New Modified Balloon-Assisted Technique to Provide Appropriate Deployment in the Closure of Large Secundum Atrial Septal Defect Using Amplatzer Septal Occluder in Children

Abstract: Background. Transcatheter closure of secundum atrial septal defect (ASD) is accepted as a safe alternative method to surgery. However, the deployment of the device across the septum using the conventional method presents difficulties in large ASDs. Methods. In the modified balloon-assisted technique (modified BAT), a Tyshak balloon (Numed, Inc) is placed in one of the left pulmonary veins and a long sheath is placed in the right upper pulmonary vein. Through this sheath, the Amplatzer septal occluder is deployed to its proper position with the help of the Tyshak balloon, which prevents the left atrial disc from prolapsing into the right atrium. This method was implemented in the treatment of patients with a large secundum ASD. In this study, defects that measured ≥15 mm by transesophageal echocardiography (TEE) were considered to be large secundum ASDs. Between June 2011 and September 2013, the modified BAT was used in the closure procedure of 30 patients (18 females/12 males) with large ASDs (group I). Between September 2003 and September 2013, 78 patients (47 females/31 males) with large ASDs were treated with conventional methods (group II). The results of both groups were compared. Results. In the comparison of the results between group I and group II, there were no significant differences between mean maximal ASD sizes by transthoracic echocardiography, mean maximal ASD size by TEE, Qp/Qs ratio, mean device diameter, failure rate, embolization incidences, residual shunt, and fluoroscopy time. However, there were significant differences in the mean ages, mean body weights, and mean PAPs between group I and group II. After adjusting for age and body weight, in terms of process failure, the conventional method was found 5.6 times more risky compared to modified BAT. Conclusion. Large secundum ASDs in children, transcatheter closure with Amplatzer septal occluder using the modified BAT is a simple, quite useful method. In addition, this method seems to reduce the procedure failure rate.

J INVASIVE CARDIOL 2014;26(11):597-602

Key words: secundum atrial septal defect, transcatheter closure, Amplatzer, new technique, children

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Editor's note: See angiographic video accompanying this article.

Contrary to belief, atrial septal defects (ASDs) are not always innocent. Many patients with ASDs are free of overt symptoms, although most will become symptomatic at some point in their lives. Symptoms often occur in the third or fourth decades of life if the defect is small, but they may occur in early infancy if the defect is large. Large ASDs may lead to congestive heart failure, frequent respiratory infections, and growth retardation in infants.¹ When ASD is hemodynamically significant, surgical closure is safe and effective; however, the morbidity associated with sternotomy/thoracotomy, cardiopulmonary bypass, postoperative complications, and residual surgical scarring cannot be avoided.² Furthermore, the surgical scar may lead to cosmetic concerns, particularly in females. The procedure of transcatheter closure of secundum ASD has been used as a safe and alternative method to surgery over the last two decades.³ The Amplatzer septal occluder (ASO) (AGA Medical) is one of the commonly used devices for percutaneous closure of ASD.³ 

However, transcatheter closure of large ASDs is difficult and usually requires multiple attempts before the device is satisfactorily deployed. Inappropriate deployment of the device results in procedure failure, particularly in cases of large ASDs with deficient rim, and the fluoroscopy time lengthens as a result of repetitive attempts. Occasionally, embolization of the device occurs as a complication of the procedure.⁴ Several methods have been developed for safer and successful transcatheter closure of large secundum ASDs. Dalvi et al⁵ described a balloon-assisted technique (BAT) with the same purpose. 

The main aims of our study are: (1) to describe the modified BAT; and (2) to compare our results using this technique with the outcomes of the conventional method in well-matched pediatric patients with large ASDs. 

Methods

Study population. This study was performed at Erciyes University Children’s Hospital’s Pediatric Cardiology Department. In our center, percutaneous ASD closure has been performed since September 2003 and 340 patients have undergone a transcatheter ASD closure procedure. Since June 2011, the modified BAT has been used in the closure procedure of large defects at our institution. In this study, defects that measured ≥15 mm by transesophageal echocardiography (TEE) were considered to be large secundum ASDs. Between June 2011 and September 2013, the modified BAT was used in the closure procedure of 30 patients (18 females, 12 males) with large ASDs (group I). Between September 2003 and September 2013, a total of 78 patients (47 females, 31 males) with large secundum ASD (group II) were treated with conventional methods. The results of both groups were compared.

The medical history of each patient was obtained and all patients underwent physical examination, electrocardiogram, and transthoracic echocardiography (TTE) before the procedure. Clinical symptoms related to ASD were determined. Defect and rim sizes were determined to assess the suitability of the defect for closure. Patients with isolated secundum ASD and without additional congenital heart disease underwent a transcatheter closure procedure. All parents were informed about the procedure and its potential complications, and written consent was obtained from each patient before the procedure.

Device. The Amplatzer septal occluder (ASO) was used in all patients. It is a self-expandable device consisting of a metal frame made of nitinol wire woven into double disks with a 4 mm connecting waist and polyester baffles sewn inside.⁴

Procedure. All procedures were conducted under general anesthesia. The procedures were guided by fluoroscopy, TTE, and transesophageal echocardiography (TEE). During the procedure, 100 IU/kg heparin and 50 mg/kg ampicillin were administered to the patients. The right femoral vein (6 Fr) was used for the delivery system and the left femoral vein (5 Fr) was used for the balloon that would support the device. A multipurpose catheter was secured in the left upper pulmonary vein using a 0.035˝ J-tipped exchange guidewire. The deflated balloon catheter was passed over the guidewire to enter into the left atrium and the sizing balloon (AGA Medical) was inflated using a mixture of 30% radioopaque agent and 70% physiological serum. The stretched ASD diameter was measured under fluoroscopy. The Amplatzer device was selected as 1-2 mm larger than the measurement obtained by balloon sizing. The multipurpose catheter was first introduced into the left atrium, then into the left upper or right upper pulmonary vein. From the right femoral vein, the delivery sheath was passed over a long 0.035˝ exchange guidewire, the top of which should be in the right upper pulmonary vein. The multipurpose catheter was advanced from the left femoral vein into one of the left pulmonary veins, and a 12 mm x 4 cm Tyshak II balloon (Numed, Inc) was then advanced to the left atrium and inflated after its deployment across the defect. The left atrial disc of the device was released in the left atrium outside the ostium of the right upper pulmonary vein, and was withdrawn toward the interatrial septum. The right atrial disc of the device was opened in the right atrium with the support of the Tyshak balloon. Thus, both discs of the device were seated over the balloon, preventing its dislocation into the right atrium. Later, the balloon was totally deflated.  When the device was seen to be in the appropriate position by TTE, TEE, and fluoroscopy, the balloon was withdrawn together with the guidewire. After a second look at the device by echocardiography, the device was released (Figure 1). 

In the conventional group, deployment of the ASO across the defect was performed as described in the medical literature.^2-4 We typically used Amplatzer devices 1-2 mm larger than the measurement obtained by balloon sizing. Initial attempts at device placement were performed using a suitable-diameter long delivery sheath (AGA Medical) positioned in the left upper pulmonary vein. Deployment of the device from the left upper pulmonary vein was performed in all patients. Before release of the device, TEE was performed to check the position of the device, presence of residual shunt, patency of coronary sinus and pulmonary veins, and mitral valve function. 

Follow-up. Patients were discharged 1 day after the procedure. Clinical evaluation, electrocardiography, and echocardiography were performed on the first day, first month, third month, sixth month, first year, and then yearly after the procedure. A low dose of acetylsalicylic acid (3-5 mg/kg/day) was given for 6 months after the procedure.

Statistical analysis. Statistical analysis to compare baseline characteristics was performed with Chi-Square and Fisher’s exact test as available in SPSS software (version 15.0 for Windows; SPSS, Inc). Continuous data were compared between groups using the Student’s t-test. Quantitative variables are expressed as means ± standard deviation and categorical variables as frequencies and/or percentages. P-values <.05 were considered statistically significant.

Results

 A total of 108 children with large ASDs were enrolled in this study. Seventy-eight patients (47 females/31 males) were treated with the conventional method and 30 children (18 females/12 males) were treated with the new modified BAT.  The profiles of the enrolled patients are summarized in Table 1. In the comparison of the results between group I and group II, there were no significant differences between mean maximal ASD sizes by TTE (18.5 ± 3.0 mm vs 18.1 ± 3.5 mm), mean maximal ASD sizes by TEE (19.9 ± 3.3 mm vs 19.1 ±  3.6 mm), Qp/Qs ratios (2.7 ± 0.7 vs 2.6 ± 0.8), mean diameter of devices (21.6 ± 3.9 mm vs 20.7 ± 4.5 mm), failure rate (1/30 vs 12/78), incidences of embolization (1/30 vs 2/78), residual shunt (0/30 vs 3/78) and fluoroscopy time (20.9 ± 4.7 minutes vs 26.5 ± 14.0 minutes), respectively. However there were significant differences in the mean age (5.4 ± 2.5 years vs 8.4 ± 4.1 years), mean body weight (19.6 ± 6.6 vs 31.1  ± 18.0 kg), and mean pulmonary artery pressure (22.5 ± 4.0 mm Hg vs 18.3 ± 3.4 mm Hg) between group I and group II.

Device embolization occurred in only 1 patient in the modified balloon technique group. In this patient, TEE examination had revealed a defect size of 28 mm, a superior rim of 7 mm, and an inferior rim of 4 mm. The size of the defect was measured as 24 mm with balloon sizing and was closed using a 28 mm ASO. Embolization of the device developed immediately after the procedure and the device was removed by grabbing it with a snare catheter. This patient underwent surgical closure. The procedure success rate  was 96.7% in group I. In patients who underwent an ASD closure procedure using the conventional method, device embolization occurred in 2 patients. The procedure failed due to device embolization in the pulmonary artery in 1 patient and in the left atrium in the other patient. The devices were removed surgically and the defects were repaired. The procedure was abandoned in 10 patients due to failure to deploy the device across the septum despite repeated attempts. These patients underwent surgical defect closure. The success rate of the procedure was 84.6% in group II (P=.11). After adjusting for age and body weight, in terms of process failure, the conventional method was found to be 5.6 times (0.672-46.814) more risky (P=.11) (95% confidence interval) compared to modified BAT.

No residual shunt was detected by TTE in any patient in group I, but was detected in 3 patients in group II; there was no statistically significant difference between groups (P=.56). No important rhythm problem, such as atrioventricular block or supraventricular tachycardia, was detected during or after the procedure. No significant difference was found between the two groups in terms of fluoroscopy time. After the procedure, echocardiographic examination revealed no process-induced pulmonary vein stenosis in any patient.

Discussion

Transcatheter closure of secundum ASD has been used over the last three decades; very recently, it has become an alternative to surgery using cardiopulmonary bypass. Transcatheter closure in cases of secundum ASD has been demonstrated in previous studies to be a safe and effective method, with high success and low complication rates.^6,7 However, in cases of secundum ASD with large defect size and deficient rim, the transcatheter closure of ASD may be difficult, and repetitive attempts may be required due to the malpositioning of the device across the septum; this consequently leads to longer fluoroscopy and procedure times, increased failure rates, and increased risk of various complications, including device embolization.^8-17 The low success rates in our cases with large ASD who underwent conventional closure prompted us to use new methods. 

Various techniques have been reported by interventional cardiologists in the medical literature, and include the left upper pulmonary vein technique; the right upper pulmonary vein technique; the dilator-assisted technique (the Hausdorf sheath by Cook Cardiology is a specially designed long sheath with the two curves at its end); the Tulip-Bud’s method; the Greek maneuver; the St Jude SL2 sheath technique; and the left atrial disc engagement-disengagement technique. These new techniques help stabilize the device during deployment, and have therefore provided higher success and lower complication rates.^18-22   

In 2005, the BAT was developed by Dalvi et al⁵ for the same purposes. In this technique, the left atrial disc of the device is opened in the right or left pulmonary vein and is pulled toward the interatrial septum. The sizing balloon, which is inflated within the right atrium, is thrust toward the interatrial septum. The waist and right atrial disc of the device are opened while the balloon is inflated. In this way, right atrial prolapse of the device is prevented due to the support of the balloon. In our modified BAT, we use the Tyshak II balloon, which is longer than the sizing balloon, in order to support the device. When this balloon is inflated within the interatrial septum, both discs of the device open over the balloon. In this way, right atrial prolapse of the device is prevented. Furthermore, when the balloon is deflated, the deployment of the device is conducted so as to be parallel with the septum. In addition, Tyshak II balloon is not required to thrust forward by a second interventional cardiologist in modified BAT.

Success rates of transcatheter closure of secundum ASD, independent of defect size, were reported to be 81.8%-100% in the medical literature.^8-21 At our center, transcatheter ASD closures have been performed in a total of 340 patients since 2003. The procedure failed due to device embolization in 3 patients and due to failure to deploy the device across the septum in 10 patients (13/340 patients; overall success rate, 96%). Apart from 1 patient, all failures were in the conventional group (12/78 patients; failure rate, 15.4%). In the large secundum ASD patients that we treated using the modified BAT, the failure rate of the procedure (1/30 patients; failure rate, 3.3%) was lower than in the conventional group, but the difference between the two groups was not statistically significant. In patients with large ASDs, multiple attempts to deploy the device during the same session result in increased time and quantity of fluoroscopy. In our study, the fluoroscopy time was found to be lower with the modified method compared to the conventional method. However, the difference between the two groups was not statistically significant. In addition, the fluoroscopy time was longer than reported in the literature. Considering the age of the patients in our study group, this increased time may have been due to larger defect sizes and the consequent requirement for multiple attempts.

Complications were classified as major and minor (Table 2). Under the influence of factors such as the size of the defect, adequacy of the rims, technical difficulties, and the level of experience of the interventional cardiologists, major complications have been reported as 0%-5.5% and minor complications as 0%-15.8%.^8-21 In our experience, the most common complication was device embolization, regardless of whether the modified BAT or the conventional method was used. No significant difference was found between the modified BAT group and the conventional group in terms of device embolization. Although device embolization usually occurs immediately after the procedure due to inappropriate ASO implantation, it may sometimes occur later. In this study, a total of 3 cases of embolization (1 in group I and 2 in group II) were observed, and these occurred immediately after the procedure. Similar device embolization rates that were reported in studies on the conventional method in the pediatric age. The rates for this complication reported by Rossi et al⁸ (0/27 patients), Cardenas et al⁹ (2/52 patients), Bartakian et al¹⁰ (0/128 patients), Behjati et al¹¹ (1/63 patients), Ueda et al¹² (1/208 patients), and Huang et al¹⁷ (1/52 patients) are consistent with the embolization rate with the conventional method reported in our study (2/78). Among the ASD series using new techniques developed by interventionists, the absence of device embolization has attracted attention in the studies of Quek et al¹⁸ (0/27 patients), Thanopoulos et al¹⁹ (0/185 patients), and Pinto et al²¹ (0/21 patients). The BAT study conducted by Dalvi et al⁵ included both pediatric and adult age groups, and there was no reported case of device embolization. In the current study, device embolization occurred in 1 patient from the modified BAT group and the device was grabbed and removed using a snare catheter. We interpret this complication to be a result of the deficient inferior rim of the defect (Table 3). 

Arrhythmias are the second most common complication reported in the medical literature, and are related to the manipulations performed during the procedure.^8-21 There was no case of arrhythmia requiring major therapy during or after the procedure in either of our patient groups. Supraventricular arrhythmia was resolved in both groups by catheter manipulation or by waiting for a while in 3 patients (1 patient in group I and 2 patients in group II). Likewise, conduction abnormalities were not seen in our experience. No patient developed thrombosis. The initiation of acetylsalicylic acid as an antiplatelet drug 1 day prior to the procedure and its regular use during the next 6 months are crucial.   

Apart from those mentioned above, none of the complications reported in the literature were observed during the procedure or during the following median 10 months, which was our follow-up time after the procedure. Although trivial residual leak was more common in the conventional method compared to the modified BAT, the difference between the two groups was not statistically significant. In a study conducted by Huang et al,¹⁷ the percentage of persistent small residual shunt was reported to be 6.4%. 

In a study on an adult population, Kaya et al²³ reported that transcatheter ASD closure by conventional method was successfully performed for 112 of the 117 patients (96%), with mean ASD diameter of 14.0 ± 4.2 mm as measured by TEE. Our modified BAT provides a similar success rate, despite the larger defect diameter in children. We think that this method, which we have applied in a pediatric age group, can also be used in adults.

No technique-related complications, particularly pulmonary veins stenosis, were seen in the patients who underwent modified BAT, during or after the process. Of note, it is important that the Tyshak balloon be deflated and withdrawn together with the guide before device release. 

Study limitations. This is a single-center study with a limited number of patients and a short-to-moderate follow-up period. The requirement for a second femoral line to ensure balloon support may be the only unwanted aspect of this procedure. Multicenter, randomized, prospective, comparative studies are required to confirm our results with satisfactory safety and efficacy of this new technique.  

Conclusion

Transcatheter closure with ASO using the modified BAT is a simple, useful method for large secundum ASD repair in children. In addition, this technique seems to reduce the procedure failure rate.

References

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From the Departments of ¹Pediatric Cardiology and ²Anasthesiology, Erciyes University Medical Faculty, Kayseri, Turkey.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted December 10, 2013, provisional acceptance given February 5, 2014, final version accepted March 26, 2014.

Address for correspondence: Dr Mustafa Argun, Erciyes University Medical Faculty, Department of Pediatric Cardiology, Kayseri Turkey. Email: dr.margun@hotmail.com