Most of us never give much thought to the small artery that runs along the inside of our wrist, the radial artery. You can feel it easily if you press your fingers just below your thumb. Yet in modern medicine, this little vessel has become one of the most important gateways to the heart. Imagine a doctor threading a tiny tube, called a catheter, through the radial artery to reach your heart. This technique, called transradial access, has transformed modern cardiology. By entering through the radial artery, doctors can perform life-saving cardiac procedures with fewer complications, faster recovery, and even lower costs than older methods that went through the leg. Many people can even walk out of the hospital on the same day. Over the past two decades, doctors have increasingly chosen the radial artery as their entry point for procedures like angiography (imaging of the heart’s blood vessels) and angioplasty (opening blocked arteries). But there’s a catch: sometimes the artery rebels. It tightens suddenly, almost like a muscle cramp, gripping the medical instruments and making the doctor’s job harder. This is known as radial artery spasm (or RAS for short). In rare cases, the spasm is so severe that it traps the catheter or damages the artery wall.