The localization and catheter ablation of PVCs represent everything we love about clinical electrophysiology. PVC ablation requires conceptualizing cardiac anatomy in 3D, and how a focal impulse arising from any source of ventricular myocardium may register on 12-lead ECG. The challenge of catheter placement and serial hypothesis testing may be rewarded by patient cure with a single application of radiofrequency (RF) energy. PVCs increase in burden and significance later in life, and PVC ablation represents an evolving niche for adult electrophysiologists, faced with an aging population seeking freedom from medication and the highest possible quality of life.

The EP program at Kadlec is growing as a referral center for complex ablation regionally and within the Providence Health System. Our approach to PVC ablation is illustrated by the salient features of several recent cases, which we are delighted to share. All ablations are presently performed using Carto 3 v3.2 (Biosense Webster, Inc., a Johnson & Johnson company) and CardioLab v6.9 (GE Healthcare). The ThermoCool^® SF Catheter was used in the cases shown. More recently, the ThermoCool^® SmartTouch^® Catheter has been used.

We approach PVC cases with the paradigm that ablation at sites adjacent to the PVC focus may be as successful as ablation performed at the site of PVC origin. For instance, a PVC originating from the RVOT may be ablated from the right coronary cusp (RCC) or vice versa, just as a PVC accessible from the left coronary cusp (LCC) may be ablated from the great cardiac vein (GCV) or anterior interventricular vein (AIV), provided the ablation catheter is within 13.5mm of the PVC focus (measured using Carto).¹ Such close proximity to a single foci may be attainable using very different catheter approaches (RVOT, RCC, LCC, aorto-mitral continuity [AMC], GCV/AIV), making successful ablation for certain PVCs possible from several sites. Despite this potential, a single site is generally clearly superior, and additional mapping is advisable before excessive ablation is delivered at a promising but sub-optimal location.

For PVCs likely arising from outside the RVOT, we routinely begin with a SoundStar ICE catheter. The SoundStar is used to create a preliminary geometry of the aortic root in 3D, first from the RA where the aortic bulb is seen in cross section (Figure 1A), and subsequently with the SoundStar advanced slightly beyond the tricuspid valve to view the aortic root en face, allowing delineation of all three cusps (Figure 1B). Defining the aortic cusps from the venous circulation will facilitate subsequent advancement of the ablation catheter using a retrograde aortic approach to the level of the cusps with precision. Finally, the SoundStar is advanced towards the RV apex to image the pericardial space at baseline, and to create a preliminary LV shell, including papillary muscle geometry (Figure 1C).

Even when the PVC is likely left sided, a complete map of right-sided structures is first obtained for the purposes of orientation (Figure 2B). The ablation catheter is first used to perform fast anatomical mapping (FAM) from the SVC to IVC, including the body of the RA and to define the tricuspid valve annulus and location of the His. From the position of the His, downward deflection, slight withdrawal, and clockwise rotation of the ablation catheter is performed to engage the CS. FAM of the CS is strongly recommended, both as a reference for left-sided structures and because advancement of the CS or ablation catheters to the level of the GCV/AIV may be necessary. Next, a complete representation of the RVOT is obtained from the pulmonic valve to the level of the His (Figure 2B), beginning along the posterior septum and continuing to the anterolateral RVOT. Performing this step thoroughly is invaluable, as clearly defined rightward structures facilitate differentiation between the RCC and LCC (Figure 2A). Both the RCC and LCC are anterior and superior to the non-coronary cusp (NCC), with the RCC closer to and completely bordered by the posteroseptal RVOT, whereas the LCC is leftward and posterior relative to the RCC, yet also borders the RVOT along its rightward aspect.² These relationships become obvious when the RVOT is completely defined, allowing accurate labelling of each cusp (Figure 2A).

When a partial response to ablation is achieved from the posterior RVOT, complete success often requires mapping and ablation within the RCC (Figure 2B). An RVOT PVC may also be ablated from the LCC or RCC-LCC commissure, given the partial contact of the LCC with the posterior RVOT.^3,4 There is a paucity of myocardium bordering the leftward aspect of the LCC, accounting for the M/W pattern in V1 for LCC PVCs.³ The LCC is also approximated by an ablation catheter advanced through the distal CS into the GCV, allowing ablation of certain LCC PVCs from the venous circulation, and vice versa. We routinely perform coronary angiography prior to ablating from within the coronary cusps or GCV/AIV. After an angiographic catheter has engaged either coronary artery, the ablation catheter may be positioned at the tip of the angiographic catheter to mark the location of the ostia, allowing Carto to measure distance from the coronaries prior to ablation. PVCs localizing to the RCC or LCC typically arise from the nadir of the cusps, which may also be confirmed using ICE, and are therefore a safe distance from the coronaries. Angiography is essential before ablating within the GCV/AIV to assess proximity to the left coronary artery, with separation >5 mm acceptable for ablation, 15-25W for ≤60 sec recommended.⁵

Figures 3 and 4 show a successful case combining the principles of our workflow. The patient is a 62-year-old male with no history of CAD and preserved LVEF, bothersome palpitations for many years, 22% PVC burden on two-week ambulatory monitor, and who is intolerant to flecainide. The clinical PVC is shown (Figure 3A), with pace mapping performed as the study progressed from the RVOT to the RCC, and finally from the LCC to the GCV (Figure 3B). Sites within the RVOT, LCC, and GCV were all within 13mm, suggesting successful ablation may be possible from any of these locations (Figure 4A). Detailed mapping of the RVOT at the start of the case facilitated the distinction between RCC and LCC, with RVOT adjacent to the RCC and LCC approximated by the GCV (Figure 4B). Good suppression was achieved from the LCC; however, the PVC continued to return several minutes after each seemingly successful RF application. Paced QRS from the AIV was wider than from the LCC and more like the clinical PVC in this regard, although other morphology features were less favorable, suggesting a focus between these anatomic sites. Ablation from the AIV resulted in PVC abolition after <16 sec of RF, without recurrence for 30 minutes post ablation ± isuprel (Figure 4C). The patient was discharged the following day and continues to be free of palpitations. 

References

1. Jauregui Abularach ME, Campos B, Park KM, et al. Ablation of ventricular arrhythmias arising near the anterior epicardial veins from the left sinus of Valsalva region: ECG features, anatomic distance, and outcome. Heart Rhythm. 2012;9:865-873.
2. Motoki K, Kurita T, Yasuoka R, Miyazaki S. Simultaneous existence of sustained double chamber tachycardias originating from the aortic sinus of Valsalva. J Cardiovasc Electrophysiol. 2012;23(4):436-439.
3. Lin D, Ilkhanoff L, Gerstenfeld E, et al. Twelve-lead electrocardiographic characteristics of the aortic cusp region guided by intracardiac echocardiography and electroanatomic mapping. Heart Rhythm. 2008;5(5):663-669.
4. Bala R, Garcia FC, Hutchinson MD, et al. Electrocardiographic and electrophysiologic features of ventricular arrhythmias originating from the right/left coronary cusp commissure. Heart Rhythm. 2010;7(3):312-322.
5. Baman TS, Ilg KJ, Gupta SK, et al. Mapping and ablation of epicardial idiopathic ventricular arrhythmias from within the coronary venous system. Circ Arrhythm Electrophysiol. 2010;3:274-279.

Disclosure: Outside the submitted work, Dr. Kneller reports speakers’ bureau honoraria from Biosense Webster, BIOTRONIK, Boston Scientific, and Medtronic.