Arhythmia: We do not usually give a misspelling but this is a frequent misspelling of arrhythmia (with two r's), meaning an abnormal heart rhythm. In an arrhythmia the heartbeats may be too slow, too rapid, too irregular, or too early. Rapid arrhythmias (greater than 100 beats per minute) are called tachycardias. Slow arrhythmias (slower than 60 be... Found on http://www.medterms.com/script/main/art.asp?articlekey=13252