Causes of Atrial Fibrillation
In a heart that is functioning normally, electrical impulses travel regularly from the upper chambers of the heart (the atria) to the lower chambers (the ventricles) to produce a heartbeat. In patients who have atrial fibrillation, the electrical signals are not directed appropriately through the atria, causing quivering rather than regular muscle contraction. The ventricles also beat rapidly, resulting in an irregular heart rhythm and elevated heart rate that can range from 100 to 175 beats per minute.
Possible Causes
The most common cause of AF is structural abnormalities or damage to the heart. Certain risk factors make a patient more likely to develop atrial fibrillation. Common causes of AF include:
- Structural heart disease associated with coronary artery disease, valvular disease, or cardiomyopathy
- Hypertension
- Obstructive sleep apnea
- Emphysema
- Diabetes mellitus
- Cardiomyopathy
In a significant number of cases, no clear organic cause of atrial fibrillation is identified. The incidence of AF doubles with each decade of life above age 60.
Mechanisms Causing AF
Although multiple risk factors are associated with atrial fibrillation, current understanding of the mechanisms causing AF focuses on 4 sources:
- Dissimilarity in the endothelial lining at the junction of the pulmonary veins with the left atrium comprises a zone of electrical instability capable of triggering the onset of atrial fibrillation.
- Nerve fibers from the autonomic nervous system – typically responsible for the unconscious regulation of numerous bodily processes (e.g., thirst, temperature, sweating, etc.) – may abnormally stimulate the heart, creating electrochemical changes in the atrial muscle and lowering the fibrillation threshold.
- The left atrium may develop structural changes such as enlargement or fibrosis, resulting in uneven conductivity.
- As atrial fibrillation becomes established in the heart, the atrial muscle undergoes electrochemical remodeling, thereby making AF self-reinforcing.
For more details about atrial fibrillation causes and risk factors, or to find out if you may be a candidate for the five-box thoracoscopic maze procedure in Ohio, request a phone consultation with Dr. John Sirak or call his appointment phone at (614) 366-7414.