Transcatheter closure of ventricular septal defects (VSDs) is now offered as primary therapy at many institutions. We sought to evaluate the clinical feasibility and safety of device closure of intracristal VSDs using perimembranous occluders. A total of 49 patients were diagnosed with intracristal VSDs and assigned to the intracristal VSD group, and another 49 patients with the same size perimembranous VSDs were selected and assigned to the perimembranous VSD group. Two types of perimembranous occluders, symmetric and asymmetric, were used, and no difference was found between the groups with respect to successful closure. The diameter of the intracristal VSD was 3 to 10 mm (mean 5.8 ± 1.4) on the transthoracic echocardiogram. The procedure time and fluoroscope time in the intracristal VSD group were significantly greater than those in the perimembranous VSD group. More defects with a subaortic rim ≤2 mm on the transthoracic echocardiogram were present in the intracristal VSD group than in the perimembranous VSD group; thus, more asymmetric occluders were used in the intracristal VSD group. All devices remained in a stable position and in an optimal shape during follow-up. In conclusion, transcatheter closure of intracristal VSDs with the perimembranous occluder is feasible, safe, and effective.
Transcatheter device closure is being increasingly performed and offered as primary therapy for ventricular septal defects (VSDs) at many institutions. The benefits of avoiding bypass are intuitive, and the relative ease of placement makes this procedure ultimately attractive. The intracristal VSD is a specific anatomic location of a VSD in the infundibular septum. Many reports have been published regarding transcatheter device closure of perimembranous VSDs and muscular VSDs ; however, no reports have been published of device closure of intracristal VSDs. We report the possibility of transcatheter device closure of intracristal VSDs using perimembranous occluders at our hospital.
Methods
By June 2009, 637 patients with perimembranous VSDs and intracristal VSDs had undergone successful transcatheter closure at our hospital. All patients undergoing transcatheter closure of VSDs in our center were evaluated with transthoracic echocardiography (TTE) and left ventriculography before and during the procedure. The contraindications for device closure of VSDs have been previously discussed. The diagnostic criteria for congenital intracristal VSDs were (1) a defect located at the 12:00- to 1:30-o’clock position in the transthoracic echocardiographic short-axis parasternal view; (2) a diameter of the defect of ≤10 mm; (3) upper edge >2 mm from the pulmonary valve annulus; and (4) the defect could not be clearly visualized using left ventriculography in the 45°/25° left anterior oblique cranial projection. From June 2006 to June 2009, 49 patients were diagnosed with intracristal VSDs and assigned to the intracristal VSD group, and another 49 patients with the same-size perimembranous VSDs were selected and assigned to the perimembranous VSD group. The baseline characteristics of both groups are listed in Tables 1 and 2 . The ethics committee of our hospital approved the study, and all patients or their guardians provided informed patient consent.
| Variable | Intracristal VSDs (n = 49) | Perimembranous VSDs (n = 49) |
|---|---|---|
| Female/male | 29/20 | 30/19 |
| Age (years) | 18.5 ± 9.3 | 18.7 ± 9.8 |
| Age group (years) | ||
| 4–10 | 14 | 15 |
| 10–16 | 10 | 9 |
| >16 | 25 | 25 |
| Weight (kg) | 38.3 ± 15.6 | 39.5 ± 16.3 |
| Trivial-to-mild aortic regurgitation | 13 | 3 |
| Trivial-to-mild tricuspid regurgitation | 0 | 2 |
| Variable | Intracristal VSDs (n = 49) | Perimembranous VSDs (n = 49) |
|---|---|---|
| Pulmonary/systemic flow ratio | 1.8 ± 0.4 | 1.9 ± 0.4 |
| Systolic pulmonary artery pressure (mm Hg) | 34.3 ± 7.6 | 36.4 ± 7.9 |
| Mean pulmonary artery pressure (mm Hg) | 19.6 ± 5.8 | 20.3 ± 6.1 |
| Ventricular septal defect diameter on transthoracic echocardiogram (mm) | ||
| Mean | 5.8 ± 1.4 | 6.0 ± 1.5 |
| Range | 4–10 | 4–10 |
| Procedural success rate | 46/49 (94%) | 48/49 (98%) |
| Procedure time (min) | 61.2 ± 19.5 ⁎ | 45.7 ± 12.3 |
| Fluoroscopy time (min) | 31.3 ± 12.8 ⁎ | 19.3 ± 7.4 |
| Subaortic rim ≤2 mm (n) | 39 ⁎ | 16 |
| Subaortic rim >2 mm (n) | 10 | 33 |
| Device size used (mm) | ||
| Mean | 8.1 ± 1.5 | 8.2 ± 1.7 |
| Range | 6–12 | 6–12 |
| Device type used | ||
| Asymmetric occluders | 42 ⁎ | 16 |
| Symmetric occluders (A2B2) | 7 | 33 |
The closure device used was a modified double-disk occluder (Shanghai Shape Memory Alloy, Shanghai, China), based on the Amplatzer occluder. It consisted of a nitinol wire mesh shaped into 2 disks with a central connecting 2- to 3-mm-long waist and available in waist sizes ranging from 4 to 22 mm. Two types of perimembranous occluders, symmetric and asymmetric, were used. In both types, the diameter of the right disk was 4 mm larger than that of the connecting waist. The only difference between the occluders was the shape of the left disk. In the asymmetric occluder, the diameter of the left disk was 6 mm larger than that of the waist, with the left disk extending toward the apex and no superior rim extending toward the aortic cusps. In the symmetric occluder, the left disk was symmetric and the diameter was 4, 8, or 12 mm larger than that of the waist and called A2B2, A4B2, and A6B2, respectively.
The catheterization procedure was performed with the patients under conscious sedation for adult patients and children ≥10 years old and under general anesthesia for children <10 years old. The shunt volume was calculated by oxymetric measurements. Implantation of the VSD occluder was performed according to standard techniques previously described. In some patients, a novel wire-maintaining technique was used in which the track wire was maintained in the delivery sheath during the procedure. If the initial occluder was inappropriate, the delivery sheath could be reintroduced over the maintained wire. The diameters of the defects were determined by TTE at the moment of largest diastolic diameter on 2-dimensional echocardiography. Usually, the waist size of the device was selected such that it was ≥2 mm larger than the implanted defect size. A symmetric occluder was usually used for defects >2 mm from the aortic annulus. An asymmetric occluder was used for defects close to the aortic annulus with a subaortic rim of ≤2 mm, and the platinum marker on the left disk was kept toward the apex. The device was released only when its proper position was determined and interference with the aortic, pulmonary, and tricuspid valves had been excluded using left ventriculography, aortic angiography, and TTE.
After the procedure, all patients underwent electrocardiographic monitoring for 24 hours. Urinalysis was routinely performed to determine the presence of hemolysis. Patients without complications were discharged 1 week after the procedure, advised to avoid contact sports, and treated with oral aspirin (3 to 5 mg/kg/day) for 6 months. All patients underwent chest radiography and TTE before discharge. The follow-up protocol included assessments after 1 and 6 months and annually thereafter. All visits included a routine physical examination, chest radiography (once at 6 months), electrocardiography, and TTE.
Statistical analysis was performed using Fisher’s exact test and unpaired t test. All tests were 2-sided. A probability value of p <0.05 was considered statistically significant.
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