Intraoperative Imaging Strategy Unique to Japan for Transcatheter Closure of Atrial Septal Defects

Atrial septal defect (ASD) accounts for 7–13% of cases of congenital heart disease (CHD) and is one of the most common CHD found in adults.¹ In patients with significant shunts resulting in right-sided enlargement, ASD closure is recommended to prevent atrial arrhythmia, decreased exercise tolerance, progression of pulmonary hypertension or tricuspid regurgitation, and development of heart failure, even if asymptomatic.² Transcatheter closure of secundum ASD was first reported in 1976³ and was approved in Japan in 2005. Today, approximately 1,200 procedures are performed annually in Japan using 3 currently available devices: the Amplatzer Septal Occluder device (Abbott, Chicago, IL, USA), Occlutech Figulla Flex II device (Occlutech GmbH, Jena, Germany), and Gore® Cardioform ASD Occluder (Japan Gore, Tokyo, Japan).¹ In the early days of transcatheter ASD closure, transesophageal echocardiography (TEE) was primarily used as the imaging mode during procedures. The prototype of intracardiac echocardiography (ICE) was first used experimentally in 1991 to visualize ASD closure devices.⁴ Since the early 2000s, ICE, together with TEE, has played an important role in the morphologic evaluation of defects, guidance of the procedure, and monitoring of procedure-related complications. To date, several studies have compared the advantages and disadvantages of ICE and TEE guidance for transcatheter ASD closure (Table). The greatest advantage of ICE is that it does not require general anesthesia, which has been shown to reduce both procedure time and hospital stay.^5–9 In addition, almost all previous studies have reported that ICE- and TEE-guided ASD closure achieved comparable success and complication rates.^6–9 Against this background, the use of ICE as guidance for ASD closure in the USA increased dramatically from approximately 10% to 50% between 2003 and 2014.⁷

Table. Previous Studies Comparing ICE and TEE in Guiding Transcatheter ASD Closure

	Alboliras et al5	Kim et al6	Alqahtani et al7	Zhao et al8	Tanabe et al10
Study period	1999–2002	2003–2010	2003–2014	2010–2011	2015–2020
Country	USA	Korea	USA	China	Japan
No. of ICE vs. TEE vs. both	20 vs. 20 vs. 0	318 vs. 237 vs. 5	1,976* vs. 2,237* vs. 0	23 vs. 23 vs. 0	519 vs. 1,428 vs. 900
Characteristics of ASD	BOD was comparable	BOD/SFD/device size were comparable	NA	BOD/SFD/device size were comparable	TEE and both-modalities groups included more complex ASD cases
Findings in favor of ICE	Lower total physician charges	Shorter procedure	Less vascular complications	Shorter fluoroscopic and procedure times
			Shorter length of stay†
Findings in favor of TEE	Lower total hospital charges				Shorter fluoroscopic time
Comparable findings for ICE and TEE	Total hospital and professional charges	Major and minor complications	Hospital charges	Procedural success and complications	Procedural success and complications

*Includes patent foramen ovale and ASD. ^†Comparison between propensity-matched groups. ASD, atrial septal defect; BOD, balloon occlusive diameter; ICE, intracardiac echocardiography; NA, not available; SFD, stop flow diameter; TEE, transesophageal echocardiography.

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In this issue of the Journal, Tanabe et al¹⁰ present a valuable report based on a prospective nationwide database, revealing trends in echocardiographic modalities used during transcatheter ASD closure in Japan from 2015 to 2020. Similar to reports from other countries, the success and complication rates were comparable between ICE- and TEE-guided procedures. They found that ICE-alone guidance in Japan was used in approximately 20% of all cases, much less than in the USA,⁷ and mainly in high-volume centers and in less complicated ASD cases. In contrast, the lower-volume centers and more complex ASD tended to use both ICE and TEE, accounting for 30% of the total. Such a careful intraoperative imaging strategy may compensate for limited experience and contribute to the high procedural success rate and very low complication rate of percutaneous ASD closure in Japan as a whole. This valuable finding reflects the unique situation in Japan, where both ICE and TEE are covered by medical insurance.

The atrial septum is well suited for imaging using ICE because of its near-field nature from the right atrium and lack of structural interference with the ultrasound. ICE is especially superior to TEE for visualizing the posterior-inferior interatrial septum.^11,12 If performed by experienced operators, ICE enables the acquisition of a sufficient image to guide the whole procedure of ASD closure.¹² However, because the effective use of ICE for interventional procedures is highly dependent on the operator’s skills, there is concern that training systems for ICE are currently not as well developed as those for TEE.¹³ Moreover, the biplane image and en face view of the atrial septum provided by 3-dimensional (3D) TEE might be superior to 2D ICE in allowing the operator to intuitively and quickly share the structure of the ASD during the procedure.¹⁴ Although 3D ICE has been developed,¹¹ it is not yet available for clinical practice in Japan. If 3D ICE is applied clinically in the future, it is expected to significantly improve the time efficiency and be used for ASD cases with complex anatomy. At present, however, it seems reasonable to use TEE or both for guidance in cases of complex ASD (wide range of rim defects, multiple or large defects, or septal malalignment), as demonstrated by the data from Japan.¹⁰

Finally, Tanabe et al note a sudden increase in the number of TEE-guided operations in 2020, and discuss that the phenomenon was provoked by the coronavirus disease-2019 pandemic.¹⁰ As this indicates, medical care is greatly influenced by the social and economic conditions of the time. Because TEE is a high-risk procedure for generating droplets and aerosols, it might be preferred for intraoperative use during emerging infectious disease pandemics rather than in preoperative evaluation. In another situation, if workstyle reform for Japanese doctors¹⁵ continues to be promoted in the future, ICE might become a recommended trend to reduce the workload of anesthesiologists and shorten procedure times. In addition, the day might come when only ICE or TEE is covered by medical insurance in Japan to reduce medical costs. Structural heart disease teams engaging in percutaneous ASD closure must continue their efforts to become familiar with both ICE and TEE in order to respond flexibly to various changes in social conditions and provide the best treatment at all times.

Disclosures

All authors declare that they have no conflicts of interest

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