Rate and Rhythm are not Enough

ST and T wave interpretation

Dr. Constance LeBlanc, CCFP(EM), FCFP, MAEdDr. Janet MacIntyre, FRCPC

LEARNING OBJECTIVES

• Actively diagnose ST and T wave changes

• Include patient characteristics in risk

stratification

• Recognize serious and ominous ST and T

wave abnormalities

Pre Quiz

• What is the reference point for the J-point?

• What is the reference point for the baseline?

• What does ST elevation imply?

• What does ST depression imply?

• What are common MI mimics?

• What simple test can help distinguish them?

The J-Point

The J-Point

Baseline?

Why Not PR?

Where to Measure Deviation?

Location of Elevations

FIGURE 8-2 The three major coronary arteries that supply blood to the heart.(3c8)

LATERAL

I, AvL, V5-6

ANTERIOR

V1-V4

INFERIOR

II,III, AvF

Contiguous LeadsLEAD I-lateral

aVR- right VI- septal V4- anterior

LEAD II-inferior

aVL- lateral V2- septal V5- lateral

LEAD III-inferior

aVF- inferior V3- anterior V6- lateral

ST Changes?

Causes of ST Changes?

ST Depression

What Else Causes ST Depression

ST Depression

Fauci AS, Kasper DL, Braunwald E, Hauser SL, Logo DL, Jameson JL, Loscalzo J

Harrison’s Principles of Internal Medicine, 17th Edition.

ST Depression

What Else Causes ST Depression

Non-Ischemic ST DepressionLVH

Non-Ischemic ST DepressionDigitalis

Non-Ischemic ST DepressionHypokalemia

Ischemic ST Elevation and Depression

Ischemic ST Elevation and Depression

FIGURE 9-2 A With acute subendocardial ischemia the electrical forces (arrows) responsible for the ST segment are deviated toward the inner layer of the heart, causing ST depressions in lead V5, which faces the outer surface of the heart. B, With acute transmural (epicardial) ischemia, electrical forces (arrows) responsible for the ST segment are deviated toward the outer layer of the heart, causing ST elevations in the overlying lead.(3c9)

The “Other” Causes of ST Elevation

Ischemic ST Elevation

Reciprocity - 1

Reciprocity - 2

What About Tombstoning?

Scalrovsky-Birnbaum Grade

The “Other” Causes of ST ElevationPrinzmetal

The “Other” Causes of ST Elevation

The “Other” Causes of ST Elevation

The “Other” Causes of ST Elevation

• AMI

• LVH

• Pacing

• Normal variant

• Hyperkalemia

• PE

• Prinzmetal’s

• Pericarditis

• LV Aneurysm

• BER

• Osborn waves

• Brugada

• IC bleed

• Post cardioversion

Other Causes of ST Elevation

Other Causes of ST Elevation

Other Causes of ST Elevation

Other Causes of ST Elevation

Other causes of ST Elevation

The “Other” Causes of ST Elevation

The “Other” Causes of ST Elevation

The “Other” Causes of ST Elevation

Other Causes of ST Elevation- BER

The T-Wave

FIGURE 2depolarization. The PR interval is the time from initial stimulation of the atria to initial stimulation of the ventricles. The QRS represents ventricular depolarization. The ST segment, T wave, and U wave are produced by ventricular repolarization.

The Normal T-Wave

The Normal T-Wave

NORMAL T-WAVE T-wave positive T-wave negative

I QRS +VE QRS –VE

II Always Never

III Can be positive or negative regardless of QRS

aVL QRS +VE QRS -VE

aVF QRS +VE QRS -VE

aVR Never Always

V1 Can be positive, negative, isoelectricIf positive, should stay positive in all subsequent chest leads

V2

V3 AlwaysIf positive, should remain positive

V4

V5

V6

T-Wave Amplitude

T-Wave Changes

Ischemic T-Wave ChangesAngina/NSTEMI

Ischemic T-Wave ChangesHyperacute T-Waves

Ischemic T-Wave ChangesWellen Syndrome

T-Wave Changes

Approach

1. Are the ST or T changes?

2. Ischemic or Non-Ischemic

3. Electrolytes?

4. Drugs?

5. Extra cardiac?

6. Benign

Post-Quiz

• What is the reference point for the J-point?

• What is the reference point for the baseline?

• What does ST elevation imply?

• What does ST depression imply?

• What is a common MI mimic?

• What simple test can help distinguish them?

Take Home Points

• ST baseline…

• J-point is change from…

• ST deviation is measured…

• STEMIs have…

• Reciprocal changes are…

• ST depression is…

• EKG misses lots of…

• Normal T-wave…

is TP segment

the QRS to the ST

from the J-point

reciprocal changes

key finding of STEMI

subendocardial ischemia

NSTEMIs!

know it