MATERIALS and METHODS
Study population
Ninety-eight adult patients screening for high probability of PH by
echocardiography were enrolled from the inpatient or outpatient
department of the First Affiliated Hospital of
Sun Yat-sen University (SYSU)
between July 2021 to April 2022. Patients with a peak tricuspid
regurgitation velocity (TRV)>3.4m/s by echocardiography, or
TRV>2.8m/s with additional echocardiographic signs from at
least two categories (the ventricles, the pulmonary artery or inferior
vena cava (IVC) and right atrium) suggestive of PH were assigned high
probability of PH. Patients with TRV range from 2.8 to 3.4m/s and the
absent of other echocardiographic signs, or TR<2.8m/s with the present
of echocardiographic signs of PH were suggested Intermediate probability
of PH[15]. Subjects with age < 18 years, acute coronary
syndrome or cardiac surgery within a period of 1 year, pacemaker rhythm,
echocardiography images might interfere accurate 4D auto LAQ
measurements were excluded. This was a single-center retrospective study
approved by the Ethic Committee of SYSU, complied with the Declaration
of Helsinki.
Clinical and Laboratory
evaluation
Demographic parameters (age,
gender, height and weight) and clinical variables including blood
pressure and clinical diagnosis were collected. The body surface area
(BSA) and body mass index (BMI) were calculated. Venous blood samples
were collected in the morning after an overnight fasting and some
laboratory parameters were detected, including serum NT-pro BNP,
creatinine, hemoglobin and glycosylated hemoglobin (HbA1c).
Echocardiography
Comprehensive echocardiographic examinations were performed in all
patients by trained experience echocardiographers using a Vivid E95
ultrasound system (General Electric Healthcare, Horten, Norway) in
keeping with the current guidelines and recommendations[16]. 2D
gray-scale images were equipped with a 2.5 MHz matrix array transducer
(M5Sc) and acquired at 50–80 frames/s over 3 heart cycles. Data from 3
to 5 beats was averaged in atrial fibrillation cases. Left ventricular
ejection fraction (LVEF) was obtained by Simpson method
from apical 4-and 2-chamber
views. LV mass (LVM) was calculated using the Devereux formula[17].
And the index of the left
ventricular diameters at the end
of systole and diastole (LVEDI, LVESI) and LV mass (LVMI) were equal to
LVED, LVES and LVM divided by BSA respectively. The Doppler imaging were
performed to evaluate the peak early (E) and late (A) diastolic
velocities of the mitral inflow, the peak early diastolic velocity of
the medial mitral annular (e’), the peak systolic velocity of tricuspid
annular (S’) and the tricuspid regurgitation peak velocity (TRV). Then,
the ratio of E/A and E/e’ were calculated respectively. Tricuspid
annular plane systolic excursion (TAPSE) was tracked in the right
ventricular focus apical four-chamber view using M-mode
echocardiography. Pulmonary artery systolic pressure (PASP) was
calculated by the modified Bernoulli formula: PASP =4×TRV2 + estimated right atrial pressure (RAP), while the
estimated RAP was based on inferior vena cava diameter and
collapsibility index. The PAWP was estimated by (43 - 0.1×TRV- 0.5×
LVEF+1.0× RVFAC+0.3× LAVi + 0.7× E/ e’ + 0:9× IVC) × PAMP/100 [4].
PAWP ≤15 mmHg was defined as pre-capillary PH, and PAWP >15
mmHg was defined as post-capillary PH.
The 4D Auto LAQ
4V probe (4Vc) was used for imaging acquisition in the apical chamber
view with the image frame rate >30 frames/s, and the
parameters of LA 4D volume and strain were acquired by software of 4D
Auto LAQ. When 4D Auto LAQ analysis mode were selected, the sub-mode
sequentially entered. Firstly, the sampling point was placed at the
center of mitral valve annulus level, then the ‘review’ function was
selected to obtain the parameters of LA volume and strain
(Figure 1 ). The indices of left atrial volume between the
various stages, including LAVImax, LAVIpreA, and LAVImin were measured
simultaneously. LA longitudinal strain parameters were also evaluated
using this technique including LA reservoir strain (LASr), LA
conduit strain (LAScd), and LA
contraction strain (LASct). Meanwhile, ePLAGS was calculated as
TRV/LASr. LA function in different phases, including storage, channel
and active systolic function were calculated as following: