Explains what an ECG records and how the 12-lead set-up is arranged, then takes the reader step by step through interpretation: rate, rhythm, P wave, PR interval, QRS complex with axis, ST segment, T wave and QT interval. A table links common diagnoses such as myocardial infarction, atrial fibrillation, hyperkalaemia and pulmonary embolism to their characteristic ECG findings, and closes with notes on axis calculation, R wave progression and voltage criteria for hypertrophy.
Topic 26 of 30 in the MU Sofia syllabus for Internal Medicine (Practical) (Medicine, Year 3). The free AceMed note covers it in 6 sections, about 207 words (2 min of reading), with 14 flashcards.
In this note
ECG: Diagnostic Evaluation
I. What is ECG?
II. Standard 12-Lead ECG Setup
III. Steps in ECG Interpretation
IV. Common ECG Diagnoses
V. Additional Notes
I. What is ECG?
Electrocardiography (ECG) is a non-invasive test that records the electrical activity of the heart via surface electrodes. It is essential for the diagnosis of arrhythmias, ischemia, infarction, electrolyte disturbances, and structural heart diseases.
II. Standard 12-Lead ECG Setup
Limb Leads (6 total):
Bipolar: I, II, III
Augmented unipolar: aVR, aVL, aVF
Chest Leads (6 total): V1–V6
III. Steps in ECG Interpretation
1. Rate
Normal: 60–100 bpm
Tachycardia: >100 bpm
Bradycardia: <60 bpm
2. Rhythm
Regular vs irregular
Sinus rhythm = P wave before each QRS, regular PR interval
3. P wave
Atrial depolarization
Abnormal in atrial enlargement or ectopic atrial rhythm
4. PR interval (0.12–0.20 sec)
Prolonged = 1st-degree AV block
Short = pre-excitation (e.g., WPW)
5. QRS complex (< 0.12 sec)
Widened in bundle branch block, ventricular rhythm
Axis deviation:
Left axis: -30° to -90° → LVH, LBBB
Right axis: +90° to +180° → RVH, PE
6. ST segment
Elevation: acute MI, pericarditis
Depression: ischemia
7. T wave
Inversion: ischemia, PE
Peaked: hyperkalemia
Flattened: hypokalemia
8. QT interval (QTc)
Prolonged: risk of Torsades de Pointes
Shortened: hypercalcemia
Continue reading free
The whole note, all 6 sections, is free with an AceMed account, with its 14 flashcards. Premium adds flashcard recall, highlights and Ask AI.
