Adili: A warm welcome to a new episode of ‘Vessels in Focus’, the podcast of the German Society for Vascular Surgery and Vascular Medicine. And welcome to Part 2 of our podcast on distal and ultradistal bypass surgery. I am Farzin Adili, a vascular surgeon and acting President of the DGG, and my guest today is Dr Achim Neufang, Head of the Department of Vascular Surgery at Mainz University Medical Centre. In the last episode, we discussed just how complex the assessment of indications and pre-operative planning for distal and ultradistal bypasses actually is, and we left off with the question of what to do if the veins aren’t long enough. Achim, it’s great that we’re picking up where we left off. Let’s get straight to the heart of the matter.
How important do you consider composite techniques to be – that is, direct composite or modifications such as the ‘hitchhike’ technique and sequential bypass, which are, of course, wonderfully described by our pioneers, such as Vollmer? How do you view the significance of these reconstructions?
Neufang:
For the younger readers, ‘composite’ refers to a combination of prosthetic material and autologous venous material. Not everyone is likely to be aware of that. I’m a big fan of the composite technique when I’m able to create an enlarged outflow bed distally via a sequential anastomosis. I don’t need to explain to you how the Deutsch bridge technique works. In this procedure, I connect two peripheral arteries with an autologous vein and then place a vascular prosthesis onto the autologous vein. It’s actually a very effective procedure because I generate a lot of blood flow, all of which goes exclusively into the arterial circulation. I always do this when I come across veins of dubious quality. Sometimes this involves an intraoperative change of plan from a purely autologous approach to discarding the poor-quality section of the vein, finding a second, perhaps slightly poorer-quality artery, and connecting the good one to the poorer one via the vein, before completing the procedure with an inflow prosthetic graft, be it biological or BDW. And then you actually have a very good prognosis.
Adili: I see it in much the same way. Well, the bridging vein bypass is, of course – let’s put it this way – quite challenging and very labour-intensive, but it’s certainly a very, very good option. There’s one question you really always have to ask in this context, which is why I’m turning to you as the veteran. How do you view the debate between in situ versus reversed, or in situ non-reversed versus reversed? Do you have a personal preference? An approach? What works particularly well in your view, and if so, when and how?
Neufang:
Well, for the younger doctors: ‘in situ’ means you don’t remove the vein at all. Not everyone has probably seen this done, but you simply mobilise the vein proximally and distally, connect the whole thing to the donor and recipient vessels, and clip the side branches via separate incisions. To do this, I have to destroy the venous valves using the valvulotome. Strictly speaking, the real issue is the geometry of the bypass. What you want to avoid, for example, is the trauma caused by vein harvesting. That would be justified in an in situ procedure. But actually, the point is that when I invert a vein, it doesn’t really matter much in the case of the rarely performed femoral vein bypass – which is hardly ever done these days – because the calibre is similar at both the upper and lower ends. It only becomes a real factor when you go from the groin to the mid-distal lower leg; there, of course, the calibre of the vein plays a very significant role. I’d really rather not perform a central anastomosis with a very narrow vein and a peripheral anastomosis with a thick vein. That’s contradictory; it’s not a good approach. The in situ method is one option here, but it, too, has its own limitations.
I sometimes find that the location of the central anastomosis is the crux of the problem. In such cases, I’d rather not, I don’t know, suture a 7 cm patch just to avoid having to harvest the vein. I don’t do that. That’s why I do it relatively rarely; my standard method is actually complete vein harvesting with valve destruction, using the non-reversed method. That opens up all possibilities – any configuration is possible. I achieve a good central-to-peripheral calibre ratio, which is actually the solution to this problem.
And if you take this a step further, this is also the situation with a potential post-operative revision – it’s not common, but it is possible. If I have a reversed bypass with intact valves, thrombectomy isn’t all that straightforward. I avoid this problem by also performing a valvulotomy on the inverted vein. I always do this. I always perform a valvulotomy, regardless of how I orient the vein.
Adili: Of course, there are certain risks involved with incomplete work; I can absolutely see your point there. What I occasionally do with an in-situ bypass, when the vein really doesn’t extend far enough upwards, is on one or two occasions I’ve practically obliterated the AFS outlet and used a bit of the AFS to effectively extend the arterial segment, then connected it end-to-end to the AFS. But let me put it this way: I think these are very, very individual decisions that you make with patients. I wouldn’t make a whole philosophy out of it, but it is another option.
Neufang:
Yes, that’s not a bad one at all. I used to do that too, but that segment of the obliterated AFS can then in turn become the seed for hyperplasia. That’s why you have to think it through carefully.
Adili:
Absolutely.
Neufang:
It’s a bit of a trick, admittedly, yes.
Adili:
Achim, the borderline vein – at what point do you say, ‘I won’t accept this vein’? It’s lovingly mapped out for us by our staff, we expose it, and then we say, ‘No, njet.’ So, when do you draw the line?
Neufang:
Well, first of all, I never rely on the pre-operative duplex scan. Unless you find absolutely nothing, or you know the vein has already been harvested or something similar. One factor is the calibre. You can assess that relatively quickly. I like to start centrally, on the thigh. There you can quickly see the maximum calibre of the vein. And if you’re in any doubt, you ligate a side branch, clip it off towards the periphery, fill the whole thing with saline solution, and then you know what the true calibre is. That’s essentially the first yes-or-no decision.
The second is that, once I’m down at the lower leg, it’s sometimes the case that the straight section of the great saphenous vein is often rather meagre. If there’s a fork off towards the dorsum and you’ve got a tiny little vein there, you can either see it straight away or use what I bought ages ago: a calliper. You can actually use it – just like in mechanics – to inflate the vein, and then you’ll have the exact diameter. Or, if you’re in a pinch, one of those paper rulers will do, if you use a pen to mark it. You can place that on top, and then you know that if it’s smaller than 3, it’s no good. I wouldn’t use that.
Adili:
Yes, I think it’s important that we emphasise that very clearly once again. You really shouldn’t use a vein that’s less than three millimetres in diameter – or at the very least, that’s what makes the difference between a bypass that lasts a few weeks or months and one that lasts for years.
Neufang:
That’s right. So that’s the quality. What I don’t do is stop at vein preparation; instead, I know which parts of this vein I won’t use. I then extract everything right up to the groin, have a look at it, and once I’ve got my length, I know whether I can now modify the anastomosis site to make do with this section – and I’d like to point out once again that we always have one arm prepared, and if I need an extra section, I go to the arm and take it from there.
Adili:
On the subject of multi-segment venous bypasses, how many segments do you stop at?
Neufang:
There’s literature on this too, and it says you can use up to four segments – that’s what I do as well. I used five segments recently. The trick with this composite or spliced vein graft is the quality of the individual segments. You have to be extremely selective and discard anything that isn’t quite right; and if you then anastomose these good segments properly, you’ve actually created a good graft.
Adili:
How do you then place the bypass? Preferably orthotopically or subcutaneously, using a tunneller or a Korn forceps – those are the sort of technical questions you ask yourself, just quick and dirty.
Neufang:
Well, I only place the bypass anatomically through the popliteal fossa if I’m working with limited lengths. These days, for the crural, distal or pedal grafts, I prefer subcutaneous placement anyway – or sometimes subcutaneous and subfascial, but still relatively superficial. Simply because it makes the whole process much easier for future check-ups. That’s one thing.
Adili:
Of course, but at the cost that if you develop a wound healing disorder, you’re naturally right at the [bypass…]
Neufang:
That, in turn, is the downside. You mustn’t do it where the skin is compromised. You can then take a middle ground, for example on the lower leg, if I place it directly subfascially. I make a skin incision, open the fascia and then proceed superficially subfascially. I believe the graft is then very well protected whilst still being clearly visible on ultrasound. I do it this way when I use the tunneller – we call it the plastic tunneller; it has a metal wire, which is quite strong, and a very small, flexible plastic tube that you thread through using a sort of long pair of forceps. That’s actually quite atraumatic, of course, but I think it’s very important to tell others that what I would never recommend is doing it in one go from the lower leg to the groin. I don’t do that. Instead, I always make an additional incision on the distal thigh and then, manually, work my way down the back of the knee, and finally perform the tunnelling. Otherwise, it’s quite simple – subcutaneously; the best and easiest method is to use a ligature clamp. You’ll probably remember this from colon surgery back in the day, where you could pass a ligature all the way round deep down – it’s very long, like this – and with that you can proceed subcutaneously in a very atraumatic way and then pull the venous graft through. It’s also a method that makes twisting the graft relatively difficult, it has to be said.
Adili:
Yes, that’s a good point; I’d like to pick up on that. Can you give our colleagues some tips on how best to ensure that the graft is tension-free, that there are no kinks in it, that there is no torsion, and that it isn’t pulled too tight?
Neufang:
Yes, well, torsion is a nuisance because it automatically means anastomoses coming apart or a venovenostomy. The best approach is to start with the central anastomosis – that’s where I always begin – and then I fill the entire bypass with pulsating blood and place it on the thigh or the leg; this course then remains visible throughout the tunnelling process and during the steps. I think that makes it relatively unlikely. If you want to be absolutely on the safe side, you can mark the vein with guide lines. I wasn’t trained to do that in the past. I might do it in individual cases, but I don’t generally do it. So that’s certainly one way of preventing torsion.
And I also believe that with step-by-step subcutaneous tunnelling, the risk of creating too much tension is also eliminated, because you’re doing it from one point to the next.
And the third point is the flexion of the lower leg when I bend the knee joint. So you should straighten it to see how the course of the vein looks, and then see what happens when you bend the knee. I think the likelihood of ending up with excess length is rather low; if the bypass does turn out to be too long and you’re moving from the subcutaneous space into the lower leg, then, by effectively running the bypass deeper within the lower leg, I can compensate for the excess length and thus avoid a kink. That works. I don’t necessarily have to re-anastomose anything.
Adili:
Yes, that’s very good. Since you’re now anastomosing proximally first – I always do it the other way round; that’s how we were taught – but basically, what you’re saying makes perfect sense. Then the next step is the distal anastomosis. Of course, we could spend a whole afternoon going over what needs to be taken into account here. But I’d like to focus on one or two specific questions. One is actually how to deal with heavily calcified target vessels. So the artery is calcified; the question is also, to some extent, about its connectivity. I once had a senior registrar who said it’s a bit like sewing a bicycle inner tube onto a double biscuit. What tips do you have on that? What’s the best way to go about it? There are also colleagues who perform a desobliteration, a crural endarterectomy. What do you think of that?
Neufang:
To be honest, I don’t think much of the latter at all. I’ve been using blood evacuation consistently since 2012 or 2013 to create the distal anastomosis. And that actually solves this problem almost completely. However, that only works if you proceed in the order of proximal and then distal. But I’ve been doing it that way for a long time, so I didn’t have to change my approach. The problem with a heavily calcified vessel is actually controlling the bleeding.
Adili:
The suture?
Neufang:
Yes, the suture, but first and foremost haemostasis. You’ve got to be able to see inside first. And if you can’t clamp it because it’s too calcified, or if you force the clamp on, then you’ve already driven in the first nail in the coffin.
Adili:
What do you think of intraluminal balloon occlusion?
Neufang:
You can do that. It works quite well with two Fogarty catheters. It’s a bit of a hindrance, though. I used paediatric feeding tubes for ages. I actually think those are the more elegant option. You can inject heparin through them. But then you always have something getting in the way during anastomosis. It’s in the way, so to speak. And I think the most elegant approach is when you have nothing in the lumen and a calcified artery, which is harder to anastomose anyway. And that’s really only possible with temporary bloodless surgery. That pushes the issue of visibility completely into the background. You have a clear view because there’s nothing inside. And there’s no blood in there either. You can see everything very clearly.
Adili:
Just a quick follow-up for the hand surgeons amongst us. Complete haemostasis – meaning by unwrapping the limb or using a tourniquet?
Neufang:
Haemostasis. And specifically, I don’t use a cuff like the trauma surgeons do, which is inflated to a very high systolic pressure. Because that’s not practical. I don’t know if you’ve ever tried it. It’s a bit of a faff. What I use is really simple. I use a sterile Esmarch bandage. And once I’ve tunnelled my bypass until it reaches the distal vessel – and it’s lying there with a [Bulldog] clamp on it and pulsating – I take an Esmarch bandage and start from the forefoot, unwinding it all the way up to the knee under continuous tension. This creates a bloodless area in the foot and lower leg. I then have to secure this bandage at the knee. You simply clip a clamp onto it. And then, if I’m lucky, I can partially unwrap this bandage from the foot towards the knee. And then you’ve effectively got a local tourniquet.
Adili:
Very neat.
Neufang:
And you’ve got a brilliant view. That solves loads of problems at once. And then you can calmly focus on the suture itself, because it’s not that easy with a rigid vessel. You can knead the edge a bit with the forceps, to fracture it. Then it’s easier. Or you can work your way through stitch by stitch. There are specially hardened needles that are simply harder and stiffer. And then it basically works quite well. But what I would never do – endarterectomy of the target vessel – is also fatal. You mustn’t do that under any circumstances.
Adili:
That’s a disaster when working with small-calibre needles. I agree with you completely.
Neufang:
That’s exactly right.
Adili:
If you absolutely can’t get through the calcification, then I’ll sometimes make a puncture just past it. Not a full-wall puncture, but I’ll puncture the adventitia instead. You can do that once in a while. If the whole anastomosis ends up like that, you’ll get a spurium aneurysm sooner or later. But that works too, and you’ll eventually get the needle through somewhere. I once spoke to some colleagues who used those old, sharp cloth clamps. And they managed to crack it open like that.
Neufang:
That’s too thick. For the arteries we’re talking about now. Someone told me that once too. Someone else once told me that he’d drilled into it. I could never quite get my head round that, because I couldn’t really picture it.
Adili:
Perhaps with a dentist’s drill.
Neufang:
We’re not the only ones with this problem. Lots of people have given it a lot of thought. One thing that works quite well is this Everpoint needle. It’s hardened. It works quite well sometimes. But not always. It’s not the solution either. But if you take your time doing it. It’s really important to insert it at exactly 90° to the axis of the wall. To hold it perfectly perpendicular.
Adili:
Absolutely. So you’ve basically already revealed all your techniques for the distal bypass to us. Or is there anything else where you’d say, ‘If I don’t do this, I’ll run into problems’? Have we covered the most important points? Or is there anything else you’d say is particularly important to bear in mind?
Neufang:
The sequence you need to follow. First of all, operability. Assessing the recipient vessel in situ. Once it’s been exposed. That’s still the most important thing. And then the next step is reviewing the overall plan. Once you know how much vein length you have. And then from proximal to distal. I don’t think it’s that difficult at all. Then you won’t run into too many problems.
Adili:
So you’ve done your bypass. Now you’re carrying out intraoperative quality control. How do you do that?
Neufang:
I’ve always done it this way since the transit time flow meter became available. They’ve been around since 1996. Our former boss was one of the first to acquire this device for cardiac surgery. We got two of them straight away. Once you’ve got used to simply assessing the flow volume and the curve you see, it’s an excellent method.
Adili:
You don’t perform angiography?
Neufang:
Not at all. I was very pleasantly surprised. I visited colleagues at Deaconess Hospital in Boston back in 1999. I was on a clinical placement there. They don’t do it there either. And I was also in Albany once; they don’t do it there either. They rely on clinical and functional assessment. That really reinforced my belief in this approach. I still do it to this day. I never perform an angiogram on a bypass.
Adili:
Fascinating.
Neufang:
If you look at coronary surgery, they don’t do that either.
Adili: You’re right about that.
Neufang:
It’s exactly the same. They’re under even greater time pressure. They’ve also got the added pressure of myocardial ischaemia at the bend. We don’t have that. We should rely on the fact that the anastomotic vessel is clearly visualised during the diagnostic phase. That no mistakes are made during anastomosis. And tunnelling simply prevents torsion or kinking. These are the kink points that can be identified with an angiogram.
Adili:
You save yourself the trouble of the toe arch. You save yourself the hassle of operating in a smock. That has a certain charm. What else do you think of ultrasound – I mean, duplex – you can also measure blood flow with it.
Neufang:
Brilliant. That’s the second thing. I think it’s very good too. We have this device that has both a high-resolution duplex probe and the flow measurement function. It’s very useful for assessing the anastomoses. And the flow in the venous graft. And if there isn’t too much subcutaneous fatty tissue, you can also visualise the course of the bypass. You can then scan down the leg. That’s brilliant. And it takes very little time.
Adili:
When do you perform a revision? When would you say, ‘I can’t leave it like this’?
Neufang:
Only if nothing decent is flowing through. If it’s 3 ml with extreme fluctuations, then you know something’s not right. And then the simplest first step – before I dismantle the whole anastomosis, provided I’m sure I haven’t made a mess of the anastomosis configuration – is simply to clamp off the bypass. I don’t need to create new blood-empty areas. It’s enough just to clamp off the bypass. And make a longitudinal incision in the vein, between the tip and the heel. Then I can effectively look inside. And the very first thing I can do is check whether there might be a thrombus inside, which shouldn’t actually be there. I don’t know if you like doing this. We have these coronary bougies in our kit. You can use 1–1.5 mm bougies to probe the vessel, so to speak. If there’s nothing to report, I occlude it again and have another look. If I see that the flow is still low, then I’ve chosen the wrong vessel. Then I check the angiogram. Is there anything further distally?
Adili:
Oh, I see – the pre-operative angiogram.
Neufang:
The pre-operative angiogram.
Adili:
And intraoperative angiography?
Neufang:
To be honest, I don’t do anything there either.
Adili:
Okay.
Neufang:
Then I have a look at the pre-operative images. Say, here’s a segment I’ve got available as well. Then I target that straight away, expose it and extend the procedure to include that segment as well.
Adili:
Right.
Neufang:
That’s my personal approach.
Adili: In your view, what are the three most important factors for the long-term patency of a bypass?
Neufang:
The very first thing is the quality of the vein. You have to use a good vein to achieve a good end result. There’s no getting round that. The quality of the vein is absolutely crucial. The next thing is compliance from the patient and other stakeholders. This includes the GP, for example, who must also support the concept of antithrombotic therapy. And not simply change it because it doesn’t suit them at the moment. Nor should they be indifferent to the configuration of the bypass. That does happen, after all. And then there are three other things. You have to make patients aware of these in advance: follow-up procedures on the limb. What’s dangerous is a knee joint step. Things like that. They can sometimes ruin the result.
Adili:
And if necessary, how long should the waiting period be? Probably as long as possible. But what would you consider the minimum?
Neufang:
I’d wait at least 3–6 months. For that sort of knee joint operation. If necessary, I’d also… Here at the university, the orthopaedic surgeons used to always ask us to check it just before the procedure, so to speak. And straight afterwards. Because it’s also possible that after a knee tap, a thrombus simply forms. And nobody notices. Because nobody’s checking. That’s a point you have to take into account.
And the next thing, which unfortunately isn’t in the guidelines, is that regular bypass follow-up can identify the ‘bad apples’. And that by making preventive, targeted adjustments, you can positively influence the long-term outcome. I’m convinced that’s the case.
Adili:
There’s also data suggesting that isn’t the case. I’m sure you’ve read it too. Studies showing that regular follow-up didn’t ultimately make much difference to the outcome. But still. Not checking can’t really be the solution either. Perhaps we’re not doing it properly.
Neufang:
Perhaps we need to… Patients often don’t notice it beforehand. You can only detect it. For example, if you know you’ve got a particularly high-risk construction – three or four pieces of hair sewn together. I’d check on patients like that regularly. In that case, simply measuring the ABI might be enough. That’s also an indicator. If it suddenly drops, something’s not quite right.
Adili:
We mustn’t finish without touching on an important topic which our listeners know is very close to my heart. That is, of course, how we can pass on these techniques, these tips and tricks, to our young colleagues under the current conditions in which we’re working – with endovascular surgery as the main competitor – how can we convey such knowledge? What are the biggest shortcomings? What can we, the older generation, do to ensure that this expertise is not lost to our speciality?
Neufang:
I believe that, first and foremost, when assessing the anatomy in a patient with an ischaemic leg, we should consider: what is the pattern? And, based on that pattern, consciously work through the design of a bypass. I believe this is where the first problem in training lies, because it is often no longer taken seriously at all. Many have lost faith in it and do not practise it, and consequently, the next generation is no longer exposed to it. I think we should discuss these steps and everything involved. All the more so when we have an interdisciplinary case conference; it’s absolutely vital to demonstrate, ‘I’m going from here to there and doing it this way and that way’, so that all the key players are on board.
And then, of course, you have to guide people through it step by step in the actual operating theatre. It’s unthinkable to simply have someone assist with a bypass. We both know that won’t work. You have to take it step by step: vein exposure, vein harvesting, vein assessment, suturing of collateral branches, valve destruction, and then, first of all, dissecting the proximal vessel. There are also an incredible number of variations. How do I handle the proximal section?
Adili: If I may just interject briefly, do you see any value in simulation or simulation models for at least practising certain techniques – such as suturing and anastomosis? we certainly don’t have ideal simulators for these things at the moment to practise these challenging procedures. But do you see a role for them in the future, perhaps also with AI, UVI?
Neufang:
A definite yes. The crucial factor is the technique of instrument handling during anastomosis. That’s absolutely vital. I believe you can practise that over and over again in simulation. Even if it’s just a plastic tube at this stage, that’s not a problem. But you learn the hand movements. Yet that’s only part of it.
Putting it into practice on a leg – I think that can only be done step by step. And the final step is actually the crural or pedal anastomosis. I’m personally quite fussy about that, and you have to be. It’s also clear that some people are well suited to learning this, whilst others aren’t at all.
Adili:
That applies to every area of what we do. You’re absolutely right. But let me put it this way: that’s almost a brilliant closing remark. Our time’s up, Achim. That was extremely entertaining. And I reckon the two of us could carry on talking for hours about bypass surgery, or vascular surgery in general. I’ve really enjoyed it. I hope you have too. Thank you very much for taking the time.
Neufang:
I really enjoyed talking about it.
Adili:
To you, dear listeners, a very big thank you for joining us again. If you have any questions or would like to share your feedback with us, please feel free to write to us at podcasts@medizinkommunikation.org. If you’re listening to us on Spotify, you can also leave us a rating. I’m already looking forward to the next episode of ‘Gefäße im Fokus’ and wish you all the very best. Stay curious and, above all, stay healthy.
