Post-thrombotic syndrome

Overview
Post-Thrombotic Syndrome (PTS) is the term used to describe signs and symptoms that may occur as long-term complications of deep vein thrombosis (DVT). It may also be referred to as post-phlebitic syndrome or venous stress disorder.

Incidence of PTS
PTS can affect 23-60% of patients in the two years following DVT of the leg. Of those, 10% may go on to develop severe PTS, involving venous ulcers.

Clinical Presentation
Signs and symptoms of PTS in the leg may include:
 * pain (aching or cramping)
 * heaviness
 * itching or tingling
 * swelling (edema)
 * varicose veins
 * brownish or reddish skin discoloration
 * ulcer

These signs and symptoms may vary among patients and over time. With PTS, these symptoms typically are worse after walking or standing for long periods of time and improve with resting or elevating the leg.

Socioeconomic Impact of PTS
PTS lowers patients’ quality of life after DVT, specifically with regards to physical and psychological symptoms and limitations in daily activities. Secondly, the treatment of PTS adds significantly to the cost of treating DVT. The annual health care cost of PTS in the United States has been estimated at $200 million, with costs over $3800 per patient in the first year alone, and increasing with disease severity. PTS also causes lost work productivity: patients with severe PTS and venous ulcers lose up to 2 million work days per year.

Cause
Despite ongoing research, the cause of PTS is not entirely clear. Inflammation is thought to play a role as well as damage to the venous valves from the thrombus itself. This valvular incompetence combined with persistent venous obstruction from thrombus increases the pressure in veins and capillaries. Venous hypertension induces a rupture of small superficial veins, subcutaneous hemorrhage and an increase of tissue permeability. That is manifested by pain, swelling, discoloration, and even ulceration.

Risk Factors
Investigators have determined that the following factors increase patients’ risk of developing PTS:
 * age > 65
 * proximal DVT
 * a second DVT in same leg as first DVT (recurrent ipsilateral DVT)
 * persistent DVT symptoms 1 month after DVT diagnosis
 * obesity
 * poor quality of anticoagulation control (i.e. dose too low) during the first 3 months of treatment

Prevention
Prevention of PTS begins with prevention of initial and recurrent DVT. For hospitalized patients at high-risk of DVT, prevention methods may include early ambulation, use of compression stockings or electrostimulation devices, and/or anticoagulant medications. For patients who have already had a single DVT event, the best way to prevent a second DVT is appropriate anticoagulation therapy.

A second prevention approach may be weight loss for those who are overweight or obese. Increased weight can put more stress and pressure on leg veins, and can predispose patients to developing PTS.

Finally, some data suggest that the use of elastic compression stockings for up to 2 years post-DVT can be an effective method of PTS prevention, while some data suggest otherwise.

Diagnosis
The Villalta scale has become the recommended tool for the diagnosis of PTS. It is a group of objective signs (ranked by severity) and subjective symptoms that clinicians may reliably use to diagnose PTS and its severity. Since signs and symptoms of DVT and PTS may be quite similar, a diagnosis of PTS should be delayed for 3-6 months after DVT diagnosis so that an appropriate diagnosis can be made.

Treatment
Treatment options for PTS include proper leg elevation, compression therapy with elastic stockings or electrostimulation devices, herbal remedies (such as horse chestnut, rutosides, pentoxifylline), and wound care for leg ulcers.

Compression bandages are useful to treat edemas. Stimulation medical devices such as Veinoplus can also reduce the symptoms of PTS. By stimulating the calf muscle pump, this device helps to remove venous stasis, to inhibit venous reflux and increases venous outflow. Thus, lowers limbs are better irrigated.

Upper-Extremity PTS
Patients with upper-extremity DVT may develop upper-extremity PTS, but the incidence is lower than that for lower-extremity PTS (15-25%). There are no established treatment or prevention methods, but patients with upper-extremity PTS may wear a compression sleeve for persistent symptoms.

Areas of Future Research
The field of PTS still holds many unanswered questions that are important targets for more research. Those include
 * fully defining the pathophysiology of PTS, including the role of inflammation and residual thrombus after completion of an appropriate duration of anticoagulant therapy
 * developing a PTS risk prediction model
 * role of thrombolysis ("clot-busting" drugs) in PTS prevention
 * defining the true efficacy of elastic compression stockings for PTS prevention (and if effective, elucidating the minimum compression strength necessary and the optimal timing and duration of compression therapy)
 * whether PTS prevention methods are necessary for patients with asymptomatic or distal DVT
 * additional treatment options for PTS with demonstrated safety and efficacy (compression and pharmacologic therapies)