Biology Reference
In-Depth Information
fraction (IVSTF), left ventricle posterior wall-thickening fraction (LVWTF),
shortening fraction (SF), ejection fraction (EF), left ventricle sphericity index
(SI), and left atrium to aorta ratio (LA/Ao). The 2DST evaluations were performed
at
T
0
and
T
1
in each patient with the software X-Strain
®
after the acquisition of
video clips, including three cardiac cycles per patient, from the right parasternal
short-axis view of the left ventricle at the level of the papillary muscles. On the
three acquired cardiac cycles, X-Strain
®
allows analysis of the motion of the
segments between points that are fixed on the epicardial and endocardial borders
of the left ventricle using special bright reference markers on the two-dimensional
image. A special rule of the software was applied, in addition, to set the points to
standardize the dimensions of the different myocardial angular sectors to be
analyzed. Therefore, the motion of the left ventricle was studied and subdivided
in six specific sectors as suggested by Lang et al. (
2005
). For each cardiac sector,
X-Strain
®
allows estimations of two parameters, strain (S) and strain rate (SR).
S quantifies the percentage of myocardial deformation caused by the lengthening or
shortening of the muscular fibers. It is calculated through the application of the
following equation:
S
(
L
-
L
0
)/
L
0
, where
L
is the final length of the myocardial
segment and
L
0
is the initial length. SR, instead, quantifies the velocity of
myocardial deformation; it is measured in 1/s (s
¼
second) and is calculated
through the application of the following equation:
S
/
¼
t
, where
S
is the strain
(percentage of deformation) of the considered myocardial segment and
D
t
is the
duration of the deformation of the same segment. Thus, X-Strain
®
allowed
estimations of the
S
and SR values of the short-axis of the left ventricle automati-
cally, relative to the radial and circumferential motions in a single cardiac cycle, as
the average of the values obtained in each of the six myocardial sectors. Therefore,
the mean values over three cardiac cycles of the following indices were evaluated:
radial S (rad S), radial SR (rad SR), circumferential S of epicardium (epi circ S) and
of endocardium (endo circ S), and circumferential SR of epicardium (epi circ SR)
and of endocardium (endo circ SR). The rotational displacement of epicardium (epi
rot Displ) and of endocardium (endo rot Displ) and the radial displacement of
epicardium (epi rad Displ) and of endocardium (endo rad Displ) were also
estimated with X-Strain
®
.
D
16.3 Results
The physical examination with particular attention to the cardiovascular system
performed in each patient at
T
0
allowed detection of weakness with tendency to
decubitus, dyspnea at rest, tachisfigmia (160 bpm in case 1 and 150 bpm in case 2),
weak pulse, crackles specifically in the middle and cranial pulmonic fields, and a
grade 3/6 systolic cardiac murmur loudest over the mitral valve. The clinical
examination performed in the same patients at
T
1
allowed evaluation of a lower
degree of weakness, the disappearance of dyspnea, an increase in the width and
reduction in the frequency of the pulse (95 bpm in case 1 and 125 bpm in case 2),
