Chairman, ladies and gentlemen, again, thanks for the opportunity to be here today and talk about this subject and thanks for allowing me to participate in the consensus document. I've been charged with talking about practical aspects of catheter ablation of ventricular arrhythmias. I want you to look at what I'm going to say is a teaser only because the document is chock full of really valuable information and I'm going to be rather limited in my discussion. I'm going to start by talking about the five issues, but first will be access considerations and the first to access the left ventricular endocardium, some of the things to think about. We know we can access the LV endocardium either retrograde through the aorta, transeptally via the mitral valve and some things that are obvious and discussed well in the document are things to consider in deciding which approach is the best for patients, including the presence of significant vascular disease, aortic atheroma, the presence of aortic and mitral valve disease. Certainly the technical skill of the operator and to some extent the anticipated region of interest because you may improve catheter stability when targeting the basolateral LV by going retrograde and the septal area for different VTs by going transeptal. Percutaneous epicardial access has now become standard of care and recognizing that it tends to be disease specific, they're not absolute and that patients with non ischemic cardiomyopathy, LV and RV cardiomyopathy are the patient groups in the underlying substrate that primarily drives us to consider that option earlier in the attempting to ablate these arrhythmias. The document nicely talks about the use of unipolar electrograms to help guide decision making, particularly in patients without any evidence of bipolar endocardial abnormalities, the presence of unipolar endocardial abnormalities predicts the presence of epicardial substrate and significant bipolar electrogram abnormalities that can be targeted in substrate-based ablation. Factors limiting percutaneous access need to be thought about in attempting epicardial access, including the status of the subxiphoid region where there's been prior abdominal surgery, history of pericarditis and adhesions, history of prior epicardial ablation, how much ablation, was there bleeding, were pericardial steroids given, and a history of prior valve surgery frequently limiting at least to some extent epicardial access and prior coronary surgery suggesting a very high risk and usually requiring surgical access. Common anatomic considerations are discussed and there are many. Probably one of the most important times we think about the anatomy is when we're dealing with LV summit VT and we know in the proximal aspect of the LV summit, which sits nestled amongst the coronary vessels and surrounded by fat, it's really inaccessible to mapping and ablation, effective ablation from the epicardium and our access is limited to the coronary venous anatomy. That coronary venous anatomy unfortunately lies next to the arteries and frequently we know that the coronary venous site that demonstrates the earliest activity is also in close proximity to the arterial vessel and cannot deliver energy and it's important to recognize that because you can, if not damage it acutely, can result in stenosis late after ablation in selected patients so it's an area where we ablate with caution and rely on an understanding of the anatomy to help us target adjacent sites when patients have earliest activation from the venous system but that venous anatomy is close to the coronary anatomy. We consider options when they're anatomically close such as the aortic root, the area just in front of the aortic valve on the endocardium or occasionally the right ventricular outflow tract. The issue is how close do you need to be to the earliest venous site in order to ablate from these adjacent structures and this again was referenced, our original article was referenced in the document suggesting that you need to be typically less than 13 millimeters in terms of the anatomic distance in order to have any chance of ablating from a structure that's in close proximity. Another area that was discussed with a nice figure in the document is related to the importance of prior surgery, especially in TET repair patients and the type of surgery that was performed and where the patch is placed related to the aortic, excuse me, the pulmonic and the tricuspid valve and the various isthmuses that can exist as a result of either the surgical incision or the RV free wall patch placement or the septal patch placement and repair of the VSD. There are other issues that are discussed related to avoiding complications, the discussion about the phrenic and the fact that it runs laterally over the lateral LV and an important structure to pay attention to, particularly in the patients where you're ablating and not ischemic cardiomyopathy patients where the epicardial scar frequently runs in this area and at the very least if you can't push it away with a vascular balloon monitor by pacing the left phrenic in the region of the left subclavian to monitor for potential injury during application of energy to the epicardium. One of the issues that was discussed also was how to protect the conduction system in patients with basal septal involvement with non-ischemic cardiomyopathies where you have inferior and superiorly directed ventricular arrhythmias and intramural MR scar, unipolar electrogram abnormalities, and before you start ablating this area aggressively it's important to detail the conduction system location and try to avoid lesions and damage to the conduction system, particularly in patients who start off with narrow QRS complex to protect that area, I mean the conduction system in the heart. Endpoint considerations discussed in a lot of detail, emphasizing of course that the gold standard is non-inducibility, demonstrated in a number of different ways including some nice meta-analysis, non-inducibility of VT through triple extra stimuli from two RV sites is the gold standard, but of course we now couple that with other endpoints such as the elimination of late potentials and or the elimination of lavas, the lavas are these multi-component electrograms brought out by pacing and premature extra stimuli to become more dramatic and frequently demonstrate late activity, and these can be targeted. Of course there's discussion in the document about the challenges in using late potential and lava ablation elimination and that the issue of how many and which sites to pace to demonstrate the late potentials or lavas, how we deal with some dead and extraneous stuff, what size electrodes should we use, how long do you ablate at each size, what is our endpoint, and how often do we remap to confirm the elimination of this important or use of this endpoint in deciding that we're done with our ablation procedure. There are other targets and endpoints, the elimination of channels defined by voltage mapping and or late potential combined with voltage mapping, scar homogenization is also described and discussed in a technique that we're fond of that's core isolation where we identify a region of abnormal voltage and then within an area where we define the machinery for the arrhythmia circuitry using surrogates of the circuitry such as late potentials and good entrainment criteria, try to encircle an area that encompasses these abnormal sites and demonstrate ultimately either lack of capture inside that circle or the clear-cut evidence of exit block, much like you do pulmonary vein isolation for this as core isolation. Very nicely in the document is this emphasis that none of these techniques have been compared head to head, so we're still not sure which is the best strategy to employ, but all of them may improve outcome beyond that end point of just non-inducibility alone. Finally, there's a nice discussion about overcoming some of the challenges to effectively ablate, starting with the use of imaging to help identify structures like the papillary muscle, use of cryoablation in selected patients where you have instability with a standard RF catheter to get adherence of the cryoablation catheter to the papillary muscle when you have a lot of instability as one option for overcoming a challenge. Other major challenge, of course, is creation of intramural scar, particularly in patients with non-ischemic cardiomyopathy where the intramural scarring has handicapped our ability to eliminate many of these VTs. Strategies for eliminating the intramural scar are discussed in detail, including the use of transcoronary arterial or venous ethanol, bipolar ablation, simultaneous two-site unipolar ablation, use of half-normal saline irrigation, needle catheter ablation, and both clinically useful and demonstrated in investigational tools discussed in the effort to try to improve outcome, and nicely done in the document. So again, this is just a teaser, just to highlight some of the things that have been described in the document. I recommend to everybody, nicely done, Dr. Bogan, Dr. Cronin, many more things to read about in the detailed documentation. Thanks for your attention. Thank you very much, Dr. Marcininski, and for all your contributions to the document. Can I ask for any comments or questions? Do you ever use jet ventilation to stabilize the catheter? I have for WPW around the parahystin region. Obviously, we use it all the time in AFib, and I could see potentially doing it in the setting of a parahystin ventricular arrhythmia. It turns out we just haven't done it clinically. I don't think any of my colleagues have either, but it would be a consideration. It certainly enhances stability, but some of the stability of the mechanical motion of the ventricle makes up a lot of the instability that gets created in the parahystin VTs that make you nervous, so I just haven't used it. I have a question, Frank. Sure. So in Asian countries, China, India, we have a lot of rheumatic heart disease patients, so their mitral valve, their aortic valve was replaced, but you have no approach. So can the needle ablation from the epicardial side do the endocardial ablation, because we have no approach? I took this slide out, and I think it's discussed in the ablation document, but I don't want to swear to it. You can approach it different ways, either epicardially, what the technique that my young colleague Dr. Santangeli has really pioneered is actually done both transeptally, and he actually goes from the right atrium through the base of the left ventricular septum into the ventricle in patients with bivalvular heart disease very nicely. It's a work in progress, but I'll let him actually describe it, because his expertise is quite amazing. Actually, just a quick comment to that. The technique has changed significantly over the last three years. Now we get access in about 30 minutes, 32 minutes, so we're trying to find a patient for this symposium to do live, so we can show how we do it, and it's a very reproducible technique and very safe, and I think we are there at this point that we can. But it gives you another option, and it's actually very nicely done. It's done on about six patients, so just more recently than the timeliness for this document, but it's a work in progress, and I think it's an important addition to the way we approach these complex patients, where access is a real challenge. Yeah, okay. Thank you. Okay. Thanks very much.

catheter ablation

ventricular arrhythmias

access considerations

unipolar electrograms

ablation endpoints