Related Experiment Video
Updated: Jun 7, 2025
08:10
Estimating Bilateral Atrial Function by Cardiovascular Magnetic Resonance Feature Tracking in Patients with Paroxysmal Atrial Fibrillation
Published on: July 20, 2022
1.6K
Diffuse functional and structural abnormalities in fibrosis: Potential structural basis for sustaining atrial
Eugene Kwan1, Elyar Ghafoori1, Wilson Good2
1Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah.
Heart Rhythm
|November 20, 2024
Summary
Fibrotic atrial regions exhibit slower conduction and unidirectional propagation, potentially sustaining atrial fibrillation. These structural and functional changes in fibrotic tissue create a substrate for arrhythmias.
Area of Science:
- Cardiovascular Research
- Cardiac Electrophysiology
- Fibrosis Research
Background:
- Structural remodeling of the atria is linked to increased atrial fibrillation incidence.
- The precise mechanisms by which fibrotic regions sustain atrial fibrillation remain incompletely understood.
Purpose of the Study:
- To investigate structural and functional distinctions between remodeled and healthy atrial regions.
- To utilize a novel transgenic goat model for evaluating atrial fibrosis and its electrophysiological consequences.
Main Methods:
- A transgenic goat model with cardiac-specific transforming growth factor β1 overexpression was employed.
- Ex vivo cardiac magnetic resonance imaging and histology assessed fibrosis, fiber disarray, and structural anisotropy.
- Diffusion tensor imaging and functional analysis evaluated conduction speeds, direction heterogeneity, and conduction anisotropy.
Main Results:
- Transgenic goats displayed an average of 21% fibrotic left atria, confirmed by MRI and histology.
- Fibrotic regions showed reduced fractional anisotropy and increased fiber direction heterogeneity, indicating significant fiber disarray.
- Conduction speeds were slower in fibrotic areas, with more aligned conduction directions, promoting unidirectional block and lower conduction anisotropy.
Conclusions:
- Fibrotic atrial regions exhibit slower, more unidirectional electrical propagation.
- Discrepancies between propagation direction and underlying fiber orientation reduce conduction anisotropy.
- Combined functional and structural abnormalities in fibrotic tissue may provide a substrate for the initiation and maintenance of atrial fibrillation.
Related Concept Videos
01:23Rheumatic Heart Disease I: Introduction
3
Rheumatic heart disease or RHD is a chronic condition that results from rheumatic fever, causing permanent damage to the heart valves.Etiology and Risk FactorsIt primarily arises from rheumatic fever, an inflammatory disease that can develop after untreated or inadequately treated group A streptococcal (GAS) pharyngitis. Streptococcus spreads through direct contact with oral or respiratory secretions. While the bacteria are the causative agents, factors like malnutrition, overcrowding, poor...
3
01:16Clot Retraction and Fibrinolysis
4.1K
After a fibrin clot is formed, the next step is clot retraction, a vital process facilitated by platelet contractile proteins, such as actin and myosin. These proteins pull the fibrin strands closer together and condense the clot. This action reduces the size of the clot, creating a smaller, denser structure that effectively seals off the damaged vessel. Clot retraction consolidates the clot and helps with wound healing by bringing the edges of the damaged blood vessel closer together.
4.1K
01:17Pathophysiology of Heart Failure
1.5K
Heart failure (HF) is a progressive syndrome involving ventricles that leads to inadequate cardiac output. It can be classified based on location and output or ejection fraction. Ejection fraction (EF) is an essential measurement in the diagnosis and surveillance of HF. Reduced EF corresponds to systolic heart failure (HFrEF). However, HF with preserved ejection fraction (HFpEF) is becoming increasingly prevalent. Also known as diastolic HF, this form of HF is related to aging. The...
1.5K
01:28Mechanism of Cardiac Arrhythmias
891
Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
891
03:03Amyloid Fibrils
9.2K
Amyloid fibrils are aggregates of misfolded proteins. Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils.
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining,...
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining,...
9.2K
01:09Introduction to Fibroblasts
3.0K
Rudolph Virchow discovered spindle-shaped cells called fibroblasts in 1858. Inactive fibroblasts, called fibrocytes, become activated by various stimuli, such as growth factors and inflammatory cytokines. Activated fibroblasts play a crucial role in wound healing, inflammation, formation of new blood vessels, and cancer progression. Uncontrolled activation of fibroblasts results in fibrosis, the excess deposition of fibrous tissue, which can lead to scarring and affect normal organs. This...
3.0K