Atrial fibrillation (A-fib, AF) - causes, symptoms, treatment & pathology

Summary

Atrial fibrillation (AF) is a heart condition where the upper chambers (atria) beat irregularly and chaotically, disrupting normal heart function. It can be triggered by cardiovascular diseases, obesity, and diabetes, and leads to symptoms like fatigue, dizziness, and shortness of breath. AF increases the risk of blood clots, potentially causing strokes. Diagnosis is through ECG or Holter monitoring, and treatment options include medications, pacemakers, and ablation procedures. While AF can be managed, it requires personalized treatment based on the patient’s unique circumstances.

Takeaways

• 😀 The heart has four chambers: two atria (upper) and two ventricles (lower).
• 😀 Fibrillation occurs when the heart muscle fibers contract at different times, causing quivering or twitching.
• 😀 Normally, electrical signals from the sinus node cause coordinated atrial and ventricular contractions.
• 😀 Atrial fibrillation (AF) occurs when electrical signals move erratically around the atria, overriding the sinus node.
• 😀 On an ECG, AF is characterized by a disorganized, scribble-like pattern due to random atrial contractions.
• 😀 AF can cause an irregular and rapid heart rate (100-175 bpm) due to random ventricular contractions.
• 😀 In AF, the atria lose the 'atrial kick,' which is a small amount of blood pumped by coordinated atrial contraction.
• 😀 Risk factors for AF include high blood pressure, coronary artery disease, obesity, diabetes, and excessive alcohol consumption.
• 😀 Tissue heterogeneity (variations in the electrical properties of cells) can lead to multiple wavelets of electrical activity, contributing to AF.
• 😀 AF symptoms include fatigue, dizziness, shortness of breath, palpitations, and potential stroke risk due to blood clot formation in the atria.

Q & A

What are the four chambers of the heart?

The heart has four chambers: two upper chambers called the atria (right and left atrium), and two lower chambers called the ventricles (right and left ventricles).

What is fibrillation, and how does it affect the heart?

Fibrillation refers to the uncoordinated contraction of muscle fibers, causing the heart to quiver or twitch rather than contract in a smooth and coordinated manner.

How does the electrical signal typically travel through the heart?

Normally, the electrical signal originates from the sinus node in the right atrium, spreads rapidly through both atria, and then moves down to the ventricles to trigger their contraction.

What happens in atrial fibrillation (AF)?

In AF, electrical signals in the atria move in a disorganized manner, causing the atria to quiver rather than contract. This disrupts the normal heart rhythm and leads to irregular ventricular contractions.

How is AF detected on an electrocardiogram (ECG)?

On an ECG, AF shows as a chaotic, irregular pattern with no distinct P waves and erratic QRS complexes, reflecting the disorganized electrical activity in the atria.

What is the 'atrial kick' and how does AF affect it?

The 'atrial kick' refers to the small amount of blood pushed into the ventricles by the atrial contraction. In AF, this atrial contraction is lost, which can reduce the efficiency of blood flow but is not typically life-threatening.

What are the main risk factors for developing atrial fibrillation?

Risk factors for AF include cardiovascular conditions like high blood pressure, coronary artery disease, and valvular diseases, as well as non-cardiovascular factors like obesity, diabetes, excessive alcohol consumption, and genetics.

What causes the electrical irregularities seen in AF?

In AF, cells in the atrium develop different electrical properties, leading to a situation where multiple electrical wavelets spread randomly across the atria. This disrupts the coordinated conduction of electrical impulses.

What is the progression from paroxysmal AF to persistent AF?

Paroxysmal AF consists of brief episodes that resolve on their own, while persistent AF lasts longer and does not terminate without intervention. Repeated episodes of AF cause stress and fibrosis in the atrial tissue, leading to more persistent forms of the condition.

What are the potential complications of atrial fibrillation?

A major complication of AF is stroke, as the irregular atrial contractions can lead to stagnant blood, forming clots that may travel to the brain and block blood flow, causing a stroke.

How is atrial fibrillation diagnosed?

AF is primarily diagnosed through an ECG, but in cases of paroxysmal AF, a Holter monitor may be used to record the heart's rhythm over a longer period of time to capture episodes of AF.

What are the common treatments for atrial fibrillation?

Treatment options for AF include medications to control heart rate and prevent clot formation, pacemakers to regulate heart rhythm, and catheter ablation procedures to destroy abnormal tissue. In severe cases, procedures like the maze procedure or AV node ablation may be performed.