Patient Population

In the present study, we analyzed, in a retrospective manner, echocardiographic measurements of the rims surrounding ASDs in patients who underwent attempted transcatheter closure at our institution. Patients with ostium secundum ASDs with maximal defect diameters of ≤40 mm who were referred to our institution for transcatheter closure from September 2007 to August 2013 were the initial candidates for our study. For the purpose of the present study, patients who underwent surgical repair or in whom the transcatheter procedure was not attempted because of comorbidities were excluded from analyses. Patients who did not undergo complete evaluations with TEE were also excluded from this study. Indications for ASD closure involved having at least one of the following: hemodynamically significant atrial shunt, right ventricular overload, history of paradoxical embolization, and orthodeoxia due to ASD.

The regional ethics committee provided ethical approval for the study. The study protocol adhered to the tenets of the Declaration of Helsinki. All patients provided written informed consent before participation in the study.

Rim Assessment and Group Classification

Assessment of defect size and its surrounding rims and relationships to neighboring structures was based on findings on TEE. Comprehensive TEE was undertaken using a commercially available echocardiographic system (iE33 with an X7-2t or S8-3t transducer; Philips Medical Systems, Andover, MA) before or during the procedure by one of our echocardiologists (Y.K., M.T.). The maximal diameter of the ASD and minimal rim length were obtained from clinical reports. These measurements were confirmed by an observer who reviewed the clinical report and recorded images. All measurements were obtained from an image at end-systole. Surrounding rims were classified into four areas: retro-aortic (RAo), atrioventricular valve (AVV), inferior vena cava (IVC), and superior vena cava (SVC). A rim length of <5 mm was considered to be deficient. The RAo rim was measured as the distance between the aortic annulus and the ASD ( Figure 1 A). This distance was measured on an upper or midesophageal view starting at a multiplane angle of 0°, with stepwise sweeping at 15°, 30°, and 45°. The AVV rim was measured as the distance between the ASD and AVV ( Figure 1 B). This distance was measured on a mid- or lower esophageal view starting at an angle of 120°, with stepwise sweeping at 135° and 150°. The IVC rim was measured as the distance between the ASD and IVC ( Figure 1 C). This distance was measured on a mid- or lower esophageal view starting at an angle of 60°, with stepwise sweeping at 75° and 90°. The SVC rim was measured as the distance between the ASD and SVC ( Figure 1 D). This distance was measured on an upper or midesophageal view starting at an angle of 90°, with stepwise sweeping at 105° and 120°. Patients were divided into three groups according to the sufficiency or deficiency of surrounding rims: patients with sufficient rims (sufficient group), patients with single deficient rims (single group), and patients with multiple deficient rims (multiple group).

Rim measurements. Distance between arrowheads was measured as length of a rim. Transesophageal echocardiographic images at 15° showing a deficient RAo rim (A) , at 135° showing an AVV rim (B) , at 60° showing an IVC rim (C) , and at 90° showing an SVC rim (D) . Ao , Aorta; LA , left atrium; RA , right atrium; TV , tricuspid valve.

In 25 subjects selected randomly, upon review of the moving images of echocardiograms, rim measurements were undertaken to estimate intra- and interobserver variability. These measurements were reported by two observers blinded to each other’s results and other echocardiographic data. One observer undertook measurements again after 4 weeks to ascertain intraobserver variability. Intra- and interobserver variability was expressed as the percentage error of each measurement and determined as the difference between the two measurements divided by the mean value of the two measurements.

Procedural Protocol

Transcatheter ASD closure was carried out with patients under general anesthesia with intubation or under local anesthesia with mild sedation for patients who were not fit for general anesthesia because of disturbed respiratory function. Hemodynamics were assessed before device deployment. The pulmonary-to-systemic flow ratio was calculated using oximetry according to the Fick principle. ASOs were used to close the ASDs in all patients. Procedures were guided by echocardiography with fluoroscopic imaging. Transesophageal echocardiographic guidance using the X7-2t transducer was the standard method. Transesophageal guidance using the S8-3t transducer or intracardiac echocardiographic guidance using the AcuNav catheter (Siemens Acuson, Mountain View, CA) was used in patients who were not fit for general anesthesia or were not eligible for TEE at the time of the procedure. A long 8- to 12-Fr sheath was placed in the atrial septum. Balloon sizing using a stop-flow method with an AGA sizing balloon (St Jude Medical) was undertaken for device selection. Balloon diameter was measured on a transesophageal echocardiographic image but not on a fluoroscopic image. The selected size of the device was identical or 1 mm larger than the balloon diameter. Otherwise, the size of the device was selected according to the maximum ASD diameter, as measured by TEE, without balloon sizing. The selected size of the device was determined under consideration of the morphologic appearance of the defect visualized by three-dimensional (3D) TEE. The selected size of the device was 4 to 5 mm larger than the maximal diameter in patients with round defects ( Figure 2 A) and 2 to 4 mm larger in patients with elliptical defects ( Figure 2 B). The selected size was 0 to 2 mm larger in patients with extremely elliptical defects ( Figure 2 C). The decision to undertake balloon sizing was based on operator preference. The selected device was deployed at an appropriate position of the atrial septum. The device and adjacent structures were assessed by echocardiography to ensure that no neighboring structures were encroached upon. Gentle pushing and pulling of the delivery cable ensured that the device was in a stable position. After the device was unscrewed from the cable, the appropriate position of the device was confirmed on echocardiography. Some patients had a complete IVC rim deficiency that was seen to impinge directly on the inferior-posterior wall of the atrium by the ASO after device deployment ( Figures 3 A and 3B).

Morphologic assessment with three-dimensional TEE. Images viewed from the right atrium. (A) Round defect, (B) elliptical defect, (C) extremely elliptical defect. Ao , Aorta.

Transesophageal echocardiographic images in a patient with an ASD with IVC rim deficiency. (A) Image at 90° showing the deficient IVC rim ( arrow ) adjacent to the IVC. The IVC rim is located at the border between the bottom of the atrial wall and the IVC. (B) Image after deployment of the ASO, showing the atrial wall being directly pinched by the device ( arrowheads ). LA , Left atrium; RA , right atrium.

Procedural Success and Clinical Outcomes

Procedural success was defined as successful deployment of the device followed by hospital discharge without procedure-related major adverse events necessitating medical treatment or surgical intervention. Minor adverse events that developed before hospital discharge but did not require intervention (e.g., cardiac dysrhythmia without significant symptoms) were included in follow-up outcomes.

Follow-up clinical outcomes were evaluated by medical interview at our institution or the referring clinic. Follow-up examinations, including transthoracic echocardiography (TTE), were planned for 1 day, 1 month, 3 months, 6 months, and then annually after the procedure. Outcomes were assessed according to cardiovascular events and adverse events. “Cardiovascular events” comprised heart failure, stroke, acute myocardial infarction, systemic arterial embolization, and new-onset arrhythmia. “Adverse events” comprised all-cause death (i.e., noncardiac death) and cardiovascular events. Patients were followed from the day of the procedure until the date of the first documented event or the time of final follow-up, whichever came first. Patients who underwent TTE ≥6 months after the procedure were assessed for residual shunting that crossed the atrial septum on color Doppler imaging. Results included in the analysis were those obtained from the last available echocardiographic examination of each patient.

Statistical Analyses

Continuous data are expressed as mean ± SD or range. Discrete variables are expressed as frequencies and percentages. Data analyses were done using JMP version 9.0 (SAS Institute Inc, Cary, NC). P values < .05 were considered to indicate statistical significance. Statistical analyses among the three groups were carried out using Pearson χ ² tests for categorical variables and one-way analysis of variance for continuous variables. Cumulative event-free survival was estimated using Kaplan-Meier analyses, and event-free survival curves were compared using the log-rank test.

Study Population

During the study period, 489 patients with ASD with defect diameters ≤40 mm were referred to our institution. Patients were referred for surgery because of significant mitral regurgitation in two patients, aortic regurgitation attributable to annuloaortic ectasia in one patient, cor triatriatum in one patient, and allergy to nickel in one patient. In one patient, a brain tumor was discovered, and intervention for the ASD was not undertaken. Thus, six patients were excluded from the study population. Risks and benefits of transcatheter versus surgical closure were explained to all patients by a physician specializing in this therapy (T.A. or K.N.), after which five patients opted for surgical repair. Another three patients were excluded because they had not undergone TEE before or during the transcatheter procedure, and therefore complete evaluation of surrounding rims was not available. One patient in whom transcatheter closure was aborted because of an elevation of pulmonary capillary wedge pressure during balloon sizing was also excluded. Ultimately, 474 patients with ASDs who had complete evaluation of surrounding rims with TEE underwent attempted transcatheter ASD closure using ASOs and formed the study cohort.

Rim Sufficiency and Deficiency

The distribution of study patients according to location of the deficient rims or rim sufficiency is shown in Figure 4 . Prevalence of procedural success is also shown. The sufficient group consisted of 101 patients with sufficient rims. There were 323 patients with deficient RAo rims alone and 15 with deficient IVC rim alones. These 338 patients were classified into the single group. Thirty-three patients had deficient Rao rims combined with IVC rims and two combined with AVV rims. These 35 patients were classified into the multiple group. Deficient IVC rims with or without additional deficient rims were observed in 48 patients. There were 12 patients with complete IVC rim deficiency (i.e., IVC rim of 0 mm) and 36 with small insufficient IVC rims (i.e., IVC rim of 1-4 mm). None of these patients were complicated by partial anomalous pulmonary venous return. No patient had a deficient SVC rim in the single group or in the multiple group.

Patient characteristics by location of rim deficiency for all 474 patients in whom the transcatheter procedure was attempted.

Intraobserver variability and interobserver variability for rim measurements was 11.1% and 12.8%, respectively.

Baseline Characteristics of Classified Groups

Baseline characteristics of the study population are presented in Table 1 . Age ranged from 5 to 83 years (mean, 46 ± 22 years). Body surface area of patients ranged from 0.73 to 2.63 m ² (mean, 1.52 ± 0.24 m ² ). There were no significant differences in age, sex, body surface area, or other complicating diseases or hemodynamic disorders, with the exception of pulmonary hypertension, among the three groups. The maximum ASD diameter ( P < .001) and the pulmonary-to-systemic flow ratio ( P < .001) differed significantly among the three groups.

Procedural Results

The procedure was successful in 463 patients (98%). Prevalence of procedural success differed significantly among the three groups (sufficient group, 100%; single group, 98%; and multiple group, 86%; P < .001) ( Table 2 ). The selected device size was significantly larger in the multiple group ( P < .001), but the duration of fluoroscopy to accomplish the procedure was not significantly different among the three groups ( P = .060). Balloon sizing was less likely to be carried out in the multiple group ( P < .001). Eleven cases were unsuccessful, eight because of technical and morphologic difficulties in deploying the device in a stable and appropriate position and three procedures that were complicated by procedure-related major adverse events during the procedures or before hospital discharge.

Table 2

Procedural details and results

	Sufficient group	Single group	Multiple group ∗	P	All cases
	( n = 101)	( n = 338)	( n = 35)		( n = 474)
Echocardiographic guidance
TEE (X7-2t)	100 (99%)	331 (98%)	34 (97%)	.403	465 (98%)
Micro-TEE (S8-3t)	1 (1%)	5 (1%)	0 (0%)		6 (1%)
ICE (AcuNav)	0 (0%)	2 (1%)	1 (3%)		3 (1%)
Size selection of device
Balloon sizing	79 (78%)	249 (74%)	5 (14%)	<.001	333 (70%)
Maximal defect diameter	22 (22%)	89 (26%)	30 (86%)		141 (30%)
Device size (mm)	18 ± 6	21 ± 6	31 ± 6	<.001	21 ± 7
Fluoroscopy time (min)	13 ± 7	13 ± 6	16 ± 9	.060	13 ± 7
Procedural success	101 (100%)	332 (98%)	30 (86%)	<.001	463 (98%)

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