Do you mean "tachycardia"?
tachycardia (tak-i-kar'-di-a) [Greek. tachys, swift; kardia, heart]. Excessively rapid action of the heart. Paroxysmal tachycardia, a temporary but sudden marked increase in frequency of heart beats, because the conducting stimulus is originating in an abnormal focus.
Please see the webpages for more details on Supraventricular tachycardia