Good afternoon, thank you very much for coming. I'm Dr. Raymond Scharf, I'm an Associate Professor of Cardiac Surgery at the Smith-Hart Institute at Cedars-Santa Ana in Los Angeles. I want to thank the Merit people for sponsoring this. I also want to introduce three very skilled physicians who will be talking to you about various aspects of lead management. Our first speaker is Dr. Mark Gallagher, I've known him for years, he's at St. George's University in London, UK. Thank you very much. I've been asked to talk about data, what are the data telling us on rotational transvenous lead extractions. Now, I'm mostly more of an operator than a data person, but I do know the data from this meta-analysis that we did a couple of years ago. On the meta-analysis, I was more the clinical person leading the project and the data guys were principally Christos, Georgios, and Sri, all very competent meta-analysis practitioners. We were working in a field that had already been meta-analyzed very expertly by Igor Dienberger back in 2013. He was dealing with an earlier time period when rotational extraction was only just getting off the ground. He did find the interesting phenomenon that the mechanical methods, which were slightly less effective than laser back then, also appeared to be significantly safer. We knew that at the time we were doing our meta-analysis, Byron Lee was running one separately, but we both continued with him because he was doing a narrower data set. He was covering a narrower time window and only consecutive series and randomized trials. We were aware of his results as we prepared ours. He showed a very massive difference in mortality risk between laser and rotational tools and also significantly greater effectiveness for the rotational tools compared to laser. We took a broader sweep. We opened the criteria as widely as we could, took the broadest time window we could, so from 1991 through to 2021, and we took the broadest criteria for the studies. Any series of more than 20 patients was considered for inclusion. We ended up with more than 20 extra series compared to the meta-analysis considered by Byron Lee. These are the studies we considered, so this is the sum of the data that I'm going to be talking about. These are the headline results. As expected from the previous meta-analysis, we did find that mechanical methods were substantially safer than laser. We also found that unlike the earlier meta-analysis, mechanical methods at this point are significantly more effective than laser is, and the relative risks are really quite substantial, though not quite as large as the narrower cohort taken by Byron Lee. We did a subgroup analysis looking at just the rotational as opposed to the entire set of mechanical extraction tools, and in this also, the rotational comes out significantly safer than laser, and even more marked here, the superiority in efficacy comparing just rotational to laser, so very substantially more effective and substantially safer. These really are the headline data, and they correlate perfectly with another study by Byron Lee looking at a totally different source of data. This time it's just MAUD data, denominated by known total rates of extraction, and from this perspective also, we get the impression of a substantially greater safety for the rotational tools compared to laser. I just wanted to mention another meta-analysis published, I think it was in the following issue of Europace compared to ours, focusing entirely on laser methods. This is a much narrower series, taken over a narrow time window, a five-year time window to 2021, looking at just laser and covering only 1,700 patients, where our meta-analysis compared, it was nearly 10,000 in each of the groups, so quite a small series due to the narrow time window. They described the mortality rate from laser extraction as being low. They've quoted here, I think, and I don't think I'm pointing effectively there. They've quoted a mortality rate of 0.08%. Now that seems an odd number from this proportion here, which would calculate out at 0.4%. That's explained farther into the paper here, where they show that the 0.08% calculated from the seven out of 1,700 is due to the random effects inverse variance weighting using arc sine square root transform, so that makes sense. I wanted to mention tandem approach, which is our go-to method, is our almost universal method now for our rotational extractions. It is going to be covered in proper detail by its inventor shortly, but I just wanted to mention that we have taken it on, and having tried it, cannot do without it, and the results are just fantastic. We're getting our procedures done faster, with greater success rates, and a much better sense of safety. I now find it difficult. If for some reason I have to do an extraction without an operator capable of helping me to do a tandem, I really don't feel it is as safe as it should be, so conclusions are that rotational tools are very safe, that rotational tools are immensely effective, and I think the tandem approach added to them improves safety still further. I think it's probably only fair to say that laser may be usable with an acceptable risk of safety within limited constraints, and that would certainly include a very liberal use of occlusion balloons, bridge balloons, and probably the arc sine square transformation. Thank you. Thank you, Mark. We'll have time for questions after all three speakers have spoken. Our next speaker, who was alluded to as the inventor of the tandem technique, is Roger Friedman. He's from the University of Utah in Salt Lake City, been a friend for quite some time. Roger. Thank you, Ray. Good to hear you. I'm going to present sitting down so I can use the mouse, kind of a mouse guy. And how do I tee up? So, I've been asked to speak about alternative approaches to lead extraction, but for all practical purposes, I'm going to be talking about the tandem technique that Dr. Gallagher just introduced. It's a technique that I've been using for several years now, and unlike Mark's talk that was largely about data, mine is going to be more on technique, so I'll be showing some Cines from a couple of cases. The tandem femoral superior approach involves first snaring the lead from below, and I'll show you the snare that we use, and then with traction on the lead from below, you go over the lead from above with either mechanical cutting sheath or with a laser sheath. The snare that we use almost exclusively is the needle's eye snare, which has two components on the working end. One is what I call the cobra head, because it's shaped like that, that you drape over the lead, and then having draped the cobra head over the lead, you then extend what I call the tongue, and the goal is to trap the lead between the cobra head and the tongue, and then you cinch it up with the inner sheath here. The lead, the doubled up lead, can then be extracted if you choose to extract femorally through the outer sheath here. So let me start with my first case, and this is a 52-year-old woman with a 10-year-old Riata lead that showed both externalization of a conductor, a known problem with this lead, of course, and electrical failure. Externalization is a little hard to see on the full X-ray, but there's a close-up showing the externalized conductors there. So in this video, you see the cobra head draped over the RV lead, and the tongue extended. Now in this single view, you couldn't be sure that you have the lead snared. It could be that the tongue is behind the lead within the cobra head, in which case you don't have it snared. It's also possible that the tongue is off to the side of the cobra head, in which case you also wouldn't have it snared. To confirm that you have it snared, you go up with your inner sheath, and you snug it up against the lead, and if you can snug it up rather than that inner sheath just sailing right by the lead, then you know you have it snared. Now in this case, after having snared the lead, I put down the locking stylet, which is a little hard to see, but it ends right about there. Importantly, we couldn't get it all the way out to the end of the lead, and this is a situation that I encounter all the time with a locking stylet not being able to go all the way to the end of the lead. In fact, sometimes you can barely get it into the lead at all, and in cases when you can't get the locking stylet all the way down, the rail that you create with your snare from below becomes all the more important. But in this case, we got the locking stylet about to that point there, which is good because then when I cinch the lead in the snare, I'll be cinching the locking stylet with it, and that'll help keep the locking stylet from retracting. And here, okay, that shows the locking stylet better right there. And now I have the lead cinched, and I'm starting to exert traction on the lead from below. If anything, I should have pulled a little bit harder to straighten this out, maybe stretch it slightly to get a really good rail. And as I'll show you in a minute, the goal, one of the goals, is to try to draw the lead away from the lateral edge of the SVC, which of course is a not infrequent area of injury that can be catastrophic. Now I'm starting to, as one operator at the groin is exerting tension on the lead from below, and of course we're also exerting tension on the lead from above, we're going over it with our mechanical sheath, making some progress, and making more progress. You can see there's significant binding between the atrial and the ventricular lead here, but we keep advancing. I've actually changed out to a different sheath now, and you can see the tension we're exerting from above is significant because the proximal shock and coil is actually starting to stretch a little bit. I don't think that I've dissociated the two leads yet from that location, but now I have. We're past that point of binding, or maybe just at it now. Maybe we're past it, and we're approaching where the lead is snared, and now we're almost at the snare, and pretty much at the snare. Now at this point, obviously you need to open up the snare to get the sheath through it, and I've done that now, and so now we don't have any tension on the lead from below, so it's as if we didn't have the snare there, and I'm sorry, but if I'd continued that video, it would have shown the lead coming out from above. This slide here is from Rob Schaller at Penn, who also uses this technique, and he very elegantly showed that when you have what he calls simultaneous traction, again from below and from above, that the lead is pulled away from the lateral wall of the SVC, and with intracardiac echo, ICE, he can see clear separation between the lead and the lateral wall of the SVC, and this is his concept of the rotating sheath, then staying away from the lateral wall of the SVC with this technique. Okay, the second case I want to show you, 82-year-old woman with a 12-year-old pacemaker for a complete heart block. Here's the RV lead, obviously, and the atrial lead is a fine-line lead, which I'm not sure is showing up too well, but it's about there. This is her pocket infection, and this is my scout CINI, just showing the two leads again. I always get a scout CINI initially to document where the leads are, initially to look at the motion of the heart borders, because if the heart borders stop moving, then you know you have a problem, and also to document how the lung fields look in case you get a hemothorax, you have a comparison picture. So now I typically go after the easier or easiest lead first, which in most cases is the atrial lead. So in this case, I have the atrial lead snared. Now with a fine-line lead, fine-line leads have been described in the past as the hardest leads to extract, because they fall apart, they're not very stout. But it turns out that fine-line leads come out fairly readily using strictly ephemeral technique. So in many cases, I won't even put a locking stylet down a fine-line lead, and I won't use any kind of a sheath from above. And indeed, with this case, that's what I did with this fine-line. This shows the fine-line lead snared, and I'm pulling on it, and it wouldn't come out, and I couldn't figure out why. And after a few seconds, I realized that we had clamped the lead from above, and as soon as I took the hemostats off, as you'll see there, the lead readily comes out from below. It's such a contrast how easily a fine-line lead will slip out from below, compared to how much resistance there is if you try to pull a fine-line out from above. All right, anyway, now addressing the ventricular lead. I have the lead snared and cinched, and going over it with the evolution sheath, the rotating sheath from above, like the last case. And again, there should have been more traction on this, but I think it's still giving you some traction, straightening out the lead. If you look carefully, you can see the rotating sheath first going in one direction, and then the other direction, which is the way pretty much all rotating sheaths these days work. And that helps to prevent lead binding. Working with the outer sheath here, this is what's called the steady sheath that is part of the merit toolkit, and working them both down, definitely should have more traction on the lead from below here. And a little further. And then eventually you get to the snare, release the snare. Usually I don't fully disengage the snare because you never know when you might want to re-snare the lead, but it's possible to open it up wide so your superior sheath can go through it. And now we're in the ventricle with the inner sheath of the Evolution, and to the end we ended up giving her a micro leadless pacemaker. So a few years back we wrote up our results, and actually the first author, Joseph Nielstein, who at the time was a fellow, is in the audience here, and in this series we were able to completely avoid SVC injury using this tandem technique. I should mention, though, that if you're not careful, it is possible to damage the SVC even with the tandem technique, and the key thing is that you have to have a good rail to be safe even with the tandem technique. So for instance, if you're pulling on the lead from below and it's stretching and falling apart and you just have some unwound coils going through the area of the SVC, then even with the tandem technique you're at risk for SVC injury. At that point you should abort what you're doing from above and finish out the case from below. So in summary, the tandem femoral superior approach gives you a much better rail than the locking stylet alone. It's especially helpful when the locking stylet can't be advanced. It prevents, I didn't mention this, but it prevents tension that you're exerting on the lead and the locking stylet from above from being transmitted to the heart. So you're not getting hypotension, you're not getting the PVCs. Pulls the lead away from the SVC, minimizing the risk of SVC injury. Often you have such a good rail that especially in the area of the SVC and the right atrium, you can advance the outer superior sheath without even using the rotational blade in that area. I didn't show this, but very often you can unscrew active fixation leads from below with counterclockwise torquing if you weren't able to retract the helix from above. If you have an occluded vein and a relatively recently implanted lead and you need to re-canalyze that vein, if you try to do that without staring from below, your lead will just pull out before you have a chance to get your superior sheath through the area of occlusion and you're going to be left high and dry. But if you have the sheath snared from below, then you have a rail to give you a basis for getting through the area of occlusion. In case of lead fragmentation, you're all set up to retrieve fragments. And as I illustrated, the approach can be combined with a purely femoral approach in appropriate leads. So as Dr. Galarga was saying, I've become psychologically very dependent on the tandem technique, and frankly I feel like extracting leads without the tandem approach feels sometimes like fighting with one arm behind your back, or maybe playing basketball using just half the court, or it feels so unsafe it's like driving without a seatbelt. So I advocate to any lead extractor to give this technique a try. Thank you. Thank you, Roger. Our final speaker expert is Matt McKillop, who comes to us from Baptist Health in Jacksonville. He's going to talk about something other than extraction, but what happens after you've done an extraction. All right, thank you. So what I'm going to talk about is how to make your life easier when you take all of the hardware out in extraction and you got to get a new implant back in. So obviously the premium is higher in these cases because you're removing all the hardware. Often these patients are dependent or they have other needs for getting a proper re-implant and so how do you leverage tools and techniques to make sure that in this patient that you're removing all of their hardware that you actually get a successful re-implantation. And so and so like I said you're committed obviously because you're extracting that hardware that patient actually has device therapy is needed so that obviously makes it more important to get a successful result. And then what you're doing oftentimes in CRT implants is you're removing a left ventricular lead from a coronary sinus branch potentially eliminating that target as an option for suitable re-implant. And so again that that increases the amount of need for tools that allow you to find alternative targets to do LV lead implantation. And then in right-sided devices so often we're extracting left-sided devices in infected patients which indicate need for right-sided implants and that has a whole set of challenges as well. And again it's sort of leveraging tools and techniques to help you do that. And so what are the things that make life difficult in a lead implant? I think this is true for extracted patients and it's true in general is that we often have difficult venous access so and that's subclavian axillary access and so and often in patients that have devices that are already in place subclavian stenosis and then beyond that for LV leads difficult CS cannulation so trying to get into the coronary sinus. Again a lot of this is a little bit more complicated in an extracted patient. Target vein so the target vein is a trouble anatomically. Stenotic veins that's true in these situations where leads are removed from coronary sinus branches and then difficulty getting leads out into the distal segment that you want to pace. And so a lot of that is contingent on proper support and getting your hardware in the place that you want it and then making sure that when everything is done things are in the place that you want that you're not dealing with lead dislodgement with slicing. And so the first thing that I think has been really helpful in my career is learning how to navigate difficult subclavian access axillary access and so this is just an example of a case that do a peripheral venogram you demonstrate an area of occlusion and so being able to kind of negotiate this and obviously in the lead management scenario doing an extraction is one way of bypassing this area and getting access but oftentimes that doesn't get you all that you want as far as free maneuverability of the leads to do in a complex reimplantation. And so what I've learned to do in my career is fibroplasty so essentially once you get once you purchase access with an extraction or just conventional access you get a wire down then the thing that I've found to be extremely useful in making the process go much smoother is to put down a non-compliant balloon and do fibroplasty venoplasty along the segment of the subclavian and axillary branches freeing up the tissue around the leads so that way you can have free maneuverability of your implanting equipment and so essentially it takes a case where you would struggle for an hour or two and make it like a case that doesn't have any disease at all and so this is to me have been an important part of my practice and so what do you do so the important concept is you have to have a wire down and ideally the typical wire that I use is an amplats wire so a stiff wire and then you use peripheral balloons that take an o35 wire that you can transit down and anywhere from six to nine millimeter in diameter and then you do balloon fibroplasty along all the segments and then that frees up the amount of scar tissue that allow you to go ahead and do a successful implant and not have to worry about proximal obstruction and so when you're trying to get into the coronary sinus for a re-implant or even a new implant one of the things that's really imperative is to understand kind of the anatomy and what are barriers and everybody's familiar with that there are some anatomic barriers for getting into the coronary sinus and so so I've been using the merit product that was developed by Seth Worley for over 15 years now which is a coronary sinus engagement kit that allows you to drop into the coronary sinus in a much more sort of anatomically consistent way and so basically this is an outer sheath that's called the coronary sinus guide and an inner guide that then you bring back in with counterclockwise torque and instead of trying to primarily engage by advancing what this equipment does is drop the coronary sinus at the the inner catheter into the coronary sinus ostium and then you can inject contrast confirm that you're in position and then guide the rest of the sheath into position over that inner catheter and so it's a very seamless way of getting reliable coronary sinus access that sort of bypasses some of the troublesome anatomy and so what's next is once you get into the coronary sinus what's key is you got to do a proper coronary sinus phenogram and I can't emphasize the importance of this enough especially in patients that have had prior extraction. You absolutely need to understand what the current anatomy is what your targets are and there's a lot of misunderstanding and assumptions that are made with venograms and so this is a balloon occlusive coronary sinus phenogram and you're not seeing anything out here and so I've been referred patients specifically in this setting where the operator has done a couple of coronary sinus phenograms didn't see any reliable target branches and abandoned the case and so one really important concept is that there is always going to be anatomy here and so what you're doing here is you're actually moving the balloon occlusion further into the great cardiac vein doing a better runoff and then what you often will see is evidence of the branch that you need to target and so you can do the same concept not with just a balloon venogram but you can do it with sub selection so meaning getting a catheter sub selected to any lateral branch and doing a runoff that way. You'd be surprised how many target branches you can identify that you don't see with sort of conventional venography and again if you don't do that you're sort of flying blind so you don't have a full appreciation of all the anatomy so once you have an idea of what your target branch is oftentimes the sort of conventional approach is just trying to wire see if a wire goes see if the lead will follow the wire and so you sit there under x-ray wiring and wiring and so this is what Dr. Worley called the poke-and-pray approach and so instead of doing that what I do and what I've done for the last 15 years is you you like I said start with a good coronary sinus phenogram you choose the branch that you want and then you set yourself up with proper equipment to get into that branch and what does that mean so the merit has a system that includes what's called the lateral vein introducer product called the vein selector and then a coronary wire so an o1 for wire and so and then what's also important is a contrast injection kit and so you have this injection kit that allows you to sub select so again so this is an abandoned LV lead and so you have a sub selector that's the vein selector that allows you to do a contrast injection and find that's the appropriate target and so what's nice is is that the the sub selectors that that are provided by industry really are only designed to be an osteo-engaging catheter so it really only gives you support at the ostium of the lateral branch very often you don't get enough target support for that branch and so what what's different about this system is that we use sort of a telescoping system that starts first with a vein selector that finds the target branch that then allows you to engage that branch with an inner catheter that goes over the o1 for wire and you have different confirmations that allow you to select different choices for the anatomy and so putting it all together what this system allows you to do is here's that outer sheath that we engaged initially and then this is the other sort of game-changing element this is a retained o1 o3 5 amplats wire and so that is a retention wire that keeps you stable in the coronary sinus you don't have to worry about losing access you're defining the branch with the vein selector with the wire and then what this does is provide proper rail for your delivery sheath which is a 5.5 French inner catheter that doesn't stop at the ostium and so what this is going to show you is is that we already engaged with the vein selector in the wire and so we know this is the target branch and so this is the outer or the inner L lateral vein introducer and what we can do is we can slide that into position and we're also defining other areas of anatomy so that if this branch didn't work we know the lay of the land we can go to alternative branches within that that lateral branch and so this is where your purchase is as far as engagement so you can see how much more support this setup has as far as delivering leads to where you want to go and so this gives you every available possibility of getting you the branch getting the lead to the branch that you want and so what the equipment also does is allow you to negotiate pretty challenging anatomy so everybody's faced with significant sort of torturous or Shepherd's hook takeoffs things that are problematic for sort of conventional equipment and so what this is this system allows you to do is actually wire these branches with multiple wires again same setup vein selector inner catheter and so so this is the vein selector this is the LVI so that's the sub selecting catheter you deliver through and these are three oh one four wires that go into that branch that create a nice rail that straightens out that pretty acute takeoff and so what that does is give you proper support and as you can see when you then advance that inner catheter you can slide that inner catheter all the way down and you can deliver the lead and so it just gives you the ability of changing the anatomy in your favor and so the last technique or one of the techniques that we can also do is the snare technique some of you may have seen this and so what this involves again is defining the anatomy with the coronary sinus injection and then wiring a branch that then finds the collateral and so this is going to come through a collateral either a middle cardiac or a posterior lateral branch that then comes out and so then what you do is you advance your snare so here's the snare here and then you can bring the snare down oftentimes they'll actually engage the snare in the middle cardiac itself but you can actually in this instance we're just using it coming down and so then you're wiring through the snare then collapsing the snare on the wire and then holding forward traction and so here's the snared wire that's holding traction and then you're literally advancing the wire advancing the lead with the wire being held on the front end and it works remarkably well and then you release the wire and then your implant is done and so again the equipment allows you to do all sorts of different variations to get the target branch that you want and not having sort of the anatomy dictate and so in summary when you're extracting obviously you're removing hardware that patient probably eventually needs a successful re-implant and so what you want to do is get equipment in place that help you negotiate a challenging implant and so what I've found is a lot of these techniques that we've developed through Merit's interventional CRT program including some of the equipment we just showed you helps you tackle any potential conceivable anatomy or anatomic variants that you have and so again sort of deploying a lot of those tools troubleshooting these different areas that are barriers to implant so I found it in my practice to be essential to getting a successful re-implant thank you. Thank you Matt. We have a few questions. Roger, one of the things we've noticed lately, not lately but for years but haven't talked about it very much is that after extractions of ventricular leads there is risk of tricuspid valve injury. Does the tandem approach in your hands reduce tricuspid valve injury or eliminate it? Ray, thank you for that question. Unfortunately I can't say that the tandem technique avoids tricuspid valve damage. We still see it. It's sporadic. It's more common with defibrillator leads that have been in for a long time. We've seen it with pacemaker leads that don't have that long of a dwell time. It can be fairly impactful on the patient requiring surgery maybe in this era now there are percutaneous techniques that can be used to repair or replace the valve but it's it's still a problem and in fact I think that tricuspid valve damage is kind of the final frontier of challenges of major complications that we have yet to solve. Thank you. Mark, you've had excellent results with what you described. One of the great advances we've seen in the last few years is the bridge balloon and some people put the bridge balloon in every case they do. What's your practice with it and what do you feel about it with the successes you've had? We like to have a bridge balloon in the room. We don't start with a bridge balloon in the patient so we we differ in that from recommendations from some of the people using a lot of laser. We have a surgeon in the building but not in the room and the bridge balloon in the room but not in the patient. That's basically the level of reassurance we require to start a procedure. Thank you and Matt what do you think is the biggest challenge you have to putting LV leads in? What do you think are the biggest challenges to putting in an LV lead? So the biggest challenge I think is getting the LV lead into the proper branch and so obviously there are a lot of choices in the coronary sinus and so finding the one that's going to provide the best therapy and so usually that's a lateral branch that's going to subtend the latest activation of territory in that patient that has lateral wall dyssynchrony and so and the the best way you can find the best target branch is to do a proper coronary sinus venogram and really carefully delineate the anatomy. So I explained some of that but the analogy I use is it's like driving down a dirt road with your headlights off and you have no idea what the anatomy is unless you actually elucidate that with proper contrast injection and there's different techniques that I do to do that but I also know that making assumptions of large territories that aren't you're not seeing anatomy there don't assume that there's not a proper branch there because oftentimes you're not filling that properly and re addressing how you're doing the contrast injection going to a different branch doing a different runoff in a different location you'd be surprised what you find as possible suitable anatomy so that to me is one of the things that I've found to be a particular barrier that's very easily addressed by doing proper technique. Questions from the audience? Our VA stuff here is not working perfectly for us. Any questions from the audience? That's probably better. Sorry, I was asking for interventional lead delivery with snaring that when we're delivered to very small collaterals we find a lot of wire binding. We've tried Corsair changing to a 300 fully jacketed and trying to try different wires where there's gonna be less binding, but we just kind of find that in small collaterals there's always binding with a lot of resistance to wire removal. Do you have any tricks for that? Yeah, I mean one is wire selection. So I use the Boston Scientific Platform, which is TroisPT. That whole series of platforms which I found to be the most helpful of finding the right collateral branches. And the other is is that you can use a micro catheter as a sleeve around that. So Merit has a product, very small micro catheter, that you move down across that which potentially can free up some of that sort of wire binding that you get in those collateral branches. And then sometimes you just realize that it's potentially not a suitable branch. You have to find some other way of finding a different collateral to use. And Matt, do you have anything like that on Vue.Medi? Have you done anything like that? Sorry, it's hard. Have you done any of that stuff on Vue.Medi so it's easily available on the internet? Have we done anything on Vue.Medi? Vue.Medi? No, but I mean there's stuff online. I mean obviously Dr. Worley has a site for this and so there's a lot of very available stuff that's been sort of published on on the internet that help kind of demonstrate each of these cases and equipment. He has a, Dr. Worley has a site called bybytips.com and so there's other areas, other sources of information that you can get looking at some of these cases and different techniques and equipment to do this. I will say I've been doing extractions for years. There are cases that I look at and I say I don't know what I'm gonna do and Dr. Gallagher and his group have a lot of stuff in PubMed and very often I find the result in their PubMed stuff just like I do with Roger. Other questions? Thank you very much for your attention. Again, thanks to Merit for sponsoring this.

lead management

rotational transvenous lead extractions

mechanical methods

tandem femoral-superior approach

lead re-implantation

cardiac surgeries

SVC injury

stenotic veins