Quantitative description of the 3D regional mechanics of the left atrium using cardiac magnetic resonance imaging

Abstract

The left atrium (LA) plays an important role in the maintenance of hemodynamic and electrical stability of the heart. One of the conditions altering the atrial mechanical function is atrial fibrillation (AF), leading to an increased thromboembolic risk due to impaired mechanical function. Preserving the regions of the LA that contribute the greatest to atrial mechanical function during curative strategies for AF is important. The purpose of this study is to introduce a novel method of regional assessment of mechanical function of the LA. We used cardiac MRI to reconstruct the 3D geometry of the LA in nine control and nine patients with paroxysmal atrial fibrillation (PAF). Regional mechanical function of the LA in pre-defined segments of the atrium was calculated using regional ejection fraction and wall velocity. We found significantly greater mechanical function in anterior, septal and lateral segments as opposed to roof and posterior segments, as well as a significant decrease of mechanical function in the PAF group. We suggest that in order to minimize the impact of the AF treatment on global atrial mechanical function, damage related to therapeutic intervention, such as catheter ablation, in those areas should be minimized.

Effect of ablation pattern on mechanical function in the atrium

“…11,12 The striking differences in contributions to active and passive atrial emptying from different regions led Kuklik et al to suggest that ablation in regions with greater mechanical function should be minimized to preserve global atrial function. 13 Given the availability of multiple widely accepted ablation procedures that target different regions of the atrium, it may be possible to choose procedures that achieve the goals of restoring normal electrical Pacing Clin Electrophysiol. 2017;40:648-654. c 2017 Wiley Periodicals, Inc. 648 wileyonlinelibrary.com/journal/pace function while preserving mechanical function.…”

Making better scar: Emerging approaches for modifying mechanical and electrical properties following infarction and ablation

“…Kuklik reported very similar findings in a separate MRI study: decreased mechanical function in patients with paroxysmal AF compared to controls, and significantly higher mechanical function of the anterior, septal and lateral regions as opposed to roof and posterior regions in both groups. (Kuklik et al, 2014) Speckle-tracking ultrasound gives similar values for strain in these regions, confirming regional variability in atrial function. (Vianna-Pinton et al, 2009)…”

“…Following this reasoning, Kuklik et al suggested that ablation in lateral, anterior and septal regions should be minimized since these regions move the most in both normal and paroxysmal AF atria. (Kuklik et al, 2014) Recently, Moyer et al used a finite-element model of the left atrium to quantitatively evaluate the potential influence of the extent vs. location of ablation scar on atrial function (Figure 4). Starting with a model of the human left atrium validated against both invasive pressure-volume and non-invasive regional wall motion data, (Moyer et al, 2015) Moyer simulated distributions of scar in locations typical of standard pulmonary vein isolation (PVI) and wide area circumferential ablation (WACA) procedures.…”

Correlation between the left atrial low‐voltage area and the cardiac function improvement after catheter ablation for paroxysmal atrial fibrillation

“…Notably, regional differences exist in the left atrial segmental function during atrial contraction, with the posterior wall having the lowest motion, probably because its motion is limited by the attachment of the pulmonary veins or compression by the vertebra . In the literature, the areas of the highest motion are controversial; however, this study corroborates a previous study with cardiac magnetic resonance imaging, which observed high mechanical function in the anterior and septal walls. Hence, the myocardial damage, which was indicated by the LVA, of the anterior, septal, and roof walls might have hindered the recovery of the left atrial function following ablation.…”