This article is the ninth in our latest series, The 12 Leads of Christmas, where each day we examine a new finding particular to an individual electrocardiographic lead.
We’re getting into the home-stretch in our little series. I wasn’t entirely sure if we were going to make it through since a few of the leads, though they are useful, don’t bring much that is particularly unique to the table. V5 is one of thoseâ€”like aVF and V4â€”and while there is still plenty to discuss, it’s not as exciting as lead III, aVL, or aVR.
Don’t lose faith, however, as I have saved three of my favoritesâ€”V2, V3, and V6â€”for last.
Anyway, let’s get on with this V5 business.
One of my favorite tricks for showing off to new techs (and letting them know that I’m keeping an eye on their work) is to guess that they were sloppy with their precordial lead placement without even seeing the patient. How do I do that?
V1 is a good place to start, looking for signs of incomplete right bundle branch block that could mean the lead was placed too high on the chest.
Another common error, however, is to bunch up leads V4-V6 on the anterior chest. Despite personally training many of the techs in my department, I still see this setup way too often:
It’s hard to make a 2D diagram that displays proper electrode placementâ€”especially when you can’t directly visualize the ribsâ€”but a much better setup is shown below:
How does V5 fit into the picture?
When you follow the R-wave progression across the precordial leads, in a normal adult ECG there should be a tiny R-wave in V1 with a larger S-wave. Though V2 usually has a larger S-wave than V1, as you move from V2 to V6 the S-wave will get smaller and often disappear while the R-wave will grow in heightâ€”these transitions should be rather smooth from one lead to the next.
Notice how the R-wave reached its maximum height between V4 and V5, and while there will still be a sizable R-wave in V6, it is not as large as V5’s. Below are a few normal ECG’s with proper electrode placement:
When V4â€“V6 are bunched up on the front of the chest you end up with V5 close to where V4 is supposed to be and V6 ends up where V5 was supposed to be. As a result, the maximum R-wave height occurs in V6 instead of V5 and there will often be a residual S-wave still present in V6 as well. Here are some examples:
We also refer to this finding of a poor R-wave progression as “clockwise rotation.” If you imagine you’re looking at a transverse cross-section of the heart from below, it’s as if the heart has been rotated in a clockwise direction. In the above cases the heart hasn’t been rotated clockwise, the electrodes have been rotated counter clockwise, resulting in the same net-effect.
There are a lot of causes of poor R-wave progression (aka “clockwise rotation”) aside from improper precordial electrode placement. One of the most common is obesity, but that is also a common reason for placing the left-precordial leads too close together on the anterior chest, so it’s hard to determine which obese patients have a true PRWP unless you perform the EKG yourself. It is also seen with COPD, left anterior fascicular block (LAFB), anterior myocardial infarction, among other things.
All of the cases shown above were performed on patients with no other cause for their PRWP progression, leaving improper precordial electrode placement as the most likely culprit. Additionally, you may notice that most of the EKG’s are a bit faded. That’s because most of these cases were collected several years ago, before my hospital instituted a somewhat structured EKG training program. While I still see sloppy EKG’s from time to time, they are nowhere near as common as they were when I first started and, as a result, I’m glad to see most of the examples in my collection are several years old.
- By Unknown (original by Onatas?) (User:Bibi Saint-Pol, own work, 2007-02-08) [Public domain], via Wikimedia Commons.
- HÃ¤ggstrÃ¶m, Mikael. “Medical gallery of Mikael HÃ¤ggstrÃ¶m 2014“. Wikiversity Journal of Medicine 1 (2). DOI:10.15347/wjm/2014.008. ISSN 20018762.
I hope youâ€™re enjoying our 12 Leads of Christmas series. You can check out the rest of the posts below (updated as new posts come out):
12 Leads of Christmas: Lead I
12 Leads of Christmas: Lead II
12 Leads of Christmas: Lead III
12 Leads of Christmas: aVL
12 Leads of Christmas: aVF
12 Leads of Christmas: aVR
12 Leads of Christmas: V1
12 Leads of Christmas: V2
12 Leads of Christmas: V3
12 Leads of Christmas: V4
12 Leads of Christmas: V6