Dear Sharon, at this site:
http://209.85.135.132/search?q=cache:b-lZXaO36DAJ:
www.drguide.mohp.gov.eg/newsite/News/HotTopics/
heart.doc+ecg+readings+explanation&cd=1&hl=en&ct=clnk
you can find out about ECG readings. I think it is very comprehensible and thus recommend reading it