What is it about?

Varicose vein surgery is now performed using pinhole techniques under local anaesthetic. This is called "endovenous surgery". This has replaced the old operation called "stripping". The new endovenous surgery has many advantages over stripping, including being performed under local anaesthetic as a walk-in walk-out procedure, much less pain, a better cosmetic result and a much earlier return to normal life. Research has also suggested a lower chance of the same vein returning by regrowth. However, many researchers studying endovenous surgery use models where veins to be tested are filled with blood, sometimes pumping through the vein, to simulate real life. Unfortunately, when patients are being operated on under local anaesthetic, the patient is tipped head down, and a local anaesthetic solution called "tumescence" is injected around the vein. This study has shown that in this situation, the blood has been squeezed out of the vein, and there is no blood in the vein being treated during endovenous treatment.

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Why is it important?

To ensure that patients get the best treatment, we have to be sure that the right amount of energy is used to close the vein during endovenous surgery for varicose veins. Too little energy and the vein will not close; too much and the vein will be over-treated, causing unnecessary extra pain and potentially more bruising. Researchers use models of veins in the laboratory to understand exactly how much energy should be given to close the vein. Many use human veins removed from consenting volunteers, while others use animal veins. Making the laboratory model as accurate as possible is essential for the results to be useful and appropriate when used in living humans. Many models include adding blood into the vein used in the model, with some being sophisticated enough to actually pump the blood through the vein, trying to simulate "real life". Unfortunately, although this may simulate a vein in a human lying down, this paper has shown that it does not simulate a vein being treated with endovenous laser ablation. When a patient is being treated with endovenous surgery, either endovenous laser or radiofrequency ablation, the device is passed up inside the vein to position it at the groin. The patient is tipped head down to empty the vein. Local anaesthetic is then injected in large volumes around the vein, a technique called "tumescent anaesthesia". This not only anaesthetise the vein and surrounding tissues but stops heat from damaging other structures. This research paper shows that when this has been done, the vein is tightly constricted around the endovenous device with no significant blood at all in the vein. Therefore, all models that include blood being in the vein are wrong. As blood will stop energy from being transferred from the endovenous device to the vein wall, this error means that models that include blood will overestimate the amount of power needed to close a vein. Hence if doctors rely on the results of such models, they are likely to use excessive energy when treating patients.


When endovenous surgery started at the turn of the last century, the heat was often thought to be used just to shrink the vein away. Our research has shown that although the vein does shrink with heat, the most crucial factor is that the cells in the vein wall are killed, so they cannot allow the vein to heal and reopen. Indeed, we are trying to ensure the vein heals by scar tissue alone. This gives a permanent closure of the vein. Therefore it is essential to give enough energy to do this, as too little will only result in cells remaining alive and the possibility of the vein reopening again in the future, leading to recurrent varicose veins. We have spent over two decades perfecting models in the laboratory at The Whiteley Clinic to test any device we use to ensure our patients get the best results. Moreover, if new devices are developed, we can use our models to ensure the recommended treatment protocols are correct. If not, we can modify them to give our patients optimal outcomes. As with all researchers, we also check the work of other researchers in the field to ensure that we have not made any glaring errors and that we all have a broad agreement. One of the significant areas in laboratory work when using human or animal veins is whether we should include blood in the model. This adds a layer of complexity, particularly if blood needs to be pumped through the vein during treatment. When we were developing our model, it was clear that there was no blood within the vein during treatment. So we created our model mimicking the vein being contracted around the endovenous device by tumescence. Subsequently, reviewers of our work have questioned why we have not followed other laboratories in adding blood to the studied veins. Therefore we performed this observational study in patients undergoing endovenous laser ablation. It clearly shows that once the devices are in the great saphenous vein, tipping the patient into the head down "Trendelenburg" position reduces the diameter of the vein. The addition of tumescence then completely closes it around the device, leaving no room for any significant amount of blood. Therefore, although we were sure of the results from simple observation of thousands of cases, we needed to publish a formal observational study to justify our previous work. Moreover, it does call into question results obtained from units that include blood in their model. Either they overestimate the amount of power needed to ablate a vein or mimic suboptimal treatment conditions where a patient may be lying flat and having endovenous surgery without tumescence.

Professor Mark S Whiteley
The Whiteley Clinic

Read the Original

This page is a summary of: Veins undergoing endovenous thermal ablation have little or no blood intra-luminally casting doubt on the results of many ex-vivo vein ablation studies., April 2023, Center for Open Science,
DOI: 10.31219/osf.io/vef4m.
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