Varicose veins usually occur in the superficial veins due to failure of venous valve system (which protects the superficial veins from high pressure of the deep vein system). The convenience of Duplex Ultrasonography for Varicose veins has driven down the demand and importance of Physiologic testing.  Some physiologic tests for varicose veins are Maximal venous outflow(MVO), Venous refill time(VRT), and Calf Muscle pump Ejection fraction(MPEF).
Venous Refill Time(VRT): It is the time taken by the blood to completely fill up the leg after it has been thoroughly emptied by the calf muscle pump. In a limb with a normal venous valve system, it is filled by the arterial system alone and takes up to 2 minutes. However, if the venous valves are incompetent, the blood leaks back and the filling time is much shorter. It is 40 seconds to 120 seconds long in people with mild/asymptomatic cases. In patients with significant valvular incompetence, it can be as short as 20-40 seconds.
Maximal Venous Outflow(MVO): In this test, we measure the maximum venous blood flow immediately after releasing a tied up tourniquet on the limb that is maximally congested. The downside of this test is that it is not very sensitive and works only when there is significant venous obstruction. Hence, even a normal test result would not rule out partial obstruction or venous incompetence.
Calf Muscle Pump Ejection Fraction(MPEF): The patient is told to do 10-20 dorsiflexions of the ankle joint of the limb undergoing testing while some physical parameter is used to track calf muscle blood volume. Normally, this would completely empty the calf venous capacitance circuit. However, in patients with severe venous incompetence, this would barely make any difference.
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Deep vein thrombosis differential diagnosis
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Peripheral arterial disease other imaging findings
Deep vein thrombosis other imaging findings
Varicose veins causes