Requirements for Creation of Fistula
My first comment is that an AVF is very much the nephrologists area … it is ‘your lifeline’ and thus should be (and is) ‘our direct interest’. My second is that although you say that you have a ‘small fistula’, you also say that the fistula is narrowed near the arterial anastamosis and that it has required repeated angioplasty to restore adequate flows.
This suggests that the fistula (maybe) ‘small’ due to poor feed pressures and a poor inflow of blood from the arterial end.
I have to say I am NOT a fan of repeated angioplasty. It is a temporising procedure, at best, as the vessels always re-stenose (re-narrow) and need repeated angioplasty at usually ever decreasing time intervals. In addition, peripherally placed stents are like a red rag to a bull to me and, in my strong view, should be avoided at all costs and only play any role in central veins (those inside the chest).
In our view, definitive surgical repair is always the best solution and here there are several options.
Though it is a brachiocephalic AVF (not radiocephalic AVF), the simplest solution would be to see if a re-anastamosis higher up … the simple resection (or removal) of the narrowed, damaged section with a re-anastamosis (or rejoining) higher up on the artery. This is usually a very good option in radiocephalic AVF but is often technically harder to do (though not impossible) in a brachiocephalic graft. Brachiobasilic veins that stenose often need either a transposition procedure or a skip native graft interposed – both well known and used surgical techniques in AVF surgery. I cannot advise on this further as I would need to know your venous and arterial anatomy – but it is worth at least considering as an option.
We abhor artificial (synthetic) veins and graft material and avoid these wherever possible. In our view, if a vein (native) is large enough to accept surgical anastamosis, why join it to a synthetic material and not another native vessel. Sometimes, when there is a problem with distance (or reach), we solve this by ‘harvesting’ (taking) a vein from elsewhere, using it to bridge the gap. The commonest one we use is the superficial femoral vein from the leg – just like is used for coronary grafts – reversed (so its’ valves are flattened by the blood flow rather than impeding blood flow) and anastamosed (joined) between artery and vein in the arm. But … our surgeons are an inventive bunch and sometimes come up with obvious solutions for harvest (like the vein that courses across the underside of the forearm … have a look at any 18 yr/old young man and look at the vein that crosses there … its often a good vein to use … and you will have one too - or most do). Native veins are always far, far better than anything synthetic. A thoughtful appraisal will almost always find an option.
A vein patch is a really good option. Our little whiz-of-a-surgeon probably uses this more commonly than all other techniques. Simply, the stenosed length (plus a bit) is opened long-ways and an elipse of vein – harvested from somewhere (anywhere) else – is simply over-sown over the stenosed length to widen and restore the lumen. And … the good bit? … they work.
Finally, the left arm – if still available to you – may be an option, but we DO try to save (where we can) an AVF in one arm before we abandon it entirely.
Here, in Australia, we are very native vein conscious – but so, too, are the Europeans – many there even more so. We only run ~80% native AVF (but precious few synthetic grafts) and mostly the remainder at any one time are IJC’s awaiting AVF creation. Italy, Germany and France are all at 90%+ native AVF. It is only the US that seems to differ. Why? … that is for the US to answer.
As for vein size, we ‘like’ to see a vein at US mapping of 3 mm or more to be sure it will mature to a nice AVF. That doesn’t mean we won’t have a shot at something a bit smaller – but the success rate does diminish @ <3mm.
Here (and also in Europe, Japan and pretty much elsewhere), the dialysis times are much, much longer and the blood flow rates (pump speeds) are much lower – again when comparing to the US. To have low dialysis times, one needs to crank up the pump speed … and I (and others) would contend that that is NOT a good thing to do. The high turbulent flow created at the venous return needle as 450ml/min of blood is squirted back into the vein at the venous end is, in my view, a potential contributor to damage to the delicate cells (endothelium) that line the vein … and may be a significant reason why venous stenosis (narrowing) is so common. Slowing down the pump speed and blood flow – and thus reducing the shear forces created in the vein at the point of return of the returning blood – is, we think, a good thing to do. The same could be said for the ‘suck’ pressures that a high pump speed exerts on the arterial feed vessel … again creating the potential for endothelial damage and feed (arterial end) vessel stenosis.
To me, it seems common sense that lower flows = less ‘disturbance’ to normal vein physiology and wall integrity.
We certainly see, in our low flow, low speed, gently used NHHD AVF very little … indeed, I would venture to say we see no evidence for AVF aneurysm, stenosis or other of the AVF issues that bedevil conventional dialysis. Maybe this is due to the low numbers, to date, of observed low flow AVF (mean = 225ml/min in our NHHD’s) – who knows? I tend to think (or hope) it is a real observation. Even then, our conventional facility-based HD patients run at 300-325ml/min (max) = much less than the US 400-450ml/min rates. I tend to think that the ‘need’ for a bazooka flow rate is probably a factor in the US decision-making ‘psyche’ re the perceived requirements for vessel size and the ‘do-ability’ of a native AVF – but that is just a guess and is impossible to know.
In addition, we, here, are strong (well – might I say emphatic) believers in antegrade-antegrade needle insertion techniques. Most dialysis has traditionally been done by retrograde-antegrade insertion. I have a given a webinar to HDC on that issue. I feel quite strongly about this. But … sadly … amazingly little research has been done over the decades on this – or, for that matter, on anything to do with fistula flows, wall integrity and the factors which might influence AVF vein protection. I stand as much condemned on that as anyone – but there is only so much one person can do!
My final comment is meant lightly and tongue-in-cheek … but there is a famous book called the ‘The House of God’ – a must read for any intern starting out – where there is a famous line “there is no body cavity which cannot be reached by a 14 gauge needle and a strong right arm”. The fistula equivalent might read “there is no native vein and artery combination that cannot be creatively used to make a native dialysis fistula”. Now, that isn’t quite true and it is a ‘facetious’ comment … but, I trust, you’ll get my drift!
NB: I have not edited this - will check later for errors or for any changes I want to make