- 12-lead EKG: how many electrodes?
- 10 electrodes — 4 limb + 6 precordial (chest). They produce 12 views (leads).
- SA node
- The sinoatrial node — the heart's natural pacemaker in the right atrium; fires 60–100/min and starts each beat.
- AV node
- The atrioventricular node; delays the impulse so atria empty before ventricles contract. Backup rate 40–60/min.
- Bundle of His
- Carries the impulse from the AV node into the interventricular septum, then splits into the bundle branches.
- Purkinje fibers
- Terminal fibers that spread the impulse rapidly through the ventricles → the QRS. Backup rate 20–40/min.
- Normal cardiac conduction order
- SA node → AV node → bundle of His → right/left bundle branches → Purkinje fibers.
- Intrinsic rate of the SA node
- 60–100 beats per minute — the dominant pacemaker.
- Intrinsic rate of the AV junction
- 40–60 beats per minute (a backup pacemaker).
- Intrinsic rate of the ventricles
- 20–40 beats per minute (Purkinje/ventricular backup pacemaker).
- Atria of the heart
- The two upper chambers that receive blood and contract first (atrial depolarization = the P wave).
- Ventricles of the heart
- The two lower chambers that pump blood out; their depolarization is the QRS complex.
- Right vs left side of the heart
- Right side pumps deoxygenated blood to the lungs; left side pumps oxygenated blood to the body.
- Cardiac cycle
- One complete heartbeat — systole (contraction) and diastole (relaxation/filling).
- Depolarization
- The electrical activation of heart muscle that triggers contraction.
- Repolarization
- The recovery/resetting of heart muscle after contraction (ventricular repolarization = the T wave).
- Electrode vs lead
- An electrode is a sensor on the skin; a lead is a calculated view of the heart. 10 electrodes → 12 leads.
- Limb electrodes (how many)
- Four — one on each arm and each leg (RA, LA, RL, LL).
- Precordial electrodes (how many)
- Six — the chest electrodes V1 through V6.
- Einthoven's triangle
- The inverted triangle formed by the RA, LA, and LL electrodes; defines limb leads I, II, and III.
- Right-leg (RL) electrode role
- It is the ground/reference electrode; it does not form a recorded lead.
- V1 placement
- 4th intercostal space, right sternal border.
- V2 placement
- 4th intercostal space, left sternal border.
- V3 placement
- Midway between V2 and V4.
- V4 placement
- 5th intercostal space, left midclavicular line.
- V5 placement
- Left anterior axillary line, level with V4.
- V6 placement
- Left midaxillary line, level with V4 and V5.
- Which chest leads are placed first?
- V1 and V2 (they anchor the rest); then V4, then fill in V3, V5, V6.
- RA electrode color (AHA)
- White — 'white on the right,' 'snow over grass.'
- LA electrode color (AHA)
- Black — 'smoke (black) over fire (red)' on the left.
- LL electrode color (AHA)
- Red — the left-leg ('fire') electrode.
- RL electrode color (AHA)
- Green — the right-leg ground electrode ('snow over grass').
- Limb leads I, II, III
- Bipolar limb leads: I = LA − RA, II = LL − RA, III = LL − LA.
- Augmented limb leads
- aVR, aVL, aVF — unipolar leads derived from the limb electrodes.
- Reversed arm electrodes — clue
- An upside-down P-QRS-T in lead I; recheck and correct placement, then re-record.
- Right-sided / V4R lead
- A chest electrode placed on the right side to look for right-ventricular involvement.
- Skin prep for an EKG
- Clean and dry the skin, remove hair if it blocks an electrode, wipe off oils, and lightly abrade for firm contact.
- Why prep the skin?
- Good electrode contact reduces artifact and produces a clean, accurate tracing.
- Standard EKG paper speed
- 25 mm per second.
- Standardization (calibration)
- A 1-mV signal must deflect the trace exactly 10 mm (two large boxes) vertically.
- One small box (horizontal)
- 0.04 seconds, at 25 mm/s paper speed.
- One large box (horizontal)
- 0.20 seconds (5 small boxes).
- Small box (vertical) amplitude
- 1 mm = 0.1 mV.
- Large box (vertical) amplitude
- 5 mm = 0.5 mV.
- Half standardization (5 mm/mV)
- Used when complexes are too tall to fit the paper.
- Standardization mark
- The square calibration pulse at the start of a strip confirming 10 mm = 1 mV.
- Artifact (EKG)
- Any signal on the tracing not produced by the heart — wandering baseline, muscle tremor, or AC interference.
- Wandering baseline — look
- A slow up-and-down drift of the whole tracing.
- Wandering baseline — cause
- Patient movement, respiration, or loose/dried electrodes and skin oils.
- Wandering baseline — fix
- Re-prep skin, replace electrodes, ensure firm contact, and have the patient lie still.
- Somatic (muscle) tremor — look
- Fuzzy, erratic spikes on the tracing.
- Somatic tremor — cause
- Shivering, tension, talking, or a Parkinsonian tremor.
- Somatic tremor — fix
- Warm and relax the patient, reposition the arms, ensure comfort.
- AC (60-cycle) interference — look
- Uniform, thick fuzz laid evenly over the trace.
- AC interference — cause
- Nearby electrical equipment, crossed/frayed lead wires, or an ungrounded unit.
- AC interference — fix
- Unplug nearby devices, uncross lead wires, check grounding.
- Flat / interrupted single lead — cause
- A broken wire or detached/dried electrode for that lead — reconnect or replace it.
- Holter monitor
- A portable EKG worn 24–48 hours (or longer) recording continuously during daily activity.
- Holter — patient diary
- The patient logs symptoms and activities so events can be matched to the tracing.
- Stress (exercise) test
- An EKG recorded while the patient walks a treadmill or pedals a bicycle under increasing exertion.
- Stress test — technician role
- Monitor the patient and rhythm; stop for chest pain, distress, or ominous changes per protocol.
- Telemetry monitoring
- Continuous wireless EKG monitoring of an admitted patient, displayed at a central station.
- Event (loop) monitor
- A longer-term recorder the patient activates when symptoms occur, for infrequent events.
- P wave
- Atrial depolarization (the atria contracting). Normally upright in lead II.
- QRS complex
- Ventricular depolarization; tall and narrow. Normal duration < 0.12 s.
- T wave
- Ventricular repolarization (the ventricles recovering/resetting).
- U wave
- A small wave sometimes after the T wave; may be seen with low potassium (hypokalemia).
- PR interval — definition
- From the start of the P wave to the start of the QRS; reflects AV conduction.
- PR interval — normal value
- 0.12–0.20 seconds (3–5 small boxes).
- QRS duration — normal value
- Less than 0.12 seconds (under 3 small boxes).
- Wide QRS — meaning
- Suggests a ventricular origin (e.g., PVC, VT) or a bundle branch block.
- QT interval
- From the start of the QRS to the end of the T wave; a prolonged QT raises arrhythmia risk.
- ST segment
- The flat line between the QRS and the T wave; elevation/depression suggests injury or ischemia.
- Isoelectric line
- The flat baseline of the tracing — no positive or negative deflection.
- 300 method (rate)
- Rate = 300 ÷ number of large boxes between two R waves. Memorize 300, 150, 100, 75, 60, 50.
- 1500 method (rate)
- Rate = 1500 ÷ number of small boxes between two R waves (most precise for regular rhythms).
- 6-second method (rate)
- Count the QRS complexes in a 6-second strip and multiply by 10 — used for irregular rhythms.
- Which rate method for irregular rhythms?
- The 6-second method (count QRS in 6 s × 10).
- Normal sinus rhythm
- Regular, 60–100/min, with one upright P wave before every QRS and normal intervals.
- Sinus bradycardia
- A sinus rhythm with a rate under 60/min.
- Sinus tachycardia
- A sinus rhythm with a rate over 100/min.
- Sinus arrhythmia
- A sinus rhythm that speeds up and slows with breathing; usually benign.
- PAC
- Premature atrial contraction — an early beat with an abnormal P wave, arising in the atria.
- Atrial flutter
- Organized 'sawtooth' flutter (F) waves; atrial rate ~250–350/min.
- Atrial fibrillation
- Irregularly irregular rhythm with no true P waves — only a chaotic baseline; atria quiver.
- Quickest clue to atrial fibrillation
- An 'irregularly irregular' R-R rhythm with no discernible P waves.
- SVT (supraventricular tachycardia)
- A fast, narrow-complex rhythm originating above the ventricles.
- Junctional rhythm
- Originates at the AV junction; P wave inverted, hidden, or after the QRS; ~40–60/min.
- PVC
- Premature ventricular contraction — an early, wide, bizarre QRS with no preceding P wave.
- Multifocal PVCs
- PVCs of differing shapes from more than one ventricular site — more concerning.
- Bigeminy
- A pattern of one normal beat alternating with one PVC.
- Ventricular tachycardia (VT)
- Three or more PVCs in a row at a fast rate — a life-threatening, wide-complex rhythm.
- Ventricular fibrillation (VF)
- A chaotic, quivering baseline with no organized QRS — life-threatening and shockable.
- Asystole
- A flat line with no electrical activity — cardiac standstill.
- First-degree AV block
- A consistently long PR interval (> 0.20 s); every P is still followed by a QRS.
- Second-degree AV block, Mobitz I
- The PR interval lengthens progressively until a QRS is dropped (Wenckebach).
- Second-degree AV block, Mobitz II
- Intermittent dropped QRS complexes without progressive PR lengthening.
- Third-degree (complete) AV block
- P waves and QRS complexes are completely dissociated — they march independently.
- Paced rhythm
- Shows pacemaker spikes before the P wave and/or the QRS.
- 5-step rhythm analysis
- Rate → rhythm (regularity) → P waves → PR interval → QRS duration.
- Life-threatening rhythms to escalate
- Ventricular tachycardia, ventricular fibrillation, and asystole — alert the nurse/provider at once.
- Shockable rhythms
- Ventricular fibrillation and pulseless ventricular tachycardia.
- Non-shockable arrest rhythms
- Asystole and pulseless electrical activity (PEA) — treat with CPR and medications.
- R-R interval
- The time between two consecutive R waves; used to judge regularity and rate.
- Regular vs irregular rhythm
- March out the R-R intervals; equal spacing = regular, varying = irregular.
- HIPAA
- The Health Insurance Portability and Accountability Act — protects patients' protected health information (PHI).
- PHI
- Protected health information — individually identifiable health data that must be kept private and secure.
- Minimum necessary rule
- Access and share only the PHI needed for the task or the patient's care.
- HIPAA violation example
- Looking up a patient's record out of curiosity, with no care reason — even a coworker or celebrity.
- Incidental disclosure
- PHI overheard despite reasonable safeguards — permitted under HIPAA; deliberate snooping is not.
- Protecting PHI — practical steps
- Secure tracings/screens, don't discuss patients in public, log off shared workstations, no personal-device copies.
- EKG technician scope of practice
- Acquire and recognize EKGs and report findings — do NOT diagnose, interpret for the record, or treat.
- In scope vs out of scope (rhythms)
- Recognizing and escalating a dangerous rhythm is in scope; diagnosing it is not.
- Task outside your training
- Decline and check with your supervisor rather than work beyond your scope.
- Chain of command
- The order in which concerns are escalated within a facility.
- Two patient identifiers
- Verify at least two — typically full name and date of birth — before any EKG.
- Never use as an identifier
- The room number or bed number — patients move between rooms.
- Standard precautions
- Treat every patient's blood and body fluids as potentially infectious for every patient.
- Most important infection-control measure
- Hand hygiene — before and after every patient contact.
- Cleaning shared EKG equipment
- Disinfect reusable electrodes, cables, and the machine surface between patients per policy.
- OSHA Bloodborne Pathogens Standard
- Federal rule (29 CFR 1910.1030) to protect workers from blood and body-fluid exposure.
- Recapping needles
- Never recap a used needle by hand; drop it point-first into a puncture-proof sharps container.
- After a needlestick
- Wash the area, report it immediately, and follow the facility's exposure-control plan.
- Transmission-based precautions
- Contact, droplet, and airborne precautions added to standard precautions for specific organisms.
- PPE
- Personal protective equipment — gloves, gowns, masks, and eye protection used as the situation requires.
- Electrical safety with EKG equipment
- Inspect cables for fraying, keep the unit grounded, and keep electrical devices away from oxygen and water.
- Patient in distress — technician action
- Stay with the patient, call for help, and follow the facility's emergency response.
- Communicating before an EKG
- Introduce yourself, explain the procedure, provide privacy and comfort, and gain cooperation.
- Why patient cooperation matters
- A relaxed, still patient produces a cleaner tracing with less artifact.
- Cultural / language barriers
- Use a qualified interpreter and adapt communication to the patient's needs.
- Labeling the tracing
- Record the correct patient, date, and time so results match the right chart.
- Informed consent
- The provider explains the procedure's risks, benefits, and alternatives; the team verifies it as required.
- Documentation accuracy
- Record findings and any incidents accurately and objectively in the medical record.
- Coordinated patient care
- Working with the nurse and team so the right test reaches the right patient and results are reported.
- Reporting a critical finding
- Promptly alert the nurse or provider when a dangerous rhythm or alarm appears.
- Septum (interventricular)
- The muscular wall dividing the right and left ventricles; conduction travels through it via the bundle branches.
- Right bundle branch
- Conducts the impulse down the right side of the septum to the right ventricle.
- Left bundle branch
- Conducts the impulse down the left side of the septum to the left ventricle.
- Atrioventricular (AV) valves
- The tricuspid (right) and mitral (left) valves between the atria and ventricles.
- Semilunar valves
- The pulmonary and aortic valves at the exits of the ventricles.
- Coronary arteries
- Vessels that supply blood to the heart muscle itself; blockage causes ischemia/infarction.
- Automaticity
- The ability of cardiac cells to generate their own electrical impulse spontaneously.
- Pacemaker (natural)
- The SA node — sets the heart's normal rate; lower sites take over only if it fails.
- 12-lead vs rhythm strip
- A 12-lead gives 12 views at one moment; a rhythm strip is a single lead recorded over time.
- How many views does a 12-lead give?
- Twelve — six limb leads (I, II, III, aVR, aVL, aVF) and six chest leads (V1–V6).
- Inferior leads
- II, III, and aVF — view the inferior (bottom) wall of the heart.
- Lateral leads
- I, aVL, V5, V6 — view the lateral (side) wall of the heart.
- Anterior/septal leads
- V1–V4 — view the front and septal walls of the heart.
- Hair removal before electrodes
- Remove only the hair that prevents firm electrode contact; clip rather than shave when possible.
- Diaphoretic (sweaty) skin
- Dry the skin and use stronger-adhesive electrodes; sweat causes poor contact and artifact.
- Electrode gel
- Conductive gel on the electrode improves the electrical connection to the skin.
- Lead wire vs electrode
- The electrode sticks to the skin; the lead wire clips/snaps to the electrode and connects to the machine.
- Posterior leads (V7–V9)
- Extra chest electrodes placed around the back to view the posterior wall.
- Amputee or bandaged limb
- Place the limb electrode on the nearest available area (e.g., the shoulder/torso) and document it.
- Pediatric EKG note
- Children have faster normal heart rates; use appropriately sized electrodes.
- Why standardize before recording?
- So amplitudes and intervals are accurate and comparable across machines and over time.
- Calibration check
- Verify the standardization mark prints as a 10-mm tall square before trusting the tracing.
- Filters on EKG machines
- Reduce some artifact, but proper skin prep and electrode contact remain the primary fix.
- Loose electrode sign
- A single noisy or flat lead while the others look fine points to that electrode/wire.
- Cardiac output
- The volume of blood the heart pumps per minute (heart rate × stroke volume).
- Bradycardia
- A heart rate slower than 60 beats per minute.
- Tachycardia
- A heart rate faster than 100 beats per minute.
- Where does a normal P wave originate?
- The SA node — producing an upright P wave in lead II before each QRS.
- Absent P waves — meaning
- Suggests a rhythm not originating in the SA node (e.g., atrial fibrillation or a junctional rhythm).
- Inverted P wave (lead II)
- Suggests a junctional or low-atrial origin, or reversed arm electrodes.
- Wide vs narrow QRS
- Narrow (< 0.12 s) = supraventricular origin; wide (≥ 0.12 s) = ventricular origin or bundle branch block.
- ST elevation
- ST segment above baseline; may indicate acute myocardial injury — escalate.
- ST depression
- ST segment below baseline; may indicate ischemia.
- Prolonged QT — risk
- Predisposes to a dangerous ventricular arrhythmia (torsades de pointes).
- Torsades de pointes
- A polymorphic ventricular tachycardia with a twisting appearance, linked to a long QT.
- Couplet / triplet (PVCs)
- Two PVCs in a row = couplet; three = triplet (a short run toward VT).
- Run of VT
- Three or more consecutive ventricular beats; sustained VT lasts > 30 seconds.
- Idioventricular rhythm
- A slow ventricular escape rhythm (20–40/min) with wide QRS and no P waves.
- Wenckebach (Mobitz I) clue
- Progressively lengthening PR intervals, then a dropped QRS, repeating.
- Sawtooth pattern
- The classic flutter (F) waves of atrial flutter.
- Fibrillatory baseline
- The chaotic, undulating baseline with no true P waves seen in atrial fibrillation.
- PEA (pulseless electrical activity)
- An organized rhythm on the monitor but no pulse — treat with CPR, not a shock.
- Counting large boxes for rate
- 1 large box apart = 300, 2 = 150, 3 = 100, 4 = 75, 5 = 60, 6 = 50.
- Why does an irregular rhythm need the 6-second method?
- Because the R-R spacing varies, so the box methods (which assume regularity) are inaccurate.
- Artifact vs true arrhythmia
- Check the patient and lead contact — artifact often disappears when contact is fixed; a true rhythm persists.
- Premature beat
- A beat that comes earlier than expected (atrial, junctional, or ventricular in origin).
- Escape beat
- A late beat from a lower pacemaker when the SA node fails to fire on time.
- Confidentiality
- Keeping patient information private and shared only with those involved in care.
- HIPAA Privacy Rule
- Sets national standards for protecting patients' medical records and other PHI.
- HIPAA Security Rule
- Sets standards for protecting electronic protected health information (ePHI).
- Verifying a records request
- Confirm the requester's identity and authorization before releasing any PHI.
- Hand hygiene timing
- Before patient contact, after patient contact, and after contact with the environment or fluids.
- Sharps container
- A labeled, puncture-resistant container kept near point of use; replaced before it overfills.
- Patient rights
- Include privacy, informed consent, respectful care, and the right to refuse a procedure.
- Right to refuse
- A competent patient may refuse the EKG; do not force it — document and notify the nurse/provider.
- Professional appearance/conduct
- Maintain hygiene, identification, courtesy, and ethical behavior with patients and staff.
- Medical asepsis
- Clean technique that reduces the number and spread of microorganisms.
- Body mechanics
- Proper lifting and positioning to protect yourself and the patient from injury.
- Latex allergy
- Use latex-free supplies for an allergic patient and post appropriate signage.
- Equipment malfunction
- Remove the device from use, label it, and report it; do not use faulty equipment on a patient.
- Incident reporting
- Document and report errors, exposures, or unsafe conditions per facility policy.
- Quality / accuracy of the tracing
- Confirm a clean, artifact-free, correctly labeled tracing before submitting it.
- Emergency code response
- Know your role and the facility's emergency codes; summon help and stay with the patient.
- Reporting chain for results
- Give the tracing/findings to the nurse or provider responsible for the patient's care.
- Scope: interpreting for the chart
- Out of scope — the technician does not enter a diagnosis or formal interpretation in the record.
- Diastole
- The relaxation/filling phase of the cardiac cycle.
- Systole
- The contraction phase of the cardiac cycle when blood is ejected.
- Pulse oximetry
- A noninvasive measure of blood oxygen saturation, often monitored alongside the EKG.
- Vital signs
- Temperature, pulse, respirations, blood pressure, and often oxygen saturation.
- Apical pulse
- The heartbeat heard/counted at the apex of the heart with a stethoscope.
- Cardiac monitor alarm
- An alert for rate or rhythm outside set limits; respond and report promptly, do not ignore.
- Lead II — why common
- It usually shows clear, upright P waves, making it the go-to rhythm-strip lead.
- Calipers
- A tool used to measure intervals and R-R distances precisely on the tracing.
- Augmented vector right (aVR)
- A limb lead that normally shows mostly negative deflections.
- Number of limb leads
- Six total — I, II, III, aVR, aVL, aVF — from the four limb electrodes.