EKG - Heights

Having looked at all the widths of the EKG, we can move on to the HEIGHTS.  Again, as we move from left to right, the first HEIGHT we come across is the P wave height.  Specifically look at the P waves in leads II and V1.  If the P in lead II is greater than 2.5 mV (small boxes) right atrial enlargement (RAE) probably exists.  If the P wave in V1 is negative or biphasic, then LAE probably exists.  This negative portion of the P wave in V1should be more than 1 box wide and 1 box down to be considered significant.

The next HEIGHT we look at is the PR segment.  The only classic significant PR segment abnormality that is encountered in the emergency department is PR depression.  This is most often seen in the setting of pericarditis.  Since there are multiple stages of pericarditis, these depressions are not always seen when this disease is present.

Next we look at the HEIGHT and shape of the QRS complexes.  Here, we are looking for Q waves in any of the 12 leads and we are looking for BBB patterns.  Go through all 12 leads systematically and look for Q waves.  Remember that leads that point in the same general direction will classically have similar shapes.  The groupings that you need to remember are:

II, III, aVF      – Inferior leads

I, aVL             – High lateral leads

V1-2 – Septal leads

V2-4 – Anterior leads

V5-6 – Low lateral leads

To recognize BBB’s, I almost always look at leads V1-3.  You should have already determined if the width of the QRS complex meets criteria for a BBB.  Remember that the QRS complex needs to be greater than 3 small boxes (0.12 sec) for a BBB to exist.  Now you need to determine which bundle is not conducting correctly.  To diagnose a right BBB (RBBB) there should be an RSR’ in leads V1, V2 or V3.  This is easy to remember if you imagine RSR’ look like “rabbit ears.”  The “R” from Right and Rabbit are all similar and will help you remember this fact.  To diagnose a left BBB (LBBB) you need a deep, wide Q/S wave in these anterior leads.  This you will just have to memorize.  There are other criteria to recognize to diagnose BBB’s but this should be sufficient to start you off.

After looking at the shape of the QRS complex, look at the magnitude of the HEIGHT of the QRS complex.  Specifically, you are looking for signs of left ventricular hypertrophy (LVH).  The two criteria I memorized are either a positive deflection in leads I or aVL greater than 11 mV, or a value greater than 35 mV when you add the absolute values of the more negative of V1 or V2 plus the more positive of V5 or V6.  The first one is easy to remember since 1 and L look like an 11 when they are side by side.  For the second criteria, you will just have to look at the Q or S in leads V1 and V2 and see which is more negative.  Take the absolute size of that complex and add it to the larger R of V5 or V6.   Remember, only one criterion is sufficient to diagnose LVH.

As you continue to move from left to right across your complexes, you need to determine the HEIGHT of the ST segment.  Again, you need to check systematically through all 12 leads of the EKG looking for ST elevations or depressions.  These findings are consistent with AMI or ischemia respectively.

The last HEIGHT to look at is the T wave height.  Specifically, you are looking for flipped T waves that are pointing in the negative direction.  This is also symbolic of coronary ischemia.  Quickly glance at the shape of the T waves.  If they are sharp and pointy instead of nicely rounded, hyperkalemia may exist.

Source: https://kchemekg.wordpress.com/ekg-test-home/