Systolic ShuntsSignificance and diagnosis method

Stefano Ermini

What is a Systolic Shunt?

It is a centripetal NON physiologic flow whose origin passes from a deeper network to a superficial one during muscle systole.

Note: only the gradient created by a muscle contraction can evoke a centripetal systolic flow. This means that these situations are not visible using the squeezing test.

N1N2 N1N3

This flow originates as a result of an increased resistance in the deep vein system

This increased resistance can be due to :1. A functional stenosis (e.g small

caliber of the superficial femoral vein or muscular compression during contraction)

2. A post-thrombotic syndrome

GSV

SSV

Giacomini

Deep Veins

Thrombosis

How to distinguish these 2 different situations

1. By shunt and DUS analysis of superficial and deep vein flow at the thigh level

2. By analysis of the popliteal flow during muscle contraction and relaxation

3. By shunt manual maneuvers

Systolic Vicarious shunt(Compensative circle)

Its function is to by-pass a deep anatomical stenosis/obstruction

It originates from a calf perforator, at the popliteal vein area, or at the thigh level.

The flow through this perforator reaches a superficial trunk, gives origin to a centripetal flow and re-enters into the deep system above the occlusion.

In the perforator the flow moves in a non physiologic way (reflux).

Hemodynamic characteristics of a Systolic Vicarious Shunt :

At the perforator level, the flow also originates during a small movement and continues after the muscle contraction is finished.

The flow during diastole can persist or not in relation to the gravity of venous hypertension.

DUS assessment of the deep system above the refluxing perforator shows the absence of flow or a stenosis

Systolic Vicarious shunt(Compensative circle)

The manual compression of the superficial trunk involved in this vicious recirculation stops the flow in the deep vein below the shunt origin

Thrombosis

Thrombosis

Compression

STOP FLOW

Systolic derivative shuntThis shunt often appears in the popliteal fossa where a centripeal flow originates in the Giacomini Vein through the SPJ or a popliteal perforator

Systolic derivative shunt2 situations are possible:• The flow from the Giacomini Vein re-enters into the

deep system through a Giacomini perforator or through the SFJ

• The flow also feeds a varicose vein whose re-entry perforator is placed below the escape point.

Re-entry point

Escape point

Re-entry point

Escape point

Systolic derivative shuntSystolic flow: It only appears during the muscle contraction and stops when the muscle relaxesThe manual compression of the superficial trunk does not stop the deep vein flow below the shunt origin.Note: the systolic flow only has a centripetal direction

>ResistanceCompression

PERSISTING FLOW

>Resistance

Systolic derivative shuntDiastolic flowIt only appears when the Giacomini Vein feeds a varicose vein whose re-entry point is placed below the escape point.

This flow is due to the pseudo-siphon effect

Re-entry point

Escape point

The siphon effect explains the presence of a relaxation centripetal flow in the Giacomini v.The siphon effect occurs when a tube in an inverted U shape causes a liquid to flow upwards first and pass above the surface level of the reservoir and continuously flow down without pumps , powered by the fall of the liquid as it flows down the tube under the pull of gravity, and discharges at a level lower than the surface of the reservoir it comes from ( http://en.wikipedia.org/wiki/Siphon ) .The real siphon effect works in a open circuit. In the venous system the circuit is closed and the effect of gravity’s potential energy is charged by muscle pump activity.

Tank A

Tank B

The Siphon Effect

Tank A

Tank B

Systolic derivative shuntThe manual compression of the varicose vein origin stops the diastolic flow in the Giacomini Vein

Re-entry point

Escape point

Compression

STOP FLOW

Therapeutic considerationsSystolic vicarious shunt:This situation must be correctly diagnosed and the role of the visible varicose veins clarified (absence of diastolic centrifugal flow)The role of the refluxing perforator is not pathogenic, as it is the origin of a compensative circle and must not be treated even if the flow has a non-physiological direction.

Foto di lella cartella clinica e schema vene

The GSV trunk has a fundamental function in a systolic vicarious shunt even if incompetent, because the flow has a centripetal direction thanks to a pressure gradient, and is independent from the valve function.This fact must be considered every time GSV trunk avulsion is planned.

Therapeutic considerationsSystolic derivative shunts:

A systolic derivative shunt is fed by an escape point that refluxes during muscle systole.This means that the outward flow is pushed by the muscle systolic pressure.Note that a diastolic escape point refluxes thanks to a gravitational aspirative gradient.

The high pressure in a systolic escape point is responsible for a high frequency of recurrences if treated.The treatment strategy of systolic derivative shunts gives better results preserving the systolic flow without interrupting the escape point and treating the diastolic shunt alone.

Therapeutic considerationsSystolic derivative shunts: