**1. Introduction**

The term chronic venous disease (CVD) has been used to describe morphological and functional abnormalities of the venous system of extended duration that are manifested themselves by symptoms and/or signs that indicate the need for evaluation and care by health professionals [1].

Usually, symptoms of leg heaviness, fatigue, and pain are the first complaints referred by patients, which together with varicose veins are present both in mild and severe cases of CVD. These complaints combined with structural changes in superficial, visible veins strongly contribute to a negative self-esteem that also characterizes this disease [2–8]. The diminished health-related quality of life (HRQL) seen in CVD is well studied [2, 8–10]. This negative impact is so important that the previous view of this condition as an aesthetic problem has been abandoned for years.

The socioeconomic burden of CVD is very high. The indirect costs are substantial and are associated with the symptoms, functional impairment, emotional disturbances and negative impact in HRQL [11]. The direct costs of CVD treatment are almost entirely related to its high prevalence, morbidity, and chronicity [11, 12]. In developed countries, around 1–3% of the health costs are due to CVD [13]. However, when patients with less severe stages of the disease are diagnosed and treated early, the physiopathology course of the disease can be prevented or even receded [14].

The severity of CVD is nowadays evaluated based on a multifactorial concept of the disease and using the standardized CEAP (Clinical Etiological, Anatomical and Pathological) classification system. Having a good knowledge of this system is very important to all physical therapist and it is important that health professionals use the same nomenclature so that CVD severity can be accurately assessed and the best treatment delivered [15].

The treatment of patients with CVD might focus on both the symptoms and secondary changes of the disease, such as edema, skin and subcutaneous changes or ulcers. Usually, initial treatment of CVD patients involves a non-invasive, conservative treatment to reduce symptoms, treat secondary changes, and help prevent the development of secondary complications and the progression of the disease. Complementary, some interventional or surgical treatments can be undertaken [15].

Manual lymphatic drainage (MLD) is a low-pressure form of skin-stretching massage, described as a conservative treatment for CVD [16] and as a coadjutant of other treatments, like stockings and surgery [17, 18]. This technique has been proposed for the treatment of venous lymphedema associated to CVD [19, 20], before CVD surgery, or to relief symptoms [17, 18, 21]. It is suggested by the literature that this physical therapy technique should be applied taking into account venous anatomy and that it should increase deep and venous flow [22, 23]. Despite controversial evidence regarding the ability of MLD to reduce edema or lymphedema, this technique when associated with other treatments, the so-called "lymphatic decongestive therapy", that also includes compression, exercise, and education, may have an important role for improving health and functional status in patients with edema associated to sport injury or related to breast cancer surgery, just to mention two common situations [21, 24–26].

This chapter will address the role of physical therapists in the management of CVD. The chapter will begin by reviewing the basic physiopathology of CVD, including the role of calf muscle pump. The CEAP classification system and the chronic venous severity score will be presented, as these are main tools for clinical assessment of CVD severity. In the remainder of the chapter, we will address the physiological effects of MLD on venous circulation and the recommendations for its use in treating CVD.
