Inappropriate sinus tachycardia (IST) is a condition in which an individual’s resting heart rate is abnormally high (greater than 100 beats per minute), their heart rate increases rapidly with minimal exertion, and their rapid heart rate is accompanied by symptoms of palpitations, fatigue, and exercise intolerance. It is more common in women, and (while one hopes not) this may be why it is all too often written off by doctors as "anxiety." Read about IST, its causes and treatment, here.

Bundle branch block (BBB) is a common finding on the ECG. Whether it is a significant finding or not depends on the circumstances. DrRich reviews BBB, explains its causes, and describes how it should be evaluated and treated, here.