Venous Outflow Obstruction In Advanced Chronic Venous Disease Biology Essay

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Despite the diversity of signs and symptoms associated with chronic venous disease (CVD), it seems likely that all are related to venous hypertension, which was attributed mainly to reflux through incompetent valves. (1, 2) However, the pathophysiology of CVD is complex, and many aspects, such as venous outflow obstruction and poor calf muscle pump have largely been ignored because of lack of means to properly evaluate these components and their specific contribution to the disease. (3)

The Neglen and Raju's series of lower limb CVD patients having their proximal venous outflow assessed using intravascular ultrasound (IVUS), left little doubt that venous obstruction, regardless its aetiology, is more prevalent than previously thought and that it appears to have an important role in clinical expression of CVD which is easily overlooked, mainly because of diagnostic difficulty. (4-6) Furthermore, the gratifying clinical results and improvement of quality of life after treating those lesions by venous stenting alone, proves that venous outflow obstruction by itself is really an underestimated major contributor to CVD even when associated deep venous reflux was left untreated. (7, 8)

Unfortunately, the obstructive component remains poorly investigated in clinical practice today since the main tool for evaluation of CVD is an infrainguinal duplex ultrasound scan (DUS) by which the pelvic outflow veins are neither properly evaluated, requiring expertise especially in obese patients, nor routinely investigated. Moreover, the complexity of venous lesions and the absence of strict duplex criteria for determining clinically or hemodynamically significant vein stenosis have made its evaluation even harder.(9) Also, ascending venography images were diagnostic in only 65% of obstructed limbs. (4, 10) While accuracy now can be improved by using digital subtraction imaging, multiple oblique projections and pressure injectors, IVUS (the most accurate morphological test) remained superior to single- and multiplane venography in detection of the extent and type of morphologic lesion of veins.(6, 11-13)

However, the utility of IVUS as a diagnostic tool is flawed by some drawbacks. Being invasive and very expensive limit its routine use for diagnosis. Besides being only suitable for evaluation of large-sized vessels means that data about infrainguinal veins will be lacking if used as a sole investigative tool. Therefore, although an important intraoperative tool, it has no place in preoperative planning and selection of patients.

The use of multi-detector computed tomography (MDCT) for visualization of the venous system seems appealing due to its capability of providing high quality 3D images depicting the entire length of the venous system. Also being minimally invasive, fast and easy to perform with high spatial resolution of images makes the technique valuable for preoperative mapping. Using direct approach by injection of contrast directly into a pedal vein will greatly increase contrast enhancement in the veins which in addition to using multiplanar reconstructions, maximum intensity projections and volume-rendered images will hopefully result in even more clear CT venographic images than indirect method injecting into an arm vein.

Management of chronic venous disease has made significant advances in the past three decades. The availability of successful new treatment modalities including venous stenting explains the growing demand for reliable diagnostic techniques capable of answering key clinical questions. The utilization of diverse venous investigations, including duplex, venography and IVUS uncovers a lot more venous pathology than anyone ever estimated.

Finally, since the combination of an undiagnosed venous obstruction together with the presence of reflux was more frequently seen in patients with severe CVD(C4-6 by CEAP classification) (3), the purpose of this study is to evaluate the combined use of ultrasound flow measurements with direct-MDCT venography in detection of venous outflow obstruction in this group of patients with advanced CVD.

AIM OF THE WORK

The purpose of this study is to evaluate the combined use of ultrasound flow measurements with direct-MDCT venography in detection of venous outflow obstruction in patients with advanced CVD.

PATIENTS

Subjects:

Thirty patients presenting to the vascular surgery clinic in Alexandria Main University Hospital, Faculty of Medicine, University of Alexandria fitting the following inclusion criteria will take part in the study.

having advanced manifestations of CVD including pigmentation and/or active or healed venous ulceration (CEAP: Clinical classes C4-C6) will be included in the study.

Exclusion criteria:

CEAP: C0-C3

Morbid obesity (BMI ≥40)

Known allergy to iodinated contrast material

Advanced systemic medical disease

Renal impairment (serum creatinine ≥1.2 mg/dl)

Lower limb ischemia (ABI ≤0.9)

Recent acute venous thromboembolism within 3 months

METHODS

SHEET

Personal data:

History: C/O pain/oedema/ulceration/bleeding/STP

Allergy, Disease (renal impairment/ DVT/ Previous ulcer), Treatment (Compression stocking or compression bandage, compliant or not) (Surgery) (Sclero)

Interventions:

Color Duplex examination (CDI):

Formal CDI in the Radiology department will be done to all patients according to the UIP Consensus Document.(14) After completion of formal examination, a proposed technique for examination will be carried out as follows:

Patient lies supine.

Recording the venous flow wave pattern in the common femoral vein (CFV) just above the sapheno- femoral junction (SFJ) in both limbs in the supine position.

Flow volume in the common femoral vein (CFV) just above the sapheno- femoral junction (SFJ) is measured in both limbs in the supine position in ml/min.

Leg elevation 45 degrees and slight external rotation of hip joint for each limb will be done for 10 seconds while maintaining the Doppler probe in place.

Repeat the measurements for both limbs in the elevated position in ml/min.

Any difference in wave pattern between both limbs should be followed by thorough examination by duplex for the possibility of presence of proximal stenosis/obstruction.

Direct multi-slice computed tomography (MSCT) scan using bilateral pedal punctures for injection of contrast will be done for confirmation of presence of obstructive lesions.

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