Is there a chance of dying during a breast reduction?

I’m 19 and I’m getting a breast reduction this Tuesday I’m extremely excited but also terrified.. I occasionally smoke marijuana but never any cigarettes, I’m not over weight but I do eat a lot of junk and don’t drink enough water :( I’m really nervous that I’m not going to wake up because I’m not the healthiest. I’ve been put under recently and it was fine. I also have a fixed heart murmur and my family doctor said it should be fine... what are my chances of death?