Venous thromboembolism includes Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE) and is a common occurrence at about 1 per 1000 adults per year. With the current pandemic, though accurate data is not available, there seems to be a rise in the number of cases. Complications include life threatening PE and long term complications like post phlebitis sequelae. Early diagnosis, prompt management, and the introduction and use of newer treatment modalities like clot aspiration and lysis techniques, as and when indicated, can prevent long term complications and improve the long term quality of life.
A 35-year-old gentleman presented to the emergency with pain and swelling of the left leg for the past six days. He gave no history of trauma, fever, difficulty walking, breathlessness or discoloration of the leg. He had no comorbidities or history of Covid-19 infection and had not taken the vaccine yet. On examination, he was stable with a swollen and edematous left leg and thigh. He had mid-calf and thigh tenderness but no dilated veins.
CT angiography of the lower limbs showed acute bilateral iliac vein, left femoral and left popliteal vein thrombosis, and the proximal left common iliac vein was narrow in calibre at the level of the crossing of the right common iliac artery, which was suggestive of May Thurner syndrome. There was a free-floating thrombus extending upward in the infra-renal inferior vena cava (IVC). A screening CT of the chest showed no signs of a pulmonary embolism at that time.
All blood investigations were within normal limits apart from an elevated serum homocysteine. RT-PCR for Covid-19 was negative, however, the Covid antibody was positive. A final diagnosis of left iliofemoral DVT with extension into the right common iliac vein and the inferior vena cava, possibly due to May Thurner syndrome and hyper-homocysteinemia or Covid induced thrombosis, was made.
The patient was anticoagulated with a bolus dose of unfractionated heparin followed by infusion. He was taken up for emergency IVC filter placement because of free-floating thrombus. This was followed by percutaneous mechanical thrombectomy and catheter directed thrombolysis under local anaesthesia. An IVC filter was deployed via a right internal jugular vein puncture.
The left short saphenous vein was then cannulated under ultrasound guidance. An ascending venogram showed acute thrombus up to IVC. Mechanical aspiration of thrombus from the femoro-popliteal segment and thrombolysis was carried out, followed by the placement of a multi-hole infusion catheter. A bolus dose of Alteplase was administered followed by a 24-hour infusion through the catheter, while the heparin infusion was continued. The patient was monitored with activated partial thromboplastin time and fibrinogen levels. A check venogram after 24 hours showed residual clots in the popliteal vein and distal femoral vein with clearance of clots from the IVC, proximal superficial femoral vein, common femoral vein, external iliac vein, the common iliac vein on the left side, and common iliac vein on the right side.
The left common iliac vein was pre-dilated with a balloon and the stenosis was treated with a stent and then post-dilated to treat the May Thurner compression. There was no residual stenosis and the infusion of heparin and Altepase was continued for a further 6 hours. The patient was continued on anticoagulation and the leg edema was significantly reduced. The patient was discharged on a newer oral anticoagulant and vitamin supplements to correct hyperhomocystenemia.
In the post-procedure follow up, there was almost complete normalisation of the limb size. The IVC filter was removed under local anaesthesia after 3 months. The patient is doing well at 6 months of follow up and has no edema or varicose veins.
Deep Venous Thrombosis (DVT) has an incidence of 1-2 per 1000 persons per year.1 The most dreaded early complication is Pulmonary Embolism (PE) which has an incidence of about 33% and together they are often referred to as Venous Thromboembolism (VTE). VTE is the leading cause of death in hospitalised patients worldwide and may occur in up to 60% of patients undergoing surgery without prophylaxis. The one-month mortality of DVT is 6% and that of PE of 12%. 50% of DVT is unprovoked having no obvious cause. Up to 10% of patients have recurrence at one year. It is most commonly located in the calf veins or in the popliteal or femoral vein; however, in about 25% of cases, it involves the iliac vein segment. Some of the main causes for DVT are advancing age, major surgery, trauma, hospitalisation, immobility, active malignancy, central vein catheterisation and limb paralysis.
The complications of DVT include acute PE, post thrombotic syndrome and pulmonary hypertension. Post-thrombotic syndrome (PTS) is a costly and morbid long term complication, seen in 20- 50% of patients. Inadequate treatment and persistent thrombus are the main reasons for the recurrence of DVT.
The 8th American College of Chest Physicians (ACCP) guidelines describe the standard treatment as Oral Anticoagulation Therapy (OAT), compression stockings and mobilization.2
However, despite optimal standard therapy, recurrence rates have been found to be as high as 30% within 5 years after the initial DVT and 20-50% of patients develop post-thrombotic syndrome.3,4
Treatment of DVT can be either medical (anticoagulation) with stockings or surgical intervention in the form of catheter-guided thrombolysis, percutaneous mechanical thrombectomy, or open venous thrombectomy. Anticoagulation with low-molecular-weight heparin (LMWH) and vitamin K antagonists (VKAs) have been found to prevent further clot propagation and prevent pulmonary embolism. However, it does not lyse the clot. The body’s own lytic system facilitates clot removal and thus recanalization, which normally occurs within 12 months. After 12 months, recanalization is unlikely to occur.5
Active early clot removal if done within 2 weeks, by any means possible, reduces venous wall and valve damage and facilitates better recanalization. This in turn results in a reduction in PTS in long-term follow-up.
PTS is characterized by leg pain; sensations of leg heaviness, pulling, fatigue, limb swelling, leg edema, redness, dusky cyanosis when the leg is in a dependent position, perimalleolar or more extensive telangiectasiae, new varicose veins, stasis hyperpigmentation, and thickening of the skin and subcutaneous tissues of the lower limb known as lipodermatosclerosis. In severe cases, leg ulcers can develop, which may be precipitated by minor trauma.6 PTS normally develops within the first 2 years after DVT and can progress over the years to more severe stages. It is diagnosed using the validated Villalta–Prandoni scale.7
Iliofemoral DVT is associated with significant post-thrombotic morbidity. Up to 50% of patients will develop PTS after DVT although with iliofemoral DVT the risk is doubled.8
Although the specific pathophysiological mechanisms behind PTS are still unclear, it is thought to develop as a result of venous hypertension, due to incomplete lysis of the thrombus, which causes obstructions of the venous outflow tract.9
Venous hypertension subsequent to DVT causes chronic inflammation, which in turn damages the vessel wall and leads to valve destruction. Early thrombus removal is therefore associated with less damage to the vein wall and valve destruction; thus removal of all of the thrombus would prevent outflow obstruction and, in turn, should lower PTS.10
Catheter-directed thrombolysis (CDT) is a new delivery technique that infuses the thrombolytic drug directly into the clot, thereby enhancing thrombolysis. Several case series have shown that CDT is associated with enhanced clot lysis. The risk of bleeding is lower than other conventional methods as lower drug doses can be used. 11,12
Recently, the first randomized controlled trial comparing CDT with standard anticoagulation – Catheter-Directed Venous Thrombolysis in Acute Iliofemoral Vein Thrombosis (CaVenT) – showed an absolute risk reduction of 14% for PTS after a 2-year follow-up. CaVenT used standard CDT and showed bleeding risks associated with CDT to be acceptable. This is the first step towards a major shift in the treatment strategy for iliofemoral DVT. At the moment, two other randomized controlled trials are being conducted.13
Aggressive treatment of iliofemoral DVT with CDT has shown that treatment of the underlying obstruction is important. In about 50% of cases, an underlying cause is detected and stented, which increases patency rates.11,14,15 The most common obstruction encountered is May–Thurner syndrome, in which the left iliac vein is compressed by the right iliac artery. The literature suggests that treatment of underlying stenosis or obstruction is crucial for maintaining patency in the long term.
DVT prevention cannot be overemphasised. Thromboprophylaxis for at-risk hospitalised patients and those undergoing surgery and early mobilization in the post-operative period are recommended based on various scoring systems. Compression stockings and devices are non-pharmacological advocated methods for prevention. Unfractionated heparin, low molecular weight heparin and Fondaparinux have all been used in pharmacologically indicated DVT prophylaxis. IVC filters are used to prevent PE when anticoagulation cannot be given or when the risk is very high. Prevention of PTS includes adequate anticoagulation, clot removal when indicated and compression therapy with active mobilization after the acute phase of the DVT has been treated.
In young fit patients with Ilio-femoral DVT, catheter guided thrombolysis gives good immediate benefit and reduces the incidence and severity of PTS.
Dr Rahul NB Resident Department of Vascular and Endovascular Surgery
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