Treatment of venous obstruction

Abstract

Leg ulcer due to chronic venous insufficiency (CVI) is known to have several contributing pathophysiological factors. In the macrocirculation, the role of incompetent valves in the deep or superficial system has been emphasized and treatment has been directed largely towards correction of reflux. Although well recognized, other aspects, e.g. obstruction to the outflow, a poor calf muscle pump, low compliance and geometrical changes of the flow channels, have for the most part been ignored. An obstructive component has been shown to be predominant in approximately one-third of post-thrombotic limbs. Reflux is found to be combined with obstruction in 55 percent of symptomatic patients with CVI.1,2 This combination of reflux and obstruction is most detrimental. It leads to the highest levels of venous hypertension and the most severe symptoms, including development of leg ulcer, as compared with either alone.3,4 Because of diagnostic difficulties and lack of appropriate surgical interventions, however, the treatment of outflow obstruction has been neglected throughout the years. Open surgery has been unattractive because the operation is rather extensive and often combined with a temporary or permanent arteriovenous fistula; it always necessitates lifelong anticoagulation postoperatively; and it has uncertain long-term patency. Therefore, venous bypass surgery has been restricted to a minority of patients with severe disabling symptoms and markedly increased venous pressure levels. Endovascular treatment of venous outflow obstruction with venous balloon angioplasty and stent insertion was introduced in the mid-1990s. Since that time, interest has refocused on the role of venous outflow obstruction in patients with chronic venous insufficiency and leg ulcers. Balloon dilation andstenting of the iliac vein has now largely replaced bypass surgery and the mid-term results indicate that the procedure is a safe and efficient alternative for a larger group of patients. Venous stenting has also led to a renewed interest in the nature and pathophysiology of venous obstruction per se, and in tests for detection of hemodynamically significant lesions. There is cautious optimism that iliac venous stent placement will be a useful modality in the management of patients with CVI and leg ulcer in the future. Several issues regarding diagnosis, indication for treatment and methods of outcome assessment, however, remain unresolved.