Chapter 19: Vein Mapping Lecture

Generally, most surgeons will not use a vein with a diameter less than ______ mm.

• less than 2 mm • Most prefer vein diameter of 2.5 to 3 mm - Smaller veins may be prone to spasm and are difficult to suture

Perforating veins

- A vein that perforates the muscular fascia and connects the superficial system to the deep system - Must always be identified and ligated - Have valves to ensure one-way flow (superficial to deep) • Arteriovenous fistula can be created if not ligated

Reasons not to use saphenous veins

- Absent - previously used as a graft, or stripped - DVT's - Unusable due to thrombophlebitis or varices - Not long enough for required bypass

Large tributaries of the great saphenous vein (GSV) include

- Anterior accessory GSV - Posterior accessory GSV - These are often involved in the different configuration

Variations in calf are less common and include

- Anterior dominant GSV - Posterior dominant GSV - Double system

GSV: Main trunk of saphenous vein lies in saphenous compartment

- Bounded by saphenous fascia superficially and muscular fascia deeply

Varicosities

- Dilated, tortuous portions of the saphenous system - Varicosities may be in subdermal branches with main saphenous trunk spared • Main saphenous can still be used as conduit; however, varicose segments should not be used - Segments of the vein may be suitable; always important to examine entire length of limb to find any suitable segments

GSV: When duplication is present, one system may be larger

- Dominant vessel is important to note for proper selection for surgery - always want to use the dominant vessel

Diagnosis: normal/healthy vein should have:

- Have smooth, thin walls - Be compliant and easily compressible - Have freely moving valve leaflets

Calcification

- Not as common as in arterial walls; often occurs in diabetic patients - Presents as bright echoes within the vein wall producing acoustic shadowing - If isolated, vein may still be used as conduit -Diffuse, intermittent calcification renders vein inadequate

Valve abnormalities: stenotic or frozen value

- Often encountered in vein that was previously thrombosed - If isolated, healthy vein segment can still be used

Interpretation of Saphenous vein mapping should include:

- Patency - Diameter - Branching - Anatomic variants • Measure the diameter of any double system • Measure at any point where a change in the vein size occurs • Compress the vein throughout its course to ensure there is no thrombosis

Recanalization

- Presents as irregular intimal surface or wall thickening - Usually not considered adequate for use as conduit

Thrombus in superficial veins

- Segmental thrombus may be encountered in superficial veins - Usually visualized adjacent to valve leaflets - Vein will be incompressible or partially compressible with echogenic material within the lumen - Doppler signals will also be altered - Thrombosed segments should be noted

GSV system has multiple cutaneous tributaries

- Usually ligated in open procedure is used - Usually spontaneously thrombose if in situ procedure is performed - May be harvested for vein patch

What information is gathered about the superficial veins for vein mapping?

- Vein patency - Position - Depth - Size - Length

Vein mapping not only provides information about presence or absence of vein but also information about the suitability of vein for use as a conduit:

- Wallstatus - Planar arrangement - Diameter

Vein of Giacomini

-Communicating vein between the GSV and the SSV -Courses the posterior thigh as either a truck projection of a tributary of the SSV

At which distance should marks be placed along the length of the vein when marking?

2 to 3 in

Small Saphenous with Thrombus

From the popliteal junction, follow the SS down the posterior surface of the calf until it passes between the lateral malleolus and the Achilles tendon

Strategies for Successful Vein Mapping

Maximize venous pressure Keep the patient warm Use light transducer pressure Use gel sparingly ti facilitate marking on skin Keep transducer perpendicular to skin surface

T/F: Complex variations can occur but are rare

True

T/F: Plantar arrangement should be noted

True

Conduit

a pipe or channel through which something passes

Vein mapping allows for...

selection of optimal vein, can alter planned surgery and surgical approach, and minimize amount of surgical dissection

Antecubital fossa

the triangular cavity on the anterior section of the arm opposite the elbow

Anatomy Cephalic and Basilic Veins

• Can be mapped for bypass; however, more common to evaluate as part of preoperative assessment for creation of dialysis fistula • Cephalic begins at wrist, courses along radius, and into upper arm; terminates into the subclavian vein • Basilic begins at wrist, courses along ulna, and into upper arm; terminates into the brachial vein to form the axillary vein • Variation occurs in branching patterns at the antecubital fossa

Anatomy of great saphenous vein

• Five common figurations -Single trunk medially in thigh with several large tributaries - Single trunk that courses anterolaterally in the thigh - Various degrees of duplication and communication - Closed loop system in thigh - Partial double system

Anatomy Small Saphenous Vein

• Has fairly consistent pattern through calf • Typically a single trunk which courses through the middle posterior aspect of calf • Terminates in the popliteal vein - In about 20% of patients, continues above popliteal fossa (cranial extension of the small saphenous vein) - Can terminate directly into the femoral vein or inferior gluteal vein, or can communicate with GSV • Also have cutaneous tributaries as well as perforating veins

Scanning Technique - Great Saphenous Vein

• Mapping begins at the groin • Very light pressure should be used so as not to compress the vessel • Vein can be followed in transverse or longitudinal - Transducer should be perpendicular to skin to ensure vein is not being imaged obliquely • In long, vein should fill screen from right to left • In transverse, vein should appear circular and centered on screen

A few words about marking on skin....

• Nonsterile probe cover should be used to keep marker/ink off of transducer face • Use limited amounts of gel (easier to mark through and keeps patient from cooling off too much) • Mark in front of the transducer where gel is not as abundant • Alternatives to markers include coffee stirrers, straws, and pen caps that can indent the skin - Final map is then drawn with permanent marker, surgical markers, or permanent liquid ink

Patient Preparation

• Patient should avoid body lotions or powders if skin marking is to be performed • Otherwise, prep is similar to other extremity venous exams

Scanning Technique - Small Saphenous Vein

• Same techniques are used for the small saphenous • Identify at confluence with popliteal vein fists • Follow and map to the lower calf • May need to follow cranial extension if present • Small saphenous artery (SSA) is usually smaller and more superficial, making it more difficult to evaluate • Vein diameters should be recorded in the proximal, mid, and distal calf

Scanning Technique - Saphenous Vein Mapping

• The great and small saphenous veins are the veins of choice for a bypass graft

Scanning Technique - Cephalic and Basilic Veins

• Usually easiest to identify in the upper arm • Basilic vein can be followed from its termination into the brachial vein - Then followed to ulnar aspect of wrist • Cephalic vein is easiest to follow in the upper arm over the biceps muscle - Then followed to its termination into the subclavian vein - Mapped back down through the arm to the radial side of the wrist

Be Sure to Image What You See...

• Vein is mapped along the entire length of the vessel • Noting larger branches and double systems • Vein will course posteromedially in the mid to distal thigh - more medially along side the knee • From the knee, the GSV is followed near the tibia to the level of the medial malleolus • The SSV is followed posteriorly from the pop fossa to the ankle

Patient Position

• Venous pressure should be maximized by placing limb in a dependent position - Reverse Trendelenburg for legs, with hip externally rotated and knee slightly flexed - For arms, arm can be extended to the side and slightly lower than chest level • Examine room should be warm • Only expose limb being evaluated