Upper Extremity Vein Mapping - Upper Arm Vascular Anatomy, Ultrasound Types, and Vein Mapping Procedure

Introduction

Patients with chronic kidney disease require frequent hemodialysis. Vascular access is important for hemodialysis due to its link with morbidity. The vascular access is monitored throughout to look for thrombosis or failure in maturation.

What Is the Arterial and Vein Anatomy of the Upper Arm?

Arterial Anatomy: Vascularization is dependent on the subclavian artery which is a branch of the aorta on the right side.

1. Subclavian artery.

• The artery is shorter on the right side.

• It is a difficult artery to scan due to a shadow by the clavicle.

• Therefore, the whole trajectory of the artery cannot be analyzed except for thin patients.

2. Axillary artery.

• It is a short artery.

• The trajectory of the artery can be visualized clearly from the lower border of the clavicle.

3. Brachial artery.

• It is a longer artery compared to other arteries in the arm.

• The artery extends along the entire length of the arm's inner face.

• The artery can be visualized by placing the arm at 45-degree angulation.

• The artery bifurcates into radial and ulnar artery at antecubital fossa.

4. Radial artery.

• The artery is placed in a superficial position.

• The trajectory of the artery can be visualized.

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• The artery originates from the brachial artery and runs its course from the arm to the wrist.

5. Ulnar artery.

• It is a terminal branch of the branchial artery.

• The initial course of the artery runs deep in the tissues whereas, the latter course is superficial.

6. Palmar arch.

• The anastomosis of radial and ulnar arteries is called a palmar arch.

• The palmar arch is of two types,

1. The deep palmar arch is dependent on the anastomosis between the radial or ulnar artery.

2. The superficial arch in the tributary of the ulnar anastomosis with radial artery.

Arterial mapping is achieved by placing the probe in the transverse plane. The short axis is used to explore arterial diameters.

Venous Anatomy

The venous drainage of the upper arm is superficial and deep.

1. The deep venous system is located along with arteries. The radial, ulnar, brachial, axillary, and subclavian veins form the deep venous system.

2. The superficial venous system is preferred for vascular access creation. The veins are well formed. The superficial venous system drains from superficial tissue to the deep venous system. The cephalic vein and basilic vein form the superficial venous system.

What Is Upper Extremity Vein Mapping?

Vein mapping is required to evaluate arm veins and arteries for size, length, and patency before dialysis or arterial bypass surgery. Ultrasound imaging with the use of Doppler ultrasound is used for mapping and is a safe procedure. The mapping can be achieved for arteries and veins. The procedure does not cause radiation exposure or injection of chemicals.

What Are the Types of Ultrasound Used for Upper Vein Mapping?

The ultrasounds used for vein mapping before vascular access implantation are:

1. B-Mode Ultrasound: It provides a two-dimensional grayscale image of vessel anatomy and associated abnormalities.

2. Pulse Wave Doppler: It records velocity over a time curve in veins and arteries. The red blood cell velocities can be analyzed.

3. Color Doppler: The real-time mean velocities of red blood cells are recorded over a colored box.

A gel is used for examination to avoid loss of the examination field due to curvature of the arm.

What Are the Benefits of Ultrasound?

The benefits of ultrasound include:

• Simple.

• Fast.

• Affordable

• Safe.

• Easily available.

• Prevents unsuccessful surgical procedures.

• Prevents morbidity in end-stage renal disease in patients with non-functional arteriovenous fistula.

What Are the Limitations?

The results can vary based on the operator's expertise in Doppler ultrasound.

What Are the Factors to Determine the Diameter and Blood Flow?

• The diameter of arteries varies by 20% during the cardiac cycle.

• Vessel area measurement errors can be 20% for 10mm (millimeter) vessels and an even higher percentage for smaller vessels like the cephalic vein and brachial artery.

• The pulsatile cardiac cycle causes an error of 20% to 100% in volumetric flow.

What Are the Requisites Before Upper Extremity Vein Mapping?

It is important to analyze patients' tolerability to the procedure or the presence of contraindications. The patient's past medical conditions like diabetes and family history must be recorded and must contain:

• Treatment planning for the patient.

• History of deep vein thrombosis.

• Trauma to the upper arm.

• Vein harvesting history.

• Intravenous drug use.

• Details on current medication and treatment procedure.

• Other diagnostic evaluation.

• Swelling, discoloration, or ulceration must be recorded.

What Is the Procedure for Upper Extremity Vein Mapping?

Vein mapping involves the evaluation of arteries, the deep vein system, and the superficial vein system.

• Patients are made to lie in the supine position, sitting, or reverse Trendelenburg to dilate veins. The arms must be relaxed and extended to the side.

• The room must be arm and the arm must be covered until the start of the procedure to prevent vasoconstriction.

• A Doppler ultrasound with a 5 to 7 MHz (megahertz) transducer is used. The superficial structure requires high frequency whereas the deep structure requires low frequency.

• Subclavian and axillary arteries are examined for any signs of central occlusion or anatomical variations. Subclavian artery imaging requires 2 to 5 MHz transducers.

• To analyze the patient’s vein the head must be raised to 45 degrees with arms relaxed.

• After evaluation, a tourniquet is applied on the proximal aspect of the upper arm to block superficial vein flow. However, brachial artery flow remains uninterrupted.

• With the B-mode of ultrasound, the superficial vein of the upper arm is examined for its diameter at the distal third region of the upper arm.

• The procedure is repeated for the brachial artery to record anatomic variations, blood flow, and diameter at the distal third of the upper arm.

• The tourniquet is removed and at the distal third of the upper arm diameter of the dominant superficial vein is measured.

• The upper arm vein mapping is done bilaterally.

What Are the Indications and Contraindications for Upper Extremity Mapping?

Indications

• Assess veins to be used as a coronary artery bypass graft.

• Assess veins and arteries for dialysis.

Contraindications

• Obesity.

• Recent surgery in the area of examination or the presence of intravenous lines, casts, open wounds, or hematoma.

• History of vein harvesting in the same area.

• Patients with severe edema or swelling in the examination area.

• Patients who are unable to remain still during the period of examination.

• Patients suffering from diabetes mellitus have compromised vascular access.

• Medial calcinosis disrupts the maturation of vascular access due to a lack of arterial dilatation.

• Any cause of stenosis like the history of central venous catheters or pacemakers.

Conclusion

Ultrasound is an important tool for kidney patients before vascular access formation. Since vascular access is associated with greater mortality risk it needs constant thrombosis monitoring. The test provides rapid results enabling quick decision-making. The upper extremity vein mapping helps with better patient care.