The study is designed to evaluate and validate impact factors to success and complication using ultrasound guided short-axis out-of-plane dynamic approach, and validate the impaction.

The study including two phase: observational phase and validation phase. In observational phase, factors relative to success catheterization without posterior puncture and success in first attempt are evaluated. In validation phase, patients are randomized into different depth group with or without injection of saline. Success without posterior wall puncture, success in first attempt and overall, catheterization time are compared between groups.

Inclusion Criteria:

• requirement of radial arterial catheterization during perioperative period
• within cardiac-vascular disease
• written consent

Exclusion Criteria:

• contraindication to radial arterial catheterization
• abnormal artery evaluated by ultrasonography