Updated: Nov 20
As promised in the blog, "Identifying PVC Location: Can We Keep It Simple, Please?"
I'm back to take a deeper dive into PVC morphology.
But, before I do, let’s have a recap.
I discussed the importance of treating PVCs, presented the 5 step 12-lead interpretation to locate the chamber of interest, and laid out alternative jobs to electrophysiology. Any snake milkers yet? And lastly, I promised further guidance to locate a specific location within a designated chamber of interest - So let's go!
Assessment of PVCs requires a deep understanding of cardiac anatomy, the location of arrhythmia substrate, and mapping techniques used to localize substrate origin. In this blog we will go deeper into 12-lead analysis – specifically for the Right Ventricular Outflow Tract (RVOT).
Why? Let’s stop to consider what structures fit so snuggly in proximity to the RVOT.
Think about this…a PVC from the posterior septal region of the RVOT should prompt us to anticipate and prepare for a potential retrograde.
Could a wide-appearing QRS from the anterior RVOT region trigger an image of an epicardial foci?
Is this region accessible from the distal coronary sinus?
THE GOAL: prepare for any potential regions (left- or right-sided) you may be mapping and how you plan to get there. Better preparation promotes efficiency, patient safety, and staff satisfaction.
The most common site for unifocal PVCs is the posterior septal RVOT…but what structures lie adjacent to this very specific area? Let’s take a deeper dive into how a PVC from different locations within the RVOT present different morphologies on a 12-lead. I will divide the regions into anterior vs posterior and free wall vs septal.
ANTERIOR vs. POSTERIOR
Once you have designated the RVOT as the chamber of
interest utilizing the 5-step methodology, examine Lead I.
If the PVC morphology is positive in
Lead I, then the area of interest is in the posterior location.
Lead I Tip:
Positive QRS = posterior
Negative QRS = anterior
SEPTAL VS FREEWALL Now that we have distinguished the anterior from posterior location, let’s evaluate the septal versus free wall aspect of the posterior RVOT.
What does and what does NOT lie adjacent to these areas?
Would you adjust the ablation settings on the RVOT free wall versus the septal aspect?
Would you prepare for a potential retrograde approach from the posterior septal aspect?
If your answer is YES…then read on.
NOTCHED or NOT…Examine inferior leads (II, III, and AVF). More notching in inferior leads is seen in PVC morphology in free wall locations. Before we dive into this, think about how a normal QRS complex appears. There are no lumps or bumps as the potential zips down the normal conduction pathway. Normal conduction occurs via the septal highway system. If you see lumps and bumps, or what is termed "notching", this is not from the septal route.
RVOT PVC Location
REMEMBER STEP 5: always view the heart in 3D... because it is!
12-lead PVC analysis can get us to the area of interest.
The area of interest may share a wall with another structure. Read that again, as they say.
Anticipate the possibility of mapping more than one chamber.
Pick up the closest heart model on hand when analyzing PVC morphology. Also, check out the intracardiac echo (ICE). Take note of the relationship between the chambers!
Need more anatomy...check out the 3D Cardiac Anatomy in EP course!
In summary, analyzing Lead I and the inferior leads (II, III, and AVF) can direct us to a specific region within the RVOT. I recognize that it is fun “guessing” the area where a PVC will successfully be treated but do not forget that our focus is, and will always be, the patient.
Familiarize yourself with the health history, medications, and what could be causing the PVCs. For example, the patient may report that PVCs occur when trying to go to sleep, only when exercising, or when they are resting after exercise...these are all CLUES!!
I would like to leave you with a final challenge:
Be a strong patient advocate!
Be prepared in advance to promote successful, efficient, and safe care of the patient!
Because without them, how enjoyable is EP?