DEFINITION of 'Attribution Rules'. A set of rules created by Canada Revenue Agency (CRA) that prevents investors from transferring assets between family members with the intention of avoiding taxes. Next Up.
Causes of atrial fibrillation. The exact cause of atrial fibrillation is unknown, but it's more common with age and affects certain groups of people more than others. Atrial fibrillation is common in people with other heart conditions, such as: 1  high blood pressure (hypertension). 2  atherosclerosis.3  heart valve disease.4  congenital heart disease.auses of atrial fibrillation. The exact cause of atrial fibrillation is unknown, but it's more common with age and affects certain groups of people more than others. Atrial fibrillation is common in people with other heart conditions, such as: 1  high blood pressure (hypertension). 2  atherosclerosis.
A: Atrial fibrillation is characterized by a rapid, irregular heart beat and can be paroxysmal (intermittent) or permanent in nature. It is caused by a dysfunction of the heart tissue or nodes, by a dysfunction of the autonomic nervous system or by a combination of both.