Venous insufficiency: Difference between revisions
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Normal venous flow is dependent on four factors: | Normal venous flow is dependent on four factors: | ||
* Dynamic Flow: The heart related flow (dynamics/spontaneous flow). | * Dynamic Flow: The heart related flow (dynamics/spontaneous flow). Flow in the arterial system is dependent on the pumping action of the heart and the elasticity and muscular activity of the arteries. In contrast, the veins, except for the major superficial veins, are thin walled with paucity of muscle; are designed for distention; and play an insignificant role in directly facilitating flow. Most of the force of the pulsatile flow produced by the pumping heart is lost as blood flows from the arteries through the vast network of capillaries (one cell layer microvessels where selective permeability allows the exchange of O<sub>2</sub> and nutrients with the tissues). What pulsatile flow filters through (dynamic flow) is of low pressure (15 mmHg). Nevertheless, it is sufficient to produce a significant pressure gradient with the right side of the heart where the venous pressure is zero. | ||
* Phasic Flow: Respiration related factors. | * Phasic Flow: Respiration related factors. | ||
* The muscle pump or the venous pump: | * The muscle pump or the venous pump: |
Revision as of 00:11, 20 January 2009
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Normal Anatomy and Function
- The superficial veins lie in the subcutaneous fatty layer of the body just beneath the skin and superficial to the deep fascia enveloping the body musculature. The principal veins in the legs are the great and lesser saphenous veins and their tributaries; in the arms they are the basilic and cephalic veins and their tributaries.
- The deep veins accompany arteries and bear the same name as the arteries they parallel. It is common in the extremities for there to be two or more veins accompanying a small to medium sized artery.
- The perforating veins penetrate the deep fascia and connect the superficial veins to the deep veins. Those along the inner (medial) side of the lower leg play a major role in the pathogenesis of the postphlebitic leg.
- The intramuscular sinusoidal veins are large, very thin walled, valveless veins within skeletal muscle. They connect directly with the deep veins.
Function
Normal venous flow is dependent on four factors:
- Dynamic Flow: The heart related flow (dynamics/spontaneous flow). Flow in the arterial system is dependent on the pumping action of the heart and the elasticity and muscular activity of the arteries. In contrast, the veins, except for the major superficial veins, are thin walled with paucity of muscle; are designed for distention; and play an insignificant role in directly facilitating flow. Most of the force of the pulsatile flow produced by the pumping heart is lost as blood flows from the arteries through the vast network of capillaries (one cell layer microvessels where selective permeability allows the exchange of O2 and nutrients with the tissues). What pulsatile flow filters through (dynamic flow) is of low pressure (15 mmHg). Nevertheless, it is sufficient to produce a significant pressure gradient with the right side of the heart where the venous pressure is zero.
- Phasic Flow: Respiration related factors.
- The muscle pump or the venous pump:
- The valves
Pathophysiology
Risk Factors
Diagnosis
Signs and Symptoms
Physical Examination
Doppler USG
Differential diagnosis of causes of venous insufficiency
Treatment
Pharmacotherapy
Surgery
Complications
Prevention
References
Additional Resources
See Also
External Links
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