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EKG / CXR Supplement

EKG / CXR Supplement

EKG Interpretation
Chest X-Ray Interpretation
Tip of the Week

EKG Interpretation

Step 1 - Assess Rate

Step 2 - Assess Rhythm

If tachycardia is present, determine if it is narrow or wide complex (based on duration of QRS complex).

If the patient has narrow complex tachycardia with regular rhythm, consider sinus tachycardia, atrial flutter with fixed AV conduction, AV nodal reentrant tachycardia, atrial tachycardia, and the WPW syndrome.

If the patient has narrow complex tachycardia with irregular rhythm, consider atrial fibrillation, multifocal atrial tachycardia, atrial flutter with variable AV conduction, and atrial tachycardia.

If the patient has wide complex tachycardia, consider ventricular tachycardia or supraventricular tachycardia with pre-existing bundle branch block.

Step 3 - Determine Axis

Step 4 - Determine PR Interval

If > 0.2 seconds, patient has first degree AV block.

Step 5 - Determine QRS Duration

If QRS duration > 0.12 seconds, patient has bundle branch block.

Next, determine if patient has right or left bundle branch block.

Criteria for right bundle branch block:

• QRS duration > 0.12 seconds
• QRS complexes in V1 and V2 are M-shaped
• S waves in V5, V6, and I are slurred

Criteria for left bundle branch block:

• QRS duration > 0.12 seconds
• Inspection of V1 and V2 reveals presence of small R or QS wave
• Notching of the R wave in leads V5, V6, and I

If QRS duration > 0.11 seconds but patient does not meet criteria for left or right bundle branch block, consider the possibility that the patient may have nonspecific intraventricular conduction delay (IVCD).

Step 6 - Assess the ST-Segment

If there is ST-segment elevation > 1 mm in two or more contigous leads and the patient has chest pain, ST elevation MI should be considered.

If there is ST-segment depression > 1 mm in two or more leads and the patient has chest pain, two major considerations are angina (stable or unstable) vs. non-ST elevation MI. Cardiac enzymes will differentiate between the two conditions.

Other causes of ST-segment elevation include normal variant, left ventricular aneurysm, and coronary artery spasm.

Step 7 - Assess for Q Waves

As a general rule, Q waves are normal if they are < 0.04 seconds and < 3 mm deep.

Abnormal Q waves should prompt consideration of MI.

You can tell the location of MI by noting the leads in which Q waves are present.

• Q waves in II, III, aVF = inferior MI
• Q waves in I, aVL, V5, V6 = anterolateral MI
• Q waves in V1-V4 = anterior MI
• Q waves in V5-6 = lateral MI

Can determine age of MI by looking at ST-segment (elevated = recent MI, isoelectric = old MI).

There are other causes of Q waves but MI should be major consideration at first.

Step 8 - Assess P Waves (right or left atrial enlargement or hypertrophy)

Step 9 - Assess for Ventricular Hypertrophy (right and left)

Step 10 - Assess T Waves

T-wave inversion in association with ST-segment elevation or depression very suggestive of myocardial ischemia.

Peaked T waves - consider hyperkalemia

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