Module Review & Final Exam
Closing review for Cardiac Diagnostics I. This lesson distills the 5 prior lessons into the highest-yield material and is paired with a 50-question final exam under the Quiz tab. Topic coverage is aligned with the RESC 2330 flashcard review — everything you'll be tested on lives in these tables.
How to use this review: read top-to-bottom, then take the exam. If you blank on any of the numbers in the boxes below, jump back to the relevant lesson before sitting the quiz.
1. Rhythm Strip Interpretation — The 5 Steps
Every rhythm strip — every time — gets the same five-step pass.
| Step | Question |
|---|
| 1 | What's the rate? |
| 2 | Is the rhythm regular? |
| 3 | Are P waves present, before every QRS, and all alike? |
| 4 | Is the PR interval normal and constant? |
| 5 | Is the QRS narrow or wide? |
Intrinsic pacemaker rates
| Pacemaker | Intrinsic rate |
|---|
| SA node | 60 – 100 bpm |
| AV junction | 40 – 60 bpm |
| Ventricular / Purkinje | 20 – 40 bpm |
Regularity
R-R or P-P variation > 4 small boxes (0.16 s) = irregular.
ECG paper math
| Box | Time | Voltage |
|---|
| 1 small (1 mm) | 0.04 s | 0.1 mV |
| 1 large (5 mm) | 0.20 s | 0.5 mV |
Wave duration limits
| Wave / interval | Normal | What "long" or "short" means |
|---|
| P wave | ≤ 0.11 s | > 0.11 s notched / wide → atrial enlargement |
| PR interval | 0.12 – 0.20 s | Long > 0.20 = AV delay/block · Short < 0.12 = ectopic near AV |
| QRS | ≤ 0.11 s narrow · > 0.11 s wide | Wide → ventricular origin or BBB |
2. Waveforms & What They Mean
| Waveform | Represents |
|---|
| P wave | Atrial depolarization |
| QRS complex | Ventricular depolarization |
| T wave | Ventricular repolarization |
| ST segment | Early ventricular repolarization |
| PR segment | Activation of AV node, bundle of His, bundle branches, Purkinje fibers |
| PR interval | Onset of P wave → onset of QRS |
| J point | Junction of the QRS and ST segment |
| QT interval | Total ventricular activity (depolarization + repolarization) |
| R wave | Always positive (in the QRS) |
QT interval rule — should be less than 50% of the R-R interval. Influenced by age, sex, and heart rate.
ST and T abnormalities (memorize cold)
| Finding | Implies |
|---|
| Inverted / depressed T wave | Ischemia (or hypokalemia) |
| Tall, peaked T wave | Hyperkalemia |
| ST segment depression | Ischemia |
| ST segment elevation | Injury / infarction |
3. Lead Anatomy
12-lead electrode count
10 electrodes total = 4 limb + 6 chest. Right leg = ground.
Avoid placing electrodes on: bony parts, broken skin, joints, scar tissue, burns, rashes.
Chest electrode placement
| Lead | Anatomic landmark |
|---|
| V1 | 4th intercostal space, right of sternum |
| V2 | 4th intercostal space, left of sternum |
| V3 | Halfway between V2 and V4 |
| V4 | 5th intercostal space, midclavicular line |
| V5 | 5th intercostal space, anterior axillary line |
| V6 | 5th intercostal space, mid-axillary line |
Lead categories
| Category | Leads |
|---|
| Bipolar | I, II, III |
| Unipolar | aVR, aVL, aVF, V1 – V6 |
Plane
| Plane | Leads |
|---|
| Frontal | I, II, III, aVR, aVL, aVF |
| Horizontal | V1 – V6 |
Artifact
Artifact = non-cardiac electrical distortion of the tracing. Always assess the patient first — artifact can mimic V-fib.
4. Wall-to-Lead Mapping & MI Localization (SALI)
| Wall | Leads | Coronary supply |
|---|
| Septal | V1, V2 | LAD |
| Anterior | V3, V4 | LAD |
| Lateral | V5, V6, I, aVL | Left circumflex (or LAD / RCA branch) |
| Inferior | II, III, aVF | Right coronary artery (RCA) |
Translate ST changes → wall → artery. This is the highest-yield exam concept in the whole module.
5. Sinus Rhythms
The sinus signature on every one of these: upright P in II, P before every QRS, all alike, PR 0.12–0.20 s, narrow QRS. What changes is rate and regularity.
| Rhythm | Rate | Regularity |
|---|
| Normal sinus rhythm (NSR) | 60 – 100 | Regular |
| Sinus bradycardia | < 60 | Regular |
| Sinus tachycardia | > 100 (typically 101 – 180) | Regular |
| Sinus arrhythmia | 60 – 100 | Irregular |
| Sinus brady-arrhythmia | < 60 | Irregular |
| Sinus tachy-arrhythmia | > 100 | Irregular |
6. Atrial Rhythms
The shared idea: P-wave morphology is altered because the impulse comes from somewhere other than the SA node.
| Rhythm | Rate | Pattern / Hallmark |
|---|
| PAC | Depends on underlying | Premature P, different shape from sinus P; interrupts sinus rhythm |
| MAR | 60 – 100 | ≥ 3 different P-wave morphologies; pacemaker shifts |
| MAT | > 100 | MAR + tachycardia; classic in severe COPD |
| SVT | 150 – 250 | P often buried in T; PR < 0.12 s if visible |
| WPW | 60 – 100 (if sinus underlies) | Delta wave — slurred upstroke of QRS |
| A-flutter | Atrial 250 – 450 (typically 300) | Saw-tooth flutter waves |
| A-fib | Atrial 400 – 600 | Irregularly irregular + fibrillatory baseline, no P waves |
Premature-beat patterns (apply to PACs, PJCs, PVCs)
| Pattern | Frequency |
|---|
| Couplet / pair | 2 in a row |
| Run / burst | ≥ 3 in a row |
| Bigeminy | Every other beat |
| Trigeminy | Every third beat |
| Quadrigeminy | Every fourth beat |
7. Junctional Rhythms
The shared idea: impulse comes from the AV junction, conducting retrograde to the atria. P waves are inverted in II, III, aVF, missing, or after the QRS. PR (when present) is ≤ 0.12 s. QRS is narrow.
| Rhythm | Rate |
|---|
| Junctional escape rhythm | 40 – 60 |
| Accelerated junctional rhythm | 61 – 100 |
| Junctional tachycardia | 101 – 180 |
PJC vs Junctional escape beat — PJC is early, escape beat is late.
8. Ventricular Rhythms
The shared idea: impulse from below the AV node, bypassing normal conduction. QRS is wide and bizarre (> 0.12 s), T wave usually opposite the QRS, P waves are absent or retrograde.
| Rhythm | Rate |
|---|
| Idioventricular (IVR) | 20 – 40 |
| Accelerated IVR (AIVR) | 41 – 100 |
| Ventricular tachycardia (VT) | 101 – 250 |
| V-fib | Cannot determine |
| Asystole | None — no electrical activity at all |
PVC types
| Type | Definition |
|---|
| Uniform / unifocal | Same shape in same lead, same anatomic site |
| Multiform / multifocal | Different shapes in same lead |
| Interpolated | Between two normal QRSs without disrupting the cycle |
VT flavors
| Variant | Defining feature |
|---|
| Monomorphic | All QRSs the same shape and amplitude |
| Polymorphic | QRSs vary in shape and amplitude |
| Torsades de Pointes | Polymorphic VT + long QT + twisting around the baseline |
9. AV Blocks
| Block | Pattern |
|---|
| 1st degree | PR > 0.20 s, constant; every P conducts |
| 2nd degree, Type I (Wenckebach) | PR lengthens progressively, then drops a QRS — pattern repeats |
| 2:1 AV block | Two P's for every one QRS; classify by QRS width (narrow → Type I, wide → Type II) |
| 3rd degree (complete) | Atria and ventricles independent — no PR pattern, no relationship between P and QRS |
10. Intraventricular Conduction Delay (BBB) & Paced
Bundle Branch Block — disruption of conduction through the right or left bundle branch.
| Width | Designation |
|---|
| 0.10 – 0.12 s | Incomplete BBB |
| > 0.12 s | Complete BBB |
ECG hallmark: rSR' or "M" complexes — "rabbit ears."
| Pattern | Block |
|---|
| rSR / rabbit ears in V1 | RBBB |
| rSR / rabbit ears in V6 | LBBB |
Paced rhythms
Pacing spikes before each captured complex = electrical capture confirmed.
11. Stress Testing (GXT)
Why & when
- Graded Exercise Test (GXT) — non-invasive; estimates prognosis, functional capacity, likelihood/extent of CAD, and effects of therapy.
- Most frequent indication: diagnose CAD.
Absolute contraindications (the pattern: severe, acute, uncontrolled)
- Recent significant ECG change suggesting acute ischemia/cardiac event
- Acute systemic infection with fever
- Acute MI within 2 days
- High-risk unstable angina
- Uncontrolled cardiac arrhythmias
- Symptomatic severe aortic stenosis
- Uncontrolled symptomatic heart failure
- Acute pulmonary embolus / pulmonary infarction
- Acute myocarditis or pericarditis
Optimal duration
8 – 12 minutes of progressive exercise.
Protocols
| Protocol | Use case |
|---|
| Bruce | Healthy individuals (3-min stages) |
| Modified Bruce | Older / cardiac-limited (adds two warm-up stages) |
| Naughton & Weber | Limited exercise tolerance, compensated CHF (1 – 2 min stages, 1 MET increments) |
Patient prep & in-test recording
- Don't test markedly hyper- or hypotensive patients
- Record HR, BP, and ECG at the beginning and end of each stage
- Crash cart and defibrillator always readily available
One termination cue to memorize
Drop in systolic BP > 10 mmHg from baseline = terminate the test.
12. Ambulatory Monitoring
| Monitor | Duration | Best for |
|---|
| Holter | 24 – 72 hours continuous | Frequent / daily symptoms |
| Event monitor | Up to 30 days | Infrequent events; loop-recorder design |
What to Memorize Cold for the Exam
If you only recall this list, you'll still pass:
- 5 steps — Rate · Rhythm · P waves · PR interval · QRS
- Intrinsic rates — SA 60–100 · AV 40–60 · Purkinje 20–40
- Box math — 1 small = 0.04 s · 1 large = 0.20 s
- Durations — P ≤ 0.11 · PR 0.12–0.20 · QRS narrow ≤ 0.11 / wide > 0.11
- QT < 50% R-R
- T abnormalities — peaked = hyperK · inverted = ischemia
- ST — depression = ischemia · elevation = injury / infarction
- 10 electrodes for 12-lead, right leg = ground
- SALI — Septal V1/V2 · Anterior V3/V4 · Lateral V5/V6/I/aVL · Inferior II/III/aVF
- Coronary mapping — Septal/Anterior = LAD · Lateral = circumflex · Inferior = RCA
- Atrial flutter = saw-tooth · A-fib = irregularly irregular wavy · WPW = delta wave
- Junctional rates — escape 40–60 · accelerated 61–100 · tachycardia 101–180
- Ventricular rates — IVR 20–40 · AIVR 41–100 · VT 101–250
- Torsades = polymorphic VT + long QT + twisting baseline
- AV blocks — 1° (long PR) · Wenckebach (longer-longer-drop) · 2:1 (every other P drops) · 3° (independent atria/ventricles)
- rSR rabbit ears in V1 = RBBB · in V6 = LBBB
- Pacing spikes = paced rhythm
- GXT — 8–12 min, Bruce for healthy, CAD is the most frequent indication, terminate if SBP drops > 10 mmHg
- Holter 24–72 hours · Event monitor up to 30 days
Once you can recite this list, head to the Quiz tab — the 50-question final exam tests every concept above.