12-Lead Electrocardiography (ECG) Hub
Electrophysiology, Rate, Rhythm, Axis, Intervals, Chamber Hypertrophy, and Acute Coronary Syndromes.
Trace Generator
25 mm/s · 10 mm/mVNormal sinus rhythm: organized P before every QRS, rate 60-100, normal intervals.
Schematic illustration, not a patient tracing.
Calipers
Δt 1600 ms · 8.00 small boxes · 38 /minAt 25 mm/s one small box = 0.04 s (40 ms) and one large box = 0.20 s. Place the calipers on two consecutive R peaks to read the rate, or on P onset to QRS onset for the PR interval.
Systematic Reading Checklist
0/8Spot Diagnosis
Generate a parameterized trace and identify the rhythm from the workspace's pattern bank. Answers are explained after each attempt.
Flow–Volume Loop Plotter
Schematic illustration, not a patient tracing.
Sharp triangular loop: PEF reached early, flows fall linearly to RV. FEV1/FVC ≥ 0.70.
JVP Waveform Explorer
Schematic illustration, not a patient tracing.
a (atrial contraction) > c (ventricular contraction against closed tricuspid) > v (passive filling), with x and y descents. Pressure 6–8 cm above the sternal angle.
Systematic 12-Lead ECG Interpretation
The 8-step standardized reading protocol: Rate calculation, regular vs irregular rhythm, hexaxial electrical axis, PR interval, QRS duration, Bazett QTc, ST-T morphological evaluation, and U waves.
Common ECG Abnormalities & STEMI Equivalents
Atrial fibrillation, ventricular tachycardia, 1st/2nd/3rd degree AV block, bundle branch blocks (RBBB/LBBB), Sgarbossa and Modified Smith-Sgarbossa criteria, Wellens syndrome, and de Winter sign.
Standard 12-Lead ECG Intervals & Cutoffs
| Interval / Segment | Normal Duration | Pathological Significance of Prolongation |
|---|---|---|
| PR Interval | 120 – 200 ms (3–5 small squares) | First-degree AV block (> 200 ms); Pre-excitation / WPW syndrome (< 120 ms). |
| QRS Duration | < 120 ms (< 3 small squares) | Bundle Branch Block, Ventricular pacing, Hyperkalemia, TCA toxicity. |
| QTc (Bazett) | < 440 ms (M), < 460 ms (F) | Long QT syndrome, hypokalemia, hypocalcemia, Torsades de Pointes risk (> 500 ms). |