A computational analysis of atrial fibrillation effects on coronary perfusion across the different myocardial layers

Area of Science:

• Cardiovascular Physiology
• Computational Fluid Dynamics
• Medical Imaging

Background:

• Patients with atrial fibrillation (AF) may experience ischemic chest pain without obstructive coronary artery disease.
• The direct hemodynamic impact of irregular heart rhythms on coronary circulation is not well understood.

Purpose of the Study:

• To investigate the direct hemodynamic effects of atrial fibrillation on coronary microcirculation.
• To quantify blood flow changes in different layers of the heart during simulated AF.

Main Methods:

• Utilized a 1D-0D multiscale computational fluid dynamics model of the cardiovascular system.
• Incorporated detailed mathematical models of coronary arteries and microcirculation (subepicardial, midwall, subendocardial layers).
• Simulated three ventricular rates (75, 100, 125 bpm) in both sinus rhythm (SR) and AF.

Main Results:

• Atrial fibrillation directly impacts coronary microcirculation, reducing blood flow.
• This reduction is more pronounced at higher ventricular rates.
• The subendocardial layers, particularly those supplied by the left coronary arteries, showed the most significant flow reduction during AF.

Conclusions:

• Atrial fibrillation has direct hemodynamic consequences on coronary microcirculation.
• AF can lead to reduced coronary blood flow, especially in the subendocardium, potentially explaining chest pain in its absence.
• These findings highlight a novel mechanism contributing to cardiac ischemia in AF patients.