There are many different ways to approach the 12 lead EKG. However, I find this system to be the best becuase in it you check for everything so even subtle findings can be seen. Yes it may take a little longer but you will do a better job and better justice to your patients.

NUMBER ONE PEARL DONT TRUST THE COMPUTERS READ!!!!

Step 1. Underlying Rhythm and Rate

The absolute first step should be to see what the underlying Rhythm and Rate is. Ignore everything and go directly to the rhythm strips on the EKG. It gives you great insight into the patients physiology. If you understand what the patients atrium is doing, what the patients ventricle is doing and than uncover if they are actually related to each other, you than have the basis to understand the rest of the EKG and it's significance.

Answer the following questions.

Are the P waves upright in II, III, and AVF?

Are there p waves before every QRS at regular intervals on the Rhythm strip? (In questionable regularity always use a caliper or a piece of paper to see if the rhythm is regular. You may get burnt if you eyeball it!)

If both of these are true than the person has SINUS RHYTHM.

Than simply determine the rate. There are many different ways to this. You can take the number of big boxes between qrs complexes and divide by 300. This will give you the rate. Or if the rhythm is irregular, like Atrial Fibrillation, than you must count the number of beats in six seconds (roughly half the page on the EKG) and multiply by 10 to get the rate.

Step 2. Examine the P waves

The p waves can also give us a lot of information. The best place to examine them is in V1 and II due to their location closest to the right side of the heart.

In V1 the p wave should be biphasic and should be smooth and upright in II. The first half corresponds to RA depolerization and the second half corresponds to LA depolerization. When there is either R or L atrial enlargement, there will be deviations from these normals.

Step 3. PR Interval

The PR interval should be between .12 sec to .20 sec.

If the PR interval is less than .12 than there is ventricular pre-excitation

If the PR interval is greater than .20 than there is AV nodal disease and a block maybe present depending on the p wave relation ship with the qrs complex and if there are dropped beats or not

Step 4. MILK the QRS for Information

- Duration - is the QRS duration wider than normal? It should be less than .10 sec. If it is greater than .10 seconds than there is disease at the bundle of his or below.

-Morphology - Is there any abnormal morphologies like an R' in V1 making the diagnosis of RBBB. Any out of ordinary looking waves on either side of the QRS

-Q waves - are there any pathologic Q waves in any of the leads. Some leads may have normal small q waves, such as III, and AVR. If there are significant q waves present, they may represent old infarcts which can be localized.

-Axis - is there any deviation of the axis. The normal axis is in between -30 to + 90. Anything less than negative 30 is considered a Left axis deviation which has numerous causes, and anything greater than positive 90 is considered a right axis deviation.

- R and S wave progressions in the precordial leads.R waves usually get progressively bigger starting from V1 and by V4 the R wave should be greater than S wave, with reversal of this pattern by V4 or V5 and reducing the size of the R wave. Where as the S wave will be largest in V1 and smallest and virtually nonexistant in V6

- Hypertrophy - are there signs of LVH? The MONEY IS IN THE VOLTAGE!! There are numerous criteria to diagnose LVH. 12mm R in AVL. 15mm R in I. Deepest S and Tallest R in precordial leads >35mm. If one of the criteria are present, the diagnosis should be made

Step 5. ST segment changes

The J point should be examined and determined if it is elevated or depressed in all leads. In general terms, elevation of the ST segments implies infarction and depression implies ischemia. However in certain cases ST depression may also represent infarction. These are one of the most important signs with a patient in the ER with chest pain and should be looked at carefully. Depending on the text you read, up to 10-20% of MI's will present with out EKG changes.

Step 6. QT segment

The QT segment is important to monitor, especially with patients on many different drugs. The QT itself is variable depending on the heart rate,shorter with faster heart rates, longer with slower. Therefore it is important to check for the CORRECTED QT TIME, also known as the QTc. THe formula is QTc= QT + .00175 (Ventricular Rate). Most EKG machines have this reading and save the time in doing the calculation. If the QTc is greater than .45 it is considered prolonged. A highly prolonged QT must not be treated likely with the risk of serious arrhythmias such as Torsade des Pointes if not addressed. Offending drugs should be stopped or other causes sought after

Click Here for Quick QTc Calculator

Step 7. T wave changes

T waves are very fickled. Inversions can be signs of ischemia. "Hyperacute" T waves can be signs of MI. However, inverted twaves can be seen in patient with LVH and is called "strain" pattern when seen with LVH criteria. Giant T waves can be a sign of Hyperkalemia, where as flattening can be a sing of Hypokalemia. Notched T waves can be a sign of congenital prolonged QT syndrome. T waves can give a lot of information but it is important to remember that they can be very variable

Step 8. U waves.

A quick check to make sure that there are no other wave forms on the EKG, such as U waves. If U waves are present, the patient may be Hypokalemic. U waves can also be nonspecific or simply baseline disturbance, corrected when the patient doesnt move when the EKG is taken.

Step 9. Final Read

This is where the art of EKG reading comes into play. After you have gone through this entire process it is time to go back and put everything together and commit to your final read. It is important to decide which most likely are benign, or not significant versus those things you found that are life threatening and need to be addressed right away. As a good teacher once told me "It is good to OVER read the EKG when you first see it, but when making decisions go back and under read it!"