2.2 Echocardiographic image acquisition
All patients were examined with the Philips EPIQ 7C ultrasound system,
and the require image were collected by S5-1 and X5-1 probes. During the
examination, all patients in the control and paroxysmal AF groups had
sinus rhythm and heart rate <100 beats/min, while the average
ventricular rate <100 beats/min in the persistent AF group.
First, after connecting the ECG, the patient was placed in the left
lateral position, and the S5-1 probe was used to observe the
parasternal-long axis view. Subsequently, the near-field area was
enlarged and the image gain was appropriately adjusted to fully display
EAT, which located in front of the right ventricular free wall and
beneath the pericardium. Using the aortic annulus as a reference, the
reference line was placed across the aortic annulus and the right
ventricular free wall, and EAT thickness was measured vertically in
front of the right ventricular free wall at end-systole. Then, the
parasternal-long axis view and apical two-chamber and four-chamber views
were collected, and four cardiac cycles were continuously recorded to
obtain LAD and LVEF which was analyzed by the biplane Simpson’s method.
Finally, the X5-1 probe was used to display the apical four-chamber
view, and the “full-volume” mode was selected to record four cardiac
cycles continuously to obtain the three-dimensional volume of left
atrium.