Conventionally, long-axis in-plane (LA-IP), short-axis out-of-plane (SA-OOP) and dynamic needle tip positioning based on SA-OOP views are commonly used method to image the target vessel during cannulation under US guidance. A modified SA-OOP that add developing line on the ultrasonic probe improve the success rate of cannula insertion into the radial artery on the first attempt.

Inclusion Criteria:

1. The diagnostic criteria of coronary atherosclerotic heart disease according to the tenth version of international Classification of diseases(ICD-10);
2. Requires invasive arterial blood pressure monitoring;
3. New York Heart Association(NYHA) classification I, II or III;
4. The American Society of Anesthesiologists (ASA) classification I, II or III;
5. Patients older than 18 years and younger than 85 years (Adult);
6. Patients signed the informed consent before the study.

Exclusion Criteria:

1. Patients with hemodynamically unstable (systolic blood pressure 60 or less);
2. Patients with abnormal results of the modified Allen test;
3. Patients with ulnar artery occlusion;
4. Patients with coagulation disorders;
5. Patients with skin abnormalities such as inflammation or hematoma at the cannulation site;
6. Patients with raynaud disease and prevalent atherosclerosis;
7. Patients with history of hand or wrist trauma or surgery;
8. Patients who have undergone radial artery interventional therapy or radial artery cannulation within 3 months on the puncture side;
9. Patients with BMI more than 40 kg/m2;
10. Patients who have participated in other relevant clinical studies within 3 months.