Describe the steps in the single-wall technique of percutaneous arterial catheterization.

The vessel is identified and confirmed using waveform from US and marked.
1. A needle (usually 21 gauge) with a stylet is advanced through the anterior wall of the vessel using ultrasound guidance.
2. The stylet is removed and the needle is withdrawn slowly into the vessel lumen. Pulsatile blood will flow out the back of the needle.
3. A guidewire is advanced into the vessel using fluoroscopic guidance.
4. The guidewire is held in place and the needle is removed over the wire while the puncture site is firmly compressed.
5. A catheter is passed over the wire into the vessel lumen.
6. The guidewire is removed, leaving the catheter in the vessel ready for the injection of contrast material.