams, and lotions block conduction.FixClean the skin thoroughly with alcohol before applying electrodes.

Interrupted Baseline

tap to flip
CauseAn electrode separating from its wire, or a broken lead wire.FixSecurely reattach the electrode and wire; follow the manufacturer's instructions to repair a broken wire.

💓 Cardiac Arrhythmias

Irregularities in the heart's rhythm. It's beyond an MA's scope to interpret an ECG, but you should recognize these and alert the provider. Tap a card to expand.

Pacemaker arrhythmias

Watch
Show up as vertical "pacemaker spikes" representing the artificial pacemaker's electrical activity — more visible in unipolar than bipolar pacing. The key challenge is identifying which beats are paced, then determining if that activity is normal or abnormal.

Premature atrial contractions (PACs)

Watch
Seen in healthy people and those who smoke or use stimulants like caffeine, but can indicate a serious cardiac problem. On the ECG, a cardiac cycle occurs early, with a differently shaped P wave.

Paroxysmal atrial tachycardia (PAT)

Watch
Seen in both healthy people and those with cardiac disease. Heart rate ranges from 160–250 BPM and lasts momentarily; patients often describe it as a flutter in the heart.

Atrial fibrillation (A-Fib)

Serious
Rare in healthy people; rapid, multiple electrical signals fire from areas in the atria other than the SA node. Heart rate can range from 400–500 BPM. Causes include MI, hypertension, mitral valve disease, heart failure, thyroid disorders, pulmonary emboli, and excessive alcohol use. Appears as small, irregular complexes with P waves that can't be identified.
Causes: MI · HTN · thyroid disorders · alcohol use

Premature ventricular contractions (PVCs)

Watch
Can occur in healthy individuals who use tobacco/stimulants, and in patients with hypertension, coronary artery disease, or lung disease. Also caused by MI, electrolyte imbalances, low oxygen, or certain medications. Appears as an early beat followed by a pause.

Ventricular tachycardia (V-tach)

Life-threatening
Seen in patients with cardiac disease, often occurring during a myocardial infarction. Identified by three or more PVCs at a rate of 150–250 BPM, with no P waves and imprecise QRS complexes.

Ventricular fibrillation (V-Fib)

Life-threatening
Seen in patients with cardiac disease or during a myocardial infarction. The ventricles tremor with no cardiac output. Appears as an erratic, jagged rhythm — sometimes called a "sawtooth" pattern.

🩺 Cardiac Diagnostic & Treatment Tools

Four devices you'll encounter often — side by side.

Holter Monitor
What it does
Records the heart's electrical activity continuously (ambulatory ECG)
Duration
Usually 24 hrs, can be up to 72 hrs
Best for
Normal resting ECG but intermittent/irregular chest pain
Patient instructions
Keep a diary, press event button for symptoms, sponge bathe only, avoid magnets/metal detectors
Stress Test
What it does
Records ECG + blood pressure while walking on a treadmill
Duration
About 60 minutes total, including recovery monitoring
Best for
High heart-disease risk, starting a strenuous exercise program, or chest pain despite a normal ECG
Patient instructions
No food, smoking, caffeine, or alcohol for 3+ hrs prior; wear comfortable shoes & loose clothing
Echocardiography
What it does
Noninvasive test using sound waves (echoes) to image heart structure & function
Duration
Single visit; results recorded on paper or video
Best for
Evaluating heart structure and detecting abnormalities
Patient instructions
No special prep noted; a transducer is moved over the chest
Defibrillator
What it does
Delivers a countershock to convert a dangerous arrhythmia into normal sinus rhythm
Duration
Emergency use only, by a trained individual
Best for
Cardiac emergencies such as V-Fib or V-tach
Patient instructions
N/A — staff must keep current CPR certification & check the unit regularly

✨ Big Takeaways

The need-to-know facts, boiled down.

A routine ECG uses 12 leads: 3 standard bipolar, 3 augmented, and 6 precordial (chest) leads.
The heartbeat's electrical path: SA node → atria contract (P) → AV node → Bundle of His → Purkinje fibers → ventricles contract (QRS) → recovery (T).
Standardization (2mm × 10mm mark) lets providers judge whether a tracing is reliable — always check it before reading results.
Four artifact types to know: somatic tremor, AC interference, wandering baseline, and interrupted baseline.
It's not the MA's job to interpret arrhythmias — but you must recognize them and alert the provider right away.
A Holter monitor is worn ~24 hrs (up to 72) for intermittent symptoms; a stress test takes ~60 min on a treadmill.
Echocardiography uses sound waves; a defibrillator delivers a countershock — very different jobs, easy to mix up!
Paper math: small square = 0.04 sec, large square = 0.2 sec, 5 large squares = 1.0 sec.

📝 Quiz Yourself

Tap an answer to see if you're right.

✅ This is the textbook's own "Check Your Understanding" quiz for this chapter — used here exactly as the book presents it.