Tall R Waves in V1

Tall Rocket Waves in V1

I like to call R waves "Rocket" waves because it reminds me that they are always positively deflected from the isoelectric line. Notice the tall Rocket waves in V1. Those aren't supposed to be there. When you see a 12 lead with tall R's in the V1-V2 leads, your eyes should be drawn to this abnormality.

Lead V1 is not supposed to have big R waves. That lead sits on the right border of the sternum at the 4th intercostal space and sees most of the heart's electrical vectors headed down toward the left hip, away from V1, producing deep negative inflections or S waves in the normal heart. That means that the V1 lead should be mostly negative in the normal EKG. Normal R wave progression shows tiny R waves in V1 growing gradually larger until they peak somwhere between V4 or V5. When you see big R waves in lead V1 think of the following differential diagnoses:

Most common

Tall, wide (>0.12 sec) QRS complex in V1 = probable RBBB

Tall, thin QRS complex in V1= probable right ventricular hypertrophy (RVH)

Less common

Tall, thin R wave with ST depression in V1 = possible posterior MI

Tall, wide or thin R wave with delta waves in V1 = possible WPW with posterior pathway

Tall, thin R wave in V1 is a normal finding in some pediatric EKG's

You are going to see the first two most of the time. The difference between those first two is the width of the QRS. Therefore, it is helpful to look at tall V1 R waves as RBBB's if wide or RVH if narrow.

Which is the EKG attached here? Well, there are tall R waves in V1. As a matter of fact there are two R waves in each complex. This is called RSR' or RSR prime. The fact that the QRS complex width is 0.144 seconds, which is pathologically wide, and the complexes are deflected positively relative to the isoelectric line verifies that the patiant has a RBBB. If you want further verification, look for slurred or scooped S waves in Lead I and Lead V6.

You can actually see each ventricle depolarize separately in the RSR' complexes of V1-V4. This is sometimes called bunny ears. Bunny ears are common in RBBB, but it is possible to see RBBB without them. In V1, there is a little R wave followed by a big R wave. Can you tell which R wave represents which ventricle? You can if you remember that the blocked ventricle always depolarizes last. That means that V1's first little R wave (R) is the depolarization of the left ventricle and the big R wave (R') is the depolarization of the right ventricle.

This patient is not having a STEMI, but if they were, could you use this EKG to diagnose the STEMI? Absolutely. RBBB pattern does not interfere with STEMI identification. About the only problem that you can't identify in the presence of a RBBB is RVH.

Doug Morris

No Stress Training

nostresstraining@outlook.com