Page 86 - Medicine and Surgery

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82 Chapter 2: Cardiovascular system

Venous stasis: Immobility, obesity, pregnancy, paraly- Prophylactic low molecular weight heparin should be

sis, operation and trauma. givento patients with immobility due to cardiac failure,
Intimal damage: Trauma to a vein, e.g. after a hip op- or surgery to the abdomen, leg or pelvis.

eration, can provide a starting point for thrombosis.
Thrombophilia:FactorVLeiden,antithrombinIIIde- Prognosis

ficiency, protein C and protein S deficiency (see page Destruction of deep vein valves occurs in half of patients,
496),drugsincludingthecombinedoralcontraceptive with the development of chronic venous insufficiency.
pill.
Other risk factors include increasing age, malignant dis-
ease, varicose veins and smoking. Varicose veins
Definition
Pathophysiology Distended and dilated lower limb superficial veins as-
The starting point for thrombosis is usually a valve sinus sociated with incompetent valves within the perforating
in the deep veins of the calf, primary thrombus adheres veins.
and grows until flow is occluded. Secondary thrombus
forms which then progresses proximally. Incidence
Common
Clinical features
The condition is often silent and pulmonary embolism Age
may be the first sign. Calf pain with swelling, tender- Increases with age.
ness, redness and engorged superficial veins are com-
mon. Clinical examination alone is unreliable for diag- Sex
nosis. 5F:1M

Aetiology
Complications
Incompetent valves in perforating veins between the su-
Pulmonary embolism is a serious complication and may
perficial and deep venous systems lead to reflux of blood
be life-threatening, particularly when the embolus is
from the deep system. This results in distension and tor-
large, e.g. when it arises from the iliofemoral segment.
tuosity of the superficial veins. Familial predisposition,
obesity, pregnancy and prolonged standing are estab-
Investigations lished aetiological factors.
Ultrasound or Doppler ultrasound scans can be used to
confirm the diagnosis; below-knee thromboses cannot
Pathophysiology
be easily seen and may only be diagnosed with venogra-
Primary varicose veins are common and show a fa-
phy. Alternatively, in patients with a low clinical risk for
milial tendency, which may either be due to intrinsic
deepveinthrombosismaybescreenedusingtheD-dimer
valve incompetence or loss of elasticity in the veins.
test. If the D-dimer is normal no further investigation is
Secondary varicose veins develop after valve function
required.
has been disrupted by either disease (thrombosis) or
occasionally trauma. The valves in the perforating
Management veins are disrupted, so that blood refluxes from the
Bedrestandcompressionstockings;patientswithabove- deep veins to the superficial veins.
kneethrombosesshouldbeinitiallyanti-coagulatedwith Impaired venous return ‘chronic venous insufficiency’,
low-molecular-weight heparin and then converted to leads to lower limb oedema, fibrosis around the small
warfarin for 3 months with the INR maintained between capillaries and veins, skin changes of eczema and ulcer-
2 and 3. Thrombolytic therapy is occasionally used for ation. These changes are referred to as lipodermatoscle-
patients with a large iliofemoral thrombosis. rosis.