ECG Basics: Intervals and Common Rhythms
ECG paper timing, intervals, axis sketch, and recognition of AF, flutter, VT, and STEMI territory ideas.
12 cards· by GuruOwl
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Try it- 01On standard ECG paper, what does one small box represent (time)?0.04 s (40 ms) at 25 mm/s paper speed.basics
- 02Normal PR interval range?≈ 120–200 ms (3–5 small boxes).intervals
- 03Normal QRS duration?≤ 120 ms (≤ 3 small boxes). Wider suggests ventricular conduction delay or ventricular origin.intervals
- 04How is QTc roughly assessed clinically (Bazett idea)?QT corrected for rate: QTc ≈ QT / √RR; prolonged QTc increases torsades risk.intervals
- 05ECG features of atrial fibrillation?Irregularly irregular rhythm, no discrete P waves, fibrillatory baseline; narrow QRS unless aberrancy/BBB.rhythms
- 06ECG features of atrial flutter (typical)?Sawtooth flutter waves (often inferior leads), atrial rate ~300, ventricular conduction often 2:1 (~150 bpm).rhythms
- 07First-degree AV block definition?PR > 200 ms with every P followed by a QRS (1:1 conduction).av-block
- 08Mobitz I (Wenckebach) vs Mobitz II second-degree AV block?Mobitz I: progressive PR lengthening then dropped QRS. Mobitz II: constant PR with sudden dropped QRS (more dangerous, infranodal).av-block
- 09Complete (third-degree) heart block hallmark?AV dissociation: P waves and QRS independent; escape rhythm may be narrow or wide.av-block
- 10STEMI territory: ST elevation in V1–V4 suggests which vessel/wall?Anterior wall — typically LAD.stemi
- 11STEMI territory: ST elevation in II, III, aVF suggests which wall?Inferior wall — often RCA (sometimes LCx).stemi
- 12Wide-complex tachycardia — default assumption until proven otherwise?Treat as ventricular tachycardia, especially with structural heart disease.rhythms