Updated: Sep 27, 2022
RN, BSN, CEPS, IBHRE Ambassador
How important is it to eliminate or decrease PVC occurrences? Don’t we all have extra beats at some point? Like before a major exam or with the anticipation of having your article accepted into EP lab digest?
I have been asked this same question by healthcare professionals outside of the dark secret world of electrophysiology...
“Why is this patient even here?” “The PVC isn’t the cause of the heart failure; the heart failure is causing the PVC!!”
Well, yes and no.
Frequent PVCs have been associated with reversible cardiomyopathy, even in the absence of sustained ventricular arrhythmias or symptoms. According to the 2019 HRS/EHRA/APHRS/LAHRS Expert Consensus Statement on catheter ablation of ventricular arrhythmias, PVC-related cardiomyopathy should be suspected in individuals who present with unexplained cardiomyopathy and frequent unifocal PVCs -- typically >15% of all beats. Interestingly, some patients with similarly high PVC burdens can maintain normal cardiac function, while PVC-induced cardiomyopathy has also been reported in patients with PVC burdens as low as 4 to 5 percent. (1)
Think about it! A premature contraction not only creates inappropriately timed systole but also disrupts the incredible intrinsic timing that maintains synchrony -- and not only AV synchrony but ventricular synchrony as well. It has been well established that ventricular synchrony is of the utmost importance. Numerous conduction disorders have been studied to best treat and re-establish this synchrony, both in diseased and healthy hearts.
The question for readers is this. Will elimination of PVCs using catheter ablation restore “normal” cardiac function? Latchamsetty, R et al. published a retrospective cohort study that included 1,185 patients (55% female; mean age 52 ± 15 years; mean ejection fraction 55 ±10%; mean PVC burden 20 ±13%) who underwent catheter ablation for idiopathic PVCs at eight centers between 2004 and 2013. They concluded that catheter ablation of frequent PVCs is a low-risk and often effective treatment strategy for eliminating PVCs and associated symptoms. In patients with PVC-induced cardiomyopathy, cardiac function is frequently restored after successful ablation. (2)
So now that we have established the importance of PVC reduction or elimination, let’s dive into how to anticipate where we will be treating and what equipment may be needed. If you could predict exactly where the area of interest would be, would you find this information helpful? Maybe save the rush in preparing for transseptal puncture or retrograde approach? You could have everything at the ready! We can all agree that anticipation is one of the cornerstones of smooth and efficient cases.
How about fun and educational as well? Believe it or not, predicting the area of interest can be fun! Take, for instance, a game we play on my team entitled The ICE Cream Challenge! Whoever guesses the farthest away from the successfully treated area must buy ice cream for the team. That is a win-win for everyone, including the patient. And they wonder what we do in dark rooms all day? Play video games and eat ice cream, of course!
“Let’s simplify a step-by-step approach to PVC localization utilizing the ECG.”
STEP 1: VECTOR ANALYSIS
Simply put, “Vectorcardiography (VCG) is a method of recording the magnitude and direction of the electrical forces that are generated by the heart using a continuous series of vectors that form curving lines around a central point.” (3)
Say What?? This definition is as obscure to me as a snake milker. Yes, that is an actual career path if this EP profession doesn’t quite pan out.
“Vector Victor!!!” Remember that as cells are polarized, the activation point starts as a negative appearing signal (QS). This signal gets progressively more prominent as it progresses away from this point. Where in the twelve leads of the PVC do you see a QS morphology? Start there.
*Think of it from this “perspective” -- pun intended!
If you are standing ON the activating signal, it has a negative appearance as it moves away from you. (QS pattern).
If you are distal to the activated signal, its deflection is positive as it moves toward you. (Taller and wider QRS complex compared to sinus QRS)
STEP 2: RIGHT OR LEFT?
A great starting point to all our combined years of education would be knowing our right from left. It could not be more relevant here. Is this PVC occurring from the right or left ventricle? Or somewhere in between? -- To be covered in the sequel. Close examination of V1 can help ascertain the origin from the right ventricle or the left.
Example: If the PVC morphology in lead V1 displays a left bundle pattern indicates (QS), a right ventricular origin as an accurately placed ECG would have V1 at this region. Alternately, a right bundle pattern, QRRS, or in slang terms, “rabbit ear” appearance, then the left ventricular origin would be in play.
Now we all know that cardiac vector isn’t as simple as left and right. If so, everyone would be treating arrhythmias!!!
STEP 3: HIGH OR LOW?
Is the ectopy occurring from high in the designated ventricle or low? The ventricular tissue extends superiorly and inferiorly within the cardiac axis. The ventricular outflow tracts sit superiorly. The RVOT, or conus arteriosus if you want to impress a date, wraps anteriorly to the LVOT, or aortic vestibule, with the aortic root nestled posterior-septal to the RVOT. Opposite this are the ventricular bodies, extending inferiorly to the apex and base. The leads that assist us in distinguishing those regions are our inferior Leads II, III, and AFV.
*Let’s review keeping in mind our good friend Victor.
An upright or positive QRS in these leads indicates a source higher in the ventricular system. What structures are truly superior in this location? Think RVOT, LVOT, Aortic root, and even the superior aspect of the mitral annulus and LV summit.
STEP 4: PRECORDIAL LEADS
Now that we know our right from left and up from down, let’s look directly from within the area of interest that we have now narrowed in on. The precordial leads are a great window to the activation patterns from the anterior (V1-2), the apex (V3-V5), and the lateral wall of the ventricle (V5-6). Where does the PVC transition? Meaning, when does it transition from negative to positive?
*Think of it as the area you are standing on as the signal starts beneath your feet and moves away. Negative to progressively positive. *And what about Leads I, AVL, and AVR? Give them some attention too! I and AVL offer a great perspective of the Lateral Wall. AVR a glimpse from the RV Free-wall.
STEP 5: THE HEART IS IN 3D
When you have all these steps and have narrowed in on a zone, it is helpful to mentally view the heart three-dimensionally (or utilize a heart model in the lab). It is difficult to fully grasp PVC location without looking at the heart as multiple structures wrap snuggly to each other.
Words of Advice: And lastly, let’s not forget what motivates us beyond the cerebral stimulation of electrophysiology. Our patients, of course! Know them before they come into the lab!!! Some of the most revealing details are in the patient's history.
HTN with LV hypertrophy Acute MI Myocarditis Arrhythmogenic RV cardiomyopathy Hypertrophic cardiomyopathy Congenital cardiomyopathy COPD Sleep apnea Pulmonary HTN Endocrinopathies Nicotine, alcohol, or stimulant use, sympathomimetic medications, or illicit drugs * Clues to diseased myocardium. A potential area of interest!
For more information and a self-paced online course visit the CHART Course Store at https://tinyurl.com/mwe8tfcx!
*Clinical Wisdom: There are so many areas for ventricular ectopy to occur. And just as many diagrams and criteria to help with location identification. If you are like me, using flow charts can be as challenging as using a folding map to navigate, also while driving around the freeway system of Los Angeles. Use this simple method to locate a window into the ballpark regions. Attention and experience will help fine-tune your recognition skills without referencing flowcharts primarily.
Ice Cream Challenge!
Now just for fun and hopefully ice cream: Here is a practice ECG. Utilize the steps!
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References: 1. Cronin, EM et al. (May 10, 2019). Heart Rhythm Journal. Retrieved from https://doi.org/10.1016/j.hrthm.2019.03.002
2. Latchamsetty, R et al. (Jun-2015). Multicenter outcomes for Catheter Ablation of Idiopathic Premature Complexes. JACC: Clinical Electrophysiology, vol 1(3) 116-123.
3. “Vector.” Merriam-Webster.com. Dictionary, https://www.merriamwebster.com/dictionary/vector). Accessed June 8, 2017.
4.“Vector-Victor” AviationAviation Humor (2022, February 26). Retrieved from aviationhumor.net/we-have-clearance-clarence/ Accessed February 3, 2022.
About the author:
Jennifer Busch, RN, BSN,
CEPS, IBHRE Ambassador is the Sr. Manager of Professional Development for CHART Healthcare Academy.
Jen's contributions include content development, CHART Plus+ project lead for CHI-St. Alexius Hospital & Intermountain Healthcare, and presenter for EP:LIVE course series and mini-courses.
Thank you, Jen, for giving 100%.