Treadmill Pilot Study (Invasive Pressure Measurements in PTS)
Condition: Post-thrombotic Syndrome; May-Thurner Syndrome
MeSH terms: Postthrombotic Syndrome; Postphlebitic Syndrome; May-Thurner Syndrome; Syndrome
Study type: Observational

Summary: 
      Patients with unilateral post-thrombotic obstruction of the iliac tract and or common femoral
      vein, eligible for stenting are included. Intravenous pressure is measured in both dorsal
      foot veins and both common femoral veins. Patients are asked to undergo a standardised
      treadmill test (3.2km/h, 0% slope that increases by 2%/2min, maximum walking time 26 min).
      Painfree and maximum action radius are noted.
    

Detailed description: 
      Rationale: PTA & stenting in iliofemoral and iliocaval venous obstruction has been proven to
      be an effective method of treatment with good clinical results. However, no proper
      investigations have been made to objectify the reduction in (ambulatory) venous hypertension
      caused by this type of obstruction. Normal ambulatory venous pressure is below 20mmHg, though
      studies have already shown a linear relationship between the incidence of ulcers and an
      ambulatory intravenous pressure of more than 30mmHg. We believe that by measuring the
      (ambulatory) venous pressure before and after stenting, we will gain more knowledge on the
      hemodynamics of venous disease and its treatment and we will obtain information that might
      identify patients at risk of stent occlusion or the forming of an ulcer in an early stage.
      Identifying these patients will most certainly influence preventive treatment in the future.

      Objective: To map the changes in intravenous pressure in post-thrombotic iliofemoral venous
      obstruction and evaluate the effect of PTA & stenting with possible identification of a
      predictive parameter for success of treatment.

      Study design: Prospective, observational study (healthy and diseased limb in one patient).

      Study population: Patients with an iliofemoral venous obstruction, objectified on duplex
      ultrasonography and magnetic resonance venography, and the indication for stenting of the
      obstructed tract(s).

      Intervention: All patients will undergo stenting of the obstructed venous tract. Patients
      receive the same therapy as they would have received not participating in this study;
      therefore this study has no influence on the treatment patients receive.

      Main study parameters/endpoints: Primary outcome is the change in (ambulatory) venous
      pressure after stenting for deep venous obstructive disease. Other important endpoints are
      the absolute values for intravenous pressure, pain free walking distance and maximum walking
      distance. Additional outcome measurements are stent patency, CEAP score, Villalta score,
      venous clinical severity score, and generic and disease specific quality of life scores.
      Finally, transverse surface area, diameter and circumference of the common femoral vein will
      be measured.

      Nature and extent of the burden and risks associated with participation, benefit and group
      relatedness: Patients have to make three visits. Each visit will take approximately two
      hours. During each test day, patients will undergo intravenous pressure measurements in both
      dorsal foot veins, both common femoral veins and a vein in the left upper arm, which are
      measured via a venflon needle or microsheath (placed under ultrasound guidance) connected to
      a pressure transducer; a treadmill test lasting maximally 26 minutes; an air plethysmography,
      which they need to undergo anyway; and a duplex ultrasound to assess the common femoral vein.
      This is a very low risk study, since all diagnostic tools that are used or also used in usual
      clinical practice and given the low risk on mild complications. Patients can experience pain
      due to the insertion and removal of the venflons/microsheaths, due to compression of the
      groin after removal of the microsheaths and due to walking on a treadmill (because of venous
      claudication).

      Amendment:

      iv in the arm vein as a control is not performed anymore. An abdominbal wall collateral is
      cannulated instead, if present.
    

Intervention name(s): PTA & stenting
Intervention type(s): Procedure
Intervention description(s): PTA & stenting of the iliac veins and/or common femoral vein. Patients who need to undergo endophlebectomy of the common femoral vein with AV-fistula creation are also included.
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Patients at our specialized venous outpatient clinic in our tertiary centre
      
Biospecimen description: 
      Blood samples for possible future research