Initial Experience and Sizing Considerations Using the Three Lobed Amplatzer Ductal Occluder
- Volume 22 - Issue 4 - April, 2010
- Posted on: 4/1/10
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ABSTRACT: Background. The recently released Amplatzer Ductal Occluder 2 (ADO2) was designed specifically for use in small children with moderate-sized shunts and larger children with small patent ductus arterioses (PDA). We report our initial experience with this device. Methods. Patients referred with PDA underwent occlusion using the ADO2. This is a fabric-free nitinol wire 3-lobed device. All cases underwent pre-, intra- and post-procedural echocardiography, with follow up at 1 day and one month. Device sizing for device waist diameter and width was based on aortography. Results. Seven patients with a median age of 3 years and 4 months (range 7 months–23 years) and a median weight of 12 kg (range 7–56 kg) underwent successful PDA closure. The median ductal diameter was 1.5 mm (range 0.4–4 mm). Both transpulmonary (6/7) and transaortic approaches (1/7) were used. Recurrent patency at 24 hours with complete occlusion at 1 month was noted in a single case. A specific device-based length assessment applied resulted in shorter than recommended device selection. Conclusion. The ADO2 broadens the spectrum of PDAs that can be simply and safely treated with devices. The flexibility of the articulations, coupled with the alternative deployment techniques, allow for increased ease of treatment in a range of small patients and specific ductal anatomies. An alternative device-specific length measurement of the duct length may result in less retaining disc protrusion. Broader experience is required to further delineate device and patient selection as well as to document its long-term efficacy and safety.
J INVASIVE CARDIOL 2010;22:190–194
Key words: patent ductus arteriosus, occluder, transcatheter, device, pediatric interventions
Since the initial description by Portsmann et al of nonsurgical closure of patent ductus arteriosus (PDA),1 the percutaneous approach has developed into standard clinical practice. Coils,2,3 and subsequently devices, 4,5 have broadened the range of patients and anatomies treatable with percutaneous techniques. In spite of the range of devices and coils available for this procedure, there remains a limitation in small children with moderate-sized shunts and larger children with small PDAs. The recently released Amplatzer Ductal Occluder 2 (ADO2) (AGA Medical Corp., Plymouth, Minnesota) was designed specifically for these indications. We report our initial experience with this device.
Population. Patients presenting with a clinically significant PDA to a single general hospital in Jerusalem, Israel, were referred for percutaneous closure with the ADO2. In instances where the PDA was larger than 5.5 mm in diameter, use of the device was not considered. Patients with additional cardiac anomalies requiring surgical correction were referred for surgery, as were patients < 3 kg in weight.
Device and delivery. The ADO2 device is a modification of the ADO1 device as produced by AGA Medical Corporation. It is one of the range of vascular occlusion devices based on nitinol wire meshes shaped in sequential lobes. The ADO2 is characterized by two low-profile retention discs for placement in the aorta and pulmonary artery (PA) (Figure 1). A connecting waist of variable diameter and length for positioning within the PDA itself is attached to the retaining discs by two articulations. This allows the positioned, relatively soft device to adapt to the patient’s anatomy rather than distorting the anatomy to its shape as do the ADO1 and other plugs.6 When correctly positioned, there are six layers of nitinol mesh interrupting flow, allowing for rapid occlusion in the absence of integrated fabric patches. The sizing of the device is based upon the waist diameter and length measured by angiography. Diameter ranges are 3–6 mm and lengths are available in 4 or 6 mm. The retaining discs have a diameter 6 mm greater than the waist and the device is symmetrical with both retaining discs being of equal size (Figure 1). This allows for either transvenous or transaortic deployment. Devices with waists of 3 and 4 mm can be delivered through a 4 French (Fr) delivery system, while the larger devices require a 5 Fr system. The delivery system comprises a braided, flexible and tapered delivery sheath with a 90° curve and a flexible delivery cable.
Procedure. Devices were deployed using either transpulmonary or transaortic approaches. The standard transpulmonary technique for device deployment has been described for both the ADO14 and ADO2.7,8 Briefly, the duct is crossed from the pulmonary artery, the aortic retainer is then exposed in the main aorta and the delivery system withdrawn to allow for the waist to be deployed in the duct itself. The pulmonary retainer is then exposed to abut against the pulmonary arterial wall. Device positioning is confirmed by aortography using a pigtail catheter positioned in the aorta. An alternative and more rapid approach is direct passage through the duct from the aorta, subsequent exposure of the pulmonary disc, followed by deployment of the device waist and then aortic disc exposure for final positioning. Aortographic contrast injections are performed through the delivery sheath to confirm device positioning. For PDAs of < 2.5 mm, a 3 mm waist/4 mm-long device was used. For larger PDAs, a device size of 0.5–1.5 mm greater than the minimal ductal diameter by angiography was used. In all cases we performed transthoracic echocardiography prior to device release in order to confirm device position and ductal occlusion.
All patients were treated with preprocedural intravenous cefazolin (30 mg/kg) as well as an additional two doses postprocedurally within 24 hours. Intravenous heparin (50 U/kg) was administered at the commencement of each procedure. All patients underwent echocardiography at the completion of the procedure the next day and at a 30-day follow-up visit.
Seven patients with appropriate PDAs were treated. The patient age range was 7 months to 23 years (median 3 years 4 months), with a weight range of 7–56 kg (median 12 kg). A single adult (23 years) was treated under local anesthetic, with all remaining cases performed under general anesthetic. Patient demographic and intraprocedural characteristics as well as follow-up results are presented in Table 1.
Device deployment was successful in all cases, and intraprocedural ductal closure was successful in all cases. Next-day echocardiography demonstrated ductal occlusion in 6/7 cases with a small, silent, but significant, shunt demonstrated by echocardiography in a single case. At 30 days, echocardiography confirmed ductal occlusion without need for further intervention in all cases.
The device was deployed using a transvenous approach in 6 cases (Figure 2). In 1 case, a transaortic approach was used (Figure 3). In an additional case, a transaortic approach was attempted and the device was well-positioned on the pulmonary side and in the duct itself. However, due to a relatively small and asymmetric ductal ampulla, the aortic lobe’s inferior aspect fell into the ampulla, resulting in extension and protrusion of the superior aspect of the aortic lobe into the aorta. This could not be corrected despite multiple maneuvers including recapture and redeployment from different angles. The device was removed and redeployed from a transvenous approach, allowing for improved aortic positioning and successful device deployment (Figure 4).
In 2 cases where the duct was very short and the ampulla large, the device deployed from the transpulmonary approach resulted in the aortic lobe falling into the ampulla, with its articulation crossing the duct and the middle lobe and the pulmonary disc protruding into the pulmonary artery. Due to the short length of the ducts, the devices were able to be placed with only one or other of the articulations in the duct. The pulmonary protrusion was considered preferable and the devices were released with excellent acute results and no gradient around the device in the pulmonary artery. One of these 2 cases resulted in a recurrent shunt detected the next day. This complex case warrants more extensive description.
A 7-month (7 kg) female presented with a moderate-sized PDA that was sized 3 mm at the waist by echocardiography and 1.8 mm by angiography. Due to the echocardiographic sizing, a 4 x 4 mm device was deployed using a transvenous approach. The duct was very short and the waist positioned on the pulmonary side with a residual leak. The device was repositioned with the waist in the duct; complete closure was achieved, however, due to the angle that the aortic disc assumed with superior lobe protrusion into the aorta (Figure 5) and significant turbulence detected by echocardiography. With a small gradient in the aorta at the device site, it was considered prudent to remove the device and replace it with a smaller one. A 3/4 device was then deployed with the waist in this instance also assuming position in the pulmonary artery. The aortic disc sat well in the ampulla with no aortic protrusion; there was no significant turbulence in the pulmonary artery and the duct was occluded with no residual flow detected by echocardiography or angiography. This was considered a satisfactory position and the device was then released with a good result. Next-day echocardiography demonstrated a recurrent or residual shunt predominantly through the device which was still well positioned. The shunt was relatively small and there was clear evidence of hemodynamic benefit of the procedure with reduction of left ventricular size and mitral regurgitation. Echocardiographic follow up at 7 days confirmed the residual shunt with no significant difference and no evidence of hemolysis. At the 30-day echocardiographic follow up, there had been complete resolution of the shunt with an excellent final result.
The ADO2 device provides a solution for the closure of small- to moderate-sized PDAs as well as large PDAs in small children. The ability to position the device such that each of the retention discs assumes its independent orientation significantly reduces the risk of protrusion, anatomical distortion and displacement. The multiple layers of nitinol (two for each of the three lobes) allow for rapid ductal occlusion in the absence of integrated patches. This reduces residual shunt risks and the need to deploy additional coils or devices and results in an extremely low-profile device during deployment. Furthermore, the transaortic approach has significant benefit, allowing the procedure to be extremely simple and rapid with the use of a single arterial puncture (often 4 Fr) and the ability to perform test injections through the delivery sheath. This is a feature that, although not exclusive to this device, certainly adds to its deployment flexibility.