The ECG Quiz organizes all ECG diagnostic statements into defined Diagnosis Categories. These categories help determine how your selections are graded, how differential and multiple valid interpretations are handled, and how results are displayed.

Each category contains multiple individual diagnostic statements used during ECG annotation. Below is an overview of each category, including representative examples.

Conduction abnormalities occur when electrical impulses are delayed or blocked as they pass through the AV node, His–Purkinje system, or bundle branches.

Examples:

• First-Degree AV Block — Prolonged PR interval (≥200 ms) from delayed AV nodal conduction.
• Bundle Branch Block (BBB) — Delayed ventricular depolarization (e.g., LBBB, RBBB) altering QRS morphology.

These diagnoses reflect ECG changes caused by electrolyte imbalance or medications affecting cardiac conduction and repolarization.

Examples:

• Prominent U Waves, Consider Hypokalemia — Low potassium levels causing large U waves.
• Short QT Interval, Consider Hypercalcemia — Elevated calcium shortening the QT interval.

Hypertrophic patterns represent enlargement or thickening of cardiac chambers, usually related to chronic pressure or volume overload.

Examples:

• Left Ventricular Hypertrophy (LVH) — Voltage criteria with associated strain pattern.
• Right Atrial Enlargement (RAE) — Tall, peaked P waves suggesting right atrial dilation.

These findings signify myocardial necrosis due to coronary occlusion. Changes are typically localized based on which ECG leads show ST elevation, Q waves, or reciprocal depression.

Examples:

• Myocardial Infarction, Acute, Anterior — Involves V1–V4; usually LAD territory.
• Myocardial Infarction, Acute, Inferior — Involves II, III, aVF; usually RCA or LCx.

Ischemia represents reduced coronary perfusion without tissue death. It manifests primarily as ST-segment depression and T-wave abnormalities.

Examples:

• ST & T Wave Changes, Consider Lateral Ischemia — Changes in I, aVL, V5–V6 suggesting lateral wall ischemia.
• ST & T Wave Changes, Consider Anterior Ischemia — Changes in V1–V4 suggesting anterior wall ischemia.

These are repolarization abnormalities not clearly attributable to classic ischemia or infarction.

Examples:

• Early Repolarization — Benign pattern with J-point elevation and ST elevation in inferior and lateral leads.
• Left Ventricular Strain — Downsloping ST depression and T-wave inversion associated with LVH.

Pacemaker diagnoses describe paced rhythms or device malfunction affecting sensing, capture, or output.

Examples:

• Pacemaker Failure to Capture (Ventricles) — Pacemaker spikes present but no myocardial depolarization.
• Pacemaker Failure to Sense (Ventricles) — Pacemaker does not detect intrinsic ventricular activity.

This category classifies primary rhythms and arrhythmia patterns observed on the ECG.

Examples:

• Sinus Tachycardia — Sinus rhythm ≥100 bpm.
• Atrial Fibrillation — Irregularly irregular rhythm with no discrete P waves.

Summary Features provide a high-level impression of the ECG or highlight issues with signal acquisition.

Examples:

• Artifact — Includes baseline wander, motion artifact, and muscle noise that distort the tracing.
• Lead Malposition — Incorrect electrode placement producing misleading ECG patterns.

The table below provides a consolidated overview of all categories and representative diagnoses used in The ECG Quiz.