User:Mr. Ibrahem/Inappropriate sinus tachycardia

Inappropriate sinus tachycardia (IST) is sinus tachycardia results in symptoms and without an identifiable cause. Symptoms may include palpitations, chest discomfort, tiredness, shortness of breath, and lightheadedness. Onset is typically sudden and symptoms may persist for years. Often quality of life is affected; though, it rarely results in long-term heart problems such as cardiomyopathy.

The cause is unclear, though it may occur as a postviral syndrome. Proposed mechanisms include an abnormal sinus node, autonomic dysfunction, autoimmune, and abnormal baroreflex. Diagnosis requires other causes being ruled out via a Holter monitor and heart ultrasound. It generally results in a heart rate at rest above 100 beats per minute with an average heart rate over a day above 90. Heart rate may be either persistently high or increase significantly with minor triggers such as psychological stress or exercise, but is not exclusively related to position.

Management may involve limiting activity; though, physical training is recommended, and avoiding caffeine and alcohol. Medications may include beta blockers, calcium channel blockers, or ivabradine, but are not always effective. While ablation is used, outcomes are mixed. Counselling may help some people. The condition may resolve after months or years. Long-term it does not appear to affect life expectancy.

Inappropriate sinus tachycardia affects about 1% of middle aged adults. It occurs most commonly in young adults between the age of 15 and 45. Women are affected four times more often then men. The condition was first described by Codvelle in 1939; though, it did not become more commonly known until the 1970s.