Week 1: Causes of AF

1. — Atrial fibrillation is caused by a problem with the electrical activity of the heart.
   
2. There are several conditions that damage the heart muscle or strain the heart may cause atrial fibrillation. These include:

• — Coronary Artery Disease - The coronary arteries are the arteries that supply the heart with oxygenated blood and nutrients. When these arteries become damaged or blocked by the buildup of fatty tissue known as plaque, the arteries become narrow restricting the blood flow into the heart. The heart being deprived of oxygenated blood can interfere with the electrical impulses causing atrial fibrillation.

• — Heart failure

• — Hypertension - When you have high blood pressure, the heart has to beat harder to supply blood to your body. This added stress on the heart can result in the left ventricular hypertrophy, impaired ventricular filling, left atrial enlargement, and slowing of atrial conduction velocity. These changes in cardiac structure and physiology favor the development of atrial fibrillation.

• — Ischaemic heart disease

• — Rheumatic heart disease - Rheumatic heart disease is damage to the heart muscle and heart valves that result from rheumatic fever. These cause the atria to enlarge, making AF more likely.

• — Heart valve disease - Heart valve disease occurs when a heart valve is damaged or narrowed and does not properly control the flow of blood through and out of the heart. (most often mitral valve disease)

• — Pneumonia

• — Hyperthyroidism - Hyperthyroidism, an overactive thyroid, occurs when the thyroid gland produces too much of the thyroid hormones, T3 (triiodothyronine) and T4 (thyroxine). Thyroid hormones help to regulate sodium and potassium channels, which create the electrical impulses that keep the heart beating. Too much thyroid hormone interferes with the flow of sodium and potassium across membranes which results in irregular impulses. In addition, thyroid hormones cause tissues throughout the body to demand more oxygen, which increases the workload and stress on the heart which can result in irregular beating, or atrial fibrillation.

• — Alcohol abuse

• — Cardiomyopathy – disease of heart muscle

• — Pericarditis - inflammation of the sac around the heart. Pericarditis can temporarily irritate the heart muscle.

• — Sick sinus syndrome – improper functioning of the heart’s natural pacemaker.

• — Bronchial carcinoma

• — Atrial myxoma - is a noncancerous tumor in the upper left or right side of the heart. It grows on the wall (atrial septum) that separates the two sides of the heart.

• — Endocarditis - inflammation of the inside lining of the heart chambers and heart valves. Endocarditis can involve the heart muscle, heart valves, or lining of the heart. Most people who develop endocarditis have heart disease of the valves.

• — Atrial septal defect - is a congenital heart defect in which the wall that separates the upper heart chambers (atria) does not close completely. An atrial septal defect allows freshly oxygenated blood to flow from the left upper chamber of the heart (left atrium) into the right upper chamber of the heart (right atrium). There it mixes with deoxygenated blood and is pumped to the lungs, even though it's already refreshed with oxygen. If the atrial septal defect is large, this extra blood volume can overfill the lungs and overwork the heart. If not treated, the right side of the heart eventually enlarges and weakens.

• — Pulmonary embolus – blood clot in the lungs

• — Lone atrial fibrillation – means no cause discovered