ECG rhythms Conduction, ST and QT
Inferior ST elevation ECG
Inferior ST elevation (II, III, aVF) with reciprocal ST depression in aVL. ST elevation in the inferior leads with mirror-image depression in aVL (and slightly in I): an acute inferior injury pattern.
A 30-second recording of the heart model, played in real time. Run live starts the engine itself with this rhythm.
Computed by the TracingsMD heart model (Junkers engine): simulated for education, not a patient recording and not for diagnosis.
Measured on this recording
| Ventricular rate | 78/min |
|---|---|
| PR | 158 ms |
| QRS | 84 ms |
| QT | 347 ms |
| QTc (Bazett) | 395 ms |
| QTc (Fridericia) | 379 ms |
| ST at J+60 ms | II +0.18 · III +0.27 · aVF +0.23 · aVL −0.18 · I −0.09 mV |
What it is
ST elevation in II, III and aVF from acute injury of the inferior wall, usually from occlusion of the right coronary artery (sometimes the circumflex), with reciprocal ST depression in aVL. New ST elevation at the J point of at least 1 mm (0.1 mV) in two contiguous leads, here II, III and aVF, meets the STEMI criterion of the fourth universal definition of myocardial infarction.
How to read this strip
| Rate | 60–100/min. |
|---|---|
| Rhythm | Regular sinus. |
| P waves | Normal. |
| PR | Normal. |
| QRS | Narrow. |
| ST–T | ST elevation in II, III, aVF; reciprocal depression in aVL, slight in I. |
Causes
- Acute coronary occlusion (plaque rupture with thrombus).
- Less often: coronary spasm, spontaneous coronary artery dissection, embolism, or aortic dissection extending into the right coronary artery (where antithrombotic therapy is harmful).
What to consider
- Suspected STEMI is time-critical: the aim is immediate reperfusion, usually primary PCI (fibrinolysis when PCI cannot be done in time), through the local STEMI pathway.
- Exclude mimics: pericarditis, early repolarization, left ventricular aneurysm, Takotsubo syndrome.
- Record right-sided leads (V4R): right ventricular infarction makes the patient dependent on preload, so nitrates can cause severe hypotension.
- Look for posterior extension (ST depression in V1–V3; posterior leads V7–V9 confirm it) and for AV block, which is common in inferior infarction.
- Repeat the ECG when symptoms change and compare with earlier tracings.
Key point
With inferior ST elevation, record right-sided leads (V4R) to look for right ventricular involvement, and use nitrates with care.
Not to be confused with
- Anterior ST elevation (V1–V4) — The precordial leads do not show ST elevation; it is in II, III and aVF.
- Acute pericarditis — Pericarditis gives widespread ST elevation without reciprocal depression (except aVR and V1). Here the elevation is regional with reciprocal change.
- Left bundle branch block — The QRS is narrow; in LBBB it is wide.