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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Several important issues emanate from this initial experience. The first is the tendency of the aortic retention disc to stretch such that, particularly if the aortic ampulla is large and the duct short, the central waist may protrude into the PA, leaving the PA retaining disc redundant. This occurs even more so if the device is significantly oversized. In our experience, this positioning was not problematic and no gradient was observed. However, in a previous report,7 2 cases with 15 mmHg pulmonary arterial gradients were noted. As such, the shorter device (4 mm) will usually be applicable unless the duct is extremely long. Recently, the benefits of this device in extremely long ducts have been highlighted,9 and this is clearly its strength. Conversely, this may require additional care with short ducts. The length of the duct is routinely measured as a straight line from an extrapolated line across the mouth of the aortic ampulla to an extrapolated line across the pulmonary arterial entrance of the duct (Figure 6).9 The manufacturer recommends that when this length is > 5 mm, the 6 mm-long device should be used.8 This measured length, although anatomically correct, does not truly represent the length of duct to be occluded. This emanates from the discrepancy between the minimal ductal diameter and the often much larger aortic ampulla ostial diameter as we (Table) and others 8 have shown, particularly in PDAs of Krichenko Types A and E (funnel types).10 As the aortic disc is 6 mm greater in diameter than the nominal waist diameter, we propose that the device length should be chosen based on a length measurement taken from the pulmonary arterial entrance of the duct to a point in the ampulla where the diameter measures the device waist plus 6 mm (the selected devices aortic disc diameter) (Figure 7). Using this length, the majority of devices will be shorter (4 mm), rather than longer. In our limited experience, all ducts were well closed with the shorter device, although according to the manufacturer’s recommendation, a longer device should have been chosen. In the single case in our series where a longer device was selected, there was some device redundancy in the pulmonary artery. This device selection method may reduce the risk of device migration, as has been reported with this device,8 possibly due to the less snug fit of the aortic disc in the ampulla.
The ADO2 device was designed by the manufacturers with the express intention that the retaining discs would be positioned in the aorta and pulmonary artery. However, in the presence of a large ampulla, the aortic retaining disc will be positioned within the ampulla and not the aorta, as described. This scenario of a large ductal ampulla aortic ostium is also important when deployment is performed from the aortic side. In such situations, the device can be well positioned in the duct, but with the aortic retaining disc falling partially (usually inferiorly) into the ampulla, leaving the superior aspect projecting perpendicularly into the aorta. This may not be correctable using the transaortic approach, as there is an extremely limited ability to push the device into the ampulla without deflecting it superiorly. This can further worsen the device’s position and may be traumatic to the duct itself, resulting in spasm or even rupture. In such instances, however, when approached transvenously, the aortic disc can be well positioned in the ampulla, while still allowing the rest of the device to assume its intended position.
The ADO2 broadens the spectrum of PDAs that can be simply and safely treated with devices. Due to the range of anatomy and sizes that are treated, a single device will always be limited as a total solution. However, the flexibility of the articulations, coupled with the alternative deployment techniques, allows this device to simplify the treatment in a range of small patients and specific ductal anatomies that are more challenging. In extremely short ducts or where the ampulla is very large compared to the aortic disc, the device may result in protrusion on either side. An alternative length measurement of the duct length to accommodate the device may improve device length selection. Broader experience is required to further delineate ADO2 device and patient selection, as well as to document its long-term efficacy and safety.
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From the Department of Cardiology, Shaare Zedek Medical Center, Jerusalem, Israel.
The authors report no financial relationships or conflicts of interest regarding the content herein.
Manuscript submitted October 22, 2009 and accepted November 4, 2009.
Address for correspondence: David Meerkin, MBBS, Director of Experimental Cardiology, Shaare Zedek Medical Center, POB 3235, Jerusalem, Israel, 91031. E-mail: meerkin@SZMC.org.il