The ST segment

Created by team@ekgdx.com on Dec. 25, 2022

Let’s talk about the ST segment

ST segment normally represents the interval between the end of ventricular depolarization and beginning of ventricular repolarization. 

Normal ST segment

✅ Usually isolectric or may vary from 0.5 mm below to 1 mm above isolectric line in limb leads. 

ST normal - EKGDX

 

ST segment elevation (STE)

ST changes suggesting myocardial injury:

✅ New STE ≥1 mm in all leads other than V2 or V3.
✅ New STE in V2-V3 ≥2 mm in men older than 40 years old and ≥2.5 mm in men younger than 40 years old or ≥1.5 mm in women.

Types of ST segment elevation include: 

✅ Convex Upward
✅ Horizontal  
✅ Concave Upward  
✅ Obliquely Straight 

ST segment elevation - convex upward

ST elevation convex upward - EKGDX

 

 ST segment elevation - horizontal

 

ST segment elevation - concave upward

ST elevation concave upward - EKGDX

 

ST segment elevation - obliquely straight 

 

ST segment depression (STD).

ST changes suggesting myocardial ischemia in the absence of LVH and bundle branch block:

✅ New STD ≥0.5 mm in two contiguous leads and/or T inversion >1 mm in two contiguous leads with R/S ratio >1.

Types of ST segment depression include: 

✅ Horizontal  
✅ Downsloping 
✅ Upsloping 

ST segment depression - horizontal 

ST depression horizontal - EKGDX

 

ST segment depression - downsloping 

ST depression downsloping - EKGDX

 

ST segment depression - upsloping 

ST depression upsloping

 

Causes of STD: MI, myocardial ichemia, LVH, bundle branch block, CNS disorder, ventricular aneurysm, electrolyte disturbance, myocarditis, WPW, others.

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References

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Thanks for joining us. 

Dr. Roig

ST segment