Initial Experience with the New Amplatzer® Duct Occluder II
- Volume 21 - Issue 8 - August, 2009
- Posted on: 8/17/09
- 0 Comments
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ABSTRACT: Background. Different devices are used for trans-catheter occlusion of patent ductus arteriosus (PDA), each with its own limitations and complications. We report our initial single-center experience with the new Amplatzer® Duct Occluder II (ADO II), which has been designed to address some of these issues. Methods. From April until October 2008, 10 consecutive patients with PDA (minimal diameter ≥ 2 mm) were enrolled for intention-to-treat with ADO II. The median age was 10.2 years (7 months to 51.4 years); the median weight was 35.5 kg (6.3–70 kg). Results. ADO II implantation was attempted in 10/10 patients. The mean PDA diameter was 3.1 mm (± 1.0 mm), and the mean device waist diameter was 4.0 mm (± 1.3 mm). In 1 patient, the ADO II encroached upon the left pulmonary artery, hence it was changed to an Amplatzer Duct Occluder I. In another patient, the shape and size of the duct necessitated the use of a Cook detachable coil. Complete angiographic closure was achieved in 8/8 ADO II implantations (100%) and in the patient with the coil. In the patient with an ADO I, complete echocardiographic closure was demonstrated at 24 hours. No device embolization or complications related to implantation occurred. Conclusions. This initial experience demonstrates the feasibility and efficacy of the ADO II to occlude PDA with a minimum diameter ≥ 2 mm. It is especially useful in smaller children with larger duct diameters. Longer-term follow up in a larger cohort of patients is required to establish safety and long-term results.
Key Words: Amplatzer Duct Occluder II, patent ductus arteriosus
J INVASIVE CARDIOL 2009;21:401–405
A patent ductus arteriosus (PDA) is one of the most common lesions in congenital cardiology.1 Since the middle ages, Leonardo Botallo’s name has normally been associated with the first description of a PDA.2 The strategies for management of PDAs continue to evolve. In 1939, Gross and Hubbard described the first successful surgical closure of a patent arterial duct.3 Porstmann and colleagues reported the first transcatheter closure of a PDA in 1967,4 and in 1979, Rashkind and colleagues performed the successful deployment of a percutaneously delivered double-disk device in an infant.5 Since then, transcatheter occlusion of PDAs has been a well-established alternative to surgical closure6–10 and various devices and coils have been used to occlude the PDA.
The Amplatzer® Duct Occluder I (ADO I) (AGA Medical Corp., Golden Valley, Minnesota) was introduced in 1999, and since then numerous studies have been published, proving its safety and efficacy as a device for transcatheter PDA occlusion.11–13 Due to the limitations in terms of PDA shape and size amenable to transcatheter occlusion, minimum weight of the patient, size of the delivery sheath/system and associated complications, further modifications of the ADO I were introduced, viz. the angled Amplatzer duct occluder, the swivel-disc device and the plug occluder, but these failed to address all the concerns. The Amplatzer Duct Occluder II (ADO II) was introduced earlier this year to address some of these limitations.
We present our single-center experience with this new ADO II in cases of transcatheter occlusion of a persistent arterial duct in patients weighing ≥ 5 kg.
From April 2008 until October 2008, 10 consecutive patients with a PDA with a minimal diameter of ≥ 2 mm were enrolled for intention-to-treat with an ADO II. The median age was 10.2 years (range 7 months–51.4 years). The median weight was 35.5 kg (range 6.3–70 kg).
Informed consent was obtained from parents of minors and from adult patients. Relevant approvals were obtained from the hospital authorities, and we conformed to our institutional guidelines and those of the American Physiological Society.
The procedure was performed under general anesthesia and fluoroscopy. Preprocedural assessment included clinical examination, two-dimensional (2-D) echocardiography (Phillips® ie33 and Phillips® SONOS 7500; Philips Healthcare, Andover, Massachusetts), chest X-ray and 12-lead electrocardiography (ECG).
Inclusion criteria. All consecutive patients who had clinical and/or echocardiographic evidence of a moderate-to-large PDA and weighed ≥ 5 kg were enrolled with an intention-to-close the PDA with an ADO II. The decision to deploy an ADO II was based on the PDA size and morphology as seen on angiography. Patients were excluded if they had evidence of pulmonary hypertension, weight < 4 kg, minimum PDA diameter ≥ 5.5 mm or an aortopulmonary-type PDA.
Device. The ADO II is a self-expanding nitinol mesh device. Nitinol is a shape memory alloy of nickel and titanium. Each occluder is made of a multilayered, flexible, fine nitinol wire mesh shaped into a cylindrical waist with retention discs on either end to secure it in the PDA (Figure 1). It has a “fabric-free” technology, which allows for a very low profile of the device and delivery system. Multilayered mesh lobes create six planes of occlusion with full cross-sectional coverage for complete closure. Flexible mesh and dual articulations provide high conformability. The central waist is designed to fill the defect and the two retention discs are designed to be deployed on the arterial and venous sides of the defect. This design allows deployment from both the arterial and venous sides (Figure 2).
These devices are available in 4 mm or 6 mm lengths, with waist sizes of 3, 4, 5 and 6 mm in both lengths, and each disc diameter is 6 mm greater than the waist size. The wire mesh has 72 braided layers on its inner surface and 144 braided layers on its outer surface. In the 3 and 4 mm waist devices, there are 144 braided layers throughout* (AGA Medical). This device is suitable for patients weighing > 6 kg and > 6 months in age.
The Amplatzer Duct Occluder II can treat all types of PDAs in the Krichenko Classification14 from 5.5 mm to < 2.5 mm in diameter. The “window-type” PDA is the only type that is unsuitable for closure with the ADO II. It is also contraindicated in PDAs measuring > 12 mm in length and > 5.5 mm in diameter on angiography. The device has a screw attachment for a delivery wire and radiopaque markers. The recommended sizes for the low-profile TorqVue® LP (AGA Medical) braided and tapering delivery sheath are 4 Fr and 5 Fr. It has a flexible distal catheter segment that allows for easy approachability. The wire for device positioning and deployment is braided with a flexible nitinol tip. The device can be deployed, recaptured and redeployed for precise and secure placement.
Procedure. Access was obtained in the usual way in the groin vessels. Periprocedural antibiotics were given according to the protocol. A descending aortogram in the lateral projection was recorded with a 4 or 5 Fr pigtail catheter to define the morphology and size of the duct. Subsequently, a 4 or 5 Fr multipurpose catheter was advanced from the venous side through the PDA into the descending aorta. A standard 150 cm (0.0035 inch) guidewire was used to exchange the multipurpose catheter for either a 4 or a 5 Fr TorqVue LP delivery sheath that was advanced from the femoral vein into the descending aorta.
An ADO II 1–2 mm larger than the narrowest waist of the duct was chosen. We chose a 4 mm-long device for PDAs ≤ 5 mm long, and a 6 mm length device for PDAs ≥ 5 mm long. Pulmonary pressures were ascertained.
The device was introduced into the delivery sheath and advanced under fluoroscopic guidance into the descending aorta, where the retention disc was deployed. Then, the sheath and the delivery cable were pulled back until the retention disc was against the aortic end of the ampulla or in the ampulla. While gentle tension was maintained on the delivery cable, the introducer sheath was withdrawn into the pulmonary artery to deploy the waist of the ADO II, and then the second disc was deployed at the pulmonary end of the PDA. With the device still attached to the cable, a descending aortogram was recorded in the lateral projection to confirm the device’s position. Once proper device position was confirmed, the device was released by anticlockwise rotation of the delivery cable. A repeat descending aortogram was recorded 10 minutes after the release to check for residual shunts.
All patients were discharged 24 hours after the procedure and given no medication. Clinical examination, 12-lead ECG, chest X-ray and echocardiography were performed in all patients prior to discharge.
Statistical analysis. All results are expressed as either mean ± standard deviation or median (range).
The PDA types and the devices used are shown in Table 1. The smallest minimum ductal diameter was 2.1 mm and the largest was 5.1 mm. The ADO II was placed in 10/10 patients with intention-to-treat (Table 1). The transvenous approach was used in all patients.
In patient no. 8, the angiographic PDA size was 5.1 mm and the length was 8 mm. A 6 x 4 mm ADO II was placed, but the waist and the right disc did not conform properly. Hence, it was retrieved back into the sheath and was replaced with a 5 x 4 mm ADO II device, which was successfully placed and deployed with optimum results.
A 6 x 4 mm ADO II was positioned in patient no. 9, however, the right disc caused partial but significant obstruction of flow to the left pulmonary artery and was protruding into the pulmonary artery more than was deemed safe to leave it in that position. There was a significant risk of device displacement as well, thus, the device was removed and substituted with a 5 x 4 mm ADO I. This patient had a trivial residual shunt immediately afterwards, but echocardiography 24 hours later showed complete resolution of the shunt.
In patient no. 10, the PDA size was 2.5 mm on transthoracic echocardiography. On angiography, the size was 2.3 mm, and it was a Type E PDA. A 3 x 4 mm ADO II was deployed, but the waist was seen to be compressed by the PDA, leading to significant protrusion of the right disc and the right articulation in the pulmonary artery, necessitating the use of a 3 x 4 mm Cook MReye Flipper detachable coil (Cook, Inc., Bloomington, Indiana).
There were no procedural complications in any of these patients. Of the 10 patients, 9 had on-table complete occlusion, while 1 had trivial intraprosthetic residual shunt immediately after the procedure. All patients were discharged home the day after the procedure. Clinical examination revealed absence of the murmur, 12-lead ECG was unremarkable and the chest X-ray showed the devices to be in optimal position. There was no evidence of hemolysis on urine analysis. Two-dimensional and color Doppler echocardiography did not reveal any pericardial effusion. The devices were in place with no residual shunts, and there were no obstructions of the descending aorta or the pulmonary artery.
Complications. There was no device embolization, no major or minor complications occurred and there were no deaths.