# Guidewire and Catheter Selection

## Guidewire Fundamentals

### Wire Construction

Guidewires are built around a core of stainless steel or nitinol, which determines their stiffness and torque response. Tips come in straight, angled, or J-curved configurations. The outer coating may be hydrophilic (Glidewire-type, which becomes slippery when wet) or non-hydrophilic (standard PTFE coating). Standard diameters include 0.018 inches for micropuncture, 0.035 inches for standard use, and 0.014 inches for coronary and neurovascular applications. Lengths range from 145 cm (standard) to 180 cm (exchange-length) and 260 to 300 cm for catheter exchanges.

### Wire Stiffness

Wire stiffness exists on a spectrum. Soft or floppy-tipped wires such as the Bentson wire are atraumatic for navigation and carry less risk of dissection or perforation. Standard wires like the Rosen and Amplatz provide support for catheter exchanges and device delivery. Stiff wires such as the Amplatz Super Stiff and Lunderquist are used for large device delivery (EVAR, TIPS) and provide maximum support through tortuous anatomy. The transition zone between the floppy tip and the stiff body is a critical design element -- a gradual taper reduces vessel trauma.

### Hydrophilic vs. Non-Hydrophilic Wires

Hydrophilic wires like the Glidewire have a polymer coating that becomes slippery when wet, providing excellent trackability and the ability to navigate tortuous vessels and traverse stenoses. However, they can advance subintimally without resistance, creating a risk of dissection. They must be kept wet to maintain lubricity and are available in angled tip (the most versatile) or straight tip configurations.

Non-hydrophilic wires such as the Bentson and J-wire have a standard PTFE coating that provides more tactile feedback and is safer for initial access and exchanges. The J-tip wire is the gold standard for initial advancement from the access site because its curved tip reduces the risk of subintimal passage.

### Common Wires by Application

| Application | Wire | Diameter | Key Properties |
|-------------|------|----------|----------------|
| Initial access | Cope / V18 micropuncture | 0.018" | Low-profile, atraumatic |
| Diagnostic angiography | Bentson / J-wire | 0.035" | Soft tip, safe advancement |
| Selective catheterization | Angled Glidewire | 0.035" | Hydrophilic, navigates tortuosity |
| Crossing stenoses/CTOs | Stiff Glidewire / CTO wires | 0.035" / 0.018" / 0.014" | Penetrating tip, high pushability |
| Catheter exchanges | Amplatz Super Stiff / Rosen | 0.035" | Maximum support, platform stability |
| TIPS | Colapinto set then Amplatz | 0.035" | Needle wire for parenchymal tract |

For access, a 0.018-inch micropuncture wire (Cope or V18) is standard. Diagnostic angiography typically uses a 0.035-inch Bentson or standard J-wire, while selective catheterization calls for a 0.035-inch angled Glidewire. Crossing stenoses or occlusions may require a 0.035-inch stiff angled Glidewire or 0.018/0.014-inch CTO-specific wires. Catheter exchanges and device delivery use a 0.035-inch Amplatz Super Stiff or Rosen. For TIPS procedures, a Colapinto needle wire set is used initially, followed by an Amplatz Super Stiff.

## Catheter Fundamentals

### Catheter Construction

Catheters are constructed from polyethylene, nylon, polyurethane, or PTFE-lined materials. The French size refers to the outer diameter, where 1 Fr equals 0.33 mm. Common sizes are 4 to 5 Fr for diagnostic work and 5 to 7 Fr for interventional cases. End-hole catheters are used for selective catheterization, while multiple side-hole catheters like the pigtail are designed for power injection and flush aortography. Torque response -- the ability to transmit rotational force from the hub to the tip -- is an important performance characteristic.

### Diagnostic Catheter Shapes

#### Flush Catheters

The pigtail catheter has a curled tip with multiple side holes and is used for flush aortography, ventriculography, and power injection. The Omni Flush is a multi-side-hole catheter with a straight tip used for non-selective abdominal aortography. The Tennis Racquet is a variant of the pigtail designed for arch aortography.

#### Selective Catheters

The Cobra catheter family (C1, C2, C3) features a primary curve with varying lengths, with C1 being the most gentle curve. The C2 is the workhorse for selective catheterization of visceral vessels from a retrograde femoral approach, engaging downward-facing branches such as the renal and mesenteric arteries.

The Simmons catheter family (Sim 1, Sim 2, Sim 3) consists of reverse-curve catheters that require reformation in the aortic arch. Sim 1 has the smallest curve and is used for the subclavian and vertebral arteries. Sim 2 is the most commonly used and works well for the carotid, subclavian, and downward-facing visceral branches approached from a steep angle. Reformation can be accomplished over a wire in the arch or using the descending aorta or iliac bifurcation.

The SOS Omni (Omni Selective) is a reverse-curve catheter that can be reformed in the aorta and is used similarly to the Simmons for visceral vessel catheterization, with easier reformation in some anatomies. The Berenstein has a gently angled tip used for selective catheterization of branches with gentle angles, commonly employed in neurointerventional work. The Mickelson is designed for inferior mesenteric artery and pelvic vessel catheterization. The RIM (renal double curve) is specifically designed for renal artery catheterization from a femoral approach, and the Vertebral (VER) catheter is used for vertebral artery catheterization.

### Interventional Catheters and Microcatheters

Straight and angled catheters serve for over-the-wire exchanges and stent delivery. Guiding catheters and sheaths have a larger lumen to accommodate intervention devices while maintaining access. Microcatheters (2-3 Fr) are used coaxially through a base catheter for superselective catheterization. Examples include the Renegade, Progreat, and Direxion, each with different tip configurations and trackability. These are essential for embolization procedures and tumor vessel catheterization.

## Matching Catheter-Wire Systems to Target Vessels

### Visceral Arteries from Femoral Approach

For the celiac trunk, a Cobra C2, SOS Omni, or Simmons 1 paired with a Glidewire is appropriate. The SMA is usually straightforward using a Cobra C2 or SOS Omni, given its ventral origin and caudal angulation. Renal arteries can be approached with a RIM, Cobra C2, SOS Omni, or Simmons 2 with a Glidewire. The IMA, with its steep caudal angle, is best accessed with a Mickelson or Cobra C1 and Glidewire.

### Supra-Aortic Vessels from Femoral Approach

The brachiocephalic trunk and right common carotid artery are accessed with a Berenstein, Simmons 1, or JB1. The left common carotid artery is reached with a Berenstein, Simmons 1-2, or Vitek catheter. The left subclavian artery is catheterized with a Berenstein or Simmons 1.

### Lower Extremity from Contralateral Femoral Approach

A crossover catheter (Cobra C2 or Omni Flush) is used to cross the aortic bifurcation, followed by a crossover sheath (Balkin or Raabe). Selective work is then performed with an angled Glidewire and a straight or angled catheter.

### Radial Approach Considerations

From the radial approach, shorter working length catheters may be needed. Simmons and other reverse-curve catheters may not reform easily from radial access, so Tiger, Jacky, or specifically designed radial catheters are used instead.

<image>Illustration showing a lineup of common diagnostic catheter shapes used in interventional radiology, displayed side by side with their tips oriented upward. From left to right: Pigtail (curled tip with side holes), Cobra C1 (gentle primary curve), Cobra C2 (longer primary curve), Simmons 1 (reverse curve, small), Simmons 2 (reverse curve, larger), SOS Omni (reverse curve with secondary bend), Berenstein (gentle angled tip), and Mickelson (steep angled tip). Each catheter is labeled with its name and typical use.</image>

<image>Illustration demonstrating Simmons catheter reformation technique in the aortic arch. Three sequential panels: (1) Simmons catheter advanced into the ascending aorta over a guidewire with its reverse curve straightened; (2) Wire withdrawn, allowing the catheter to reform its reverse-curve shape against the aortic arch wall; (3) Reformed Simmons catheter pulled back to selectively engage a downward-facing visceral artery (such as the SMA or renal artery) with the tip directed caudally.</image>

<image>Diagram of common guidewire types showing cross-sectional construction and tip configurations. Three wires are displayed: (1) Standard J-wire with coiled tip, stainless steel core, and PTFE coating; (2) Angled Glidewire with hydrophilic polymer coating, nitinol core, and 3 cm angled floppy tip; (3) Amplatz Super Stiff with short floppy tip, long stiff body, and gradual transition zone. Each wire shows diameter markings (0.035 inch) and relevant construction details.</image>

## Clinical Pearls

The best approach is to start with the simplest catheter-wire combination and escalate. A Cobra C2 and Glidewire will accomplish the majority of selective visceral catheterizations. A wire should never be forced -- if it does not advance freely, the operator should reassess position with a contrast injection or fluoroscopy before pushing further.

Hydrophilic wires can dissect vessels silently, so constant awareness of wire tip position is critical. When reforming a Simmons catheter, gentle technique in the arch is essential to avoid embolizing atherosclerotic plaque. Exchange-length wires (260+ cm) should always be used when swapping catheters to maintain access.

A 0.035-inch stiff wire (Amplatz or Rosen) should always be available on the table for emergent catheter exchanges or bail-out situations. Microcatheters are essential for superselective embolization and should be used coaxially through a stable base catheter. Every operator should know at least three catheter shapes and when to use each before starting any angiographic case.

## References

- Defined Practice Standards: Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Kandarpa K, Defined by Defined by Machan L. Handbook of Interventional Radiologic Procedures, 5th ed.
- Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by Defined by IR Playbook (IRPlaybook.com) -- catheter and wire selection guides
- Defined by Defined by Defined by Defined by Manufacturer specifications for Terumo Glidewire, Cook Medical catheters, Merit Medical devices