1. Lackawanna College Vascular Technology Program
Venous Hemodynamics
Lackawanna College
Vascular Technology Program

2. Special Function of Veins
Capable of constricting and enlarging, storing small or large quantities of blood, making blood available when necessary
Venous pump
Regulating cardiac output

3. Right Atrial Pressure
Blood from all systems flows into the right atrium (Central Venous Pressure)‏
Right atrial pressure is regulated by:
the ability of the heart to pump blood out of the right atrium
the tendency of blood to flow from the peripheral vessels into the right atrium

4. Elevated Right Atrial Pressure
Weakness of the heart
Any effect that causes rapid inflow on blood
increased blood volume
increased large vessel tone
dilatation of the arterioles
Increased blood volume will increase venous return, overloading the right atrium.
Increased large vessel tone througout the body will increase peripheral venous pressures.
Dilatation of the arterioles, which decreases the peripheral resistance and allows a rapid flow of blood from the arteries to the veins.

5. Cardiac Output The amount of blood pumped by the heart depends on:
the ability of the heart to pump
the tendency of blood to flow into the heart from the peripheral vessels

6. Flow patterns and venous resistance
Cardiac influence
Venous pressure and flow are affected by cardiac activity
This effect is most pronounced in the thoracic vessels.
Cardiac influence is usually not apparent or is reduced in the lower extremities
Cardiac pulsatility

7. Flow patterns and venous resistance in lower extremities
Respiratory variation
During inspiration, diaphragm moves downward and increases intra-abdominal pressure.
IVC is compressed and venous outflow is temporarily reduced or stopped.
Flow resumes during exhalation.

8. Respiratory variation and cardiac pulsatility are sometimes seen in the same flow sample

9. Flow patterns in upper extremities- central veins
Cardiac pulsatility is usually apparent and pronounced.
Respiratory variation occurs, but flow during inspiration INCREASES, due to changes in thoracic pressure.
Subclavian vein

10. Pulsatile flow due to congestive heart failure

11. Venous Resistance Very little muscle tone, easily collapsible
The only thing to keep them open is transmural pressure
Extrinsic compression will collapse vein

12. Venous Hemodynamics Venous Valves Hydrostatic Pressure Respiration
Calf Muscle Pump

13. Venous Hemodynamics
How does blood get back
to the heart ??

14. Hydrostatic pressure arterial pressure gravity & gravity Venous flow V
The pressure in an artery and vein when standing is high due to hydrostatic pressure. This venous flow has a long uphill battle to get back to the heart, against the effect of gravity.
Venous flow
distal capillary bed

15. Capillary bed perfusion is dependent on a pressure gradient
Low pressure in
venules
High pressure in
arterioles

16. Hydrostatic pressure, affect on lower veins:
 transmural venous pressure distally
venous distention
venous pooling
 in capillary perfusion
 in venous return
 in cardiac output
Click to next slide
If you stand in one place for too long
without moving……

17. Hypotension !

18. We need a Pump!

19. Calf Muscle Pump
With exercise (i.e., walking), the calf muscle will contract, forcing blood out of the sinuses in the calf muscle
Blood will move towards the heart

20. Calf Veno-motor Pump semilunar valves are abundant in calf
abundant veins in calf: PTV’s, Peroneals, ATV’s, Gastrocs, Soleal sinuses, Greater & Lesser Saphenous, Perforators
abundant skeletal muscles

21. Venous Valves
Arranged so that the only direction blood can move is towards the heart
Combined with the calf muscle pump, a walking adult will maintain venous pressure at feet of about 25 mmHg

22. Normal Valve

23. Hydrostatic Pressure Weight of the column of blood When standing:
right atrial pressure = 0 mmHg
ankle pressure= 90 mmHg
Will move proximally as pressure rises

24. Incompetent valve- popliteal vein

25. Varicose Veins
Elongated, dilated, tortuous superficial veins that are usually incompetent
Deep veins are surrounded and supported by muscle

26. Varicose Veins Primary Secondary
Congenital, inherent weakness of walls
May become prominent following pregnancy
No abnormality of deep veins
Secondary
DVT
Absence of deep venous valves
Congenital absence or atresia of deep veins

27. Valvular Incompetence
Congenital absence of valves
When veins enlarge as in pregnancy and when collaterals enlarge (increased volume)‏
Secondary to DVT

28. Venous insufficiency symptoms
recurrent swelling
varicose veins
venous claudication
stasis dermatitis
ulceration

29. Varicosities

30. Stasis Dermatitis

31. Venous ulceration etiology (theory)‏
1. Chronic increase in intraluminal pressure.
2. Increased vein wall permeability, plasma and fibrinogen leak out into surrounding tissue.
3. Fibrinogen converts to fibrin.
4. Barrier formation between capillaries and tissue,
results in a decrease of O2 and nutrient delivery.
5. Subcutaneous bacteria invasion

32. Venous Ulcerations

33. Normal Venous Flow Spontaneous Phasic Augmentation Competent
Proximal compression
Distal compression
Competent
Non-pulsatile

34. Spontaneous Flow Blood should be flowing consistently in all veins
Spontaneity may be absent in the most distal veins (i.e., posterior tibial at ankle) due to decreased speed of blood
Absence of spontaneous flow may indicate obstruction

35. Phasicity of Flow
Should recognize a respiratory component to blood flow
Decrease with inspiration (lower opposite upper)
Increase with expiration (lower opposite upper )
Absence of phasic flow (continuous flow) indicates proximal obstruction
Thrombus
Extrinsic Compression

36. Normal
Spontaneous Phasic Flow
Respiration

37. Normal Spontaneous Phasic Flow
Abnormal
Continuous Waveform CFV
No respiration variant

38. Augmentation Proximal Compression Distal Compression Valsalva Maneuver
Flow should cease with proximal compression
Upon release, significant increase in flow should be noted
Flow during proximal augmentation indicates valve insufficiency
Valsalva Maneuver
contraindications
Distal Compression
Large increase in venous flow should be encountered
Increase should be immediate
Decreased augmentation may indicate DISTAL obstruction

39. Proximal Augmentation – cease flow
Normal response
Release

40. Normal response
Abnormal – valve incompetence

41. Distal Augmentation
Distal Squeeze
Distal Squeeze

42. Squeezing the calf forces blood flow to the upper leg– we see this in the doppler as augmentation

43. Competence Flow should always be toward heart
Proximal compression or Valsalva maneuver (VM), flow will cease in veins
When abnormal, flow will be retrograde (reflux) during compression or VM, indicating incompetent valve

44. Pulsatility
Since there is no pulsatile “venous heart” other than the calf muscle, no pulsation should be noted in venous flow
When pulsatile venous is encountered, it is a good indication of right heart compromise (i.e., CHF)‏

45. Normal Spontaneous, Phasic,
Non-Pulsatile Flow
Note: pulsatility in both legs may indicate right side heart disease.
One leg may indicate A-V Fistula
Abnormal
Pulsatile Flow