Keywords: left atrial function; strain; end-stage renal disease;
hemodialysis
Introduction
The occurrence and development of end-stage renal disease (ESRD) is
complex, which causes different degrees of damage in cardiac structure
and function. Cardiovascular complication is by far the most important
reason for death in patients with ESRD on hemodialysis (HD) therapy
[1]. In the past, the focus of clinical research has been on the
left ventricular morphology and function, but the change of left atrial
(LA) function was often overlooked. Previous studies have shown that LA
dilatation is closely related to the sustained volume and pressure
overload, which can predict left ventricular hypertrophy, high filling
pressure, and even mortality. [2] Thus, LA parameters have important
clinical value in assessing the risk and prognosis of cardiovascular
complications.
In clinical application, conventional echocardiography is the most
common noninvasive method of evaluating cardiac structure and function
in almost all patients with ESRD. However, it may not be sufficiently
sensitive to detect early and subtle changes in ESRD with preserved
ejection fraction, especially before serious cardiac involvement occurs.
The EACVI NORRE study recently recommended the use of LA deformation
imaging based on two-dimensional speckle tracking echocardiography
(2D-STE)[3]. 2D-STE has been used in previous studies on LA function
of this triphasic nature to document subclinical dysfunction.
Four-Dimensional Auto Left Atrial Quantification (LAQ) is a new method
using three-dimensional(3D) data, which has a simple workflow and offers
a new diagnosis method, evaluating the value of LA volume and emptying
fraction aside from strain parameters analysis in the ESRD. LAQ can
directly show LA endocardial contraction and provide sensitive and
reproducible indices of myocardial dysfunction; thus, myocardial
deformation was assessed directly and angle-independently [4].
The LA cavity volume is measured from a semi-automated segmentation
algorithm during the cardiac cycle. The method calculates the
deformation of the 3D model by solving a state estimation problem, which
was constructed from an extended Kalman filter combined with LA
geometry, a motion model, and edge detection algorithms. The strain is
calculated based on the length change of different lines in each
anatomical direction. The longitudinal strain is calculated by eight
longitudinal lines from an automatically constructed triangular grid,
which is connected to 2 opposite LA basal points (Figure 1). To
calculate circumferential strain, 7 circumferential lines are
equidistantly distributed between the LA base and apex (Figure 2).Then,
strain is calculated for each frame time according to the following
formula: s(t)=(L(t)-L(tref))/L(tref) X 100%, where L(t) is the line
length at time t, and tref is set as the end diastolic time point of
left ventricular. Global strain in each direction is obtained by
calculating the average strain of the respective directional lines.