CONTENTS
morphology
- Scooped or down-sloping morphology:
- Ischemia.
- Digoxin.
- Hypokalemia.
- LVH or RVH with strain.
- Flat STD is especially suggestive of ischemia
distribution
- Diffuse STD with STE in aVR pattern: 📖
LVH 📖
voltage criteria for LVH
Romhilt-Estes (4 high prob; ≧5 def)
- Voltage criteria (3 points): any
- R or S in limb leads ≧20 mm.
- S in V1 or V2 ≧30 mm.
- R in V5 or V6 ≧30 mm.
- LV strain pattern: 3 points (1 with digoxin).
- LAA in V1 (terminal P-wave is >40ms and >1 mm): 3 points.
- LAD: 2 points.
- QRS >90 ms: 1 point.
- Delayed intrinsicoid deflection in V5 or V6 (>50 ms): 1 point.
Hypokalemia 📖
- 🔑 Q-TU prolongation with broad, bifid TU-waves.
- 🔑 Diffuse downsloping/scooped STD:
- May produce a down-up morphology.
- Often greatest in the left precordial leads.
- 🔑 Prominent, peaked P-waves in inferior leads.
digoxin 📖
- 🔑 Scooped ST depression (which may cause a down-up T-wave configuration).
- 🔑 Short QT interval. 📖
- 🔑 Unusual rhythms 2/2 increased automaticity & AV blockade:
- Accelerated junctional rhythm (+/- AF).
- Ectopic atrial tach with block.
- AF with slow ventricular rate.
- AF with 3rd degree block.
RV strain pattern due to PE or RVH 📖
features of STD
- STD in V1-V4, and to a lesser degree, the inferior leads.
- Downsloping STD in a strain pattern.
inferior OMI: STD in aVL +/- Lead I
💡STD may be the first sign of inferior OMI.
key features of inferior OMI 📖
- 🔑 Inferior STE (may be subtle).
- 🔑 STD in aVL (+/- Lead I):
- aVL may also show down-up T-waves (mirroring inferior hyperacute T-waves).
- If STD in aVL is absent, you should question the diagnosis of IMI. However, STD in aVL can rarely be hidden by simultaneous lateral ischemia (in which case you would expect to see STE in V5/V6).
- 🔑 Adjacent territories are also ischemic:
- Posterior ischemia (~V2-V4):
- ST depression/flattening (a more subtle form of ST depression).
- Hyperacute posterior ischemia may cause loss/inversion of T-waves in V2-V4.
- Reperfusion may cause down-up T-waves or tall T-waves in V2-V4.
- RVMI may cause STE in V1.
- LCX occlusion may cause STE in V5, V6.
- Posterior ischemia (~V2-V4):
lateral OMI
- STD may occur in the inferior leads.
- Lateral STE or hyperacute T-waves may be seen.
posterior OMI 📖
features of STD
- Maximal in V2-V4 (may extend into the left precordium).
- ST depression may have a scooped morphology (the mirror image of coved STE).
- Precordial STD without inferior STD (pattern doesn't fit subendocardial ischemia).
other key features
- The mirror test suggests ischemic morphology.
- Tall R-wave in the right precordium (inverted Q) may be seen in some patients.
anteroseptal MI –> STD in V5/V6 and/or inferior leads
- 🔑 ST vector is oriented superiorly:
- STE from V1-V3 or V1-V4.
- STE in aVR and aVL.
- STD in V5-V6.
- STD in inferior leads (especially III and aVF).
- 🔑 Loss of septal Q-waves in lateral leads.
- 🔑 RBBB is often seen (qR in V1).
- General features of anterior MI:
- 🔑 Hyperacute T-waves (bulky, +/- terminal QRS distortion).
- 🔑 Q-waves and/or loss of R-wave voltage (Q in V1 can be normal, but it shouldn't extend further).
De Winter pattern
- STD followed with an immediate transition into a hyperacute T-wave.
- Classically, this occurs in the anterior leads (but it may also occur in inferior or lateral territories).
- Indicates nearly complete coronary occlusion (should indicate emergent catheterization).
diffuse subendocardial ischemia
- Mild subendocardial ischemia
- STD is usually maximal in V4-V6 & II
- Severe subendocardial ischemia
- If very diffuse, it may also cause STE in aVR and V1. 📖
exaggerated atrial repolarization
- Prominent P-wave followed by scooped, up-sloping STD
- It tends to be diffuse and can also cause STE in aVR.
- Frequently seen in patients with a vertical heart configuration that generates tall inferior P-waves. 📖
To keep this page small and fast, questions & discussion about this post can be found on another page here.
