Acute DVT, symptomatic chronic DVTs and Post Thrombotic Syndrome… it’s time to find out more.

Post thrombotic syndrome (PTS) is a common, but often underappreciated complication of deep vein thrombosis (DVT).

Venous thromboembolism (VTE) is the term used to describe a blood clot in the venous system of the body. Veins carry blood back toward the heart after the blood has been pumped to different parts of the body and the oxygen used. When a blood clot obstructs a vein, the blockage slows or can even stop blood flow. Whilst not the case for everyone, when veins become blocked, they can cause painful and difficult to manage symptoms. In particular the larger veins in the pelvis, the iliac veins, are prone to this problem.

Tuk discussion illiac veins

Thrombosis UK’s Jo Jerrome met with Vascular Surgeon, Mr Baris Ozdemir, to learn more.

A new member to the North Bristol NHS Trust, Southmead Hospital vascular team, Mr Ozdemir began training as a vascular surgeon in the London rotation, including under the guidance of Mr Stephen Black at St Thomas’ Hospital. He was inspired by both the significant, and often rapid benefit vascular intervention could bring to highly symptomatic patients.

Why might a vascular surgeon be involved in treating DVTs?

"The iliac veins are responsible for most of the pelvic venous drainage. If a blood clot develops or spreads into the iliac veins, the effects can be immediately painful and often long-lasting. As a vascular surgeon, we have a few options which can bring relief and benefit to certain patients, although these will not suit everyone and are invasive treatments."

When can someone first be referred to you?

"Our first contact can be via an urgent referral for an ‘acute DVT’ that is known or suspected to be in the iliac vein."

"Any healthcare professional can call our service and request an urgent referral, and we will see the patient within 24-48 hours. In these circumstances, it would be a person who has been diagnosed with a DVT very recently, and no more than 2-3 weeks, so this is known as an ‘acute case’."

"As a service we will review and see many VTE patients, working within a multi-discipline team, we are able to review tests, confirm any suspicion of DVT in the iliac vein and counsel the individual on recommended treatment options. For many this will focus on anticoagulation, reducing on-going risks and supporting recovery."

"However, for symptomatic patients, experiencing a great deal of pain, swelling and/or impact on their previous life and mobility levels, this may also include consideration for vascular intervention."

What options can a vascular surgeon offer?

"Up to half of patients with an iliac vein DVT will develop ongoing problems with the leg in the future. These include swelling, pain, heaviness, skin damage and ulceration. We suspect that the patients who are most symptomatic are the ones most likely to develop these long-term complications which is called the post thrombotic syndrome. In acute DVT patients with clot in the iliac veins, there is evidence to suggest that if treated in the first two to three weeks, ‘thrombolysis’ treatment is effective in reducing pain and swelling acutely and probably more importantly, longer term complications.
“The aim of thrombolysis treatment is to rapidly dissolve a blood clot acutely to prevent complications in the future. This is achieved through administering ‘clot-busting medication’ through a catheter (a tube) inserted through the vein, usually in the back of the leg, extending into the veins in the pelvis so that medication is directly administered into the thrombus. Unfortunately, the evidence from research is quite dated compared to our modern approach. Much of the evidence is observational, however those who are most likely to benefit would be:

(i) Newly diagnosed with a DVT that involves the iliac veins
(ii) Have extensive pain, swelling and discomfort as a result of the DVT
(iii) Be considered low risk for bleeding

We would then expect there to be a very good chance that symptoms would significantly reduce, and on-going recovery be improved."

"We are fortunate in Bristol to have a ‘hot clinic’ every weekday where we see the majority of our acute referrals within 24-48 hours and the multi-disciplinary team will be able to carry out the required investigations rapidly. We often see patients not suitable for thrombolysis treatment, but we are happy to still review and confirm that their “conservative” treatment is optimised, discuss and explain the diagnosis, reassure them that if things change, they can come back for a further assessment."

"It has to be stressed that thrombolysis is not suitable for all DVT patients. Most specialists feel that those who have little pain, discomfort, or swelling are unlikely to gain benefit. Patients where the DVT does not involve the veins in the pelvis or abdomen do not appear to get a benefit. Furthermore, there are risks associated with the procedure, the clot-busting drugs carries a risk of causing bleeding too, so everyone initially undergoes a full assessment and is counselled before a shared decision is made with the patient."

"For those who are not suitable for thrombolysis, they are very likely to still be treated with anticoagulation (blood thinners) but their potential benefit from thrombolysis treatment would be low and out-weighed by risk factors such as bleeding."

"Thrombolysis treatment can mean a three to four-day hospital stay, and although minimally invasive, it is not pain-free. Therefore, in more recent years some centres have been able to offer a combined approach that adds mechanical removal of clot in conjunction with the thrombolysis. These approaches typically use special catheters/devices that allow aspirating (sucking) away the clot. These techniques can clear veins relatively quickly - in hours rather than days, thus shortening the hospital stay. Often a narrowing or stenosis of the iliac vein is found after clot removal. This may have been a contributary factor to the clot, and usually needs treating. At the end of the clot removal process a final check with an intravascular (from within the blood vessel) ultrasound determines if there is narrowing that needs a stent to hold the vein open. In practice, this is required in the majority of patients."

"Anticoagulation will usually then be used to stop the clot occurring again with the duration of the anticoagulation depending upon the cause of the DVT, if it is a recurrent DVT, and the extent and position of the DVT."

Tuk discussion Mr Baris Ozdemir

Mr Baris Ozdemir - North Bristol NHS Trust Southmead

Are there any treatment options for patients who have long-term pain and swelling due to one or more DVTs?

"The second line of therapy is for those with a ‘chronic DVT’ this is someone who had a DVT more than a month previously but has continued to struggle with pain, an enlarged limb and swelling."

"Chronic DVT can lead to post thrombotic syndrome (PTS), which can be a debilitating, life changing condition. The veins are either blocked or valves that normally allow blood flow only to the heart are damaged. These factors lead to a congestion of blood in the limb and a build-up of pressure. As a result, as well as pain and swelling, a person may have skin problems in the affected limb, skin discolouration, and possibly suffer from ulceration."

"PTS patients can be referred into the vascular team in Southmead through a formal referral via their GP, practice nurse, or a specialist consultant (typically a vascular surgeon or haematologist) in another hospital."

"For chronic DVT and PTS patients, the first thing we do is carry out a full review including scans for detailed imaging. At every step discussion and counselling are important. It is very important to look at the full history and for the vascular surgeon to talk with the person, understanding both the symptoms and impact the DVT has had on the individual’s way of life, and their aspirations for improvement, and what treatment might, or might not be able to offer."

"There are also risk factors that must be discussed so that together the patient and vascular team can consider whether there is a viable option for treatment that will relieve or reduce incapacitating symptoms and/or the intensity of care currently needed to manage the symptoms, such as reduction in the number of dressings required and the size of the swelling."

"So, the ultimate aim in managing chronic DVT or PTS for me is to improve the physical impact the DVT has caused."

"We ensure that conservative management in terms of elevation, skin care, stockings, dressings and bandaging are already implemented. In some patients these measures do not adequately address the pain, swelling or ulceration. In those with chronic blockage or narrowing of the iliac veins the mainstay of treatment would therefore be to improve blood flow and decrease pressure in the leg by stenting. Venous stents are placed to open up narrowed or blocked veins. Dedicated venous stents are typically larger than most arterial stents, very strong, flexible with a greater crush resistance. A successful outcome would mean reduced pain and swelling for the person or healing of an ulcer."

How effective is venous stenting?

"From the case studies available internationally, venous stents appear to be effective when used to treat the pelvic and abdominal major veins. They should not be used to treat the veins in the thigh or calf. Unfortunately, the major clinical trials that used thrombolysis to treat acute DVTs did not use stents in a way that reflects modern standards of care. Currently major centres use stents designed specifically for veins rather than generic arterial stents. In practice most patients undergoing thrombolysis now are stented and this was not the case historically."

Does having a venous stent mean life-long blood thinners?

"An often mis-conceived concept about vascular stenting is anticoagulation. Unlike a stent in an artery which will never be covered or re-lined by the body, a stent in a vein will, so every individual will be assessed and a decision on anticoagulation and length of therapy, will be made based on the individual, not on the fact that a vascular stent has been implanted. In general, the ‘rule of thumb’ is, that if, before the stenting, you did not need life-long anticoagulation therapy this is unlikely to be altered just because a vascular stent has been used."

Do all vascular services offer the DVT treatment options you have highlighted?

"No, vascular centres may specialise in different areas, so it is important to check:

Checklist: Is this service suitable for my condition?

Does the service use intravascular ultrasound?



Does the service use dedicated venous stents?



Has the team had appropriate training for deep venous interventions?



Does the team have an established programme and protocols for deep venous disease management and intervention?



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