The adrenal glands are two glands that sit on top of your kidneys that are made up of two distinct parts. 1  The adrenal cortexâthe outer part of the glandâproduces hormones that are vital to life, such as cortisol (which helps regulate metabolism and helps your body respond to stress) and aldosterone (which helps control blood pressure).
There are many possibilities. Some of them include: A) Diseases of heart have to be ruled out, e.g. problems with heart muscle or heart valves are a common cause of both PAC's and PVC's. B) Systemic causes (not related to heart) have to be considered also, e.g. anemia, thyroid overactivity. C) Autonomic and neuro-cardiogenic causes can also have same manifestation, e.g. increase in heart rate with standing because of drop in BP.
Therefore, it is named premature atrial contraction, or PAC. A PAC is premature, because the it occurs earlier than the next regular beat should have occurred. Most often, patients with PACs complain of palpitations. However, rather than reporting sustained racing heartbeat, they usually describe missing or skipping of the heartbeat.