Study population and design
After approval from the institutional ethical committee and written consent of the patient and their parents, 50 ostium secundum ASD patients and 20 age-matched control healthy subjects were recruited.
The ASD patients with haemodynamically significant left to right shunt (Qp/Qs > 1.5), dilated right-sided chambers denoting volume overload and/or pulmonary hypertension, who were referred for elective transcatheter closure, were included in this prospective observational study. The inclusion criteria included the presence of isolated ostium secundum ASD with a diameter of > 5 and < 40 mm and sufficient edges (> 5 mm) except for aortic one and pulmonary vascular resistance (PVR) < 5 Wood units/m2 and < 2/3 systemic vascular resistance (SVR) [11].
The criteria of exclusion were those with insufficient ASD rims (except aortic rim), other types of ASD, irreversible pulmonary hypertension or PVR > 2/3 SVR and any associated condition that may result in systolic or diastolic dysfunction, such as any type of arrhythmia especially atrial fibrillation, hypertension, diabetes, ischaemic heart disease and heart failure or LV diastolic dysfunction.
For all cases, a comparison was made between the findings of the 2D-TTE-derived tissue Doppler (TDI) and strain (S) imaging before, at 24 h and 1 month after intervention.
According to the WHO and USA, age limits of childhood, adolescence and adulthood and the age of ASD patients at the time of transcatheter closure, the researchers divided the study group into two subgroups: group-1 was a group of children and adolescents whose transcatheter closure was done at age less than or equal 19 years old (n = 34), and group-2 included adults who underwent transcatheter closure at age > 19 years old (n = 16) [12,13,14].
Transthoracic echocardiography
An iE33 ultrasound system (Philips Healthcare, Best, The Netherlands) equipped with a 2D cardiac probe S5–1 (1–5 MHz) was used to conduct all standard TTE imaging with ECG gated views of grey scale, M-mode, tissue Doppler (TDI), 2D colour Doppler and S and SR.
The echocardiographic views included long and short parasternal views and apical two-, three- and four-chamber views. Throughout the subcostal view, we primarily used 2D images and coloured flow images to determine the size of ASD, the anatomical characteristics of the defect and its relationship to the superior and inferior vena cava. The sample volume was set at 5 mm for continuous wave (CW) and pulsed wave (PW) Doppler images. Each view was stored in cine loop with three cycles and a frame rate of 40–80 Hz for offline analysis by using the Q-lab software following the European Society of Cardiology (ESC) speckle tracking-recommended protocols [15].
Left atrial diameter (LAD) and RV and LV end-diastolic diameters (RVEDD and LVEDD) were quantified from apical four-chamber (A4C) view and were estimated using M-mode image in the long-axis parasternal (LAP) view. Consequently, the RVEDD/LVEDD ratio was obtained. Tricuspid annular plane systolic excursion (TAPSE) has been acquired from the lateral point of the tricuspid annulus in A4C view through the M-mode approach [16]. In parasternal long-axis view, the left ventricular and aortic dimensions were measured on a parasternal long-axis view. Additionally, 2D-TTE and derived Doppler measurements were used to estimate the pulmonary/systemic shunt ratio (Qp/Qs) through the following equation: [RVOT (RV outflow tract) VTI (velocity time integral) × RVOTd (RVOT diameter)]/[LVOT (LV outflow tract) VTI × LVOTd (LVOT diameter)] [17, 18]. CW Doppler echocardiography of the tricuspid flow provides the estimated systolic pulmonary artery pressures (sPAP) [19, 20]. Using tricuspid regurgitation jet velocity (V) and simplified Bernoulli equation, the sPAP is best derived from RV systolic pressure (RVSP): RVSP = 4(V)2 + derived RA pressure [21].
LV diastolic function assessment
Tissue Doppler imaging (TDI) was estimated at the basal-lateral and septal mitral annulus from the A4C view to calculate the early diastolic velocity (e′) and late diastolic velocity (a′) (normal values: septal e′ = 8 mm/s, lateral e′ = 10 mm/s, respectively) [22].
2D strain imaging
The examination of patients and healthy subjects was done in the left lateral position before, at 24 h and 1 month after the ASD closure. Then, the 2D harmonic images of LV and RV for later offline processing were recorded. For offline analysis, 2D strain data were collected and processed in a cine loop format (movie clips) in all apical views. In the apical two-, three- and four-chamber views, the left ventricle’s endocardium was drawn automatically in the end-systole over the entire heart cycle. Afterwards, the RV endocardial borders were tracked manually then divided automatically into seven segments by the same software of LV (basal, mid, apex and apical segments of the septum and lateral wall), where the septum was shared between both ventricles and the average RV free wall longitudinal strain was measured as a mean value of three segments of apical, mid- and basal lateral wall.
The Q-lab data analysis (Philips) software showed the global and regional peak longitudinal S for the respective segments of the LV and RV (GLS, PLSS, respectively) after approved of the cine loops by the read operator.
Perioperative assessment
In the perioperative assessment of ASD patients, TEE was performed for all patients to assess the suitable device size. All patients aged more than 40 years underwent the diagnostic coronary angiography before intervention.
Procedural details
Under general anaesthesia, the transcatheter closure of the ASD was carried out with fluoroscopic and TEE assessment. In patients with ASD and pulmonary hypertension, the assessment of pulmonary artery pressure and PVR was done under 100% FiO2 before ASD closure. According to the exclusion criteria, all patients with elevated left atrial pressure (LAP) and left ventricular end-diastolic pressure (LVEDP) > 12 mmHg at baseline were assumed to have LV diastolic dysfunction and were excluded from the study [23]. In the present study, device size was chosen after adding 2–4 mm to the widest defect diameter according to TEE guidance or by using the balloon stretching diameter of transcatheter stop-flow technique. Then, the selected Amplatzer Septal Occluder (AGA Medical, Golden Valley, MN, USA) was implanted. For complex cases, the balloon-assisted technique of device deployment was used.
Statistical analysis
The researchers used the Statistical Package for the Social Science (SPSS) 24.0 (IBM) for statistical analysis. The histogram and Q-Q plot were used for testing the normality of data. Continuous variables were presented as mean ± standard error. Comparison between the different groups was done by using independent two-tailed t test. The paired t test was used to compare the results of the same group before and after the intervention. The statistically significant data was considered when P value < 0.05.