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Transcatheter closure of congenital heart defects with the use of septal occluders has been widely accepted as a preferred treatment; however, the high cost of these devices limits their clinical application in some countries. Few clinical data are available regarding lower-cost products. Accordingly, we evaluated the efficacy and safety of the Chinese-made Shanghai Shape Memory Alloy (SHSMA) occluder in patients with congenital heart defects. From December 2001 through December 2008, a total of 180 patients with congenital heart defects (ages, 3–68 yr; mean age, 17.35 ± 13.22 yr) underwent transcatheter closure with use of the SHSMA occluder: 73 had atrial septal defects; 64, ventricular septal defects; 40, patent ductus arteriosus; and 3, complex congenital defects. The mean diameters of the defects were 20 ± 7.6 mm (atrial septal), 4.9 ± 2.1 mm (ventricular septal), and 5.6 ± 2.2 mm (patent ductus arteriosus). The procedural success rates were 98.6% for atrial defects, 98.4% for ventricular defects, and 100% for patent ductus arteriosus and for complex defects. The overall incidences of sequelae were 5.5%, 9.4%, 2.5%, and 0, respectively. Six months postprocedurally, complete occlusion was associated with a significant decrease in the right ventricular Tei index in atrial septal defect patients (P <0.05) and with improvement of body mass index in 11 children. These results suggest that the SHSMA occluder is a safe, effective device for the transcatheter closure of congenital heart defects. For confirmation, a randomized controlled trial with more patients and a longer follow-up period is warranted.
The interventional approach has become increasingly preferred for the treatment of many congenital heart defects (CHDs), including atrial septal defects (ASDs), ventricular septal defects (VSDs), and patent ductus arteriosus (PDAs). Some severe sequelae that may affect the outcome of the interventional approach are receiving increased attention from researchers.1,2 Occluding devices currently in use include the AMPLATZER® septal occluder for ASD closure and the AMPLATZER® muscular VSD occluder (AGA Medical Corporation; Plymouth, Minn), the CardioSEAL–STARFlex® occluder (NMT Medical, Inc.; Boston, Mass) and the GORE HELEX septal occluder (W.L. Gore & Associates, Inc.; Flagstaff, Ariz). The short- and intermediate-term results achieved with these devices have been documented.3 Because the high cost of these devices can limit their widespread clinical use in some countries, there is a need for alternative, lower-cost products that are safe and effective. We conducted a preliminary evaluation of the efficacy and safety of a Chinese-made occluding apparatus, the SHSMA occluder (Shanghai Shape Memory Alloy Co., Ltd.; Shanghai, PRC), in patients who had ASDs, VSDs, and PDAs.
From December 2001 through December 2008, 180 CHD patients (87 male and 93 female), of ages 3 to 68 years (mean age, 17.35 ± 13.22 yr), underwent transcatheter closure with use of the SHSMA occluder at Affiliated Yancheng Hospital of Southeast University (PRC). Defects comprised 73 instances of ASD, 64 of VSD (including 11 intracristal VSDs), 40 of PDA (including 1 in association with dextrocardia), and 3 of complex CHD (1 VSD + anomalous inferior vena cava [IVC] drainage, 1 ASD + VSD, and 1 PDA + VSD). Chest radiographs and electrocardiograms (ECGs) were routinely performed upon the patients' hospital admission. All patients underwent preoperative ultrasonography. Those with a right-to-left shunt or other conditions that made closure unsuitable, such as overly large defects or defects too close to valves, were excluded from the study.4,5 We had written informed consent for all patients in regard to the use of the SHSMA occluder, and the implantation protocol was approved by our hospital's Medical Institutional Review Board.
Interventional Procedures. After the patients were given local anesthesia or combined intravenous anesthesia, occlusion procedures were performed according to the guidelines in the manufacturer's product literature. Monitoring of the patients was achieved by means of continuous transthoracic echocardiography or radiography.6,7
Complex CHD was treated with simultaneous transcatheter therapy. In the patient with VSD + anomalous IVC drainage, a track was successfully built through the anomalous IVC drainage that returned to the right atrium from the azygos vein and then reached the superior vena cava. In the patient with ASD + VSD, the VSD occluder was deployed before the ASD occluder was deployed. In the patient with PDA + VSD, the PDA was closed before the VSD was occluded.
Characteristics of the Occluders. The SHSMA occluders that were used in this study cost one half to two thirds the price of AMPLATZER septal occluders. The single-use SHSMA occluders, made from a shape-memory alloy of nickel and titanium, include 3 special kinds: the bent, eccentric PDA occluder; the thin-waisted, large-rimmed ASD occluder; and the “zero” asymmetric eccentric VSD occluder.
Unlike the AMPLATZER muscular VSD occluder, the SHSMA VSD occluder comes in symmetric and asymmetric models. The symmetric VSD occluder, which has a symmetric left disc, is commonly used on defects with rims that are more than 2 mm below the aortic valve. It is available in sizes ranging from 4 to 20 mm. The “zero” asymmetric VSD occluder, with a left-disc diameter larger than that of the waist, is appropriate for use on defects with rims that are less than 2 mm below the aortic valve. It is available in sizes ranging from 4 to 16 mm. The left disc extends toward the cardiac apex, and the superior margin is flush with the edge of the waist so that the distance between the superior edge of the waist and the aortic valve is 0. The right disc of both VSD occluders is similar to that of AMPLATZER VSD occluders.
The waist sizes for the thin-waisted, large-rimmed ASD occluder range from 8 to 16 mm. In contrast, the radius of the left disc is 12 mm larger than the waist, and the radius of the right disc is 8 mm larger than the waist. Therefore, it is designed for use in patients with small-diameter ASDs with atrial septal aneurysms or in patients with porous ASDs.
The bent, eccentric PDA occluder is similar to the AMPLATZER duct occluder. The diameter of the waist ranges from 6 to 16 mm.
Figure 1 shows the SHSMA occluders that are available for the treatment of each defect.
Tei Index Measurement. The Tei index is defined as (a – b)/b, where the time interval “a” is measured from the cessation of tricuspid inflow to its onset, and the time interval “b” is the duration of the right ventricular (RV) outflow velocity profile. Before each procedure and 6 months thereafter, color-Doppler echocardiography of the patients was performed with use of a Hewlett-Packard Sonos 5500® ultrasound system with a 2.5-MHz transducer. Two cardiologists, blinded to the treatment and clinical status of the patients, worked separately and then compared the measurements. Tissue-Doppler recordings were acquired as digital loops in apical 4-chamber and long-axis views. The Tei indices of sites at the anterior wall, posterior wall, free wall, and interventricular septum in the tricuspid annulus were measured as previously described.8,9 The measurements were recorded at least 3 cardiac cycles from the end of inspiration and 3 cardiac cycles from the end of expiration, and their values were averaged. The difference in the Tei index before the procedure versus 6 months afterwards was evaluated in the ASD group (n = 73), the VSD group (n = 64), and the PDA group (n = 40).
Follow-Up. All patients underwent a clinical examination, ECG, chest radiography, 24-hour Holter monitoring, and transthoracic echocardiography before hospital discharge, 6 months after the procedure, and yearly thereafter. Patients were monitored for 8 to 92 months (mean duration of follow-up, 45.6 ± 28.8 mo). We recorded the occurrence and treatment of intraprocedural and postprocedural sequelae. We recorded the incidence of concomitant or device-related diseases, such as severe anemia, erythrocytosis, and infective endocarditis. We also noted quality-of-life components.
Data were expressed as a frequency or percentage for nominal variables and as mean ± SD for continuous variables. Comparisons of clinical parameters, including those of the Tei index values pre- and postprocedurally, were performed with a paired-sample t test and the use of SPSS software version 11.0 for Windows (SPSS Inc., an IBM company; Chicago, Ill). A value of P <0.05 was considered statistically significant.
Table I shows the patients' characteristics. Initial deployment of the SHSMA occluder was successful in 178 of the 180 patients (98.9%), and no deaths occurred. Per patient, the average cost in U.S. dollars of each ASD occluder was $3,670.50; of each VSD occluder, $3,529.30; and of each PDA occluder, $3,105.80. Eleven patients with intracristal VSDs underwent treatment with “zero” asymmetric VSD occluders, and 8 ASD patients underwent treatment with thin-waisted, large-rimmed ASD occluders. Of the SHSMA occluder types, only the bent, eccentric PDA occluder was not used in this study.
Table II summarizes the sequelae. There were 6.1% in all patients (11/180), with 5.5% in ASD patients (4/73), 9.4% in VSD patients (6/64), 2.5% in PDA patients (1/40), and none in patients with complex defects (0/3).
Six of the 180 patients (3.3%) experienced intraprocedural sequelae, which involved 2 dislocations of the device and 1 instance each of air embolism, acute cardiac tamponade, atrioventricular (AV) block, and occluder deformation.
The lone deformation of an occluder occurred because of improper manipulation in a 5-year-old boy who had a VSD (Fig. 2). After the deformed device was successfully withdrawn, a new occluder was successfully deployed. One dislocated occluder fell into the right atrium and lodged in the tricuspid orifice of a 19-year-old female ASD patient, who then developed ventricular tachycardia and underwent surgical removal of the occluder. The other dislocation, in an 11-year-old boy who had an intracristal VSD, occurred when the occluder suddenly fell into the abdominal aorta as the right disc was released. The dislocated occluder was removed by use of a snare and a 6F multifunctional catheter, and a new occluder was successfully embedded.
Second-degree type II AV block occurred transiently in a VSD patient as the delivery sheath passed through the defect. In another case, air embolism occurred when the left disc was deployed in a 9-year-old boy who had an ASD: he developed sudden chest pain, nausea, and vomiting, and he lost consciousness. His heart rate decreased to 30 beats/min. An ECG showed 3rd-degree AV block with ST-segment elevation in leads II, III, and aVF. The air embolism was diagnosed, and appropriate measures were taken. Finally, cardiac tamponade occurred in a 45-year-old female ASD patient. As a 26-mm ASD occluder was being replaced with a 24-mm ASD occluder, she developed chest pain, bradycardia, hypotension, cardiac enlargement, and weak heartbeat under fluoroscopy, and she lost consciousness. An echocardiogram showed a growing pericardial effusion, and the patient underwent successful pericardiocentesis across the xiphoid process.
Five patients (2.8%) experienced postprocedural sequelae: 1 patient, AV block; 1, intermittent left bundle branch block (LBBB) with AV block; 2, sinus bradycardia with an accelerated junctional rhythm; and 1, nosebleed.
Third-degree AV block developed on the 2nd postprocedural day in a VSD patient, who recovered 2 weeks later after temporary pacing and therapy with hormones and atropine. On the 3rd postprocedural day, another VSD patient experienced intermittent complete LBBB that developed into complete LBBB complicated by 1st-degree AV block on the 7th day after the procedure. His condition returned to normal by the 13th postprocedural day after treatment with glucocorticoids and atropine. A 28-year-old man with a 22-mm ASD, in whom a 28-mm occluder was deployed, developed sinus bradycardia and accelerated junctional rhythm the day after the procedure. The condition resolved after a week of treatment with glucocorticoids and atropine. The other such case occurred in a 15-year-old female ASD patient in whom a 5-mm occluder was deployed: the arrhythmia developed on the 3rd day thereafter and resolved on the 10th day, after treatment with glucocorticoids and atropine. The nosebleed occurred in a 22-year-old woman on the 2nd day after PDA closure. Aspirin therapy was discontinued, and she underwent electrocoagulation. Two weeks later, aspirin therapy was resumed, and no nosebleed recurred during 8 months of follow-up. All 5 patients were treated appropriately and recovered well.
During the 8 to 92 months of follow-up, no severe aortic insufficiency or residual shunt was observed in any patient. No other new-onset sequelae and no cases of severe anemia, erythrocytosis, or infective endocarditis were recorded. Kaplan-Meier analysis with log-rank tests showed similar accumulative rates of freedom from any complication among the ASD, VSD, and PDA groups.
Tei Index. The Tei index values significantly decreased at 6 months after the closure procedure in comparison with the baseline values in ASD patients (P <0.05); however, the corresponding decreases in VSD and PDA patients were not statistically significant (Fig. 3). The Tei indices for the complex-CHD patients are excluded.
Quality of Life. Four of the 180 patients got married, and 1 experienced a healthy pregnancy. Before the procedures, 28 children had a low body mass index (<15); however, by the end of the follow-up period, 11 showed improved nutritional status (body mass index, ≥15). After hospital discharge and adequate recovery time, no child missed school for cardiac-related reasons, and most of the adults considered themselves to be more effective in their employment after the procedure than before.
Although no large, randomized controlled trials have compared the substantial differences in long-term outcome between surgical closure and transcatheter closure in CHD patients, transcatheter closure is increasingly preferred for treating certain types of heart defects. The advantages include fewer sequelae, shorter procedural times and hospital stays, higher rates of successful occluder release, higher rates of complete occlusion, and better cosmetic results.10 Apart from difficulties related to implantation techniques and drawbacks in mechanical design, high cost may be the reason that occlusion devices have not yet achieved widespread clinical use in many countries. Our study showed satisfactory results of transcatheter closure with the use of the Chinese-made SHSMA occluder, which costs less than do similar devices for VSD, ASD, and PDA closure.
In our study, occlusion was successful upon 1st deployment in 178 of the 180 patients (98.9%). Notably, the types and incidence of the sequelae in our patients after SHSMA occlusion were similar to those reported after closures performed with the AMPLATZER septal occluder.11–15 Deformation and dislocation of the SHSMA occluders are rare overall. If a device becomes dislocated during ASD closure, often the reason is that the defect is too big or has a deficient edge, so that the septum cannot adequately support the occluder. In our study, 1 dislocation occurred in a patient whose defect had a very high, thin edge; the other dislocation was attributed to improper manipulation. We observed no substantial valvular inadequacy, residual shunt, or hemolysis during the follow-up period, which may be the result of proper choice of occluder, detailed preoperative ultrasonographic testing, and strict inclusion criteria. In early procedures, ASD closure was associated with a higher incidence of air embolus: this sequela often occurred at the time of occluder release. Towing the occluder in liquids within the sheath—thus fully removing the air before the procedure—is an effective way to avoid air emboli.13
Atrioventricular block has frequently been reported in VSD patients who have undergone transcatheter closure: the approximate incidence is as high as 5.7%. The underlying mechanism may be associated with direct-compression trauma from device deployment and a subsequent inflammatory reaction or scar formation in the conduction tissue.16,17 In our study, the incidence of AV block was low, and all patients recovered well. Butera and colleagues16 reported that young age was significantly associated with complete AV block: their patients who experienced complete AV block were younger than 6 years old at the time of the procedure. Most of our VSD patients were adults or older children. In addition, in comparison with the AMPLATZER occluder, the SHSMA occluder's longer waist (3.5 vs 1.5 mm) causes less strain to be placed on the septum—thus reducing the risk of AV block. Selection of an appropriately sized device and careful monitoring contribute to the early recognition and prevention of sequelae such as AV block.
In recent years, the incidence of moderate-to-severe sequelae during PDA closure has decreased to less than 1%.18,19 In our study, we attribute the episode of nosebleed to a temporary elevation of blood pressure after PDA closure and to the patient's aspirin therapy.
Although the risk and difficulty of transcatheter closure in patients with complex CHD are inherently higher than in single-defect closure, we selected appropriate instruments for the treatment of our 3 patients who had complex CHD. All 3 patients recovered well and experienced no sequelae.
The evaluation of RV function plays a role in the clinical management of CHD patients and is closely related to outcome.20,21 Investigators have recently shown that the Tei index is useful in evaluating global RV function.8 Despite the large standard variance of the Tei index in all types of CHD patients in our study groups, our results showed that complete occlusion significantly decreased the Tei index at 6 months postprocedurally in ASD patients, indicating improved RV myocardial performance; this is consistent with findings in previous studies.8,22–24 To date, however, the underlying mechanism of improvement in the RV Tei index after ASD occlusion has not been clearly identified.
Several limitations of this study must be mentioned. Ours was a single-center study that involved a limited number of CHD patients. Furthermore, this study did not include a control group of patients who underwent closures with a similar occluder, such as the AMPLATZER septal occluder; accordingly, no final comparative analysis could be achieved. A multicenter randomized controlled trial is warranted in order to determine the long-term efficacy and safety of the SHSMA occluder in CHD patients. In the meantime, our study suggests that the SHSMA occluder is a viable device for transcatheter closure in CHD patients, due to its low cost and clearly curative effect.
We thank Dr. Yongwen Qin for providing helpful critical observations on this manuscript.
Address for reprints: Zhi-Feng Dong, MD, Department of Cardiology, Affiliated Yancheng Hospital, Southeast University, Yancheng 224001, PRC
Drs. Sun and Z.-F. Dong contributed equally to this description of a single-center study at Affiliated Yancheng Hospital, Southeast University, Yancheng, People's Republic of China.
Disclosure: The occluders used in this study were provided by Shanghai Shape Memory Alloy Co., Ltd. (Shanghai, People's Republic of China).