Thursday, January 5, 2012
The rate in sinus tachycardia is rarely so fast and is influenced by emotion, exercise and posture. The onset and cessation are gradual. Palpitations caused by panic are often wrongly diagnosed as paroxysmal tachycardia. The rate in article flutter rarely exceeds 160 and although as with paroxysmal tachycardia, the rate is uninfluenced by exercise and posture, in flutter it may be suddenly halved by change in the degree of A-V block. The majority of paroxysms of supraventricular tachycardia gives rise to few symptoms and cease spontaneously but they can be unpleasant. If the attack is prolonged, cardiac failure may develop, but usually improves rapidly with the return of normal rhythm. Death is rare in a paroxysm. The prognosis depends on the underlying disease and it is largely for this reason that ventricular tachycardia is a serious condition.