How did she get a broken heart?

My younger sister Michelle is 17. She is in her senior year of high school. When she was younger she was diagnosed with a heart murmur. But lately her heart was beating at 180-190 beats per minute while just sitting down. She went in and had a cardiologist look at her and she was diagnosed with not a heart murmur but mitrocardial something something. (She can ramble it off perfectly- I forget!) Anyway- she is going to go in for surgery next Wednesday. They will cut into her leg and send a laser up to her heart and basically burn a nerve in her heart that is misfiring. I got a phone call from my Mom a couple of days ago letting me know that Michelle (despite the medication she is on) came back from Young Women's with her heart racing at 180 again. They had gone to bed that night and the next morning it was still at 180. My Mom said you could look at her chest and see her heart beating. They had taken her into the cardiologist and he upped her medication but to pray for it to work because the heart surgeon that is supposed to do her surgery is on vacation (aren't they always?!!!). He is skilled in the procedure that she is having done and if she had to have the surgery in the next couple of days- it would just be the doctor on call that day. I got off the phone and turned to Maddie who had been watching me the whole time. She immediately asked me what was wrong with Michelle. I told her that Michelle's heart was having a hard time working right and that we needed to say a prayer to Heavenly Father to make it better. She looked at me and said "I will say it." She asked Him to stop making Michelle's heart broken. When it was done she said "There, now she will be all better." I knew she would find out about the surgery so I explained that we needed to keep praying for her because she is going in for surgery next week and that she would be in the hospital. Maddie looked at me and said "If we pray for her and she goes to the hospital- then she will be just fine Mom- you don't have to worry. I will pray for her all of the time then." She then turned to me and said "How did she get a broken heart anyway?" I said that she was born with it. Maddie looked at me and said "I better never get a broken heart." I told her that she was born with a strong heart and hopefully it will always stay strong. I had read a friend's blog this morning that was talking about how sometimes we can learn so much from little children. How they are so full of hope and so sure of what we have taught them. I have been so worried about my sister and hearing Maddie tell me that if we keep praying that she will be just fine. If all goes well with the surgery- Michelle shouldn't have any more heart problems for the rest of her life. She can go on as a normal teenager and be a mother one day. I am just so glad that I am raising a little girl that is so sure that her Heavenly Father will help with anything she asks Him to.