sinus tachycardia [L, sinus, hollow; Gk, tachys, fast, kardia, heart] , a rapid heartbeat generated by discharge of the sinus node. The rate is generally 100-180 beats/min in the adult, although most clinicians would be suspicious of a rate of 90 beats/min or higher. Sinus tachycardia is also indicated by a heart rate greater than 200 beats/min in an infant and 140-200 beats/min in a child. Sinus tachycardia is the body’s normal response to exertion, congestive heart failure, cardiogenic shock, acute pulmonary embolism, acute myocardial infarction, and infarct extension.
