When is it time to move on?

I am a cardiac ICU nurse. I’m still within my first year of nursing. I started in January and have been off of orientation for 6 months. A week or so before getting off of orientation, I kept getting asked to take care of the open-heart surgery patients. I never felt that I was ready. I wanted to get comfortable with taking care of patients routinely before I started taking the sicker patients. I recently just started to feel comfortable and now they’re making me take care of the open-heart patients now. It’s really scary because these patients are so unpredictable. I love learning about them but right now I’m questioning whether I should continue my career at this facility. I want to continue to learn from experience while taking care of these patients but I want to do it in a healthy environment. I don’t feel as though there are many people that are knowledgeable about taking care of these patients on my unit. I don’t wanna be stuck in a situation where something goes wrong and I have no one to turn to. My coworkers say they’re a phone call away but it’s not the same as them actually being there for advice. I’m wondering should I stay and continue to learn or take my career somewhere else? What’re your thoughts?