Is Clexa an alternative medicine for Attention Deficit Disorder?

I was at the doctors yesterday to get evaluated for Add. The doctor said he thought I might be experiencing anxiety instead. I thought I fit more with the Symptoms of Add. However, the doc said since anxiety runs in my family, he thought I should be prescribed Celexa. I also have a congenital heart defect, and he did not want to prescribe Ritalin since that is a speed drug and may make my heart problems worse. He said that the Celexa will help with the Add. Is that true? I'm nervous about taking it, since I'm new to anxiety/anti-depressants, so what can I expect after taking this drug? I'm picking up the medicine later today and have to work on Saturday morning. Will this affect my working abilities? Sorry for all the questions and I would have asked my doctor all of this, but he just gave me a quick summary of the drug, and I wasn't ready for questions since I didn't expect to be prescribed Celexa or any medicine that day?